Khurana, Subhash Chander (1981) Growth, development and...
286
Khurana, Subhash Chander (1981) Growth, development and yield of potatoes. PhD thesis, University of Nottingham. Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/13729/1/256347.pdf Copyright and reuse: The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf For more information, please contact [email protected]
Transcript of Khurana, Subhash Chander (1981) Growth, development and...
Khurana, Subhash Chander (1981) Growth, development and yield of potatoes. PhD thesis, University of Nottingham.
Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/13729/1/256347.pdf
Copyright and reuse:
The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions.
This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf
For more information, please contact [email protected]
GHOid'l'H 2 DEVi~I..DPHENrr fJJD YIELD
OF POTATOZS
by
SlJPTj".C::;.l CF!"Dnn TTIIUnA····1A p S (P P U TUDllIA··IA)_Jil'._"J_ .[1-\1') l,jl\ 1\.. .Li. ~~ , .L.J. C. ...,•. \.•• ,.LJ il 1~
F.Sc. (Il.A.U.,EISSAP).
Thesis submitted to the
Un i ver-si ty of Nottingham for the degree of
Doctor of Philosophy
Dep)rtmeLt of Agriculture and HorticultureUn i versi ty of No t t i ngham
School of AGricultureSutton Bonington
LoughboroughLeics.
IJ ovember, 1981
BEST COpy
AVAILABLETEXT IN ORIGINAL ISCLOSE TO THE EDGE OFTHE PAGE
BEST COpy..
, .AVAILABLE
, Var'iable print quality
,
TO MY PARENTS
ACKNOWLEDGEMENTS
I am greatly indebted to Professor J. D. Ivins and
Dr. J. S. McLaren for their interest, enthusiastic guidance
and encouragement throughout the present work.
I would also like to thank Mr. J. Craigen and other
members of the Biometry unit, Library staff, Mr. C. Roberts,
all technical staff of the department of Agriculture and
Horticulture, especiallY Mr. D. Hodson and Mrs B. Hull and all
others who helped in the present work.
Finally I wish to express my thanks to the Association
of Commonwealth Universities for financial assistance and
Haryana Agricultural University for study leave.
S.C.K.
CO::T;';r··TS
1 IJ:TRODuc'rIO;:
P~'be
1
2.1 3
2.1.1 Effects of pho tope r i od2.1.2 Effects of temper" ture2.1.:~) Effec LE;of liC!lt
345
2.2 om l~CTIVL3 7
2.3 8
2.3.1 Exneriment GR1 8
2.3.1.1 Prenaro.tion of pots and p.lan t i ng2.3.1.2 'I'r e a trne n t s2.3.1.3 Exoe r imen tu l desiGn 'lEd pr-ac t i ca'l
detn.ils2.3.1.1+ Gr-ow th c:lr..Alysis
2.3.2 Ex'.)erimer.t GR2
2.3.2.1 Pr-epar at i.on of pots and p lan ting2.3.2.2 Treatments2.3.2.3 Experimental design and pr-ac t.Lco.l
details2.3.2.4 Gr owth ilu,dysi.s
2.3.3 Experiment GH1
2.3.3.1 Pre ~nra t i on of :)01;S .md p.lant ing2.3.3.2 '1'1'e ,_l tme n ts2.3.3.3 Experimental design and pr-ac t i.cal,
details2.3.3.1+ Gr-owth .::U1 ::.J.l ys is
2.4 m~SUL'rs
B8
99
10
1011
1111
12
1212
1213
15
2.4.1 Exoe r iment Gl{1 15
2.1+.1.12.4.1.22.1+.1.32 .li. 1 .1+2.4.1.5
StolonStem
1515151617
Le;_,fTuber':::'otal dry mat tel' .ic cumul a t ion
19
2.1+.2.1 Stolon2.1~.c:.2 Stem2.L:-.2.3Le:::2.h.2.1+ Tuber?l:-.2.5 ToLil rlr,Y r:_d:tol' -:ccu::mlJ1_jo,
2.4·.3.12.1+.3.22.4.3.32. i+.3. 1+2.1~.3.5
DISCUSSIOJ;
1920202122
23StOJ_OllStem1,0 '.fTuber'I'o ta.I dry Height
232323242426
3 CHEHICAL co::r~ROL OF GHO'.vTH
3.3
3.4
3.5
osr [_;CTIV1~~S
3133
j:AT~mIALS Mm HETlIODS 34
3.3.23.3.3
3.ll-.13.4.23.1+.33.ll-.43.4.5DISCUSSIo;~
Expe r i.men t.a.l design and pr ac t i cu Lde t.ri LsGrowth :m·J.]_ysisFin_,_l harvesting
34363639
Stolon and stem growthLeaf grow thLigh t .in 'te r-ce p t i.onTube r c;rowth ,.And development'I'o t.rl. dry mc.t te r accurnul.a t i.on
394041424344
4.1
lj.2
4.1.1il-.1.24.1.3
Phys.i o.l og i c al, i,\ge1:1 t.e r=-o r-opp i.ngLicht Ln te r-cept ion
4949525355
/. "Zt • ./
Exner imer. t }'1 5'1
~·.j.1.1 Exr.er i.mentzL desiGn ,~'ld r)r;).ctic "1
de t ..:i.~~sIf.3.1.2L~.3. 1 .34 •.5.1.44.3.1.5
4.3.24.3.2.1
1+.3.2.2~.3.2.34.3.2.[1-4.3.2.5
4.3.3.2It.3.3.31+.3.3.4
Lt. 3. 1+. 24.3.4.3Lt.:5.t~.4
/+.3.5.24.3.5.3,
4.3.6.211-.3.6.3
G:{'O\'Jth ;:u.-~r.J_ysisSpr-cu t ::;rov!thduriES stort\geIle.rsur-emen t of soil ':i',tercon te : L
5,'758595960
,C;xperiment F2 60Expe r irnen tal design Qndpr:_;_cticalde taiLaGrowth ana,lysisSprout growth during storageMeasurement of soil water cortentFinal harvesting
606162626263
Experimental design and or-ac t i c.d.de t.ri LsG r 0\" th.m :.llysisSprout ~rowth duriGG storageFi:1n.l hur vestir:l~
Experimental design ~nd practic.Qde tai LsGr-ow th clTlalysisSprout growth during storuGeF'inul hurves t iug
65666666
Experiment F5 67
Exper-Lme n t.al. design and pr ac t i cc.IdebilsGrowth :..m:uysisS)rottt growth during stori..lge
676868
Experiment F6 68Experimental design and oracticalde t.ri LsGr-owth a,n:llysisSJrout growth during storage
686969
I ,-'+._;
1+.1.;..2.1.1+. Lf-. 2. 2.Ir.lr.2.3
4.1.1.2-"4·.4.2.5-1+. Lt. ?(;
Lt. !+. 3.1i!.Lf-.3.2It. Lt. 3. 3
Lr. 4. 3. Lf11.i.;.3.5LI.L!.3.6
4.4.6.1
L~.i+.~.1!1.L1-.7.2
'1.h.? 34. L~.'? .1+
1+.4. (4
DISCUSSIO~
If-.5.1L1-.5.2£+.5.31+.5.l1
:=xnerirnent }'1
E:;lerG81~ce :.c:d stem nurce rSt02.0L grov!th nr:d de ve Loprne rtGr ow th ,·'.nd de ve Lopme nt of s tem.I'dl erfIJigh t b ter-ce ot ionTuber grO'.·:th and development'I'ot aI dry r;,,:;tter .iccumul.c t ion
Experiments: F2; F3; F4':~mercellce .uid stem numberStolon growth u~d developmentGr-ow th .u.d development of stemTid LeifLight interceptionTuber gr0\1th).lld development'I'o t al. dry mu t te r .iccumul.ct i on
Conroe ti t i on be twe e r; two compone n tsw i th in plot
Crop ev~por~tion
Light interception und pot~to growth
Leaf ~rea index ~nd ohotosyntheticallv.c t i vo r,.ldLltion (PAIn interception ~Jry matter oroduction
Ex.ie r i.rne n t FS
Emergence uid stem numberGrovlth '.Dj de vel.opmen t of stemi..i.:d ledTuber growth and development'_L'otD dry m:,tter .ic cumu.Lat ion
3~rout gro~th during storageEr:lerc;enceTuber Cro\Jth .u.d de veLopmerrtGe~erul crop gro~th
'70
'70
81
8132
83868689909094
959898
102
103
106
108
108109
111
111
112113114
114
118
118120122127
5
6 13/
'? AP?Ei:DICEL3
GEC.-JrE I Al·:D
AJSTFACr
,~x0er:~rrel~ ts v.ore CO:lC;UC Led L. i~ro"J~;l r oor.s LO otudj t~e oh o to-
ne r i odi c r-e scouse o~' Fer. ::~. Lei Crown. 11, f ietd exoe r ime nt s the effects
of s)routi,[_; l.ech r: -ue s :..ul the ')o.sslbi.ity o f nii x i rg of d i f'f'e r-e . L
'Jbysiologj,c,d,l:y,,-?;ed tubers dcdl use O[.';.)l: t gr-ow th reGu11 tor I -)0333
»ies:« studied. [))rout JrO'llth of the tubers used for :)l:,ntillg 'Jos studied
dur i:1C s tor i;e. ~"ight .in Lor-c e o t Lon ~ LLc ohot ocyn the t i.cul.t.y act i ve
i t :.':cl'e:!sed ttcJ.oc l t i.or. of ,"i.:3simiL; te a to tte tubers, wh i.ch resulted
Sprout ;:;ro·,.-lLh \\",S l ine ar ly r-e , .t ed to the .i n i t ieL t ube r we i gh t and
ri <'l degrees . 4°~ r 1.co ve C' rom o o i-m.mcy St()ri'~ tubers in the cold
Le fore nl·J. ti ~>'; increlse:i the w:ri),ui nur.oo r ,:11 thus the pr opor t ior; of
lYlin s tems i· t h e f i.eLd , Iirne to reach 50,.'; en.e r-ge nce \'Id,S not reduced
"'1 ( t '+10" , .. , • I' "t')'~o.d tubers stored .', ;J _ l, un CLL .t ell;_,' oe ore [l.L,(Jl lng delayed
tuber ini t irt i o.. out or.ce the tuber 11:d oe e n id, tiiAted the n the effect
growth or developme~t ~.s ~o more ~ffected by the physiological age
of the seed tuber. YieLls from m.ix i.ug different phye i.o.Lcg i co.Ll.y aged
tubers were rot different from those expected.
1'1;e DL.jor f.!ctordfecting the gro ..!th of t.ie cr-op 1I"S the 'd.,ter
su~')ly. ':_'heo'Jer~:;_l "hotosynthetic conve r-a ior: e f'f'ec iency of the
( d . , t v T -1 ',"" '.t- I' ) I.~,g . r,Y \'Jelgn!"lt.. ':'.~, l:J cer ce o teo i'i .ie 3. '+23 ar: 1,)(,:') in ,ose nce
c~nopy
of
,.LIlY app.rr-e r.t \·.':.tel' stress whi I.e il 1(),/S; .i t ,LS cnl.y 2.L;9c due to w.ite r
stress.
1
Crop C:,LOOY is b,sic·.l·:~Y " cor.ve rte r of soLar ener-gy to dry matter.
Po t.z to crop ~ro':Jth h.rs oee r; considered or..Ly in terms of led ar-e.; index
(LAI), 1e"f,ro' durtiol~:.ud :leLlSSir.lj~.~tioL r-ite , Cr-op gr-owth r.a te
for var ious .Jgricuj t.urc.I crops h.rs been f'ourd to be pos i t iveLy corre-
lilted to the liGht .inte r-cep t.ed by the c:;r:o:)/ (Biscoe .ind GCJ..Llclgher,
19'1'7; ·,'.liEi3ms et al., 1965). Published r-e nor ts on 1igh t iL terce ptionc
in _l)ot'ltoesare f'ew (Scott and i;iilco}{son, 1978).~
There 'iPge~r to be i.l. considerable genetic difference in the photo-
periodic dependence of po ta toe s (Hur t i et :.1., 1975; 1"lendo<:;aand Hayne s ,
19'(6). Potutoe a wre o.l nnted .i t different times in the field due to
various r-exsons such :{S wea the r, It is accented 'tha t there is .;l. oal ance
be tween growth of tubers and rest of the plant, .myth i ng whi.ch favours
the growth of one w iLl retard the gr owth of others (Eoorliy. 1978;
Varieties differ in their rutes of sprout growth at Lt given temp-
erature (Headf'o rd , 1962; Short :md Shotton, 1970). Physiologically old
seed h.xs beer: found to Lncr-e aae tuber yield ear Ly in the season but the
effect change d :J.G the hrr ves t i r.g Wi.'S delayed and in some cuse a it became
negative (0'3rien ~Ld Allen, 1978; Allen et al., 1979) which was assoc-
ia. ted w i th Lowe r L1\1 Ln the caae of old seed, whi ch may be overcome by
m·iEipuL.i.ting ap.ic ing , Higher tuber yields have been reported by mixing
eo.rly"u'1.d Late crop var ieties (Schepers .md Sibma" 1976), but the mixed
product m~y be o~ly useful for st3rch industry or other uses for which
~ mixed product is ~cceptable.
In this the s i s r esponse of Pen t l and Crown to photoperiod and irr-
:..tdLJ:lce is studied it: Growth rooms. Effec ts ofnhysiologic"ll age,
2
t.ube r-scu.d 1}r:J333 (:):;_ ..uit f,rO'., t:l reguJ."tor, rci: :1,3 be e r, s tud.i e d in the
field by aocuen t i c.I har-ves ts for cr-o» gro't,th ;.Iul,}'sisllollg w i th regular
1 igh L measur eme II ts.
2. PHOTOPERIOD AND LIGHT
2.1 LI'l':~Ef1TUIE l';_~VIc.::,l
l~ffects of envi r-onrner: t h ..ive lone; oee.. reeosnised 'JS 'Ur:ODe; the most
i:;:~ort:(nt f:~cton' Lnf'Lue nc ing tuber f'orrn.i t i.o.: by the~lot"to 81il.nt
(G~ir:'Jer:1l1d AI1(rd, 1923; '3u<.;!l:1811, 1925; rcClel1..,lfd, 192E; Dor-oshe nko
et 'll., 1930; /,rthur et,1.., 1930; "ier:wr, 1940; Driver .uid Huwke s ,
19L1-3). 'I'he re is~c~:no.st:;eu::r'{l .'\_;reei:lent tl.o t env i r-onrne n ta l factors
wni ch s t irnulate hau i.ri ~ro1:lthJ-=-so deLay or i,:hibi t tube r i z.c t ion ,
2.1.1 Effects of nhoto~eriod
'l'here'C~~)e,r to be cons i de r-abt e genetic differences .ir: the photo-
period de oer.dence of l)obtoes. Schick (1931) observed that four German
vur i.e t i es showed 1i t tle r-eaponae to a reduction of pho tope r iods to 12
hours, wh~le three South Americ~l varieties showed a very striking
response. Different resoonse to photoperiod, for the varieties Alpha
.nd Eer-steL'ing h:)5 been reported by Bodl aende r and Earinus (1969), arid
l<urti et 3,1., (1975) r-eoor ted for the varieties Kufri Lauvl ar , Kufri
Jyoti, Kufri Jiev~'-r:.,nd SLB/~,~405 a. Mendoza ar.d Huyne s (1976) re-
~orted differerces i!1 critical day length ~mong potuto clones of three
Llxonomic gr oups r and i.ge r.a ;phure jc;; tuberosum.
The vur i e ty Kuf'r i, Sindhuri, previously grown e,t oon t inuouaT igh t
for 47 d~ys did not form tubers for 60 d~ys ~t 14 hours day length while
cn.l y 11 short d~Jys (g hours) were required for tubers to initiate (Hurti
and Bane r jee , 1976:J.).
l<urti et.\l., (1975) reported Lncr e.iso in tuber yields in var i e t ies
Kufri Lauvk ar , Kufri Jyoti, Kufri .Jee vun arid SLB/Z 405,-, under short days
cornpar-ed to nu tur-u l dDY length in summer (temperate c.li.mate },
IIigher tuber y i eLde ur.der short diys (e,-1 () hours) compar-ed to long
d ays (18 hours) lnv8l1so beer: r-e norte d iJ,Y some other wo.rke r-s , GreGory
::'nd Chapm..n (1962) fa!' ned ;';cClure. Lr.cont r-rst to tl.e se , aome wor-ker-a
h uve r-epor te d highe r yields unde r 1011[,; d'q.s (18 hours) compar-ed to
short days (12 hours) t Bo.r.m (1 ~)59) for the v-u-Le ty Arr:d: Pilotmd
:;:.odJ.u,ender .md Ii;urinus~?o~ ~erstelir:g and 1\.1;;1h:lo
Iricr-ease in tuber .induc bon due to pho tope r-Lodi sm h.is been r-eLated
to Lr.cre ase in :1eve Is of c,'!tokio I r;s (L'ngilLe ;,nd Forsline, 1974 j Forsline
and Langille, 1975), and de cr euae in levels of gibberel1ins (Okazawa,
1960 j Pail ton v.nd ',Jale ing, 1973), w i th increase in short day cycles.
2.1.2 Effects of temoer~ture
The effect of tempe r-a tur-e is s imiLar to th.rt of photoperiod, higher
temperature promoting vegetative growth wld ~ower temperature stimulat-
ing tube r-Lza t ion , P'lan t s of the variety Sebago previously grown under
non .induc iug coudi t ione g:we higher tuber yields ':At 22/18 compared
to 32/1SoC (r'iellzel, 1930). Bor-ah and I'Hlthor~e (1962) reported decrease
in the oercentQge of assimilates diverted to the tubers with increase
in terr:per.:J,ture:.;,nd Gregory (1954) reported .et decrease in tuber to top
weight ratio with increase in temper~ture. Tuber initiation was in-duced by Lowe r i rig the t.emoer a tur-e to '/°C for about a week , in plants
growing at 20/15 or 25/15°C (16 hours day length) by Burt (1964).
Sah a et al. ,(197ll') r-enor ted an incre.').se in tuber yield \,..ith de cr ease
in only night temperature. Like photoperiod there is considerable
var i ance among pot.i to varieties .in t.eraper-ctur-e dependence. i:Jith in-
cre'.lse in night temper:::.ture from 20 to 30oC, reduction in tuber yield
was 80 and '75;0 for the v.ir i e ties Kuf r i Jyoti and Kuf r ; Chandr-amukh i
respecti vely, while Kuf'ri Sindhuri Lliled to form tubers at 300C (Saba
et i{l., 1974).
Optimum t.emper-ut.ur-e requirement for cell;)' var i.e ty is influenced by
other envi r-onmea ta.l L~ctorG such as ,1hotoperiod and irr:)di::.Ylce.
vr,s 8 hours .uid ~:t 17/1UoC where day length w:~s 16 hours.
Effects of light
The influence of light on growth and yield of potatoes is deter-
mined by the irn.dicuJce level, its duration and qua.l i ty of the ligh t ,
7'hotosYllthesis of :J si:l;:;le Le uf :is wel.L :18 of the CLUJOpyQS ;:, whole
Lncr-e ase s Viith .inc rease in Lr-r ad iance until an optimum is reached
(Ku et al., 19?7j Sale, 1974). Pohjuhk.a.lLi o (1951) reported change in
top to tuber r-a t i o HI f'uvour of top with decrease in Lr r-adi ance , Borah
(1959), r-epor ted a 68 to '7?;<: decrease in tuber dry wei gh t with decrease
in irradiance by 45;',; in the var i.e ty Ar-r-an Pilot, in both the green
house and field. Differences were higher .ir: growth rooms, tuber weight
" -2-1per pl an t ut 64 .md 120 ca l. cm d Wb.S 1 and 14g respectively.
SimiL~r resul t s were r e oor t.e d by BodLaonda r (1963), in this experiment
tuber ini t i a tion "Ivas deLaye d by 27 and 54 days vii th de cr ease in irradi-
Cince from 16000 to 8000 'md 3000 lux respectively. Even in a region of
high so lar input (d;-,ily soLtr input .iver age s 25-30 ~W:ln-2), Sale (19'73)
r'epor ted de cr ease in tuber number- :u;d increase in time between tuber
ini t ia tion arid rnax i.mumbul.k i.ng rette, w i th increase in shading.
Exper Lments unde r con trolled condi t i oris provide very useful
6
Lnf'or mat i.on , but s oe c t r a.l photon distribution (SPD) tuy af'f'e c t several
as oe c t s of »Lan t gr owth and de veLoomont (hcL~1.reIl .ind Smith, 1978) and- -
SPD is different for di I'f'e r-en t light sources (!.icCree, 19'7c~).
2.2
There·u·e cona Lder-able differences in response of various po t« to
varieties to the euv i r-onmer.t (Ch.ip te r 2.1 ).Dot·:.toes :{re »Lan ted at
different times .').nd so some ::)hoto_oeriociicnd lizht t r-ea trnents wer-e
given to the vur i e ty Pen tLand Cr-own La unde r-s t.rnd its response to the
env i r-onmen t .JS this v.ir i e ty \~:l.S to be used .in 'I number of experiments
in the field.
"u
2.3 i'lA'rERIALS Mm NE'l'HODS
Out of three, two (Expe r irnenta : GR1 ar.d GR2) were carried out in
growth rooms and third one in g.lasehouse (;::xperiment GB1). Potu to
var i.e ty Pen tLand Crown "/iAS used for '-1.11the experiments.
2.3.1 Experiment GE1
Preparation of oats and p1~nting
Pots of 25cm diameter wer-e washed thoroughly in hot water and
filled with John Innes potting compost No.1 (de tu iLs given in Appendix A).
One mmnyl.on rnesh was kept over the compost and apically sprouted
tubers (details for seed source given in Appendix B) of uniform size
were p13nted on top of the mesh to study tuber initiation and stolon
growth per i.odi cul Ly , Pots (indi vi duul.Ly ) were. covered with double
polythene shee t whi te inside arid black outside, wi th a hole for sprout
to come a\Jt. Pots were kept in gr owth rooms at cons t an t temperature
of 15°C and 16hrs photoperiod until emergence.
Tre Cl tmen ts
After em~rgence on 12 Feb. 1979 pots were given photoperiodic
treatment according to 'I'ubl e 2.3.1.1. In growth rooms (Saxhill),
warm whi te fluorescent tubes were used as the source of light.
Irr:.J.di::wce in pho tosyn the t i cel Ly ac t i ve r:lJ1ge (400 - 700nm) was main-
t.J.ined:"s 450 UE~-2S-1 (Photon fluence r:.:tte) on pot level (measured
Using qUClntummeters with cosine corrected sensor heddsj lambda
)
instrument). Photoperiod: 16 hours day in case of long day (LD) and
10 hours day in case of short dUJ (SD) i:<ndday-night temperatures of
200/15°C was maintained. The temperature in the growth rooms were
continuously recorded on thermographs, fluctuations being of the order
of i10C.
Ex-oerimental design and uractical details
Due to limitation in the number of growth rooms available, plants
were treated as replicates and data vias analysed as completely random-
ized design. Number of replicates used at different time are given
in Table 2.3.1.2. Although there were 1-3 SEDs, depending upon the
number of replications for different treatments (Table 2.3.1.2), but
for aimp.li.f icat ion only one SED is shown which is for comparing the
treatments with different number of replications.
After roots had grown to the bottom of the pot j 150ml of supplem-
entary solution containing: 50g (NHLj-)2S04,9.2g KfW3 and 7.5g NH4H2P04
per litre was given every week (Burt, 1964). Plants were irrigated
w i th ordinary t3.Pwater as aridwhen required. Datilon length of
stolons, le:J.vesof axillary branches and number of: stolons, leaves,
axillary branches and tubers were recorded without harvesting. Tuber
was judged when tip was swollen, twice the diameter of the actual
.stolon.
Grm.,.thAnillysis
Due to fewer number of p.lant.s ava i.Lab.l e cn.Ly2 growth analyseswere carried out: h9:lnd 66 doss after emergence.
10
Plants were stored in a cold room (4°C) until they could be
dissected. 'I'he number of Le ave s per _?lcmt on main stem and axillary
branches were counted seDarately, at the same time, the leaflets were
removed from the pe t ioLe, Length of the rnaan stem and the'lXillary
branche s meaeur-ed arid petiole and stems were combined for stem's dry
weight. 'I'he leaf urea was determined using the DUDChmethod,
("\'i::J. tsar. and 'datson, 1953) as modified by Radley (1963), which
invol ves tak ing discs of known diameter and dr-y weight ',I[dSused
jnstead of fresh.
Fumber of maL1:lnd br-unched (defined in Apne£x E) stolons, were
removed, counted and their tot:Jl length measured. Roots were difficult
to separate from the peat and were not collected .::.tedroots which were
uttached to the stem and stolons were removed emd discarded. Tubers
were removed, riddled, counted and weighed before being sliced finely
wi th a kni f'e and dried. Dry weights wer'e obt ai.ned by drying different
parts se oar-a te Ly in the oven at 85°C to cons tan t weight.
Experiment GR2
2.3.2.1 Prepo.rution of DotS und planting
Same as described e~rlier, 2.3.1.1. except that tuber pijces
.weighing 7g (instea.d of whole tubers) w i th single eye were taken
using et cork borer (same dinme te r in .dL the c.::;.ses) and :planted in
moist aand 2cm deep at 15°C (uet:1.ils for source of seed given in,
Appendix C). After one wee.: tuber pieces were selected for uniform-
ity of spr ou t and planted on to'!') of the mesh and covered with verm-
iculite before covering with double rolythe~e sheet.
2.3.2.2 'rre :.'tmen ts
This experiment W:lS conduc te d dur ing 1980 .uid there «ere 4 tre: ..t-
ments: oomoi ra t ions of 2 »ho tc per i ode i ,«, 16 hours (LD) .nd 10 hours
( D) 2' " 1 1 ( t - J)." Ir\~ U"'J-2S-1 (HI)S and l.rr,lQli'.Ece Leveis on po .ieve r 1.e. -oo _',j, and
290 UEl~-2S-1 (LI) (400 - ,?OOnm). Cous t.urt temoer-at ur-e of 15 ~ 1°C was
mai n t afr.e d , Res t s ame ,tS de.scri bed e:J.rlier, 2.3.1.2.
Ex~eriment~l desiGn :Ind Dr~cticul det~ils
S::uneis described e ur-Lie r , 2.3.1.3 but no d,t:J. I-U.tS recorded with-
out growth ."',n:,::'ysis exce o t tuber .ini tittiol~Uld he i gh t of the mai n stem.
Five :pJ.':"l.ntsper tr-eu trnen t wer-e used for meusur ing height of the mai,n
stem. 5, '1,3,4, .rid 3 plan t s wer-e har-ve s t ed for gro\rlth Lcllalyses carried
out c..fter 29, !~1, 51, 66 and 81 di,Ws of emergence r-es oec t i veLy ,
2.3.2.4
Same ;J.,S described ear-Li.er, 2.3.1.4, but growth :.;Jl:.J.lyses were carried
out at frequent intervals.
12
Experiment GE1
Preparation of pots ~1d pLantl~S
Same as described earlier, 2.3.2.1, except th~t seed pieces
(2.3.2.1) were pLillted i:; 17.5cm po ts , 2cm deep if. J.I. po t t ing
comoost number 1. Fats ':fere kept i:' :;reclJ house wher e temper a tur-e
var ied from 100C min. to zo?c mu. Pots ',Jere not covered w i th any
poLy the ne sheet. Deta i.L for source of seed is given in Appendix C.
Tre;:;_tments
10 days after emergence (on, 11.4.1980), pl(mts were selected
for uniformi ty and wer-e ei ther left under na tur al, gl asehouse light
or under, muslin, red or blue shude s (Cinemoid filters vere used for
red and blue shades) in .m unhe.i te d gL,sshouse. Air maxi.mumand
minimum temper-atur-e cbtai.ned from nearby meteorological station is
gi ven in Figure 3.3. 2b. 'l'r-anam.i t tance ('+00 - '700nm) measured (2.3.1.2.)
through the sh.ides was 21.97, 33.10 and 32.67, percent for red, blue
and muslin shades respectively. Spectr;ll photon distribution measur-
ed using scanning spectroradiometer is given in Fig. 2.3.3.1.
Phytochrome state was 0.56, 0.49 and O.ltlt for muslin, red and blue
.shades r-espe c t i ve2.y and 0.54 for na tur-a l [;l:l.sshouse.
Experimenbl design il.'1dpr:Actic:,l debils
Due to number of Li.mi tc t ions of shude s , :.\vdil·.~ble, pLmts were
used as replico.tes and duta Was analysed as completely randomized
design and there were three r-ep.l i cut es , Only mai,n stem length was
measured w i thout harve s t ing, Rest same aa described ear-Li.er , 2.3.1.3.
Grm/th :malvsis
Same :AS described e.rr-Li e r , 2.3.1.4" but only one growth analysis
\'/as curried out.
Table 2.3.1.1 ..
Det~ils of treatments
'I'r-e a trner. tname Detail
LD Long d.xys f'r-orn emergence onward.
LS 17 long ddys from emergence onward,followed by short days.
LSL 1? long days from emergence onward,f'oLl.owed by 20 short days dnd thenlong days only.
SD Short duys from emergence onward.
SL1 17 short days from emergence onward,followed by Long days.
SL2 37 short days from emergence onwar-d,f'ol l ov....ed by long days.
rrilble 2.3.1.2. Numbe r of r-ep.l.i.c at i ons for d i f'f'e r-en t treatments used
for anal.ys icg ddt', ,it di f'f'ere r.t time.
Days afteremerc;ence
10,13and 18
23, 28,31 and 35 45 66
Treatment
LD 17 5 5 2 2
LS 12 Q 3 5u
LSL It 2 2
3D 18 12 6 2 3
SJ...1 6 6 3 3
8L2 6 4 2
.20 .20T-
I
~ .00 .003Bo 520 660 Boo 3Bo 520 520 660 Boo
T-
I
III
C\JI
S 1.20 (c) 1.20 (d)~..~Cl) 1. 00 1.00
.Bo .Bo
1.20
1.00
.so
1.20
1.00
.60
.40
.6.0
..00
.40
.20
.003Bo 660 Boo520
Wavelength, nm
.Bo
(b)
.60
.40
.60
.40
.20
3Bo 660 Boo520
Figure 2.3.3.1 Spectral scan (400-BOOnm): (a), glasshouse (12=00);(b), red shade (12=40); (c), blue shade (12=30); (d), muslin shade(12=42), taken on 4th March 19BO, with a scanning spectroradiometer.
2.4 IESULTS
2.4.1 Ex-oeriment GR 1
2.4.1.1 Stolol1
Length of the m.ri n and branch stolons (Append ix E) and thei.rnumber
is given in Figures 2.4.1.1. and 2.4.1.2. Stolo!:!numberet!1d their length
was not affected by the treatments until tuber initiation after which
LD continued to produce more; main u.swell 3S branch stolons and their
length was also more. Plants whi ch hud 17 short days in the beginn-
ing and then moved to LD (trei.!tment,SL1) behaved like treatment LD
and tree<tments LS and LSL l.ike SD. Data for stolon weight is given in
Table 2.4.1.2 and was higher in treatments LD and SL1.
2.4.1.2 Stem
Length of the main stem (data not presented) was not affected
until few days :lfter tuber initiation, after which pl~nts in SD started
diverting most of their assimilates to the developing tubers while in
LD stem length was still increasing. Ax iL'lar-ybranches, which started
developing little before tuber initiation (Fig. 2.4.1.3) continued to
develop and gr-ow at f aater rate in tr-eatmen ta LD and SL1, while in
others rate was very 10'01. Data for total stem weight is given in
1'able 2.4.1.1 which w';tshigher in t.r-eatmen ts LD and SL1.
2.4.1.3 Leaf
Due to shortage of number of p.lants for growth ana.lysi s it was
A'IU
decided to count number of Leave s and measure their length without
harvesting. Internode length was not affected by any of the treat-
ments thus number of leaves and their total length did not vary until
tuber initiation afte r which LD ol an ts had more Le.ive s and their total
length was also more. Number of leaves on uxi I l ar-y br anchea were more
in treatments LD and SL1 and their to t al, length was aLso more (Fig.2.4.1.4).
Lower leaves from trea trnents: LD and 5L1 started coming off after about
40 days of emergence, but they were still growing, while in others it
started slightly later. Total leaf 'J.rea after 49 and 66 days of emerg-
ence is given in Table 2.4.1.1. Specific leaf area and ratio of leaves
to stem is also given in Table 2.4.1.1, and was lower in treatments LD
and SL1. Thus leaves in theBe treatments were either thick or stored
carbohydrates which were beillg diverted to tubers after tuber initiat-
ion in other treatments.
2.4.1.4 Tuber
_Percentage of plants forming tubers is given in Figure 2.4.1.5.
p'Lmts which were only under LD did not initiate tubers until 66 days
after emergence when the experiment ;-JaS terminated, while all pl.DB ts in
case where they had only SD or given SD after 1'.1days of emergence
formed tubers by the end of experimer: t, suggesting th.rt tuber stimulat-
ing conditions have more effect if given few days after emergence,
ro.ther than straight from emergence onwur-d, Data on number of tubers
per p'lan t is presented in Figure 2.4.1.5 and weight of tubers in Table
2.4.1.2. Although plants which were shifted to SD after 1'7 days of LD,
initiuted tuber but stimulus in the begining wus not enough, as they
had lower numbe r of tubers, but by the end of experiment (66 days after
emergence) they did not vary from the plants which were only under BD.
1/
2.4.1.5 1'ot:J.ldry matter accumulatior:
It was observed t.h.i t roots »iere more in tre.i trne nts 1D and S11,
but could not be se o.sr-a ted, thus to txl dry weigh t pr eser.ted (1':3.ble
2.1+.1.1) is excluding roots. t)ercenta[~eof'cssimLltes out of to t.xl
dry weight diverted to tubers were Lowe st .in tr-eatment S11. It appe ar-s
t.ha t 1D given 'After 3'7duy s uf emer-gence (treJtmer;ts: 1SL"nd SL2) did
not ~ffect the assimilate distributio~ as indicated by the percentage
of tubers out of total dry vre i.ght.
'r",ble2.4.1.1. The effects of photoperiod on some morphologic:J.l
characters of notato.
Ratio ofSpecific leaf 1eaf area leaf to stem Stem drl1 Total dryar-e a dm2 g-1 dm2plant..,,1(w t basis) w t g plant w t g plant-1
Days afteremergence
66 49 '-,oo 49 ,-,-00 49 66 49 66
Treatment
1D 2.18 1.91 40.3 63.2 1.45 1.26 12.85 26.19 32.6 61.4
1S 3.52 3.03 5'1.3 42.G 1.68 1.90 9.64 7.50 34.9 53.3
1S1 2.94 2.51 1+4.2 38.3 1.66 1.86 8.92 8.35 37.5 74.1
SD 3.6LI- - 3.71 1+8.0 41.8 2.10 2.19 6.30 5.17 43.4 52.0
S11 2.39 2.04 45.8 55.'? 1.34 1.41 14.68 19.60 39.2 63.7
S12 3.41 2.48 40.8 29.5 1.61 2.51 '1.94 4.74 43.6 73.7
SED 0.456 0.179 ?48. 4.85 0.211 0.149 1.794 1.451 6.89 7.42
1'.',
crable 2.h.1.2. The effects of photoperiod on dry we igh t 0" •J. •
(a) tuber, -1 (b) stolon, ' ;.. t--1cr' nlaEt g0 .t. , .~)..Lctn \J ,
and CC) percentage of tubers out of total dry \'le igh t.
:l b c-Days after49 66 4·9
,..,/+9 66emergence bo
Treatment
LD 0 0 1.16 2.15
L3 8.0 31.0 1.13 O.,?O 22.9 58.0
LSL 12.0 49.6 1.81 0.'71 29.2 67.3
SD 23.2 35.0 0.68 0.56 53.5 64.8
SL1 3.3 14.8 1.65 1.75 8.0 21.5
SL2 22.8 56.1 0.62 0.63 46.6 76.5
SED '7.86 7.78 0.437 0.546 15.85 9.23
37 0 LD 375 o 8D0 L8 o 8L1 flJ
r--j 6. L8L 6.8L2 /I 300 /+' /~
J:3tilr--j
,/ 8EDsP<,/
El 225 qrCJ
" ,..c:+' I I,bO~(J) 150r--j I ~ I~0 (5'r--j0+'CIl 75 75I::''';
til~
0 05 15 25 35 45 55 65 5 15 25 35 45 55 65
375 0 LD 375 0 8Dr--j 0 L8 0 8L1t 6. L8L 6. 8L2+' 3001::' 300
~tilr--jP< /El
/CJ
" 225 225 /..c:+'bO /q,Qj
0I::0 150 150 / SEDsr--j0
/+' \.CIl 'A 1/..c: \CJ
~1::. 75 -b 75 6. ...til1-0~
0 05 15 25 35 45 55 65 5 15 25 35 45 55 65
Days after emergenceFigure 2.4.1.1 The effects of photoperiod on total length of the
main and branch stolons.
~I
+-' 45 0 LD 45 0 8Dq(Ij 0 L8 0 8L1rl0..til f::,. L8L 6. 8L2q 90 36 36rl /0+-' ~ /til
q I \ /'r! 27 \ 27 8EDs(Ij / /s I /'1-i I I0
/ /1-.
10---6QJ
~18 18
I,¢~ I!:sIr/J
9 9 0'
o5 15 25 35 45 55 65 5 15 25 35 45 55 65
90 0 LD 90 0 8D 0~I 0 0 8L1 /L8+-' /q 6. L8L Lt. 6. 8L2(Ij /'_' 72 720.. /tilq ¢0rl /0+-' 54 54til /~ / 8EDsoq
/til1-..0 36 36 I /'1-i s:0 1,/1-. "1:1QJ.0 Cf§ 18 18~ 1/
0 05 15 25 35 )-15 55 65 5 15 25 35 45 55 65
Days after emergence
Figure 2.4.1.2 The effect of photoperiod on the number ofmain and branch stolons.
rlI
.p 420 o LD@rl 0 LSp.
8350. ~ LSL..
D:l<:r:
~ 280
_ f:::,
10
O~ ~ __~ __,---,---,15 25 35 45 55 65
25 0 LD
o LS
~ LSL20rlI
.p~Qj
15rlc,..
~ !~
10J0
'-t(l).o~
5J:<!;
I
I0.,'15
b '. _.8- ___
./ ---./ ---'0_Rf-I---.----r-------T .,-
~3~5 (~~~~25Days after emergence
o SD
o SLl
~ SL2
/I //
II/
/I/
95/
I,
.I
/
/
I SEDs
.0
/
'iO /r /
O_II~-~15 25 35 45 55 65
~/~-," ~
O+..J..L___-,---.15 25 35 45 55 65
Figure 2.4.1.3 The effects of photop~riod on number and total lengthof the axillary br~nches (AB).
o SD I ISEDs
.8o SLl ~/
~/
/
~ SL2 8
210,
140_
25
20
15
10- f:::,
5
~ 1800 0 LD1
+,~~1500ElC)
[/)"1200(I):>(\j(I)~G-; 900o..c::+>b.O 500~(I)~r-I(\j+> 30008
180 o 8Do 8L1A 8L2
18EDs
o L8A L8L 1500.
1200_
500
300
o B I~~'15 25 35 45 55 5515 25 35 45 55 55
210_ 0 LD 210 0 8D0 L8 0 8L1
175 A L8L 115 A 8L2 I8EDs~ YJ1 140_ 140 /+>~
/m~P., /" 105 105 I /[/)
(I):> /(\j(I)
_0~ 70._ 10G-; /0 I/~ A(I) ,35 f(f.0 __ -e- -;-,~ -B 35 /9~ .- -e-:. - /.- [:"
I/ ~--=-=--a•0 0-,15 25 35 45 55 55 15 25 35 45 55 55
Days after emergenceFigure 2.4.1. 4 The effects of photoperiod on number and total length
of the leaves contributed by axillary branches.
0 L8 0 8Db. L8L 0 8Ll
b. 8L2(J) 100 fT- 0- -0- - - -i!l 100H(IJ I,0;:l
I+"ro 80 / 80(IJ
~ (/J0G-i
ID re- -0-6- - - -e(J) 60 I0 60 I,.q+" I(J) I+" Is:: Ittl 40 I 40rlP.,
6 6G-i0 I(IJ Ib.O 20 I 20ttl I+"s:: I(IJ ICJH I(IJP.. 0 0
20 29 38 47 56 65 20 29 38 47 56 65
0 L8 0 8Db. L8L
7\0 8Ll
30 30b. 8L2
I \24 \ 24lA _
I -~"'-A 8EDs,_ r \I
+" 18 I \ 18~ ~rl \,P., p"H(IJ 12 12.0§ /s::H(IJ 6 6.0;:lE-t
20 29 38·· 47 56 65 20 29 38 47Days after emergence
Figure 2.4.1.5 The effects of photoperiod on number of tubers andpercentage of plants those formed tubers.
1"./
2.4.2 .sxperimcl!.t Gl~2
In general there was no Lr; teraction between phc toper-Lod and
Lr-r-adi ance levels except in f'ew par-amete r s of the pLant gr-owth , thus
the results in gener-al, ur-e presented c..s the effect of photoperiod and
irradi3l1ce levels.
2.l~.2.1 Stolon
Number of mair: stolons (average) went up to 19 pla.nt-1 and was
not affected by any of the tr-ea tment s ; irradiance did not affect their
total length ei there After tuber initiation growth of main stolons in
SD was negligible wh i l,e in LD they continued grO'.-lir-g(Fig.2.4.2.1).
Branch stolons started coming little before tuber initiation. HI in-
creased the total number of branch stolons as well as their total
length in LD whiLe 11 Lncr-e ased number .u.d their total Leng th in SD.
T':J.;:ing SD arid LD together I HI .incr-e ase d slightly number of branch
stolons as weLL as their tobl length (Fic;s.2.4.2.2 arid 2.4.2.3).
LD increased number of branch stolons and their tota.l length \Vas also
more (Figs.2.4.2.2. and 2.4.2.3). Specific weight for m3.in stolons
went up to 2.4mg cm-1 of its length'lnd of branch to 2.03 and was not
nffected by ,my of the treatments. Data for total stolon weight is
presented in Fig. 2.4.2.4 WId was much higher ih LD, 3fter tuber
ini tintion. St.o Lo» we ight \'/:3.S also sligh tly h igher in HI as compare
to LI.
20
2.4.2.2 Stem
LI stimulated extension of the main stem (Fig.2.4.2.6) and little
after tuber initiation (TI), effect was more in"LD as SD almost stopped
growing. Rate of appearing axillary branches (AB) in SD was slightly
lower (Fig.2.4.2.8) and difference increased after TI. AB present in
SD almost stopped growing after TI, thus at the time of final harvesting
their average length was 11.52cm while in LD it was 21.25cm. Total
length of AB; wh ich is product of number of AB present and their average
length, is presented in Figure 2.4.2.7 and was much higher in LD.
Effect of irradiance on number of AB vias variable; more AB were present
in HI before TI, after that rate of appearance was h;gherin LI. Their
total length was higher in LI (Fig.2.4.2.7). Data for total stem
weight is presented in Figure 2.4.2.5. 51 days after emergence SD
stopped diverting assimilates to the stems as their weight was almost
constant, rate of stem growth in LD was very high after 41 days of
emergence. Irradiance did not affect the total stem weight at all
(Fig.2.4.2.5)
2.4.2.3 Leaf
Photoperiod did not affect the internode length and length of the
main stem and total length of AB were higher in LD (tigs.2.4.2.6 and
2.4.2.7), thus no. of leaves present on the main as well as AB were
higher in LD (Figure 2.4.2.9). Increa.se in stem length (Figs.2.4.2.6and 2.4.2.7) due to L1 was prirnarly due to extension of internode
length, thus there was no difference in number of leaves due to irrad-
iance. Leaf size in general was not affected by any of the treatments
and aver-age Le rf s i ze for the Leaves on main stem 2went up to 2.05dm •
Total leaf area was much h i.gher 2.1: I.D espe ci alLy after '1'1, while irrad-
iance levels did not .if f'ec t it (Figure 2.4.2.10). Le ave s we.i.gh t did
not increase in proportional to leaf area thus resulted in difference
in specific Le af i).re.·~(FiC.2.4.2.11). Eoth LD ;md FI de cr ease d spec-
ific Le af are:~, therefore they .ir.cz-ease d , either leaf thickness or
celluLrr dens.i ty or stored car-bohydrv.t.e s or cornbin.it i or, of these factors.
Ef'f'e c t of irr;ldi.:.mce :':':ld photoperiod 0;1 LetlssimiL.ltion r ute LiAR) is
givenb Figure 2.4.2.12; wh i.ch ahows that leaves were more efficient
in producing dry mat ter- ill tr-e.strnent lII. This may be explai ned by the
fact that more pho tons were available per uni t LA. Lower NAR in LD
could be a t tr-Lbu ted to the mutuul eh.rd i.ng of the Le ave s due to higher
LA. LD increased leaf to stem r:ltio in favour of stem especially :lfter
'1'1 (Fig.2.4.2.13). Al though irr:tdiance did not affect the total stem
weight (Fig.2.h.2.5) but leaf weight 'das higher in HI, wh i.ch resulted
higher leaf to stem ratio (Fig.2.4.2.13).
2.4.2.4 Tuber
Tuber .in.i tic, t i or; ('1'1) was exam i.ned by removing ve rmicul i te , at
intervals of 3 to 5 duys , Lr-r-ad iance did :1Ot af'f'e c t TI in combination
'>'Iith SD, where nLan ts ini t i a ted tuberS:lfter 32 days from emergence,
but El e nh.uiced TI in LD where it \'Jas 38 d.iys aftor eme r gence , Some
of the plants unde r tr-ea tmen t comb i.nat ion of LD and L1 intitiated tubers
after 41 d37S of emer-gence but :.t:'..l·)=.:cnts did not h.ive tubers even when
h.:c,rvested, 51 days after emer-gcnce I ',hen 3 out of 4 pl'Jlts had tubers.
In g. erloral tot aL number ,'~.'"'v.re Ll, :_~C" Ch . t 1.. •• h . S_. d - -._ _ ~._, L_...Clr ':lClgfl' 'das mUCI.!. 11lg er In D
(Fir. 2 4. 2 111), U. • I. . -r _ El i'lcre:"sed tuber number in LD Gut decr-e.xsed in 3D.
Tuber we igh t was Lncreased under both photoperiods by HI but effect was
more evident in LD.
2.~.2.5 Tot:~l dry m:,tter :Jccumul'Jtioll
Roots could not be sepa.r;ltedfrom the peat so t.otal, dry we igh t
(TD'lnpresented in F'igur-e 2.4.2.15 is without roots. LD increased TDW,
which was affected in two ways: due to higher leuf area, they inter-
c~pted more photons and further they had more time for photosynthesis.
Later in the season leaves started coming off the stem and were not
included in TO',I. HI also Lr.cr-e ased TD'l!pr i.mari.Ly due to more number
of photons avai.Lub.le , which increased I!AR also (Fj_g.2.L~.2.12).
Little after tuber initiation there was no competition for assimi-
lates between tubers and huulms in SD as indicated by the evidence that
stolons stems and leaves, almost stopped imparting assimilates
(Figs.2.4.2.4; 2.4.2.5; 2.4.2.10; 2.4.2.11), which resulted in to a
higher percentage of tubers out of TD'I'!(Fi;:-;.2.4.2.16).HI also in-
creased the proportion of tubers out of TD'\·!(Fig.2.4.2.16). In SD
effect was one way, as there wus enough induction so percentage increase
in tuber weight was due to higher ouan t i ty of assimilates available.
In Lu it might have affected in two ways: one by stimulatir.g tuber-
ization and another by rtla':d!lg more aas imi.Latee , ava.iLabl.e,
240 SEDs0 SD
o LD/0
200 //
;- /- /- -0160 I,_I /+'
s.:::
/'1lrlP.
S 120 I /o
"..s::tos.:::Q)rl 80s.:::0rl0+'Ul
40
o ~------.-------.-------r------'I-----------'6525 45 8035 55
Days after emergence
Figure-2.4.2.l The effects of photoperiod on total length of
the main stolons.
90 Irradiance 90 Photoperiod r0 HI 0 SD0 11 0 1D /
75 75 /r--II
/+> 601/ I SEDsi:l 60til
r--IP<
/I-. 45 45Q) r: ---0.0
~i:l /i:l 30 30 /0 Ir--I
/0+>
~Cl) 15 15 ""0 025 36 47 58 69 80 25 36 47 58 69 80
Figure 2.4.2.3 The effects of photoperiod and irradiance on numberof branch stolons.
Irradiance Photoperiod550 550 70r--I
/I Cl+> 440 440i:l /tilr--IP<fq /u 330.. 330
I / I SEDs~+>~§3 /r--I 220 220 ?-- --0i:l0
/r--I0+> 1,10 ./Cl) 110
_A,/
0 025 36 47 58 69 80 25 36 47 58 69 80
Days after emergence
Figure 2.4.2.2 The effects of photoperiod and irradiance on totallength of branch stolons.
Irradiance Photoperiod1.8 1.8
HI SD P,..... II LI Ld+> 1.50 1.50 /§ /..;~ 1.20 1.20 /bO
" / I SEDs+>'tb ·90 .90 I II'r-! }l IQ)~ / ?---ci1:: .60 / .60'tj
q0..; ·300 .39+>Cl)
0 025 36 47 58 69 80 25 36 47 58 69 80
Figure 2.4.2.4 The effects of photoperiod and irradiance ontotal stolon dry weight.
35 Irradiance 35 Photoperiod,_ fJI
28 0 HI 0 SD /+> 28q /Cl! 0 LI 0 LD'it /bO 21 1/ I SEDs"
21}+>
'tb'r-! /Q)~ 14 14 /:s '/
l1'~ /Q) /+>U'J '7 7 0/ ~
...121 0
0 025 36 47 58 69 80 25 36 47 58 69 80
Days after emergence
Figure 2.4.2.5 The effects of photoperiod and irradiance ontotal stem dry weight.
50 Irradiance SOl Photoperiod I SEDso HI t 0 SD BI
I o LD 1//
40 o LI .B 40J../ J21
/a 30 ,0 3°1
/I/tJ /
// r 0
" 0'/
I~
..c::of.:> ./IlO /I:l 20 20<Ii rt.-;
av~~:of.:>
Ul 10 10I:l ;:J~r'rl
~
0 0-,---, ---,10 24 38 52 66 80 10 24 38 52 66 80
Figure 2.4.2.6 The effects of photoperiod and irradiance on maJ.n stem length
.560-'.l Irradianceo HIo LI
ILl////
.0./
./)2r
/j
-::;::;-
O-..;--,------.·.r----,--- I
J(; 4'1 :3H Cl') f5()2')Days after emergence
560_\ Photoperiod Po SD I
. /81 0 LD I44 .~ I\ II1 JZl336
1 •
I I/2 2 (~'1 {Zf
I II112--1 'I
I .21 ~
I// »-cr ./~-
O'-rG=~-r---'----r--25 JG 41 58 69 80
ISEDs
·Figure 2.4.2.7 The effects of photoperiod and irradiance on totallength of the axillary branches (AB),
Irradiance30
25,_I
-f-) 20$::1alr-i~"
15~c.....0 10!-.(J).oS 5~
025 36 47
Figure 2.4.2.8the number
58 69 80
Photoperiod30
o SDo LD
25 I
//
I / I SEDs,B
."..
20
15
10
5
o25 36 47 58 80
The effects of photoperiod and irradiance onof axillary branches (AB).
ft- -I:]-:20 (a) /' 225 (b) 110 SD f SEDs 0 SD /
,_LD /I 18 0 LD / 180 0 /-f-)
§ ,I " SEDsr-i~ 16" J /!-. 135(J) /.oS 14 /$::1
c..... 90 ;Ial(J) 12hi
10 45
8 025 36 47 58 69 80 25 36 47 58 69 80
Days after emergence
Figure 2.4.2.9 The effects of photoperiod on number of leavescoming from the main stem (a) and the axillary branches (b).
100 Irradiance 100 Photoperiod SEDs,_I 0 HI 0 SD 11~ /J::: 0 LI 0 LDtil 80r-i 80 /Pt
C\J /~ /
" 60 ~til 60 ./OJ~ ./til
~~ 40til 40OJI-=l
20 20
36 47 58 69 80 36 47 58 80O'_--~----.---~----~---,25 o
25Figure 2.4.2.10 The effects of photoperiod and irrandiance on
total leaf area.
HIPhotoperiodIrradiance
o o SDLD,.._4.1
I
o LI4.1
2·90'
_-El....<,
I SEDs
2.90<,TI-_
25 36 47 802.5014---~----.---.----r--~
2558 69 36 47 58 69 80Days after emergence
Figure 2.4.2.11 The effects of photoperiod and irradiance onspecific leaf area (SPLA).
Photoperiod Irradiance
2.20'r-!+>til!-t
~ 1.9+>til
0+>~tilQ)H
2.2
1.9'0-_- --_
~ ...........................
"El'\lSI\\\
o SDo 1D
HIoo 11
1.3\b----El
1.0~----~---'----'---~----~2525 36 47 69 80 36 47 58 69 80
Figure 2.4.2.13 The effects of photoperiod and irradiance onleaf to stem ratio (dry weight basis).
Photoperiod Irradiance4.00
3.40
2.80o SD
1Do HI
o 11C\JIEl
~ 2.20 /1\/ \
\'\
o
1.60
1.00+-----,---"'"1-'-----'1"'----r __-----w
2536 47 58 69 47 58 69 808025Days after emergence
The effects of photoperiod and irradiance on netFigure 2.4.2.12assimilation rate (NAR).
Se.:)
rlI t: t:.+>s::tilrlP.
bO
" 33 I+>..c:eo
I'r!QJ SEDs~~ 22H'Cl
HQJ
~I:;
1·1
50_
~orlI
+>s::til·rl 30_p.
" I IH IQJ SEDs.0
3s:: 20.HQJ.0;:jI:;
10_
Days after emergence
Figure 2.4.2.14 The effects of photoperiod and irradiance ontuber numbers and tuber dry weight.Key: 0., SD; 0 ,LD; closed symbols, HI; open symbols, LI
Irradiance Photoperiod
8 0 HI 0 SD800 LI 0 LD
,_ 64 P 64I /oj.) /§7i. 48 / 48/C) ,;i I';3:.'"
SEDs~ 32 32
16
80o
25 36 58 69Figure 2.4.2.15
16
o
total dry weight (TDW).The effects of photoperiod and irradiance on
80 Irradiance 80 Photoperiod0 HI 0 SD0 LI 0 LD
64 64 I SEDs
';3:.
~ 48 48~0oj.) -::'l 32 ..... ......0 32'"~ 1Y(j)
.o::'l 16 16.~
~ ,..o-----[]......-
,/
0 025 36 47 58 69 80 25 36 47 58 69 80
Days after emergence
Figure 2.4.2.16 The effects of photoperiod and irradiance onpercentages of tubers out of TDW.
2.4.3 Experiment GH1
Due to fewer number of replications there was more variation in
the data.
2.4.3.1 Stolon
I:umber of main as well as branch stolons and their total length
was higher In control (Table 2.'+.3.1).
2.4.3.2 Stem
Length of the main stem is presented in Figure 2.4.3.1. All the
three shades used at i.mul.ated stem extension and difference was visible
even two days after moving them under the sh:tdes. Control had higher
number of axillary br~1ches ~d their total length was also more
(Table 2.4.3.1), but difference \V3.S not si.gni f i can t due to variation
in the data. Although plants were taller under shades but total stem
we i ght was higher in control (Tc,ble 2.4.3.1).
2.4.3.3 Leaf
Increase in Lengtlt of the rnoin stem by shades \-lelS purely due to
ex teris i on of in ternode, ,is there "Jas no difference in total number of
leaves (yellow or deud + green) recovered from the muin stem (Table
2.4.3.1). No. of Leavea present on axi Ll.ar-y br::mches were higher in
control and leCl.veswere bigger in size in control and their total leafarea was also more (Trible 2.4.3.1) Lncr-ease in Leaf we igh t was not in
proportion to the leaf area, resulting, differential values for specific
leaf area. All shading increased specific Le af area (Table 2.4.3.1).
Leaf appeared slightly thicker in control but were not measured.
2.4.3.4 Tuber
Plants under muslin sh.ide did not form tubers at a.l L, while in
red shade there was only 1 tuber plunt-1 as compared to control where
there were 12.7 tubers plant-1, tubers dry weight for red shade vias
negligible (2.7mg pLmt-1), while in control and blue shade s it was
1.42 and o.4g pL-mt-1 respectively (T·,ble 2.1+.3.1).
Tot·od dry v/eight
Control had higher total dry weight (T:;ble 2.4.3.1) and quan t i ty
reduced by sh.ades was a.Lrnos t propor tionuI to the number of photons
t r anemi tted through the respective shades. Percen tage aas imi.Late s
directed to the tubers were eoua.l in CO!l trol .md blue sh.ide a,
c...:.,;
'I'abl,e2.4.3.1. The effects of different type of ehad i r.g on morphologicoU
chur-acter-s .md tubers, Lt~) days after emergence.
Treatment cOElrol mus l i r: I\Qd Blue SiD
r:o. of axi Ll.ar-ybranches (AB~Pl -1 1+. '/5 1.0 1.33 0.33 1.728Total length ofAB, -1 22.7 6.lf 5 P 2.2 '7.73cm pI .,_)
\0. of greer. leavesmain 1-1 13.25 11.6'7 11.67 9.33 1.214on stem, p
I'~o.of ye Ll.ow or deGdleGves coming frommain stem,pl-1 0.50 2.6'7 2.6'7 4.00 0.894Average siL;e of leavescoming from ma.i n stern(dm2) 1.03 0.61 o J,~ 0.56 0.096• T i
S'Jecific le::!f"re" dm2,.-1 2.66 3.94 4.82 5.02 0.134::<. c•.r.. , d G
r;o. of main stolons, pI-1 15.3 10."/ 10.0 9.0 2.96Length due to mai::lstolorls,cm pl -1 57.1 24.6 1?9 21.1 1'7.48No. of br-anch stolons,1-1 r?3 3.3 0.0 O.? 2.91')
Length due to b~,:.~nch9.3 1.6 0.0 0.6 3.31stolons, cm p1-
'l'uber b 1 -1 12.'1' 0.0 1.0 4.0 3.35num ers,o __
Tuber weigh t, -1 1.42 0.0 0.002'7 0.40 0.304dry g DlTotal dry weight, g pl -1 10.57 3.91 3.16 2.9'7 1.035Tot:J.l -1 3.18 1.62 1.63stem \'.eight,gul 1.32 0.39'rota.lstolon we i gn t ,g :91-1 0.33" J.O(' 0.05 0.03 0.11Percel:tage of tubers outof TD'd 13.4 0.0 0.1 13.3
48ao~
.r::+'eo>::: 32OJrl
SOJ+'til
16
80 SEDsBlue shadeRed shade
Muslin shad
fJ/
/
0-4-_- ,-- ~~---I-------~-- ---T---·----~---- r~~-----·--r--·~---~---T---'5 11 11 23 29 35 41 41
Days after emergence
Figure 2.4.3.1 The effects of shading on maln stem length.
2.5 DISCUSSION
There is ger:eral agreement between experiments: GIll and GR2 that
SD stimulated tuber:bzation (even there were some s ess iLe tubers) arid
decreased haulm growth after tuber initiation. In Experiment GR2
where growth analysis was done regularly, after 41 daya of emergence
there was no increase in len~th of stolons or stems ~:d ~fter 51 days
of emer-gence there vias or.Ly r.egligible growth of stolons, stems and
Leave s Cin term of weight) so iumost etll the assimilates produced, were
be i.ng directed to the t.uber-s , It may be easy to explain this after
understanding the theory of tuberization.
I t has already been mentioned (Chapter 2.1.1) thu t Imler levels of
gi bberellins and higher levels of cytokinins were de tected in SD as
compare to LD. Further exogenous u.pplic::J.tiol1 of gibberellins have
been found to inhibit t.uber i za t i.on (Lovell and Booth, 1967; Hammes and
Beyers, 1973; l-lenze L, 1980), on the other hand Pal.me rv und Smith (1969,
19770) demonstru.ted the requirement for cytokinins in tuberization of
excised stolons of Solanum t.uoer-osum .in vitro; similu.r results were
obt aLned by Haux and Langile (19'('8), using Ziatil: riboside instead of
kinetin. V/areing and .Ienn i.nga (1980) found that er:dogenous Abscisic
iicid (ABA) sUP:9lied by the le:J.ves \'l:J.Snecessdry for tuber development
in Solanum and i gena , but there \.j:_;._s LO s i gn i f i can t difference in ABA
contel1t in diffusate~ from induced to non-induced leaves. Further
more a non·induced le:J.f could induce tuaerization when grafted on to
an induced stem cuttings ('.'iareing and Jennings, loc. cit.). Supply of
exogenous cy tok in ins plus AJA did not cauae tuber f'ormut i.on in one-node
cuttings f'r-om.a non-induced ~)lCl.ntof Solullum :mdic,cu.l (ilil.reing and
Jennings, 1980). They argued that the clones of SoLmur:1 andigen/i., they
used have &11 obligate short-day requirement where as many cul, ti var-s of
Solanum tuberosum have no ilbsolute requirement for SDi but give a
quantitative SD response. Thus it might be possible that a second
factor \13.Spresent L1 Solanum tuberosum .indepe nderrt.Ly of the photo-
periodic pre-treatment. Thus it may now be concluded thc t the tuber-
ization in potato is promoted with increase in ratio of cytokinins
and unknown tube r-Laa t ion s t iuul.us (UT.')) to gi.bber-eLl ina , Production
of the UTShas been suggested to be promoted by SD (';Jareing, 1982).
Tuberiz3.tion involves cell divisions in the sub-apical region of
the stolon apex (Booth, 1963; Cutter, 1978). Cytokinins, have been
suggested to Lnh i bi t .rp'i cuL meristem and promote cell division in the
sub.apical region (Palmer and Smith, 1970); thus with increase in levels
of UTS and cytokinins, tuber ini t i at i or; occurred and w i.th a further
increase in number of short days, the ratio of cytokinins and UTS to
gibberellins increased. This further stimulated cell division in the
SUb-apical region of the stolons and theJ._pical meristem might have
been inhibited to the extent that stem and stolons stopped /Srowing
and aJ.I assimilates produced by the leaves were directed to the tubers.
In Experiment GR1, after 35 days of emergence treatment LS had
3.64 tubers per pl ant and 85. Z':' of the pl ants had formed tubers, while
in treatment SL1, there were only 1.5 tubers per pl an t and 66.7% of the
plants h3.d tubers; but both of them had equCtl number of short days by
that t irne , with the di t'f'e re nce that LS '.'las given short day after 17
days of emergence and SL1 straight af te r emergence. Furthermore
number of axi Ll.ar-y br anche s , their total length, no. of leaves on
Qxillary br anche s and Le.ig th of stolon, c.ll were higher in S11 as
compare to tr-ea tmerrt LS. In:ln ano the r treatmen t , 1SL, which had 20
short day cycles but af' te r , 17 days of emer-gence ; tuber we i.ght after
49' .ind 66 days of emergence \Va.s23.2 and 35.00g 91:'l,t -1 whiLe in SL,
4 8 -1 .it was 3.3 and 1 • g p.lan t r-espe c ti ve.ly , Stem we igh t which is in-
creo.sed by non-inducing conditions was also higher in SL1 thM LSL.
Specific leaf .J.rea, Vl':{S Lower .in 31,1. fes we have seen ear-Li.er that
effect of photoperiod is ou.m t i t a t i ve , thus difference of only 3 short
day cycles cannot be the only reo.SOD, thus there must be some other
factor affecting it.
l!urtJ' and Sahu ("ococ::), . L... 0<-,., I -' (./ , found thut 20 SD cycles Given immediately
after emergence or 20 d:~s o.fter emergence, failed to initiate tubers,
while 15 SD cycles were enough when given 40 or 60 d.iya after emergence,
wher-e plants were ke p t .ir: continuous light and harves ted after 90 days
of emergence. In ,:'1.11 expe r imen t where pl an ts in .rddi tion to '? old
leaves had: 3 young (less thai: 3cm) t.er-m.i na.l Leave s or one young
termir:al leaf or \·,ithou t·,ny terminal Leaf , Tuber wei ght was highest
where there wus no young term.~Yl:"'.lLerf ....nd Lowes t wher-e there wer-e
three young term.' n'11 Leave s (Hummes .md Beyers, 1973).
Thus it follows that the ratio of production of cytokinins and
UTS to gibberellins is more in old leaves compd,red to younger ones
'-'.nd obviously ratio of old to young Le.ive s Lncr-ease s \-.rith age of the
plan t ,
In case 0: tr-eatrae n t LD: ill Expe r imen t GR1, there W'.lS no tuber-
iZ,Dtion until 66 duys:·.fter emergence whei: this expe r imen twas term-
in:~ted, whiLe in Exoer imen t GR2 under h igho r irr;~di'Ulce' level (l~O 0
U:'H-2 -1..c,:,: S , -1still lower th~n GH1), some tubers were recorded (10g plant ) •
This clearly shows that tuberization is f~voured by lower temperature
as in Experiment GR2, tempe rutur-e ,-J,),S i5°C during day .md night while
it. ExperimentGR1 temper-at ur-e \1;').S
Resul ts are ill genera]_':lgreemen t '.vith pri vious workers (Gregory,
1956 i Bor-a....1J. and !'!l'lthor'_,,)e, 1062' Sl. ter 1q68· Q.,}, ., et .,1 197tc•~ ..I , --'."_ , " ,U:"'Ul.'_.\. ':......-L. , r,
l'~enzel, 1980).
It t lower irr:l.dia.nce level i:1 expe r-Lmen t Gl~2 .ir; combi n-it ion VJith
-1 QLD, tuber weigh t ·..ns O.5.~ ClLl'1t af t er u1 days of emer gence but ,··~t
hieher irr:ldiar;ce level i» combinat icu "lith LD tuber weigh t vn.s 14.5g
pl,::l.l1t-1• SimiL:crJ.y in expe r imen.t GH1 pl:.cr:ts under musl i,» ahade did
not 'tube r i.ze whi.I.e p.l.anta grov/il:g in n...t.ur-al glass house .rt t ained
1..422: of tuoe r s per ?lant (there v;;_~sno difference in ape c tr-al, photon
distribution). Similar resul ts in Growth rooms were obtaine d by
Borah, (1959) in vari e t.y Arrun Pilot (irr:.Hii:.Ulce levels wer-e 61+ and
128 co.I cm-2 day -1). Either induction i.ncrease d I,!i th Lnc re ase in
irradicmce levels, or D.l ter-nati vely, tuber induc t i.on was a.l r-eady there
and the add i t i onul, aas i.miLat es ava i.LabLe due to higher number of photons,
were diverted to the tubers. F~vouring the first~y?othesis, analysis
of endoge nous ~ormones .in SOl:J.llUr.1:.u,dir;en:J. showed t.h.rt Low light
intensi t:y Lncr-eased levels of .ic.i.d i.c Gibberellins in Leave s of short
day pLmts ('~;oolley and 'dare i:1g , 1972). 'I'lrus under higher light intens-
ity ratio of cytokinins a~d UTS to gibberellins might have been higher,
""hich resulted hit:;her tuber \'Jei,;ht.
'rot::li dry mat ter Droduced ',idS reduced oy decrease i1: irradia.n.ce as
earlier reported by (Pohj;"hk,.~llio, 1951 ; i3odl:.\I~r"der, 1963; Sale, 1973;
BorQh,1959). NAR'lias low in LD due to mutuQl shuding a~d high in HI due
to higher ~umberof photons available for photosynthesis. Specific leaf
o.reo. increased with decreo.se ill irro.dicu,ce levels; e.g. l'~x8eriment GR2
and GH1, o.nd vias hig:,er ii, S">as com::>lre to LD 0.5 fouEd, oy Dorah (1959).
R,,,tio of le2ves to stem (o~, \'!eiG~;_tb:.lsis) decreased i,: LD :lfter tuber
initiatio!1, due to co:. tinuous f.;rm·,tL of the stem.
jU
cre~lse in Lr.te rnode ler,gL1 (0.'::. comn.u-e t r e itmen t a 701,).] ':r in Exper-
iment GE2 ar.d rnusl in v.nd control in Exoe r imeut Gi~1). Iccre:Jse in stem
length of po tut o due to de cr-e.xse Hi r(d,Lt'cOl' :kS',,:LSO be en r-enor te d
es.r Li.e r- (Bore11, 1959; BodLender, 1963) .ir.d m.iy be reL,ted to higher
UJ;:ount of cibberel1ins "reduced under Lowe r irrHl.:i:,flce ::'evels Clolley
de cr-erse ill phy tochromo .sL.,~e. For exunol e , iu crc',trnent bl ue and
m~slin shide ir. Expe r imer.t 3:11, to t.il r adiut i.on '11<,,8 the sume , but plants
were t.rl.Le r unde r blue ch:«lc where Ohy Lo ch rome s ta te ',-1,,),3 Lowe r than
Ul'.der muslin. Stirr.uL"tory r-e aponee CLell::r,th) of flr red ( >'700nm) and
Lnh i bitory of red Ugh t «,?OOr:m) is es tvbl i shed i~'l v.crious crops
(Imr:oft et J.l., 19'(9; Jtcques, 1)68; Satter .ind '.,'ether'1.J.l, 1968).
Effect of sDectr~,l nhoton di e tr-i bu t ion 0;: t.uber i z.at i on is not QuiteL '. ;.
cle·'.;r from this exoe r irne n t :J.S to ta.; r,di :;,t i or, w.isicon Iounded vii th light
nU::;,_lity. Howe ver blue li.::::llt :lQOearsto howe SOI:1ea t i.mu.la tor-y effect on
tuoeriz",tio{, ,1S per-cen t"se of .:,ssimiL,tes diverted ;;0 tubers were equul.
in pl!Ul ts grO'.-JEunde r blue sh.ide s .:Jl1J n:.l tur:.l C;l',;,ss ;1ouse while irrad-
ie.nce 1'lCeS much less ur:.der blue sh:)de. Fur~her there '.-:3,S no tuberization
in plunts growr. under mu.sli~ or red shade.
3. CHEMICAL CONTROL OF GROWTH
j1
3.1
c:r:Ol'!!l tubers m·.·.]r-espond i.Jy CC'S.il~G to (JU1i;:·.md 'OJ grmvir:c out s tolor.s
(E:-.mmes .md l.e L, 1975; i'~eLzel, 1980; l.ur t i -md B'lr~erjee, 1976b;
1962; Tizio, 1?64; Dyson, 1965).
The .i nh i o i tory effect of G;, OIl t ube r+f'or-mu ti cn h.rs Le d to the
eXoeriment,l ,;!nlic:~tio:; of ;_r,rO'.lthr-e t.vr-de r, t such :'05 ?-chloroethyl tri-
rr.ethy~ ammon ium chloride r ccc i. ',,'her: o lvr.t s we re .eit ae r s)r::yed w i th
of ....er i a.l stems ','.d Le.if .•re. wer-e de cr e.ised (Kr ug , 1961; Jyson, 1965;
GUl:::lsen,,_rld 1I:lrris, 1969, 19'71; Kum.rr .ud 1.!arei"G, 19'/4; JIurti arid
Sah'l, 1975'0), tuber \:ei!,;h t \·Ji.S i!:cre·)seci e sne c icl Ly follmring eee app.l i>-
c:.:tior, (0yso.], 1:;65; Il.urme a ,".•d LeL, 1975; lle nze L, 1980). If eee was
a~)~)lied ar-ound tuber ini t i. t i or: (1'1), E,er, tuber numbe r-s wer-e increased
(Gun·lse::lc. and ll ur-r i s , 196); GifIorLl .u.d j·:OOY·oy, 1967).
The e f f'e c t of ecc is gre:Atcr ur.de r- coud i t ior.s , whi ch s t imu.l a te
,. . .,i.e nze.r (1930) reported greater
incre::1se in tuber weight due to eee.~): .ic, t ion .ir: p1,); t s crowing a t
hiGher temper" tures (32/18 or 32/23°C) com'):lrcd to 10'.:or temDero.ture
'Jhotopcriod:_c ex~)eriment, " unmes.nd Lel (1975)
reported c;re:\ter .i.ncr-e.ree i?l tuber ','!ei;ht due to eee :p!)lic:.ltioYi in
:oLmts grm'li:JZ .it 18 hour-s cL_y Lengtri corr-iir-e d to 12 hour-s; The effect
of eee was more in L!vour of tu be r-s V::10J: ni troCCYl \-!><] 3)~Jlicd at higher
r a to s (GUJW_sc:j.:~ and Har-r i s , 1969).
The Lnh i c.i tory e f'f'e c t of eee on grO'..'th is tl':.lISi toz-y and de cr-ease s
ste~dily over ~ ~eriod of 42 d~ys ([rue, 1J61). Jhe~ ece wus used at
the rnte s of 5Crnl, '7,)C) or oe r
rr, te of the a tern crm'ith ',\'·!.S Low for .l »e r iod of 30 d.iys I'o.Ll.ow ing eee
a1;)~')lic;:ltio;, and tuber .in i t iut ior; \'!'--~S enh.inced but fiLed tuber weight Vias
not af f'e c te d (Dyson , 1965).
?: -dime th~·l-'l:1inosucc:i.Ll;:liclcid (:3) h:".d simLL,l' effects to those
of eee C;iviqj :.l Ger:er,-,l de cr e.ise i:-, h.rul m grOi,th (D:,'so:: .:'.:ld Humphries,
1966) and tuber numce r cud tube r ero'llth '.-lere Llcrecll3ed :;:;_rticuL:-.rly in
the ')eriod follOlviLg i ts ",~»)licutio,: but fin.ll tuber yield \'I:1S not
,'ffected (Humphr i.ec ~;_rld D~'son, 196';').
A more rece.i t.Ly ay.ithe s i ae d erO':lth rC'::;l1Lltor, ;J)333 (Imperi;.ll
er_emic:;l Lndue t r i.es ) h.is oee , GhO',-Jl". to decr ec se culm lenGth and in-
cre.')_se aeed y i el.d et -,':"'L~. , Up t ake of
~)P333 ','I:lS largely from the soil vi a roots :_,nd .ic t i vi ty, or :~t Le as t the
observed r-esponse "/'':'S m:'.int.:,ined over_, lonL~ period. It wa5 considered
t~(ji3_tthe Gener,l reS::JOlJ8e to :)-0533 ';:~,Ssi:'1il.JT to that of eee and '39
3.2
effects 0:: Luber y.ioLd s , t. }jj,:-::hcr :)2.'o)ortioll or to t;.»! oLrn t dry mrt te r
in the tubers woul d »r ovi.de the »o ter t:i '11 :or Lncr-e.rse d pr-cduc t ivi ty
vestiGe" ted .ir: si;:;;~_e ;Jlo~s, '..: j t:l se''1uc:1 ti:'_ h.ir-ve s t.s for crop growth
Y+
The experiments were car r i.ed out en the Universi ty of Kotti ngham
farm, at Sutton Bonington, over the two ye ar-s , 1979 and 1980. In 1979,
soil \-JllS aandy cl.ay Lo.irn ([<'ield 32) '.~Ed Ln 1980, it vuus smdy Lourn
(Field 10).
On receipt, seed (det~il for seed source in Appendices B :md C) of
the vnr-i.ety Pent l.and Cr-own, was examined for di se.rse etc. ln 1979 seed
was infected vii th f.:i1izoctonia sol:mi Kuhu (Black scurf). All severely
affected and deformed tubers were di.acrr-de d and r-emaini ng tubers were
Qrra ..nged 'A~ic:ll' end uppermost in i.l single layer in chi tting trews.
Seed was then stored (Table 3.3.1) untiJ.. pl an td ng and irradiance to
avoid e t ioLat ion of the spr-on t during s tor age WiAS 2.3 ~ O.l~ UEIvl-2 S-1
(warm white fluorescent tubes), on top of the tubers. Rel~tive humidity
Experiment:,l design ilnd 1)ri-{ctici_~.ldetilils
:2reatment de toiLs .ir-e gi ver. in Table 3.3.1. SiEgle app.l.i.cat i.on of
-1PP333 @750iS ~;.i. hu \'JaS gi ven vis i, apr-ay , covering the whole plot
equally i.e. p.lan t.s and bar-e so-il. There uere no cul t i vat i one after
pLurting and weeds wer-e effectively controlled, us ing ~l. mixture of
parG.quot and Li nur-un itt r-ecornmended dose ,J.t about 5~':emergence. Over
the period when stems were emerging, nwnber of stems were counted for
10 plants per plot, OE every other day in the begimiin;g,when stems were
emerging .it fast r ote and on every Ij - 5 duys La te r- all, until no further
increase took p'l ace , Dat;). for r-ainf'cLl , screen temper-uture and soil
temper.:l.ture ,~,t 10<;:r.1dep tli VllS obt.i.ine d f r om :_,ne .u-by meteorological
a t.at i.on , w i thin one kilometre of the expe r iment.s.l si tee r~dinfcdl
totalled for every five dJjs is presellted in FiGure 3.3.1 and screen
(ma.x. and rain , ) and soil tempe r ature ,~t 10cm depth, oath .rveruge d for
every 5 d~ys ~re prese~ted in Figures: 3.3.2(a,b) ~~d 3.3.3(:..:.,b)
r'espe ct i vely.
Light Ln te r-cept icr. ir. the pho torsyu the t ica.l Ly ac t i.ve r ange
(400 - 700nm) was measured 2'1 situ us i r.g Q,nYltummeters (Lund;.;;.
instrumeEts) w ith remote cos inc corrected sensor heads , SimulLu:eous
r:adings were taken from above and beLow the cr o» cunopy iat r-andoml.y
selected Dositions. Reflect~nce in t~e 400 - 700nm range was considered
to be low (Scott et al., 1968) and relatively constant and consequently
\v:..:.snot included in the r-eudi nga, To decide, the number of readings
per plot; in 19'79, 40 r-ead i.nge per plot were tuke n for few plots of
EXperiment F1 and co-efficient of vari:ltion w~s worked out for all the
40 r'ead.i nge and the r. selecting r-undom.ly 5 .md 10 out of l~O ('rable 3.3.2).
It w,').sdecided to take 10 readings pe r plot. Er; order to mi.nimi se
the influence of solar height, all r-ead inge were taker; between 10.30 -
14.00 hours. Early in the season when ground was not covered completely;
readings were LIken around the p.lan ts and thus per-cent age light inter-
ce:9tion was ~djusted for ground cover, mea.sured using the grid.
The grid consisted of <) r-ectangu.l ar metal, fr:une, w i th strings, at
, 15cm spacings pulled tightly acr-ose tile f'r-ume, Size of the frame was,
150 X 90 sq.cm to cover, 2 ridges. The gr-ound cover ""<s recorded by
~lacing the grid ut two places in Cl plot und looking downw~rd.
Recommended p.lar t protection me.rsur-es were t aken .md crop stayed
hea.l thy dur ing both ye~U's :IS L.r as insect pest .md di se nse s were
concerned.
3.3.2 GrOlvth an:.l1'Isis
Seven gr-owth :.iI'.:i.lyses were c.u-r i.ed out during bo tn ye.~lrs.
Sampling W&sfre~uerit early in the seaso~, to obt~in ~~ idea of earlier
tuber gr owtn , ~~:.:.tcha.irro l.e co.rs i s ted of, 2 .in 19'79 .ind 4 if: 1980,
adj:lcent p.l.an te .~;nd car-e '.:as taker, th.rt a t I eas t one gu:~rd p.l an t was
left between each si:u;'!Jle. At e ach hir-ve at f'o lixge of the selected
plants Vias cut off at soil leve2_';_wl tne.i unde r-gr-ound p.rr ts of the
plar:ts we re lifted cur-e f'u.lLy , using a fork. All tile tubers, however
small, were recovered. Plants were stored in labelled polythene bags,
~t JOe to. d' t d~ q un l~ lssec e • La ut ternp t w·_,s m~.de to recover r-oo ts umd those
whi.ch we re a t tached to the s tems were removed:,u;d diacnr-ded , Labor-a-
tory procedure for gr-ow th :m·Qysis \'k, co the a.ime ~.lS described in 2.3.1.4,
except that s talons were no t measure d;
K,rly Ln the se·~)sor, the Le.rf .ind s t.er: m.ite r i i.L from the whole
s,'Jnple were used ir: de te rmir.Lng the dry;;, .. t t.er co.rte r.t , 'out as sample
size .iLcreased,
i!lg all tbe s i ze o ;' s·ir.nLe.
·After cornpLe te ae ne ac i.ng , gUtI'd pL.c!:ts on either side of the rOI';
't/ere har-ve s te d w ith :, f'oz-Ic, r-om.rining pl un ts , excluding 0u.~rd rOI·/S
Were har-ve s ted w i.th ,_ tr"ctor ope r-ate d oo ta to digge r (Jonson), and then
picked manua.lLy , 'l'uoer s wer e stored in .labe Ll ed sucks in ~\ cold room
~j_t 4°C, un t iI p.rase d through the riddle. Piddles a·r.ciL(ble for griJ.ding
large qu~ntities of produce were slightly different from the one used
for growth;n.:,lJ'se~. Fecords v/ere r-,.cde Yor the :~ur;.oer ;\1:(1 fresh weight
3?
Table 3.3.1. EXDeriment~l dettils
19'79
Pre -91:311 t ingstorage.
9"/ days a t 4°C,followed by 13 d~ys ~t120C .md 22 days a t SoC.
S~ed size 105.3 "t 1.31g
Plot size 5 r-ows of 6.56H e ..ch
Tre a. trne nts There we re 5 tre«t-men ts: 1)P333 epr.ryedon; 5th June or 13thJune or 2nd July or16th July illd control(no spr..,y).
h'e t'l' 131""'" h-1... r l aze r uf,g :'.(All given beforePI;~nting) (15:15:15; N:P~5:K20)
Dose of pp333 , , -17'SO'gl.l. nil
1980
90 duys i: t 4°C,followed by 39 dctys at120C .ind 1 eLlY at SoC.
15 th Aor iI
'17.5 "t 1.26g
8 rOIlS of '/.20H each(control)
10 rows of '?20H each(p:J333)
76X36cm (control)G1X20cm (up333)
There were 2 treat-ments: pp333 sprayedon; 23rd Eay :J.ndCall trol (no spriJ.Y).
(15:15:15; I::P,205:K,20), -1750g a , i , ha
of tubers in each grude .·_ald, aub-zs enoLe of 350g to 4Kg 'lld.S taken,
depending upon the quun ti t.y of tubers in e .ch gr·de, for dry we i.ght ,
T:tble 3.3.2. l<e:m per-cent age Li.gh t .ir: te r-cep t ion be fore a.djusting
for ground COVerl!ld CV:'~,OL 21.6.79.
VARIETY 2entl,ndCrown Record
Renlic.ltionne; of
r e.tdd ngs CV% me un CV%
40 pr + 0.9 1 83.6 + 1.78 2.1300 -
10 84 + 1.3 1.5 83.4 + 3.331 - - 2.77
5 83 + 1. .3 1.5 82 + 3.5 4.3- -
1.lf-2 86.5 : 0.86 0.996
2 10 84.'( -: 1.46 1.73 88.5 +- 0.92 1.06
5+83.3 - 2.6 3.12 86. '76 + 0.89 1.02
I
I :
------~-----------------~I:~--~I~~·----------------------------~--~--~8I .i.. I
, II f-
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I
~-_ .........--1 :>.L-,, __ -13
, t-:J
i
I II (])i:----------------------4--------~I~~§J t-:J
i., I
lI ]: :>.
r-----_,~I1i IIr-------'ll .';:jI Hl --I ~
L..--------r---~--r-_,r__.--_.--_.--_r--_r--~~i 'i
o 0 0 0 0L.I'\ ..::t (Y) C\J o
oco0\rl
'0§
Ul
ttl>rOLr\
?>1--1Q):>Q)
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eos:1'rl1--1
+' ;:jP. rOQ)Cl)
U0
Q)1--1;:j+'eo cO
;:j 1--1c:r.: Q)p.SQ)
+'
?> 0rl;:j~ s:1
'rlSrOs:1cO
Q)s:1 0;:j~
><cOSs:1Q)
ttl>Q)1--1~ CJCl)
cOC\J
rl'rl (Y)1--1P. (Y/
c:r.:Q)1--1
?o'rlf:r......:::t 0 \0 C\J CO.,'. C\J C\J
JO a.rn '+B.ladura,L
?. •rl;::1r-;,
s::'MS
"1:Js::cd
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XcdSs::
~(!)(!)
~'""'oU)
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rl ,'M (Y)
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0~
.~\
r-oC\J
\0 C\J
+'oo
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UJ>.cd'd
Lr\
i;OJ:>OJ
H0~
+J 'dCJ OJ0 eo
tUHOJ:>tU
+J 0\P. t-OJ 0\rJ) r-1
eo!=1'rlH,g.s:1. +Jeo P.
;:j OJc::x: 'd
ElCJ0r-1
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u0
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OJ1-;) P.
ElOJ+'r-1·rl0UJ
~ @~ 0\
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r-1 CV)
'rlH CV)
~ OJH;:jeo'rlIi.
0 \D C\J coC\J
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:>,CIJ'"Cl
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'"ClQ)!lDCIJHQ)?-CIJ
+>P-< 0Q) OJCl) 0\
rl
!lDs::'rlH;:1'"Cl
!lD;:1 ,.q<I; +>
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StJ0rl
:>,rl +>;:1 CIJ
f-:>
00
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f-:> Q)P-<SQ)+>
:>, rlCIJ 'rl~ 0
Cl)
@0\
Prl (Y)
'rlH CV)
P-<<I; (Y)
Q)H;:1eo'rlIi.
0 \D C\J OJC\J rl rl
JO s.rn ~:e.rCldlUCl.L
3.4 RLSULTS
Soil tempe r-ntur-e , a t 10cm depth ,"~1d screen, rn.;x , and min. a.i r
temperature did ~ot vary substantially between yc~rs (Figures 3.3.3(a,b)
.ind 3.3.2(_>, b) ). However, r~i:lf:tll (Fig.3.3.1) did differ be twe e n
ye ar s w i,th :J. no t i ceubl y dry period, in the men ths of J une v.nd July
duriLg 1979.
Dependi~~ u~on the results of 197), Lhere were only 2 treatments
in 1980 i.e. p~:)333 aprayed on 23rd H,,-y, 1980 and control, arid Cl. further
treated plot 1:1:;S p.lan ted at closer syCl.ngs (61X20cm). Gener-al, growth
of the crop was more rapid in 1980, in the absence of a dry period.
Stolon ,lYldstem growth
Before tuber ini t i at iou , .irnmedi .ite Ly .if t.cr s:)r1yin(; the pp333,
total dry we ight of the s to.Lo.is cmd to tu .rumbe r of stolons were in-
cr-eaaad in tr-eate d plots. ;~\'t the Lmpor t.rn t result 'd-,S th,.t, whee
plant growth reguL~tor \,/",_sspr.lyed be f'or-e tuber .in.it i a t ion , the per-
ce ntage of stolons out of tab} dry weigh t 1;J:lS higher in tre.rted plots,
for exampLe ,~dter lt4 d.iys of p.lan ting, in c.iso of G5 pe r centuge of
stolons out of to tul, dry we igh t 1.~j_S 3.55 compar-ed to 1.85 for control.
~imiLJ.rly il: 1980, "48 d:.ys .if te r pLu,ting the pe r cen tage of stolons out
of total. dry we ight w.rs 4.35, while .in con trol it W:JS 2. GO.
~o effect of np333 wus found on the cumber of stems, nor the
"'x"l b ' (~~)", t i ; ary r-ancues hD, present. Howe ver , stem exteus ion '.v;).5 decreased
in both yeu-s ir, t.re.rte d pL1: t s , Figure 3.Lr.1 ahows tbat pp333 decreased
the aver-age Length of t.he m.iinatema iJ_TId t.re r-espor.se V/,:J.S substantially
affected stem he igh t (19?9), rr ther- where s~ri~yi?1g Vi~lS done earlier in
the season for example, G5, the rite of stem extension, later in the
ee aacr; was not much Lower th.m control. This m.iy be e xp.lai.r.ed by
lower up take of the cnemi c.cI due to dry ".Nec( there The p.i ttern of
?p333 effects on .rve rrgc .inte r-node Leng th 'tI,_,S s imi.Lar to tha t for stem
Le ng th (Fig.3.J+.2), indic .t ing Uut"l1 r.n ter-nodes i~rO'.-vingaf te r- <lp[.)l-
Lcu t i on were shortened. 11, 1979, Le.ive s for the Lus t two growth
'-uDlyses were not ccun ted, thus .ive ruge if: te rr.ode Leng th could not be
ce.l cul.a ted , Dat a for tote I dry weigh t oflbove ground stems (AGS) is
presented in Figure 3.4.3 und wus reduced in both years by the growth
reguLato r , Growth of under ground stem (UGS) WiJ..S not '_tffected, re-
sul t ing in d.i f'f'e r-ent io.l v.rl.ues for fiGS to DGS rrt io , on weight basis
(Fig.3.4.4 ) :;,Ed ',;ns higher in control ir: both year s ,
3.4.2
Decrease in stem Le r.gth v-u.s due to de cr-ec.se ir. internode length,
thus led cumber we re uo t .rff'e c ted , During both ye~<rs the foliage was
a darker shade of green following uptake of pp333. The area of individual
Le.ave s ',vas de cr-eaae d by pp333 ~lr.d the effect was more pronounced in
1980.
The growth of-leaves in control plots wus lower in 1979 comp3red
to 1980 (Fig.3.4.5 ), and , in .add i t i.on , up t.ake of pp333 may have been
lower under the drier conditions.
Irrespective of time of .ippLi.c.s t iou , p 1979, the DD333 - treated
plants had 11 Lower Le.if .ir-e., .inde x since le::fclre:1. aLUlt-1 was decreased
and pIan t spuc ing 'vias the same :,l5 the control. In t r-eo tmen t , G5, plants
h:,d >. highe r L!,I th .n , G18, 1 Iter ill the se.rson did ol onts s trr ted
growing out of' its effect. Since 1e::f':"'8',. oer ;"ll:~nt '..!:'s expected to
be decr eased , the tr-eate d :Ire S in 1980 wer-e C11nnted t closer spn.cing
in order to ut iLase vrlI the .rv.ri Lobl e «er i .1 sp.ice , for compari son of-1
productivity 'ireJ unde r full c.inopy cover. Therefore,lthough the
:Jver'~ge Le.rf .ir-e.. ',Jas decr-eussed by :)()333, the Le.rf .u-e.. .i r.dex 'N'lS
s imi.Lar to that of the control dur i.i.g the 1980 experimen t , except ,'jt
the peak , wher; con t.r-ol LAl wen t uo to 5 .urd np333-treuted ,fBB 3.5.
Ir: 1980, iJp333- tr-eated plants senescedJ few days e .u-Li er thm the
control, resulting in ~ more rapid decline in LAI.
Changes in Leaf "rei). reflect ch.inge s in Leaf exoane i on Ln two
dimensions but ac tua.l leaf Growth occurs ill three dimenei ons , 'rhere-
fore ,'il though ')1)333 decre::sed Leaf »r-e.. the differences in Leaf dry
weight were not in proportion, resulting in differenti:J.I values for
specific Le.if ar-e.:, Specific Leaf .-lrel \oJdij decr-eise d , in both years,
by pp333 and the decr e.xse \r1::lS evident throughout the growing season
(Fig.3.4.6). It (pre ired thltPD333 h.id .increaaed either leaf thick-
ness, ,cellular density or stored carbohydrate, or a combination of these
factors. In the case of G5 (1979), the effect on specific leaf area
seems to diminish later in the season.
, 3.4.3 LiGht interception
Figure 3.4.7 shows that the nroportion of ?AR intercepted by the
crop canopy WD.S altered oy np333 tr-ea trnent , In 1980, light interception
vns s irni.Lar for con trol and [In.333 tre -J. tments be tween ?O - 105 d3YS after
planting (middle of the growing seIson), during this period LAI was,..
higher than 3.0 C_'.ndlight .inter-cep t i.on "'FiS independent of LAI at indices
of more than 3.0. LlU hard Ly r-e.rched 3.0 .in 19?9"-nd consequently
t re a tment differences wer e eviden t thro1ii;hou t the growing season ruther
than a t no.rticul:ir times.
Tuber growth :~d development
The effect on tuoe r Dumber dur i ng 19?9 '-"';S v.rr iobl e (Fig.3.4.8).
G5 decreo.sed tuber number, l;-;~'y be due to very 101': Leaf ar e. index .rt
the time of tuber ini t i:. t io.i, AI though G1 S sligh Uy reduced LAI, but
Lncr ease in ava i.LabiLi,ty o f :-;_ssimil:ltes by de cr-eas.i.ng the stem gr-owth ,
increased tuber numbers. In 1930, tuber number in pp333-treated nlot
were affected in two wuys: firstly, due to closer srucing, there was
higher Le af ar-e« index :It the time of tuber .i.ni t i at ion , .md secondly,
due to r-e t ar-dut i on of stem;rowth more .lssimilutes were :wailable for
tubers. 'I'hus tuber numbers were i.ncr-e.cse d severalfold (Fig.3.lt.8).
Since totill light interception w~:..sno t much different,'lJ.though stem
growth w~s reduced, but there were not enough assimil~ltes available for
i)_11 those tubers to gr-ow , thus differences a t f i.n.r]. h.ir-ve s t wer-e re-
duced.
In 1979, 818 Lncr-eaee d tuber weigh t , es r-Ly Lr: the season by making
more aas i.miLate s uvcliL.lb=-e. Since Leof '"re:' index was reduced by a.LL
the p-;>333app.l i c.i t ions (1979), thus f i.nc.I tuber yield \'IUS higher in
control (Fig.3.4.9). In 1980, pp333-treuted plot was plrulted at closer
S~')acing, thus total ligh t illterce9ted by the canopy during the growing
seQson was the same, If then total aas imiLute s ava i.Labl e wer-e equal in
both tre ctmcn t s , p:::J333by r educ ir.g stem gl'o\'1th and m.iki.ng more assimi-
lates available for tuber .Gro·",th, r-esu l ted in 16ib higher tuber yield
area -1 over control (Fig. 3. 4.9) itt i'il,:'ll h.rrves t ing•
. Although taL,] tuber y i.eLd is .i.mpor t.mt , the distribution of tuber
, .'i _)
sizes making un the to t.xl yield muy :~}so be of importence in practice.
In both ye ar s , the IY:_J333-tre·,ted crop h·'d.l. highar- pr-opor t ion of tubers
in the 35 - 60r.;mr' ..G1ge th"L the control (?i;::;.3.'t.10.:', b).
3.4.5 rrot:;,l dry r:kltter :)ccur.1uLttio!:.
,Roots were not collected ·.llld those pr-ese nt OL stems or stolons
were removed and di.ac.cr-de d , thus t.ot.i.l dry weight (TU:I) presented is
exc l udi.ng roots. Lat.e r in the ae.ison (er:d of July) Le cve s started to
f a l.L off ;,nd were not collected from the ground. The TD\'!uchieved in
1979 was sUbstanti;lly lower ellD in 1980, reflecting the l~ck of rapid
srowth dur ir.g the dry period in June and July of 1979 (Fit~.3.4.11).
In 19'79, P?333 :'.t:Jll t i nes of l:)plic·tion reduced TJi"i, since p.lan ts
were shorter .r.d took U~)lessler:i.:J sp.ice , In 1900, np333 treatment
-1':J':S grown .it closer SraCi;lg to de te rmi.ne if dry m.it.ter production are a
could be .incr-er.se d, 'I'here 'tJ,";'8 very little d.if'f'er-ence i~l dry weight m-2
wi th l)P333 .md closer ap.ic ing cor.par-ed to trie cor. trol (Fig.3.4.11).
1',1though the gr owth regula tor 1110wed closer ap.rc ing IIi thout visible
crowding effects, inter-pl~nt competition for w~ter, nutrients and
soil space Iil:1Y have influenced the crop pcr I'or-m.u.ce,
~Given thut t.otal, dry mat te r pr-oductior: 'lre:;;-1 Ions slightly de-
creased (1979) or airniLar- '.'lith closer SP'~Cil:S (1,)80) it was of obvious
imporb.nce to determine the distribution of th.rt dry m.it t.er- since tuber
Yields i~re the commercial product. Figure 3.ll-.12 Lnd i oa te s tha t in both
ye~rs there w~s :J. higher proT'OrtioE of tot 11 dry wei3ht :J.lloc:J.ted to the
tubers ire the pp333 tredment. The r'edi s t r i.cu t ion of dry weigh t ents
more evident e~rlier in the se~soll, probajly bec3use tuber initiution
occurred 4 - 5 d.iys c.u-Li er w i th pp333.
110
88
66
22
66
22
Key: D,G5; O,G18; 6. ,G2; v,G16; o,Control
1979
o~ ~_June July August
Key: D,PP333; o,control
1980._ B'
$if-
/////
¢//
/ __-----Brn --~-r: --a-----.~----
~-.
O.....__--.,.----.- ..-~- ...------__"T-------June JulyMay August
Figure 3.4.1 The effects of PP333 on average plant height.
55
46
3'1
28
19
s 10o
....c:+'tID$:lQ)
rl
Q) 55'd0$:l!-iQ)
+'$:lH 46
3'1
28
19
1979Key: 0, G5; 0' G18; o,Control
..e--------E)./
././
./.f2f
-:-:
,/,/
G---ff
~--
-r--------· -·--·--------r·------15 15
June July
1980Key: 0 , PP333; 0, Control _--8--J2j--
./ -
-:./
,/,/
./~/////
¢/
_-_-B--.-----_£]
10....__-----,-----.---·---i----r--------.15 15
Figure 3.4.2
May June July
(main stems only).The effects of PP333 on average internode length
i1
I135J
III
102~iI1
58J
Ii
341oL:-------- ..-----r...------..---..-------..-..-..-.--.-_._--,._--_._-----
170...,I 1919!
June
Key:170_,
!I,I
iI
135~
1980
I
102i1I
III
58J
fd- __
/ p' ------=:-=-.:E1//
//
~-/
/ ~c:--_A__---v
/
July August
.Q/' "-o ,PP333; o,Control /' /' "-
/' "-cp ""-/ "-/ ""-/ ~
/////¢///
Mayr .--.._._- -.-. 1- _ --- .'_--'_"
June July August
Figure 3.4.3 The effects of PP333 on dry weight of aboveground stems (AGS).
O,G5; <>,G18; A,G2; V,G16; °,Control
055
042
030
018
././cp.
/
B- -_../ -
././
005(/)
June July Augus~0:::><,(/)0<:t:
0, PP333; o,ControlX101 Key:06'1 1980 Jd-_
/ -- -- ~B/
055 ///
¢
042 ///
q5030 I -~
I --~I
018 I
#
005May June July August
Figure 3.4.4 The effects of PP333 on the ratio of total aboveground stem to total under ground stem (dry weight basis)(AGS/UGS).
X'10 1052-
1Ij
o ~2)
031JIr
010
Key: O,G5; O,GlC); .6.,G2; V,G16; Oj Cont.z-oL1979
_--0,0- --
/ 0---------__-4//
Io 00.J----------r--------.--.---- 1
_. _
~/ \/ \/ \/ \\
V\ \o
/¢/
)/J-:
O 0'o 0 ----,---------.- -------- .---r----------.--.----r---.----------
May June July August
H
j
X101
o 5.2joi2
I
010
June July August
Key: 0, PP333 ; 0, Control1980
Figure 3.4.5 The effects of PP333 on leaf area index (LAI).
1050June J.lly August
rlIt10
C\J
~ 30 SOlKey: O,PP333; 0, Control
1980 _G.
~ / <,<,
Cl) / <,
3010J / <, _-0-/ <, ---e--/
I ¢
20 '01 // 7----
20301
/ /)OJ// \
/ ~
1090
Key: O,G5; O,G18; ~,G2; 'V,G16; Oj CorrtroL
1979
10 50-'-------r---------------l---------- ---------r---------May June July August
Figure 3.4.6 The effects of PP333 on specific leaf area (SPA).
20June July August September
s:::0''';+> 0, PP333; 0, Controlp, Key:~OO1-< 1980QJ+>s::: /',.;
~n / ~~ 8{' » \p., qf e-- \'* I ~
I <,
68 I"(\)
\I \ \I \52 I \
I c.'9.<,
¢ B
36 //
0
20June July -r- August Sept.
Figure 3.4.7 The effects of PP333 on photosynthetically activeradiation (PAR) interception.
100
8{'
6R
52
36
Key: 0,G5; 0,G18; 6.,G2; V,G16; O,Control
1979
225
180
135
90
45
C\JIEl
~ 225OJ
~s::~OJ 180~
135
Key: O,G5; O,G18; ~,G2; v,G16; O,Control
1979
o -I--------------------r------June July August
Key: 0, PP333; O,Control1980
Figure 3.4.8 The effects of PP333 on total tuber number.
till
<) , G18; 6. , G2; V, G16; 0, Control s::Key: 0, G5; .,-i
+>-1515 Ul
.-l (l)al :>-
1979s:: I-i.,-i alrx..s::
I1()C () !(~u, -1
0i!
9L:5JAPI
II
530JIII
3-15_1
0 0-C\J --- ---.--------------I June AugustSeo"+>..ceo
.,-i(l) Key: 0, PP333; o ,Control~ 1575
l>. 0I-i 1980rc::J
I-i(l)
0.o;::J 12608 e
././
./9{'5 '/
y~
-~'/
~_/
:/10
././
./-:
0~_H_=a__=-=-----=---0-----1----------------1-----------June July August
630
315
Figure 3.4.9 The effects of PP333 on tuber dry weight.
80 •
40
•60 •
••
20 ••o
G18
o 0
o 0
o 0
o 0
•••••••
G2
••••••• •G2
•••
o 0
o 0
o 0
• •
G16
•••••• •
Control
o 0 0
G16
••
o :::>
• •• •• •••
o
•
92 daysafter planting(DAP)
•••••
G18
•••••
o
tJ 0 0 0
o 0
Control
•114 nAP•
••
0>60mm
[!] 35-60mm
~<35mm
G>57mmo 32-57mm
Final harvestingFigure 3.4.10a The effects of PP333 on proportion of tubers In
size grades (dry weight basis( (1979).
• • •
. ..oj.) 0... ..__"--_-'--~-I
~'r-!Q)~
t>'0
HQ)
.g 70oj.)
~60
Control PP33380 - •
•••••• I---
• • ...
60 -
• •40 -
• •• •20 -
• ••
107
Control PP333
••• •• •• •• • 1
••
r--- •• •• •• •
135Days after planting
Control PP333
0
0
II III 0 ~
40
0
0
C
0
0
rrrn- 0 ~
20
0,
Final harvesting
G >60nun
G 35..,.60nun
8 < 35nun
OJ]] >82nun
D 57-82nun
0 38-57nun
I~~~d < 38nun
Figure 3.4.10b The effects of PP333 on proportion of tubers ln sizegrades (dry weight basis) (1980).
-1500Key: O,G5; O,G18; ~,G2; V, G16; O,Control
1979
1200~1i,I
q'JIJ!'-' -II
II
600
1300~
I
oL --r-------------------- ---- ---------r----- -------------July August
sa--////
June
C\J 1 c: r'oI ... ,~I J
S!:lO~
::;:~ 1;~OOE--l
Key: 0, PP333; 0, Control
1980 -:/"
././
./50
//
//
/¢/
,?
300//
125-:
/'J2fo _-0'..J.---'=-__ r---------------r-------
May June July
900
600
August
Figure 3.4.11 The effects of PP333 on total dry weight (TDW).
80
'15
60
45
30
15
0
~E-i'i-i0
+J;::J0
10-< 80_w'§+J
*'12
54
18
Key: 0, G5; 0, G18; .6, G2; "'V, G16; 0, Control
1979
-'-----,------------------;----
June July August
Key: 0, PP333; 0, Control
1980
Figure 3.4.12 The effects of PP333 on percentagesof tubers
out of total dry weight (TDW).
3.5
ion of the grm'Jth ret;ulator, ;:;:)333, I!ere:ou!ld ill two ye.ers of expe r i »
ments , Ilowe ver , the m,.lC}li tude of the r-e scor.se 'du.s lower in 19'79 probably
be et.use of drier cond i t i ons (FiC.3.3.1). '';:'11eLn ter-ac Lion with soil
moisture pr-o b.ib.ly r-eLi te s to upt,kcmll eubae quen t tI"111s;Jort in the
xylem r;;.ther t.h.m d i f'Fe r-er.ce ill grO'.:th recu.,l tor .ic ti vi ty ~ ~.
'I'o tal, dry m.rt te r pr oduc t i on \J:)S sliGhtly de cr-e.ase d in 1979 irresoect-
ive of the time of :,,~)'plicitior: of the grm·!th recul'-Itor and it may be
tha t h.id up t k e of prJ333 beer. gre,:ter tho n t llrcer effect would have
been f'ound , II: 19'79, there '.ns :i de cr-ease in dr-y weight ,Lmt -1, and
sir:.ce pl ant der.s i ty ':/:lS the s,'.me ·'.S for tile control, then cC decr-ease in
;->roduct ivi ty ui. i t ,~rcl-1 Hi th rn333 rcsul ted. Ilowevor, since individual
9limt size VI:lS de cr-eaae d the po te nt i iL exi a te d to irlcre:~se plant density
w i thou t sufferill,';'" de trimer: t,~l degree of'lLm t compet i t i.ori, The experi-
',"eigh t un i t-1
~re:l was not decre~sed at closer plant s~acing combined
w i th p)333.
'I'otal. dry mi tter produced by the c.mopy depends on the light inter-
ce_?ted by the C~,llO~)y. Si!1ce L,~I \'I',ISreduced by ~,ll the p_)333 treatments
L1 1979, Li.gh t intercented 'ler unit 'lre:, \'IitS lowered ,md this resulted
in lOi-Jer tot::,J dry mltter in thc tre·,ted~)lots. Ir: 1980, LAI was
Blightly reduced durinG the ~e(J: but L1 W~6 ~ot ~5 LA! in pp333 during
th:J.t geriod ~·!.~sover 3.0, for liCht :terccotio!1 ioDS indepe:ldant of LAl
:,t it:dices of more th::L 3.0. 'ire:;,tcci·ll.lL:S interce'lted more r:ldiation
e:::.rly in the se::501: wher; so;_~r rJ,di.:...tior: 'IJ ..fj hig;}, :md so· toL'.l dry
An add i t i one.L f'ac to.r , 0 ther than solely the degree of pp333 uptake
which m~y hiJ.ve influenced the 1979 results is the possible interaction
between the phys i.o'log i cru s t a tus of the pl;"r.t and "·:~tter stress. The
control p.Lunts ere'cl more slowly ..md yielded less in 19'79 th m in 1980.
The crop was visibly .~ffected b;y dr-ough t Lr: 1979·,nd the calculated
net aas i.m.iLat ior. r-ate C:AE) de cr-e.ised dur ing the dry »e r i od , whereus no
de cr-ease in i·.APW:J.S found i:; 1980.0il333 h.id little effect on ::AR in
1980, or in 1979 with the exeeution of the dry period. During the
d::-iest period (second week of July), the control lJAR fell from 7.0 to
-2 -1 81.1g m day while the !JARof G5 and G1 treatments were maintained
-2 -1at 3.0 and 4.5gm day respectively. Therefore, the efficiency of
dry matter accumul.u t ion \·us chr-e e to four times h ighe r in the pp333
treatments during the drought period. Other growth regulators such as
eee have been reported to increase toler(lDce to \Vater stress (Teubner,
1961) and the effect may be r-el.a te d to changes in physiological status
iL response to Cl general r-et cr-dnt i.on of haul.m extension growth.
Reduction in notato haulm growth and some degree of redistrubution
of dry matter to the tubers has been reported f'o.lLow ing vrpp.l i.ca't ion of
ccc (Dyson, 1965; Gunase na .irid Harris, 1969, 1971), and 139 (Humphries
and Dyson, 1967). t,Hth the'1.pplication of pp333, haul.m gr-owth was de-
cr eaaed arid there vldS some redis_tribution of dry mat te r to the tubers •
.In 19.79, the pe r-cen tugea of aas imi.La tc s diverted to the tubers were
lower in G5 ., compared to G18. This was probably related to a greater
uptake of the chemicul by the G18 treutment us LAl \Jas 0.7 at the time
of its application while G5 was spr-ayed 4 - 5 days after emergence and
soil uptake must have been very 10\01 as weuther "1:':lS dry in that year.
Percentages of assimilates diverted to the tubers were higher in treated
plo ts and since sp::cing w::.s the aame for -;;reated :,lS \\Iell:1s controls
which resulted in lower LAI in90333 tr-e.it ed plots JEd so the finu.l
tuber yi.eI d w:~s higher in the con t.r-o.l, In 1980, the per cen t.age s of
aas imi.Lates diverted to the tubers were much h.i.gher them in the control
and differences were evident throughout the season , :probc~bly related to
more uptake of the cheml.c al. in a wetter season. SiI,ce t.ota.L light
intercepted by the treo.ted?lots ,·,us the s;',r.Jeas in the controls, final
-1tuber yield wus 16 per cent higher urei:. th.in con tr-ol , The foliage
was darker green, as occurred with CCC (Gifford and EoC/rby, 196'l),
and the leaves were either thicker or denser. Chlorophyll content per
unit are3. was 25 - 35% higher ir.. leaves from pp333 treated "Olants in
an ad jacen t experiment in 1980 (Hcl.ar-en , pers. commun, },
The higher proportion of dry weigh t f'our.d in t he tubers of chemically
manipulated plants is useful only when present in the appropriate tuber
size. pp333 resulted Ln :_,higher proportion of tubers in the size
. range of 35 - 60mm. 'v/hen ni trogen w:,s app.l i.ed early Ln the se ason , LAI
was higher at tuber initiQtion compared to late application or no
nitrogen. Since LAI was high, the assimilates available for tubers
vlere more and this resul ted in :.l higher number of tubers (Gunaaenc and
Harris, 1968) • Pratt, et al., (1952) , have shown that irrigation during
the period of tuber set increa.sed the yield of the crop by increasing
the number of tubers set, whereuo? when w:lter was applied later in the
~euson, irriGation-had the effect of increasing theci.verage tuber size
rather than tuber numbers. Photosynthetic efficiency of the canopy is
higher when soil mosture content is high U~oorby" et :11., 1975; Legg et
c~l~, 1979) thus Lr-r i.gat i.on a t tuber set increased the ava iLabi.Li ty of
&ssimil~ltes for the deveLoping tubers, which resul ted Lr. higher number
of tubers. The mechun iam unde r Ly i.ng the pr eser.t exper iment may be re-
lat~d to dry mutter redistribution at an early stage of growth. For
4'7
eX9J11ple, the number of tubers present ',/J.S s irniLar 'out it may be that
the amount of 'lsimil::l.tes diverted to those tubers w,',~sinitia.lly higher
in the pp333 t r-eatme nt , If et max imum r a tc of gr-ot ...th for individual
tubers is iJ.ssumed theri the add i t i onul .ias inri.Lat e may h.ive stimulated
growth of tubers whi ch o the rwi ae woul d not have GrovJrl at tD~l.t time.
Since more tubers woul.d the n h.we CA t tr ac ted more assimi1a te produced
subsequently, i.nd i,v.i.dua.I tubers wou.l d h.rve h.id f'ewe r- c.ssimiLltes due
to inter-tuber cornpe t i t i on, The resul t of such ., me charrism , r'e Late d
to assimilate ~v~il:Jbility ~t particular growth stages, would be to
produce more tubers within the medium size n.lnge,'~s was found with the
p:_)333 treu tmen t , Encr-e aae ill Lumber of tubers hits also been reported
when eee (Cunuaena and IlJ.rris, 1969; Gifford and Hoorlll~*,) 1967), or
ethrel (Gar-c ia - Torres and Gomez -Cumpe , 1972; Hurti et ::.;.1., 19?8;
Bil.nerj;ee et a1., 19'79; Pe r-uma.l,et :3.1., 1979) were spr-ayed a t tuber
initiation phuse.
Ifenk ....e'.:'.nd Allen \1978), showed that at Lowervp.Lan t density (24960
...., h -1) 11 t b d 1 d f th .. t i t d '0 t h i h~Uoers a a . u ers eveLope ram .ose 1nl la e ut et 19 er
-1 1plant density (74880 tubers ha ) about 1000000 tubers ha- were
initiated (June) but only 78000, developed (August). In 1980, all the
tubers Lni t i.e t.ed in pp333 tr-e.i ted plots did not develop. It may be
,explained 'th.rt ::l t higher p:Lmt density LAI .rt tuber initiation was very
high, thus more tubers were .ini t ia te d , but the r-ate of increase of LA!
Has 10\'; due to .inte r-pLant cornpet i t ion, Thus all the tubers which had
ini tiated could not develop because the aas imiLa te s ava i.Lub'Le following
tuber initii.J.tion \'Jere not enough for:.J.ll those tubers to develop.
In addition to any benefits from manipulation of the physiological
processes within the crop, the altered canopy structure may have agro-
nom:tc benefits under particular circumstaLces. For eXdIDple, the canopy
48
micro-environment may influence the build-up and spr-ead of pathogens,
and the decr-ease d canopy height may decr euse the degree of lodging
and rotting of stem tissue which often occurs under wet conditions.
In 1980 lodging occurred in cor.t.r o.l plots .md rotting of stems W:J..S
observed, but rotting of stems \'hlS more in Experiment JTl~ where stem
-1number-a area were increased by using large seed. 1:0 lodging occurred
in the sprayed ([')9.333) l)lot.
4. PHYSIOLOGICAL AGEl SPROUTING
TECHNIQUE AND SPACING
4.1 LIT.E:RATURE REVI£~'I
4.1.1 Physiologic~l ~ge
It is well known thn.t for a period Immed i.ate.Lyafter harvest, no
appr-eciabl,e sprout Growth "/i:'..lb":e place on seed tubers, even when they
are stored in conditions ide~l for growth. The length of this period
of inactivity is referred to as the 'dormant' period (Burton, 1963) and
it ranges in normal storage conditions (100C) from 5 to 14 weeks after
harvest. The dormant period is largely determined by variety (Krijthe,
1962; Bu;rton, 1963; Bornman and Hamme s , 1977; Reust, 1978) though not
related to mo.turity classes i.e. early varieties do not necessarily
start growing before main crops (Emilson, 1949). Hany features of seed
crop husbandry also affect the length of the dormant period e.g. time
of planting (Jones; O'Brien (both quoted by Ali, 1979); Allen et al.,
1979); site of production (O'Brien and Allen, 1975; \'/urr,1978b); time
of haulm destruction of the seed crop (Hutchinson, 19780.; Vlurr, 1978b);
time of harvesting (O'Brien and Allen, 1975; Toosey, 1964 ); and state
of maturity of the tuber at the time of harvesting (Krijthe, 1962;
Hutchinson, 1978b; \vurr, 1978b). Temperature during storage also affects
the length of the dormant period (Schippers, 1956; Sadler, 1961; Headford,
1962; Burton, 1963; Short and Shotton, 1970; \Vurr nnd Allen, 1976;
Bornman and Hammes, 1977; Hutchinson, 1978b; Allen et ale, 1979; Jones
et al., 1981). \oJurr(1978b) stated that differences due to date of
defoliation of seed crops on sprout length were due to its effect on
dorm<lncy br-eak and 0'Brien and Allen (1981) regarded all seed stockswh i ch do not sprout i.e. until dormancy break as the same. Thus the
period of post dormancy break is important for this may affect the field
50
growth.
Occe buds huve begun to grow however, the e~vironment in the
store, eape ci al Ly the tempero.ture, becomes extremely important in
determining subsequent sprout growth. The gr-owth of sprouts is pos i tively
related to temper a tur-e over the r-ange from u minimum of 4°C to 25°C
(Sadler, 1961; Headford, 1962; Morris, 1966). Growth rate of sprouts
at 300C was 10\'1 due to deatl: of the sprout~.I.pices, Lut.er dea th of
sprout apices occurred a t 25°C also (Head f oz-d, 1962). Horeover sprouts
produced 0. t such high temperatures are bulbous in shape [mel restricted
at the base where as those produced at lower temper-atures are more
firmly at tached (Davidson, 1958; Short and Shotton, 1970). Due to this
oreason temperatures higher than 15 Cure not usually used in the store.
A linear r-eLat iorish ip between total sprout gr-owth per tuber and temp-
erature accumulated over base temperature from dormancy break has been
reported by several workers, when tubers were stored in conditions
ideal for sprout growth immediately after dormancy break (;vurr, 1978b;
Ali, 1979; RaVJi, 1981). Toosey (1963) and l-lade c and ?erennec (1962)
described physiological age as the physiological state of the tuber at
any given time. Recently the research groups at University College ofV/ales and NVRS, Hellesbourne have suggested the measure of physiological
age as day degrees above a base temperature from dormancy break •
. (O'Brien and Allen, 1981; Ali, 1979; \vurr, 1978c).
Varieties differ in their rates of sprout growth Qt Q given temp-
erature (Headford, 1962; Headford and Ingersent, 1962; Short and Shotton,1970; Allen et al., 1979; Bod.Laender and Harinus, 1981) and thus may
emerge at different times in the field. Greuter differences in sproutlength at the time of planting have been found to affect the emergence
and tuber initiation ('rr), physiologically old seeel emer-ging and
51
initiating tubers before the physiologically yOlli~gseed (Headford, 1962;
Toosey, 1963; Fischnech and Krug , 1963; Younger, 1975; Raquf, 1979;
Ali, 1979; Rawi , 1981). LAI .md total dry wei.ght a t the time of 'I'I
wer-e higher in nhysiologically young seed (R<~quf, 1'979; Rawi , 1981 j
Younger, 1975) though difference varied between years arid var-i.e t i.es ,
In the variety HomeGuar-d ,'l close relationship be-tween tuber yield and
physiological age has been found, tuber y ieLd being increased with in-
crease in phys io.Logi.cu'l :J.3e but the effect changed as the harvesting
VI'!S delayed and in some cases it became negative (O'Brien and Allen,
1978; Allen et al., 1979; Raquf, 1979). Decrease in tuber yield with
increase in physiologico..l age o..t later harvests was associated with a
decrease in LAI and total dry weight w i th increase in physiological age
(Raquf, 1979; Rawi , 1981), which may be overcome by decrease in spacing.
Ali, (1979) work ing , with the var i.e ty Desiree and Jones et al., (19811)
wi th the var Let ies Arran Comet and Desiree also reported increase in
yield with increase in physiological age but in these cases also the
effect disappeared as the har-ves t i.ng W:1.Sdelayed. !'·bjor concern in main-
cr-oo varieties is not the ear-Ly yield but the f'LnaL yield which may also
be affected by the total duration of the bulking period of the crop.
Younger (1975) found that physiologically old seed emerged earlier and
senesced earlier than the physiologicaUy young seed. But still if
early in the season LAI in the C:1.seof physiologically old seed is in-
creased by decreasing p.lan t spacing and thus making greater use of solar
radiation of th a t time of the year (Allen und Scott, 1980) then even if
it senesces earlier, the poter:tial exists for higher tuber yields.
Stem number is now considered us the unit of population in potato
(Allen and Bean, 1978). There are two types of stems which may emerge
ab()v.tground i.e. main and br-anch stems (defined in Appendix E).
52
Differences in sprouting regimes cause differences i~ oroportions of
different types of stems produced by the seed tuber (Allen, 1978;
Younger, 1975; Bagley, 19,/1). So stem numbers ;..,s such may not give the
right Lde a of populat i.on but sizes of different types of stems have not
been studied.
4.1.2 In ter-cro')Ding
Ddf'f'eren t crops or var i e ties are mixed depending upon their habi t
of growth to ensure better light interce1jtion and extensive exploration
of the soil for r-emoval. of water and nutrients. Inter-cropping of
mai ze and bear.s is quite common in sever-c.I parts of tropical America.
(Pinchinat et ,')1., 1976). F'i n.luy (1974) reported that 98% of the cowpea
is inter-cropped in Africa. Ln te r=cr-opp i.ng of cotton .rnd summer onion
is practised in Egypt (Nasr, 1976). Over yielding of grains for mixtures
due to the early f'Lowe r i.ng arid m.rtur-at i on of one comnonen t than the other
has been reported by the Lntern.rt iona.l Rice Rese.ir-ch Institute (1974).
In potatoes inter-cropping may be useful when one component emerges
first and grows at the exoe nae of «no the r while the latter may have
advantages later in the eeasou, Schepers and Sibma (1976) obtained
higher yields in var ious experiments by mixing ear-Ly and late crop
varieties of potato. Smith (1978) obtained signific:mtly (P: 0.05)
higher yield by mixing Ar-r-an Comet and PentLmd Cr-own in ulternate rows,
compared to PentLmd Crown grown alone. Chowdhury (1980) also obtain-
ed higher yields, when Desiree arid Hujestic Here mixed v;i thin or be-
tween rows than the higher yielding monoculture. This increase in yield
Was associated w i th increase in Leaf urea duration. r'~ixing of different
varieties especially within the row may be only useful when the product
53
is required for starch industry or for other uses for which a mixed
product is accep tab.l e , 'dhee s or-outed:'cld unaor-outed seed of the same
variety were mixe d al t.er-n.iteLy w i thin or be tween rows higher tuber
yields were obtained than the higner yielding rnonocu.;ture but the in-
cr e ase was higher .in hajestic th.m Oesiree and the effect al so varied
between years (Chowdhury, 1980).
4.1.3 Light interception
Potato crop growth has often been considered iL terms of the LA!,
leaf area duration and net ~ssimilation rate (Watson, 1952). A linear
r eLat ionsh i.p hus been reported between tuber yieldmd Leaf area duration
when leaf ar-e.r indices ubove three were·J.ssumed to be three (Bremner
arid RadLey , 1966; Bz-emner+and 'I'aha , 1966; Gunaseria and ILlrris, 1968 ;
Chowdhury, 1980), which implies that light interce~tion, or photosynthetic
efficiency, does not limit yield ut Lea f dTe'l indices gr-ea te r than
three. Published reports on light .inte r-cept i.on .in po t atoe s are few
(Scott and \-Jilcockson, 19'/8; Allen and Scott, 1980; Bean and Allen, 1981),
while crop growth rate has been related to radiation intercepted in
barley, wheat and augar-bee t (Biscoe:md Gallagher, 1977) and maize
(It/iUL.ullS et d., 1965).
'I'otal, gLobal radiation has "bee n four:d to be pos i ti vely correlated
'with the yields of several crops (Sibm,-l, 19?O)md potato tuber yields
have been related to total radiation during the growing season (Scholte
Ubbing, 1959). However, Leaf photosynthesis is easen ti al.Ly a wave-
length dependent with photosyn the t ic.i.l Ly active r-adiat ion (PAR) being
defined as radiation between 400 - (,OOmn(lkCree, 1972). Although the
ratio of PAR to lotal r;"dii..ttion appears to be reJatively insensitive to
54
atmospheric fuctors, and when considering both direct :Anddiffuse
radi.at ion is often tuken :~sbei ng 0.5 (l'io;lteith,1969), it rn.iy be am-
portant to measure PAR int.er-oept ion withi n crop cur.oo ies, One f'~ctor
which may Lnf'Luence w i thin canopy meaaur-ements of total r id i.ati.on,
r-eLi tive to P,\R, is the transrniasi.onof w.rveLeng the ..bove ,/OOnm (Holmes
and Smith, 19'77; Scott etll., 1968), with the relative differences
being related to le~f canODY size und ch~racteristics. Puckridge wld
Ra tkowsky (1971) in whe« t .md Jeffersmd Shibles (1969) in soybeans
reported increases in photosynthetic efficiency of the crop canopy with
increase in LAI.Thus a study involving regular meaauremen t.s of sprout growth during
storage and various crop characteristics in the field along with regular
measurements of light interception may help in a better understanding
of the growth and development of the potato crop in relation to yield •
.',
55
4.2 OllJ:i:CTIV':':S
Greaterphysiologic~ll age resul ts in .m .i.ricr-ec.aein the percentage
of total dry matter found in tubers but reduces LAI which ultimately
results in lower final yields. If LAl is increased by m~nipulating
the density then potential existed for h igher tuber yield ,it f ina.l
harvesting. ;."ith this in mind the experirnen t iD 19'79WiiS carried out.
Depending upon the resul ts 0btai.ned in 19'/9,wher-e p).1ysiologicalage did
not affect the emergence or senescence or tuber yield, but bigger seed
emerged first and ser-esced first, in 1980 it was decided to repeat the
treatments of 1979 (Exps, 1<'2,F3) and since different seed sizes emerged
and senesced at different times, in theory if they are mixed, then
potential exist for Lncr-ease in tot.a'l durat i.onof the crop, So Experi-
ment F4 was undertaken to investigate this nnd seed with greater differ-
ences in physiological age were mixed.
Emergence in 1979 may have been af'f'ected by the growth rate of
sprouts rather than physiological age or length of the sprout , There-
fore sprouting techniques were changed before plar.ting by keeping them
in the dark, to see its effect on emergence nnd further growth and develop-ment.
In 1980 cold treatment of seed took more time to initiate tubers
than apical or multi sprouted when counted from the date of 50'/0 emergence.
This may have been c.tffectedby longer days, as cold tre:tled seed emerged
later and day length increases in spring i:l.ndshort days do stimulate
tuberization (Chapter 2). Thus in 1981 it was decided to see the effect
of time of planting on early tuber yield aridother treatmen ts were in-cluded to have results for two years. Since emergence w.as not affected
by differences in physiological age of the seed (except cold) in 1979
and 1980. It was decided to investigate minimum number of day degrees
above which emergence would not be elilianced(Experiment F6).
r::' ):J(
l1ATERIALS AIm H£THODS
The experiments were carried out iJ.t the Uni versi ty of No t tLngham
farm, at Sutton Bonington, over the three years: 1979; 1980; 1981.
In 1979 (Exp , F1), soil VlUS sandy clay loam (Field 32) and in 1980
(Exps. F2, F3 an.dF4) and 1981 (Exps. F5'J.nd F6), it VliJ.S sandy Lo am
(Field 10 and 6 respectively). On receipt, the seed (details for seed
source in Ap-pendices: Bj Cj D) in general was handled in the same w~
as described earlier (3.3), except that in 19S1 seed was affected with
Rhizoctonia and thus Vias treated with Polyram (d:hthiocarbamate)
(100g PoLyr am dissolved Ln 50 litres of w,'J.terand seed dipped for 2
minutes).
4.3.1 . Experiment F1
Experimental design and or-acti.cal,details
There were 2 vari.eties, Pentland Crown and Record. Each variety
\Vas given two sprouting treatments (physiologiccll age), apical
(stored at 120C for 110 days, starting from 20 December, followed by
22 days at SoC) and multi (stored at 4°C for 97 days, starting from
.20 December, followed by 13 days-at 120C ~nd 22 days at SoC), and then
planted at 2 spacings between plants, 30 and 40cm. Thus there were 8
treatments, all combinations of 2 physiological ages, 2 spacings and
2 varieties. 27th December was taken as the date when dormancy of the
seed was broken ""stotal sprout length per tuber on the tubers stored
at 120C was about 3mm ('Ivurr,1978b). Thus apical and multi had 912.',
° .and 192 day degrees above 4 C from break of dormancy respectively.
The seed sizes used in the experiment u.regiven in Table 4.3.1.1.
Table 4.3.1.1. The weight of seed sizes used (g).
Replicates I II III
Variety
Pen tland Crown 34.1 ~ 0.39* 61.6 ~ 0.52 +105.3 _ 1.31
Record +39.6 _ 0.59 51.5 :.0.'72 +63.0 _ 0.48
* SE, ce.Lcu'lated by weighing 40 tubers .ind.iv.idua.lLy in every case.
The experiment was planted on 1st. Hay 19'79in r:mdomized block
design, consisting of 3 blocks. Spacing between rows was 76cm. There
were 6 or 8 rows (depending on spacing treatment) of ~trnetres each to
accommodate 96 tubers per plot. -1Fertilizer at the rate of 1318Kg ha
(15: 15: 15; N: P205: K20) vias given before p.Lan t i ng, Other details
sueh a~: stem emergence; light interception; plant protection measures;
weed control ; rainfall and temperature etc. were the same 3.S those
described in Chapter 3.3.1.
4.3.1.2. Growth analysis
Nine growth cmalyses were carried out for the vilrietyRecord and
eleven for the variety Pentland Crown. Inaddi tion Cl. few plants were
harvested from specific replicdtion (as size of the tubers used affected
slightly emergence) to have Cl better idea of tuber initiation. Hethods
of harvesting and laboratory pro.~edure, were the same as those described
in Chapter 3.3.3 (2 plants were harvested at each growth analysis),
except that foliage was not cut off the ground in the field rather it
was harvested along with underground parts 3.lld separated into main and
branch stems in the Labor-at or-y, to study the contribution made by
different types of stems, par t i.cuf ur-Ly the LAI. 1:1 general s tat i s t i cal,
analyses were done as f'nctcr-LaI randomized block design, thus residual
degrees of freedom (RDF) was 1L~. But for studying different type of
stems analysis was done :,s a split plot design. RDF for split plot
analyses is given on the Figures itself.
Sprout growth during storage
Length of the sprouts on 40 tubers (10 per truy) each of the 3
sizes (Table 4.3.1.1) and of the two treatments (apical and multi) in
the both vcr-i.et ies was measured on: 23rd J..:tn.; 7th Fe bs ; 13th March;
11th and 28th April, in the case of apical and 11th and 28th April in
the case of multi.
4.3.1.4 Measurement of soil water content
Volumetric soil wate r content was determined at weekly intervals
be tween Hay and October for al.L the 24 plots using a modified version
of the l..Jallingord _neutron probe (Bell, 1969). Essentially this consists
of the emission of fast neutron from a sealed radioactive source
(some Am/Be mixture) and a count of the density of the cloud of slow
neutrons resulting from collisions with the hydrogen nuclei in the soil
wnter. Aluminium acceas tubes were installed ill the furrow about one
,', metre inside from guar-d pLant , Soil profile was monitored to a depth
of 100cm at 10cm depth Lnter cd.s, 'I'he dute of ini tic ...l extraction of
Go
water by roots for individual soil horizons was determined as described
by NCGowan (1973).
This was as described eGlrlier (Chapter 3.3.3)
Exnerimer,t F2
Experimental design and nructical details
There"'fJ.ere9 tr-eatmen t.s , details are shown in Table 4.3.2.1. The
variety used was Pentland Crown.
Table 4.3.2.1. Details of experimental treatments.
Treatments
Apical
Hulti
Cold
Ml1 25, A+l'l36,MC 25, A+C 36,N+C 25, M+C 36,
Details
Stored at 120C from 28.11.79 to 12.4.80(both days inclusive)
Stored at 4°C from 28.11.79 to 26.3.80and at 120C from 27.3.80 to 12.4.80.
Stored at 4°c from 28.11.79 to 12.4.80
+ = two sprouting treatments mixed byplan ting a.Iternn tely along the row. 25and 36 is the spacing in cm w i thin rowfor that particular treatment.
N.3. Apical, multi and cold were planted ot 36cm spac.irigwi thin row.
All seed was moved to 8°c 24 hours before planting on 14.4.1980.
61
14th December W:3.S taken as the date when dormancy of the seed
was broken (Chapter 4.3.1.1). Thus apical, multi and cold had, 972,
140 and 4 day degrees above 4°c from bre.ak of dormancy , respectively.
Seed sizes used were 116 : 2g in replicdion 1 nnd 62 :.0.98 in
replication>2 and 3.
The experiment was p.Lanted on 14th April 1980 in randomized block
design, consisting of 3 blocks. Spacing between rO\'JSwas 76cm. There
were 10 or 7 rows (depending an spacing w i thLn row) of 5.40 metres each
to accommodate 150 tubers in the case of 36cm nnd 147 in the case of
25cm spacing w i thin the row. Fertilizer at the rate of 1318Kg ha-1
(15: 15: 15; 1':: P205: Z:20) was given before p.Lant i.ng, Other details
such as: stem emergence; light interception; plant protection measures;
weed control; rainfall and ter.1peratureetc. were the same as those
described in Chapter 3.3.1.
4.3.2.2 Growth analysis
8 growth anal.ysea were car-r-Ledout and 4 plants were harvested
per plot at each growth analysis. In addition a few plants were
harvested from specific replicCltes (as size of the tubers used affected
slightly emergence) to aid the .iaseasmerrt of tuber initiation. Hethods
of harvesting and laboratory procedure were the same as those described
for Experiment F1 (Chapter 4.3.1.2). In generul statistical analyses
were done as randomized block design, thus residue:.ldegrees of freedom
(RDF) was 16. But for studying different type of stems'malysis was
done as a split plot design taking stem type within the plot as a sub
plot. Similarly for studying growth of 2 types of plants within plot
62
was also done o.sspli t plot design , taki.ng the 2 types of plants in a
plot ilS sub plots. RDF for suli t plot ,mi_l_lysesis given on the Figures
itself.
Surout e;rowth duriLg stor-age
To study the growth of individuc.l sprouts, eyes were numbered, the
first eye (eye No.1) on the aui caL end .ind then working down towar-da
heel end systematicclly wi th last eye numbe r given to the eye closest
to the heel end. 40 tubers (10 per tray) each of the 2 seed sizes
(62g and 116g) illcase of apical and 30 tubers of seed size 62g and 20
of the 116g in cuse of multi were used for sprout measurements.
Apical sprouts were measured on 14 and 21 December; 8 [illd21 January;
4 ond 18 February; 3,17 and 31 Harchj 11 April and in multi on 1 and 11
April.
4.3.2.4 Heasurement of soil w:.l.tercontent
Soil water content W:J.S measur-ed for 18 plots (Replications 1 and 2)
as described earlier (4.3.1.4).
Final harvesting
This was as described earlier (Chapter 3.3.3).
4.3.3, Experiment F3
Experimental design and Dr~"ctic',llde t.ri.Ls
There wer-e4 tre')'tments, combi.net i.onaof two physiological ages
(apical and multi) and 2 aprou ti.ng treatmen ts (L,st:~'1d slow). Det ai.Ls
are given in Table 4.3.3.1. Again the vari.ety used v/aB Pentland Crown.
Table 4~3.3.1. Details of expe r-Lmen tal. treatments
Treatments De t ai.Ls
Apical slow Stored at 120C from 6.12.79 to 12.4.Bo
Hul ti slow Stored i:.lt4°c from 6.12.79 to 4.3.80 andat 120C from 5.3.80 to 12.4.Bo.
ApicJ.l fast Same as anical slow, but covered withblack pol~thene sheet from 6.4.80 untilplanting.
}1ulti fast Same as multi slow but covered with blackpolythene sheet from 6.4.80 until planting.
N.B. All seed was moved to BOc 24 hours before planting on14.4.Bo.
15th December was taken as the date when dormancy of the seed was
broken (Chapter 4.3.1.1), thus apical cUldmulti had 964 and 316 dayodegrees above 4 C from break of dormancy respectively. Seed size used
was 77.5 : 1.26g.
The experimen twas plan ted in randomized block design, consisting
." of 3 blocks. Spacing between rows was 76cm and between plants 36cm •
There were 6 rows of 5.40 metres each accommodating 90 tubers per plot.
All other details were the same as those described for Experiment F2.
Growth analysis
Six growth ana.Ly.sea were carried out and 4 ul ants were harvested
per plot at each growth ana.lyae s except for one (6th Jur:e), when 2
plants per plot were har ves t.ed, j\'iethod of harvesting and laboratory
procedures were the sume :lS those described for Experiment F1
(Chapter 4.3.1.2). In gelleri..tl statistical analyses were done as a
factorial randomized block design, so residual degrees of freedom
(RDF) was 6. But for studying different type of stems (mo.i,nand branch),
it was done as split plot design taking stem type within plot as sub
plots and RDF WJ.S 8.
Sprout growth during storage
91 tubers out of 12 t r-ays in case of apical, (46 slav; + 45 fast)
and 34 tubers (out of 4 trCl.Ys) Ln case of multi (14 al ow + 20 fast) all
wi th numbered elyes were used for sprou t me.rsuremen ts. In the case of
apical slow sprouts were measured on: 15th ancl.24th Dec.; 9th and 22nd
Jan.; 4th and 18th Feb, ; 3rd, 18th and 31st Harch; 10th April and for
apical fast, the first 9 dates were the same and after that these were
'measured on 9th, 11th and 13th Apri.L, In case of multi slow sprouts
were measured on: 12th and 18th Har'ch ; 1st and 9th April and for multi
fast in addition to these 4 dCl.tes sprouts were also measured on 11th
and 13th April.
In addition some tubers (6 per treatment before the st.ar-t of fast
and 3 after thut) were used to study the SDrout weight, 3 times before
planting and 2 times after planting but before emergence.
Fin~l hnrvesting
'I'hi.s vias as described earlier (Chapter 3.3.3).
Exuerimen t FLt
4.3.4.1 Experimentc.lidesign and practical details
There we re 4 treatments: 336j S25j I3+S25j I3+S36, where:
B = Seed stored ut 4°c from 6.12.79 to 4.3.80 and at ~.2~C
from 5.3.80 to 12.4.80 'lndseed size was 204 :.5.7g
(316 d d b 4°C).~1.Y egrees a ove
C = Seed stored at 4°c from 6.12.79to 12.4.80 and seed
size was 62 ~ 0.9 (4 day degrees above 4°c).
+ = Two seed sizes (B,S) mixed by planting alternately
along the row.
25 or 36 = The spacing in cm used for that particular treatment
within row.
All seed waamoved to 8°c 24 hours before planting on 14.4.80.
The variety used was Pentland Crown. The experiment was planted in a
randomized block design, consisting of 3 blocks. Spacing between rows
Was 76cm. There were 6 or 4 roVis (depending on spucing within row) of
5.40 metres each to accommodate 90 tubers in case of 36cm and 84 tubers
in case of 25cm spacing wi thin row. All other detai.Lswere the same
as those described for Experiment F2.!II
4.3.4.2 Grmvth ,:~Lll'';sis
Six gr-owth .mal.ysee wer-e carried ou t:md 4 ';)l:mts were harve s ted
per plot out OE 1st July ocLy one r-epl i.cu t ion w;_~sh.ir-ves ted and on 15th
July 2 replications were harvested, while on remaining dates all the
three r-ep.li.ca t i oria were hL~rvested. In add i t ion i.l. fe\-! plants were
harvested from specific replication to help with the determination of
tuber initi.J.tion. Methods of harvesting ~ld laboratory procedures were
the same '.l.S those described for Exper i.ment F1 (Chap tez- 4.3. ,1'.2) except
tha t differen t type of stems and ax iLl ar-y branohe s were no t studied.
St3.tistical an.d yse s were done :lS r andom.i ze d block design, thus resid-
ual, degrees of freedom (IWF) W:.J.S 6 where illl the three replications
wer-e harve atcd and 2 where, only 2 r-eo.li cn t iona were harvested.
Sprout crmvth during stordge
j~yes wer-e numbered ~,s described earlier. 20 tubers from 2 trays
were used in the cuse of B36 for spr-ou t measuremen te on: 12th and 18th
!--i,3.rchj4th and 11th A~)ril.
Finul harvesting
'I'hi,s \-:::lS the s ime '-cs described ear Li e r- (Chupte r 3.3.3).
',.
6'7
Ex·oeri.:nent 1"5
EX1Jerimenbl design lind pr:~ctlcal details
There wer e 6 t re.rtmen t s i cold 6; :.,)ic.~l 13; /~+C 13; cold 16;
ap i cal. 22; A+C 22, whe re :
cold = Seed stor cd v.t L~oC frOIJ 1ltt:i Dec. 1980 until 24
hours before pl;m tinge
api cul, = Seed stored at 120C from 14th Dec. 1980 until 24
hours before 1JLmting.
= Ap'icol UY.d cold mixed by p.lcrrt i.ng ill ternately
1 tl (F.~ 1 -..; 1)a. eng 'le row ltJ. t.,/. •
6, 13, 16 and 22 are the d.rt es of pl.an t ing in the month of
April for -:nrticuLlT t.r-eatmen t s , All seed was moved to 8°c
24 hours before }l~~ting.
The var ie ty used ':IL.s DentLund Crown and seed size \-J:J.S52.8 -: 1.1g.
22nd December 'Ins t alce n as the d',tte when dorm.mcy of the seed was
broken (Chap t.er- L;-.3.1.1). SO .ipi.caL 13 .:t:ld:J.!_)ic:J.l22 h..id 892 and 964
d~'.y degr-ees above 4°c from dorrn.uicy ore.:,';( respectively and cold had 4
day degrees only.
The experiment was p.Lanre d in u r.:J.ndomized block design consisting
of 3 blocks. Spac i.ng between r ows wa.s ?6cm and be twee n plants 36cm.
There were 5 r-ows of 7.92 metres e ach :iccommod'.ltine; 110 tubers per plot.
Fertiliser the rate of 11251(g 11.]' -1 (1?:1'7:17; I'. P205: KP) givencl t .. was
before p.lan t i.ng , All other de ta i.Ls were the aame .:J.Sthose described
for Experiment F1.
68
GrO\.,rth ,-uul vsis
Seven Growth :tu1.1yses wer-e c.u-r i ed out .ind for e xch , l~ p.Lants wer-e
har-ve s ted 1jer ol ot , ;'lethods of h.u-ve s t i ng .md Lrbo r.it or-y pr'cce dur-ee
were the aame )8 those used for Exne r i.ment Fll-. ,st:,<tistic'.'.: :1nn.::' yses
\'1').s done ::tS f'ac tor i a.L (2 d.i tc s x 3 trertmen t.s i.e. d£:lictl, rnu.l t i .md
1i.+C) r:mdornized block de s ign , Thus r-es.idu.i; decrees of freedom I"las 10.
S:)rout ?jrm'lth durin0 storlce
I';yes were numbered vrs described 'olrlier (Ch.ip te r '+.3.2.4) 29 tubers
out of 3 trays were used for sprout measurements on: 22nd Jec.; 5th and
20th JUl".; 4th~,;ld 1,?th Fe o., : 3rd .u.d 1'/Ll IL,rchj 1hth April 1981.
Exnerimer.t F6
4.3.6.1 Exnerimental design dnd prdctic~~ details
There were 10 treatments: 4D; 24D; 48D; 80D; 1230; 134D; 2320;
280D; 352D; 920D, wher-e numbers before 0 s tand for the number of day
degrees gi veY);bove 4°c 'from br e.rk of dorm.incy , Seed used was the same
as that used in Experiment F5. 'l'r-ea trnent 9200 \-Jas the aarne as upi.ca L
in E~periment F5. For the rem~ining treatments seed was stored at 4°C
until moved to 120C on: 3rd, 12th, 18th, 24th, 31st Mdreh ~~d 6th, 10th
Ll.nd13th Apr i.L, to ob t.ci.n the r-equ i red number of day de gr-ees mentioned
above. All seed was moved to 80C,24 hours before 9lacting on 16th
April 1981.
The exce r imen t \viJ.S pl.an ted ill ,\ r'.mdcm.iz.ed bl ock design consisting
1980 (Experiment s: F2; F4)
0 • 0 •• 0 • 0
0 • 0 •• 0 • 0
0 • 0 •• 0 • 0
0 • 0 •• 0 • 0
1981 (Experiment F5)
• 0 • 0
• 0 • 0
0 • 0 •0 • 0 •• 0 • 0
• 0 • 0
0 • 0 •0 • 0 •
Figure 4.3.1 Planting patterns in mixed plots.Key: ., sprouted (i.e. multi or apical); 0, unsprouted (Cold).
of 4 blocks. Spacing between rows was 76c~ ;illdbetweec ?luLts 36cm.
There were 3 tubers per r-epl i.c.s t ion, A~_l other details wer-e the same
as those described for Experiment F5.
4.3.6.2 Growth im:<lysm
All plan ts were h.u-vested 64 days ufter pLan ting Tnd growth para-
meters studied are presented in Table 4.4.8.2.
Snrout growth during storage
Ten tubers per treJtmclltwere used for sprout meusurement on 23rd
Earch, 8th and 14th Apr iL,
L~.4 R~SUL'rS
4.4.1 Sprout growth durinG storage
The following dc,tes wer-e tiken as the days when dormancy of the
seed was broken : 27th December (Exp. F1) j14th December (Exp.F2);
15th December (EXIl.F3)j 22nd December (Expc, F5 and F6) when sprout
Length per tuber reached abou t 3mm (\1urr, 1978b), and the number of
si:.l.ydegrees shown 'tlerecounted from these dates. In the case of multi
t.r-eatmen t , it took about 50 - 60 day degrees to reach a sprout length
of 3mm tuber-1 (Figs.4.4.1.2 and 4.4.1.3) but day degrees shown here
are from the date they were moved to w~rm conditions (above 4°c) as
it was thought that tubers had broken dormancy by then. Residual
degrees of freedom and the \-ID.;; the ditn were anal.ysed is shown in
Table 4.4.1.1.
Total sprout length per tuber increased with increase in tuber
size (Figs.4.4.1.1; 4.4.1.2; 4.4.1.5). Tubers of the same size of
two var-Let i.ea: PentLmd CrowTl'...nd Record (Fig.4.4.1.1) had the same
sprout length. Linear regression between tuber size arid total sprout
length per tuber for both varieties (Exp. F1) of apical treatment
measured on 28th April (900 day degrees a':.Jo'le4°c from dormancy break)
accoun ted for 98)t.of the v.ir iance (Fig.L~.4.1.5). Similar relationships
are evident for other dates of measuremeLts (Fig.4.4.1.1). Sprout
numbers a.lao Lncr-eased with increase in tuber size ('l'ables4.4.1.2 and
4.4.1.3). Tot:...l sprout length per tuber Lncz-eaaed with increase in
day degrees above 4°c (Figs. 4.4.1.1; 4.4.1.2; 4.4.1.3; 4.4.1.6i 4.4.1.7).
Growth rate (extensior..)of the sprouts was increased by storing the
tubers in cold (3 ! 10C) before moving to warm conditions for sprouting
/1
(Figs. 4.1+.1.1; !+.l~.1.2; 1~.1+.1.3; 1~.1'.1.7). For ex.unpl e in 1979 growth
r~te of Pentl~nd Crown from 11th Anri~ to 28th A~ril was 33.6mm per 100
day degrees above 4°C for mu.lti whi.Le this figure for'''picJ.l \-I3.S '7.66
(average of 3 Geed sizes). St.or i.ng the tuce r s ill cold C3 ~ 10C) before
moving them to \J,~.'.rm cor.di t ior.s for epr outir.g .i.lso il:cre;,.sed the number
of s or-out.s (T,:.;_bles4.4.1.2 c.lla i+.4.1.3).
In 1979 it vns observed fhu t some sor-cu ts s tcppe d growi.ng during
storace in the c~ie of 'ioical treatment. To invcstiCJ.te this in detail,
in the following two years, eyes were numbered (Cha?ter 4.3). If there
"Jere more th.in one snrou t on :.my eyCf then they 1derellso numbered, in
this vlay the growth of .ir.rl i vi duu.l sprouts wxs mo.ritored. In case of
ap i cal., on the bas i a of the length 0 f the sprouts :·t t'.J.irie:3.by the end
of the stor3.ge oeriod, sprouts were divided into four categories: those
tru thad r eache d be tween 2 to 3mrr:; 3 to 6mm; 6 to 9mm or over 9mm
(Fig.lt.4.1.L~J.). Sprout grmJt:l ra te of _ill apr out.e less th.m 9mmw;.rs
low but the .irnpor t.crt r-eauL t was that they stoooe d growing, while others
(>9mm) con t inue d to gr-ow (Fig.4.1~.1.1+). Simil:cr results wer-e obtained
for ~xperiments F3 ~nd F6, where for Gimolific~tion growth of only two
types of sprouts is shown i.e. <9md>3mm (Figs.LI.4.1.4 .md 4.4.1.7).
Fur the r it "k',S found th at apr ou ts whi ch con t inued to grm, were usually
present on the eye number 1 (rl';.cb1e1~.4.1.3). But if this eye was
damaged then it ','/:.1.S not necessarily so th.. t eye Humber 2 would continue
to grow, as in miny c.cses sprouts on tile he eI. end were seen growing
while others st opped , The length of the s or-ou ts 011 different eyes is
shown in Figure 4.4.1.8. In Expe r irne n t s F2 and F6 or.Ly u few tubers
had damaged eyes and so the s or-out Le.ig th is gr c.ite r on eye No.1, while
in Experiment F3 eyes vJere drmuge d HI m,::y tubers, ..nd so there Vias no
difference be tween different eyeoosi t ioria 'IS [,-,1",5 apr ou t length is
';'2
concerned. Data in Figure 4.4.1.8 for growth of sprouts on different
eyes is presented only for 3 d~tes but similar results were obtained
for the remaining d~tes of me~surements also. Another factor which
should be tuken into cons i.der-at ion is the number of eyes present on the
tuber and data for this is shown in Table 4.4.1.5. Storing seed in the
cold (3 + 10C) before moving them to warm conditions for s?routing
removed the inhibiting effect of the dominating eye (T()ble 4.4.1.3 and
4.4.1.4). For aimplification, d.rta from different experiments is pre-
sen ted for the List measur-ement only but similar results were obtained
for other measurements also. Lowe r values for sprout length and their
number from e"J'eno ,? onwar-ds were not due to the fact that their growth
was inhibited by other growing sprouts but bec3.use these eyes were not
present on all the tubers (Table 4.4.1.5).
Total sprout length in case of mul ti vJ:.lsequal to api ca.l,by the end
of storage in all the four experiments (Figs.4.4.1.1; 4.4.1.2; 4.4.1.3;
4.4.1.7), but length of the ~ongest sprout (LS) in the case of multi
was much lower than that in the ap.ical in al.L the experiments (Table
4.4.1.6). To investigate this further, growth of the longest sprout of
2 types of treatments is presented in Figure 4.4.1.9. Although total
sprout growth rate waa much higher in multi (Figs.4.4.1.1j 4.4.1.2;
4.4.1.3; 4.4.1.7), due to intersprout competition, growth of the longest
sprout was not hi_gher than the apical.
'73
Table 4.1+.1.1. Residuul. degrees of freedom (RDF) for vur i ous Figures
Fig./Table ~;o.
Fig. 4.4.1.1
Fig. 4.4.1.2apicalmulti
Fig. 4.4.1.3
Cipical (slow)ap i c a.l (fast)multi (slow)mul ti (fQst)
Fig. l~.4.1.4(a)
( b)
Fig. 4.4.1.5
Fig. 4.4.1.6
Fig. L~.4.1.7
For differen tcategories
iilldTables presented i~ this Ch~pter.
RDF
118
48
18
10
Remar-ks
Analyaed us comp.l eteLy random i.zeddesign(CRD) tuk i.ng tubers :_LS z-ep.Ldcutea,
sarne as abo veaame as above
Different number of tubers were involvedfor cornpu t ing their mean ;91 for first 8 dates u~d 46 for last date4534 for first 3 dates and 14 for last date20
Anu.l.yaed as split plot design taking seedsizes as main plots and categories assub-pl.o t.s, 'I'r-ays (8) were t.ake n as replicates.Anal ysed ilS CRD, trays (6) were taken asreplicates. (Fust not included).
4
Hean for 19 tubers.
For total sprout length meCln for 29 tubers.i r; cuse of ap ical,and 10 in case of mul ti
lm:Alysed :lS CRD, tuk i.ng trrys 0) as replicates.
continued ••
Fig./Table No. RDF
Fig. 4.4.1.8(a) 66
(b) 22
cc)11050
Fig. L~.4.1.9(a)apical
multi(b)apicul
nul ti
Table 4.4.1.2 234
Table 4.'+.1.3
Table 1+.4.1.4 11
'I'able4.4.1.5
Tuble 4.4.1.6(a)
(b)
Rem~rks
Anulysed as split plot design, taking seedsize as ma.in plot and eyes as sub plot.'I'r ays (8) were tuken as replicates.CRD, tr'_;ys(3) tuke n as r-ep li.cctes,
All dates ano,lysed asFor first 2 datesFor Las t date
CRD LJ:ing trays asre?licates (fust notincluded ).
MeaD for 19 tubersNean for 10 tubersNean for 46 tubersHean for 14 tubers
AnalysedJ.s factorial (seed size X physiologicalage) CRD, Li.kbg tubers us re_?licates.
Mean for different number of tubers specified0.arlier for different experiments. In Exp.F3tubers from fast treatment were not included.
For Exp F3 and F4 an.a'lyaed as CRD bking trays(2) CiS replicates. In case of Exp , F6 theyare mean for 10 tubers.
Calculated from different number of tubers:Exp.F2, 70 for 62g tubers and 60 for 116gone;~Xl:).F3,125; Exp.F4, 19; Exp.F5, 40.
Analysed as f'ac torial (seed size X physiological:c..ge)GRD, taking tubers as renlicates.Diff. for different Exps.: Ex.?F2, 126; Exp.F3,121 (both ann.l.yae a as f'ac t.or-i.al, CRD). Exp.F4,me.:J.Ilfor 19 tubers; Ex.?F6, mean for 29 tubersin the cuse of api.cul,and 10 tubers in thec.ase of r.ml tie
/5
Table 4.4.1.2. The effects of var-Le ty, tuber size ('rs) 'lid phys i.o.Logi cal,
age (PA) on s~rout number on 28.4.1979 (Exp. F1).
I'umbe r of apr ou ts 2mm tuber -1over
Pen tLand Crm-ID Fecord
PA Ap i ca l rlul t i ;":e:1.n PA Anic"l Nul. ti 11ean
TS,g 1'S,g
34 2.70 5.27 3.99 40 3.58 4.83 4.20
62 3.90 6.1(, 5.03 52 3.85 5.55 4.70
105 4.63 8.82 6.'72 63 3.90 6.30 5.10
mean 3.'74 6.75 mean 3.'78 5.56
P Crown Record
S2:D for age (mean ) 0.267 0.187
SED for tuber s i z.e (mean) 0.328 0.229
SED for body of the tdble 0.463 0.324
Table 4.4.1.3. The effects of tuber size (rs) wld eye number on sprout
number of different size categor-y (SC), (2-3 days before
planting).
-1Number of sprouts, tuber on different eyes.
~xp. F3 Ex:). F4 Exp , F5 and F6.c:;xp. F2
53TS,g 62 116
Treatment 3.pic ,3-1 apic:;l multi(slow)
336(multi )
«o i.cal. 352 D(multi)
SC, mm 2-9 >9 2-9 >9 !2-9 >9 2-3 >3 2-3 >3 '2-9 >9 2-3 >3
Eye no.
1 0.13 0.58 0.08 0.7 0.39 0.30 0 1.21 0.16 1.63 0.14 0.52 0.2 1.0
2 0.23 0.08 0.35 0.03 0.39 0.17 O.O,?0.71 0 1.75 0.38 0.14 0.2 0.8
3 0.18 0.10 0.3 0.10 0.28 0.35 0.09 o. '/9 0 1.3'?0.34 0.10 0.3 0.8
4 0.15 0.08 0.48 0.08 0.35 0.35 0.29 1.07 0.05 1.32 0.45 0.14 0.2 0.7
5 0.25 0.08 0.33 0.13 0.46 0.26 0.29 1.61l- 0.05 1.32 0.45 0.14 0.1 1.0
6 0.10 0 0.25 0.13 0.26 0.24 0.14 1.36 0.21 0.95 0.38 0.03 0.4 0.7
7 0.13 0.10 0.13 0.05 0.41 0.20 0.36 0.'110.42 1.32 0.10 0 0.3 0.9
8 0.15 0.10 0.10 0 0.26 0.04 0.21 0.57 0.26 0.84 0.17 0 0.4 0.3
9 0.10 0.25 0.10 0.13 0.13 0.24 0.07 0.21 0.16 0.63 0.14 0.06 0 0.1
10 0.15 0.13 0.2 0.08 0.02 0 0 0.14 0.05 0.26 0.14 0.03 0.1
11 0.05 0.08 0.05 0.10 - - O.O,?0.14 0.05 0.16 0.0'70.03 --12 - 0.03 0.03 0 0 0.05
Total 1.6 1.45 2.4 1.53 2.96 2.02 1.5 8.57 1.42 11.57 2.75 1.34 2.2 6.3
Table 4.4.1.4. The effects of tuber Slze and eye number on total sprout
length (2-3 d~ys before plonting).
Snrout length, mm tuber -1 differenton eyes
Experiment F3 F4 F6 F6 F6
Treatment i-1ulti B36 352D 280D 232D(slO'.-:) (multi )
Tuber size,s '78 204 53 53 53
Eye No ,
1 11.42 19.12 9.1+5 9.25 9.15
2 6.91 19.14 6.40 6.70 8.25
3 6.54 16.72 6.15 6.75 5.45
4 11.61 11~.49 5.15 3.85 9.35
5 13.98 14.53 7.77 5.75 6.05
.6 11.96 9.75 7.30 6.80 3.15
( 6.82 12.42 6.30 6.10 2.95
8 4.86 7.34 2.40 3.90 3.55
9 2.14 5.68 0.55 2.35 0.50
10 1.18 2.72 1.00 0.20 0.60
11 1.20 2.01
SEB 1~65 3.01
'-j I)(U
Table 4.4.1.5. 'I'he effect of tuber size on number of eyes.
Percent~ge of tubers had these eyes
Lxperiment F2 F3 1"4 F5
Tuber size,g 62 116 '('8 204 53Eye .No.
6 97 98 94 9? 100
7 94 98 82 93 100
8 86 95 50 90 97
9 61 88 29 80 90
10 19 65 14 60 62
11 6 23 8 37 24
12 0 12 0 17 3.4
N.B. At least five eyes were present on every tuber.
Table 4.4.1.6(a). 'I'he effects of phye io.Logi ca.l age (PA), var i e ty and
tuber size ('rs) on .leng th of the longest sprout,
-1 ~ 4 )mmtuber on 20•• 1979 (Exp.F1 •
:?entl::md Crown Record
PA Anice,l l';ul ti l'iecm 0' • ' 1 j,lul ti Mean'11 i~PlC:,L
T.3,g TS,g
34 19.05 8.68 13.86 40 16.35 10.50 13.43
62 18.70 9.07 13.89 52 17.75 11.22 14.49
103 20.43 9.85 15.14 63 19.32 10.68 15.00
mean 19.39 9.20 me.in 1'7.81 10.81
P Crown Record
SZD for age (mean) 0.440 0.415
SED for tuber size (me an ) 0.538 0.509
SED for body of the t.ab l,e 0.761 0.720
Table 4.4.1.6(b). The effects of physiological age (PA), sprouting
treatment (ST) and tuber size (TS) on length of the-1longest sprout, nun tuber (measured 2-3 days before
planting).
Exp. F2 li'3 li'h F6
TR SPL TR SPL 'ill SPL 'l'R SPL(mm) (mm) (mm) (mm)
TS,g ST
62 14.? fust 29.8 1336 16.0 + 0.48 920D 19.6 ~ 0.56
352D 10.9 ~ 0.87
116 18.5 24.4 280D 10.5 +slow - 0.55
SED 0.53 SED 1.0'/ 232D 10.4 + 0.50-
PA PA 184D 9.1 ~ 0.63
apical 22.3 aDicul 31.6 128D 8.3 + 0.62-rr:ulti SOD 4.9 +multi 7.0 15.3 - 0.53
0.54 SED 1.20 48D 1.77 +SED _ 0.31
\.JherejTR = treatment; SPL = sprout length.
GO
rlI
IQ
50_1 /II
: I~.O il 1!P'I 1/
-',o. I rp~j '1 1/1
I / / I .') r-. r!J/ IGU_ AI
10!
Pentland Crown ISEDso l05gL::.. 62go 34g
ApicalMulti
I
i-I () ~-------r'-'--"-"'-- T----·-··---T··------···T ...····-,··---···-·----·---r--·----·-····--r----,
100 20 0 J00 (~0 0 ~)(; i ) C()C) 'H):') t~C0 900
,,
iC (J' I.J. -i
I,;i ffJI40_! Iff
IIII Cj)
30.1 /1 I1/1 IIII
20_ I{~~
Recordo 63gL::.. 52go 40g
ApicalMulti
ISEDs
100-1 O-+----,---·--···r··-·-- ----T- ..---.T-----.-.-.--.-T.--,----------,-.---,
200 300 400 500 GOO 100 800 900oDay degrees above 4 C from dormancy break
Figure 4.4.1.1 The effects of tuber size, variety andsprouting technique on total sprout length duringstorage (Experiment Fl).
75
GO.
i.5
30.
15
rlI
~..c:to 1:5j;:l(])rl
+';:joaGO.Ul
rlcd+'o8i.5
30
15
1;'rilll~
./1SEefor mean
/.I
o Slowo Fast
ApicalMulti
/ I
// I
/ ./8........--:r//
'/
O-+----,----r----.-50 150 250 350
'-'550
1
950i.50 G50 750 850Figure 4.4.1.3 The effects of sprouting technique on total sprout
length during storage (Experiment F3).
6. llfigo 62g
ApicalMulti
II SEe
I
I
I
-- ..--,----,---- ---T------,---- 'T 1 --·--1
150 250 350 oi.50 550 GSO "lSC, 850 950Day degrees above 4 C from dormancy break
Figure 4.4.1.2 The effects of tuber size and~routing techniqueon total sprout length during storage (Experiment F2).
rlI
50
40
30
20
10
Experiment F3 I SEDsI ~/
I .0./
./
I /.0/
.ff»:_./
I B-:-:
.ff»:_./
.Er»:/
B-:::r:. ././ 1---8----9--- __Df------f.=Of------<Ot:t---0
~-o
o >9mm
o <9mm
I
II
~ 0-+---,---.----.--,-----.---.---.-----.-----,'§ 50 150 250 350 450 550 550 '150 850 950+'
gj,.; 50+'tlOs::OJrl
+'g 40HP,U)
30 I
Experiment F2
o >9mmA 6-9mm
o 3-6mm
+<3mm J: SEDs.a
./_-8'
:l: .a-r _
.a--r E-_/
_/
20
r_-Er
2-10
-A------i:r-----/::;-- -ubA----A----8----t:r-----:
oj~~~~t;~~-~-- -?:=~=_u~------ J T-- _~====~====~====~c==~
50 150 250 350 ~50 550 550 '150 850 950Day degrees above 4°c from dormancy break
Figure 4.4.1.4 Growth of sprouts of different categories(see text for details) during storage.
1;~CiIII
'1()~:4I
••,;613')1'-'lII
10"'1'--"-, --T----T-···- . l" ....- 'I
50 150 "'J'Day degrees above 4°c from
dormancy breakFigure 4.4.1.6 Total sprout length
per tuber during storage(Experiment F4).
rlI
J.,(!).0::l+-'
~".£1
+-'~~(!)rl
+-'::l0J.,P;Cl)
~)s_,I
III!
rl '51I (. 1,J.,
I(!).0::l+-'
~ r55 I"-I" i
.£1,
+-'
IQo~(!)rl
25~+-'::l0 IIJ.,
~
1Sj.-,
III51100
~ma for meanI rl
1
H(!)
.g+'
~ 50",.s::::
+'till 0~(!) £Irl /
+' 40 /;j .00 /HP<Cl) tD
30 ---I30 50 70 90 no
tuber Slze, g
I
I
Figure 4.4.1.5 The relationship betweentuber size and total sprout lengthmeasured on 28 April (Experiment Fl)
y=20.48(+1.38) + 0.36(+0.02)x% varian~e accounted f~r 98.2,residualstandard deviation 1.23.
I SEa for meanI Total
SEDs'>9mm
~/
.R!:./
///
;{IISEa' for mean
<.9mm
Figure 4.1~.1.7 Total sprout length and sprout length of differentcategories during storage. Experiments: F5 and F6.Key: __ , Apical; --, Multi.
I
'1'-- 1 1 r-·-·-----T-----T ..'-----"---'--'---,
200 30Cl C; IJU ~-)ClU h:i~' 'N)U t3 00 80 ()Day degrees above 4oCfrom dormancy break
Experiment F372 520 936o 0 t:::.
*
3_
oJ--,----------r------r---r---- --r-------T-----T-------r--------r-- ----,-----1o 1 2 3 4 5 5 1 8 3 10 11 12
....c: 0+' " . --r"eoI=l r' '/'1 r;> J I. 5 5 9 10 11 12(!J ur-I
+' -15_ Experiment F5::s I0
1,,11-<P< *Cl)
:J112 568 9040 0 t:::.
I
I Ii I,
5JII
II
3~
01 -T T- , - -- - I - r- 1
0 1 () J ~ 5 5 '1 8 9 11G
Eye Number
r-II
Experiment F2
56 416 952o 0 t:::.
*
I I
'.. Figure 4.4.1.8 Total sprout length contributed by differenteyes during storage, for apical treatment only.* Day degrees above 4°c from dormancy break and SEDs to
cQmpare between eyes.
30_
24
18
12
8 :c
Experiment F1I SEs for mean
o Apical (slow)o Multi (slow) I
I
I
.I
IIjZj
~/O~-----'------'------r---------- r-------,-----,-------r----,50 150 250 350 450 550 850 '750 850 950
~.r:: 30_, F6+' Experiments: F5;bOc IQ) Irl
I
+' I o Apical;::!0 24J o Multi~c, ICl) i
I I SEs for meanII
18_
I
12_ .r II
8
O-,---------I-----------r------ ----r---- -----r--" ---I' - - 1--- - --------'1------- - -,-------,
50150 250 350 450 ~<50 850 '750 850 950oDay degrees above 4 C from dormancy break
,;
Figure 4.4.1.9 Length of the longest sprout during storage.
4.4.2 Experiment F1.
Soil temperature, at 10cm. depth, screen, max and minimum air
temperature and rainfall data are presented in Figures 3.3.3a, 3.3.2a,
4.4.2.1 .emergence ar:dstem number
The variety Record started emerging about 10 days after Pentland
Crown, but emergence was more homogenous in this variety thus the
difference in time to 501b emergence was reduced to 8 days (Fig.4.4.2.1.).
Once emergence had started the rate of emergence was higher in Record
while physiological age and spacing did not affect it. Inspite of
differences in the length of the longest sprout at the time of planting,
physiological age did not affect the emergence, may be due to the fact
that total sprout growth rate was higher in case of multi (Fig.4.4.1.1.).
Stem number stopped increasing after the end of June and thus were
averaged for the various dates of gr-owth analyses carried out after that
as there wetsno significant difference between different dates. The
total number of stems per unit area were higher at 30cm. (22.11,M-2)-2spacing as compared to 4Ccm. (17.09,H ) but this increase was in pro-
portion to the increase in number of plants per unit area. Apical
treatment increased the numb=r- of br-anch stems in both varieties
(Fig.4.4.2.1.). Record had a higher number of branch stems but a lower
number of main stems and total stem number was also higher in this
variety (Fig.4.4.2.1.). There \vilS no increase in the number of axillary
branches (AB) after the end of June and so they were averaged for all
dates of gr-owth analyses. AB wer-e higher in Pentland Crown (Fig.4.4.2.2.).
Apical treatment increased tl:e number of AB in Pentland Crown but
decreased in Record (Fig.4.4.2.2.). It may be explained by increase
in total stem number by this treatment (ApicaJ.) in Record, which in-
creased shading of the lateral buds. Similarly planting at closer
spacing also decreased the number of AB. In Pentlund Crown about 98%of the AB present were contributed by the ma.i,nstems, this may be
because branch stems were fewer in number (Fig.4.4.2.1.) and further
they were smaller in size (Fig.4.4.2.15), thus lateral buds may have
been shaded and stayed dormant. Development of AB depends on the
release of dominance from the apical bud, which may be related to the
lower auxin production by the lateral buds. Thus development of AB
may be related to the speed of ground cover by the crop canopy. To
investigate this the le~f area duration for a period of 30 days from
the date of 50}~ emergence (LAD'E30) was calculated and plotted against
number of AB present (Fig.4.4.2.2. ). Number of AB present decreased
with increase in LAD'E30 i.e. with the increase in speed, with which
ground was covered by the canopy. Speed of ground cover was faster in
Record.
4.4.2.2 Stolon grO\vth and development
The variety Pentland Crown increased stolon weight (Fig.4.4.2.3)
for a longer time and this may be related to delay in tuber initiation
(TI). The variety Record initiated tubers 5 days before Pentland Crown
(Table 4.4.2.1), when counted from the date of 5O;~ emergence. Thus while
Record started feeding its tubers, assimilates in Pentland Crown may
still have been used for stolon growth. Stolon growth slowed down
after TI in both the varieties (Fig.4.4.2.3). Early in the growing
season before TI, apical treatment increased stolon weight per unit
area (Fig.4.4.2.3). Percentage of stolon dry weight out of total dry
weight was also higher in this treatment. Spacing, did not affect
stolon growth or its number (Fig.4.4.2.3). StoLon number were also
unaffected by 9hysiological age. Like stolon weight, stolon number
also stopped increasing after 'I'L, Stolon number were higher in Pentland
Crown. In general before TI stolon gr-owth \Vus found to be linearly
related to the LAI of the canopy (Fig.4.4.2.4).
4.4.2.3 Growth and development of stem and leaf
In general main sternswere slightly longer than the branch stems
but on an overall basis they were longer in Pentland Crown than in
Record (Fig.4.4.2.5). Physiological age mld spacing did not affect
the plant height. Total number of stems were higher in Record (Fig.4.4.2.1)
and they had higher weight of under ground stem (UGS) (Fig.4.4.2.7).
Increase in weight of above ground stem (AGS) was not proportional to
the UGS, in fact Record had decreased AGS wei.ght , This may be explained
by the decrease ir-height of the plant (Fig.4.4.2.5). Physiological
age did not affect the stem weight, while plonting at closer spacing
increased stem weight (UGS as well as AGS) per un i t area (Figs.4.4.2.6 and
4.4.2.7). Thi& may be due to higher number of plants per unit area.
Record emerged 8 days later (Fig.4.4.2.1) and thus had lower LAI
early in the season (Fig.4.4.2.8), when considered from the date of
planting but it was much higher in Record when considered from the date
of 50;6 emer-gerice, and the rate of increase in LAI was also higher thus
later on it had higher LAI than Pentland Crown, but later it declined
rapidly due to earlier senescence (Table 4.4.2.1). Apical treatment
decreased LAl (may be due to decrease in stem no.) Although the effect
was not significant at any date of Growth analysis but was consistent
during most of the growing season (Fig.4.4.2.8). Planting at closer
spacing (30cm.) increased the LAI and the eI'f'ecttwus consistent through-
out the growing seaSOL (Fig.4.4.2.8). This may be due to the higher
number of plants per uni t area. Overall about SO;:{, of the LAI was
contributed by the rnain stems in Pentland Crown while in Record this
figure was 52%. Apical treatment increased the number of branch stems
thus decreased the proportion of LAl contributed by the main stems,
from 82 to 57% and this degree ot:decrease (25%) was the S3ll1efor both
varieties. Although there was no increase in the number of AB after
end of June but existing branches continued to grow. Size of AB may
be studied by working out their leaf area sep&rately and is presented
in Figure 4.4.2.9. LAl contributed by the AB (LAP AB) was higher in
Pentland Crown. Number of AB were also higher in this variety. Closer
spacing and multi treatment decreased the LAI'AB. This may firstly be
due to a lower no. of AB present in these treatments and secondly due
to higher competition, as they had higher number of stems (main + branch)
(Fig.4.4.2.1). Higher LAl' AB in Pentland Crown and the treatment apical
was mainly due to the higher number of leaves present on the AB of
these treatments. There vJaS also a slight increase in the average leaf
size of the leaves present on the AB, due to these treatments.
Apart from the leaves present on the AB, the total leaf numbers
were ned.ther affected by the varieties nor by the physiological ages.
\llhileplanting at closer spacing did significantly increase the total
leaf number (Fig.4.4.2.11) but average leaf size was slightly decreased.
Although total leaf numbers were not affected by the varieties and
physiological ages but the important result was that leaves coming from
different type of stems were affected. In the case of Record more
leaves were contributed by the branch stems and the reverse was the
case for Pentland Crown (Fig.4.4.2.12). Apical treatment which in-
creased the number of branch stems, also increased the proportion of
leaves contributed by the branch stems (Fig.4.4.2.12). Leaves present
on the ABwere much smaller in size, thus average leaf size for main
and branch stem presented (Fig.4.4.2.13) was calculated w.i thout
including these leaves. Leaves coming from the branch stems wer-e much
emal.Ler and difference \'las gr-ea te r in the variety PentLand Crown
(Fig.4.4.2.13). Branch stems of multi treatment had much smaller leaves
than those of the api ca.l treatment.
Decrease in leaf size resulted in di f fer-en t ial, vu.l.ues for leaf to
stem ratios (Fig.4.4.2.14). Br-anch stems had a lower Leaf to stem
r a t i,o and the difference was gre ..rt er in Pentland Crown, Leaf to stem
ratio of br-anch stems W2S increased by the apical t.r-ea tment
(Fig.4.4.2.14). Spac ing did notJ.ffect the leaf to stem r at i o of any
particular type of stem. In gener:li leaf to stem r-at i,o vias slightly
decreased by planting at closer spacing.
Total above ground stems are usual.Ly accep ted as criteria for plant
population in po tato , thus it may be important to study the size of the
different type of stems. Size of the stem is presented in term of LA
per stem (Fig.4.4.2.15). Branch stems were much smaller than the
corresponding mai.n stems .md this difference was greater in Pentland
Crown. Apical treatment increased the size of muin stem in Pentland
Crown but decreased it in Record. However size of branch stem was
increased by the api.ca.L t re a tment in both varieties but degree of in-
'. crease was more in Pentland Crown (Fig.4.4.2.15).
The effects of varieties and spacings on specific leaf area is
86
presented in Figure 4.4.2.10. Specific leaf area was higher in Record
and at closer spacing, this may be related to the mutual shading by theleaves as both these treatments increased the LAI also. Decrease in
specific leilf area due to decrease in irradiance was also found in the
experiment GR2 (Chapter 2). Physiological age did not affect the
specific leaf area.
4.4.2.4 Light Interception
Figure 4.4.2.16 shows the proportion of PAR intercepted by the
crop canopy. Quantity of PAR intercepted by the canopy viaS increased
by planting at closer spacing and this increase was in proportion to
increase in the LAI (Fig.4.4.2.8). Effects of variety and physiological
age on PAR interception were also similar to their effects on the LAI
(Figs.4.4.2.8 and 4.4.2.16). Helationshin between LAI and light
interception is shown in Chapter 4.4.6.
4.4.2.5 Tuber growth ~~d development
'l'uberinitiation (TI) was considered as the date when tuber dry-1we igh t of 0.25g plant was reached and was calculated by interpolation
from the growth analyses and addition:u sampling data, taken frequently
during the early growth of the crop. TI in Record occurred 3 days later
than in Pentland Crown (Table 4.4.2.1) but when considered from the date
of 5CJl;6emergence it was in fact 5 days ear-Li er- Ln Record (Table 4.4.2.1).
Apical treatmeEt enhance, TI (one day) by enhancing the emergence
(Fig.4.4.2.1) thus there was no difference in the number of days taken
.for tuber to ini tiate when coun ted from the date of 5a:!~emer'gence,. ,
Table 4.4.2.1. The effects of variety, physiologic~l age and spacing
on number of days taken: from planting to tuber initiation eTI) (TIP);
from 50}b emergence to TI (TIY); from planting to senescence (S£1JP).
'rIP TI.t: SL'NP
V.J.riety
Pentland Crown 49.92 20.83 159.8
Record 52.67 15.58 137.9
Physiological age
lvIulti 51.92 18.25 150.3
Apical 50.67 18.17 147.5
Sp~cing
30cm 51.50 18.17 149.3
40cm 51.08 18.25 148.4
SED 0.453 0.497 2.90
Record gave consistently higher tuber weights as well as tuber numbers
throughout the growing season (Figs.4.4.2.17 and 4.4.2.18) but final
tuber yield was higher in Pentland Crown because it stayed green in the
field for a further period of 22 days after Record had senesced
(Table 4.4.2.1). Just after TI apical treatment did give higher tuber
weight and number (Figs.4.4.2.17 and 4.4.2.18) but this difference soon
disappeared and final tuber yield was not affected and tuber numbers
were increased by the multi treatment. Planting at closer spacing'increased tuber number us well ·"stuber we igh t (F;g 4 4 2 17 d 4 4 2 18)~ • .L s. • •• a..'1 ••• •
8b
The effect of sp::..cingon tuber number \'Id.S more, early in the se3.son
(Fig.4.4.2.18), which may be attributed to the incre:J.sein LAI by plant-
ing at closer sp:J.cingbut subsequently percentage of increase in LAI
decreased along with the season due to higher interstem competition,
thus differences at final harvesting were reduced. Tuber numbers are
usually related to the total stem numbers as the latter increase the
LAI at the time of TI and this was found to be the case in the present
experiment (Fig.4.4.2.19). 'I'ubernumbers which result seems to depend
on a~similates available for their growth for some period after TI.
Thus it was of interest to look at this in further detail. Leaf area
duration for a period of 30 days (LAD'TI30) was calculated from the date
of TI and is plotted against tuber number (Fig.4.4.2.20). About 98.7~
of the variance in tuber number was accounted by linear regression
between tuber number and LAD'TI30 in Record and Tc~J in Pentland Crown.
Record and Pentland Cr-own had two separ-ate significantly different
regression lines. Record developed 1.10 tubers per unit of LAD'TI30,
wh iLe this figure for Pentland Crown was 0.78. This difference may be
explained by the fact that a higher perceZltage of assimilates were
allocated to the tubers in the case of Record (Fig.4.4.2.25).
Total tuber yield was found to be linearly related to the total
leaf area duration (LAD) accumulated over the whole season by the crop
canopy (Fig.4•.4.2.21). Tuber yield per unit of LAD \'I<.3.S 5.31 in case
of Pentland Crown and 6.34 in case of Record. Higher efficiency of
Record may be related to the higher percentage of assimilates allocated
to the tubers (Fig.4.4.2.25). Since higher tuber numbers were found in
Record, assimilates available for the growth of individual tuber were
lower, which resulted illhigher proportion of medium sized tubers.(Fig.4.4.2.22). At final harvesti.ngRecord gave 7Z;b of the medium
sized tubers <32-51mm), while this figure for Pentland Crown was only
3716most others being larger. Closer spacing (30cm) and multi treat-
ment also increased the proportion of medlum sized tubers but difference
was not significaDt. Tuber size ~ay be related to the yresence of AB.
Because AB present, may increase the amount of aas imiLates ava.i.Lab'Le
for a particular tuber to Grow .md thus increase the tuber size. To
examine this Le af ar-ea duration contributed by the Ai3 (LAD'.AB) '!las cal-
culated and lS plotted og,Clinst tuber weigh t over 57mm (Fig.4.4.2.23).
Lme ar regression between tuber wei.ght over 57mmand LAD'AB accounted for
631b of the var-Lance in the tuber weight over 57mm.
4.4.2.6 Total dry matter accumulation
Roots were not collected and those present on stems and stolons
were removed and discarded, thus the tobl dry weight (TD~J) presented
is excluding roots. Later in the season (end of July) leaves started
to falloff and were not collected from the ground. Pentland Crown
completed 50% emergence about 8 days earlier than the variety Record
(Fig.4.4.2.1) and thus had higher total dry weight early in the season
but crop growth rate was higher in the variety Record and thus TDlv
produced by the canopy of this variety was higher during the middle
part of the gr~:)\oJingseason CFtg.4.4.2.21+). Later it senesced before
Pentland Cr-own (Table 4.4.2.1). Planting at closer spacing also in-
creased the Tl;r.{per unit area (Fig. 4. 4. 2. 24) whi ch may be due to the
higher number of photons intercepted by the canopy (Fig.4.4.2.16).
Physiological age did not affect the TD;.,r(Fig.4.4.2.24). Various
components making up the TD'\oJ may be of importance as tubers are the
economic part of the crop. Record allocated a higher percentage of
')()
assimilates to the tubers (Fig.4.4.2.25) and less to the AGS. Apical
treatment also resulted in an allocation of a higher percentage of
assimilates to the tubers ana this effect was consistent throughout the
growing season (Fig.4.4.2.25). Planting at closer spacing increased
the percentage of assimilates culocated to the stems and decreased to
the tubers.
4.4.3. Experiments: F2j F3j F4.
4.4.3.1 Emergence and stem number
As in experiment F1 (1979), apical and multi treatments of
experiments F2 and F3 started emerging at the same time (28 days after
planting (DAP) (Figs.4.4.3.1 and 4.4.3.2) but the time to reach 5~fo
emergence in case of api caL was 34.3 days in experimen t F2 and 31.7 in
experiment F3, which may be due to the fact that apical in experiment
F2 made more total stem number and proportion of branch stems was
higher (Fig.4.~.3.2 and Table 4.4.3.1) and branch stems may have emerged
later. Cold started emerging 34 DAP but emergence in cold was more
homogenous and difference in time to reach 50% emergence was reduced
to 5 days compared to multi and 3.7 days compared to apical
(Fig.4.4.3.1), while in experiment F4 the difference in time to 50%
emergence was 8 days, between S25 (cold) and B.36 (multi). This may
.be explained by the difference in seed size in two experiments.
"~Ct-io 30~ • •!-<Q)
~z20.
25
20
15C\JI
S"!-< 10
Q)
~$:1
s 5Q)
+'Cl)
50.
Stem number averagedoVe!' Va.r10U~ growthanalyses.
SEDsI II ~ __----{J
I ,r ~~~,..¢' .... ~
1'/ ,,~1
o
•• o
o
16 20
•0 •
1 II.ijI I 0I II I 0~ Date of 50% emergence, II I anditsSEDI.I"
•5 10 15 20 25June
25 30May
Figure 4.4.2.1 The effects of variety and physiological age onemergence.
o o y =78.24 (2:_11.39)-2.24(2:_0.53)x% variance accounted for 70.4residual standard deviation = a 64.
10·ur-----------r----------.----- ,- ~20.0
LAD/E30, daysFigure 4.4.2.2 The relationship between leaf area duration,
accumulated over a period of 30 days from the date of 50%emergence (LAD/E30) and the number of axillary branches (AB).
10.0 15.0 30.0 30.0
Key.:,0, Pentland Crown; 0, Record; open symbols, apical; closedsymbols, multi.
Variety
o Pentland Crowno Record
7.0 200C\J I I III s
b.O 5.6 I SEDs 17.-+'..c:
~ ~eo'r-! r \Q) I \~ 4.2 I \ C\J 15» h--- ---Q._
IS IH SEDs.-0 "D .- ~Hs::: Q) ,0
~ 13 1r-1 2.80I+' s:::
U) \s:::
~0 \r-1
1.4 $112\U)
\0
0 9
Physiological age Spacing7.0 7.0
1.4
C\JI
S
b.O 5.6 5.6.-
+'~.r-!Q)
~ 4.2~.-0
s:::~ 2.8o+'U)
4.2
o Multio Apical
2.80 30cm0 .40 cm
1.4
ci
0Sept. June July Aug. Sept.
oJune July Aug.
Figure 4.4.2.3 The effects of variety, physiological ageand spacing on stolon dry weight and the effects of varietyon stplon number.
2.50 y == 0.067 (~ 0.279) + 2.49 (~ 0.51) x
% varlance accounted for 73.7Residual standard deviation = 0.29
2.10
0
C\I 1.70 0ISeo
+'..c::eo 1.30'rl 0OJ~
~'d
s:: .900 0rl0
0 0+'co.50 .20 .40 .6 0 1.00LAI
Figure 4.4.2.4 The relationship between stolon dry weightand LAI. Key: o , Pentland Crown; 0 , Record.
"+'fib'rl 30OJ..c:~~ 20p.
OJeo~ 10~
60SEDs
I·
50
40
_......0-_ 0
_,.O'" -0- - - -/ -0/
o//
......a'o 0
--0
Pentland CrownRecord
o
o
-Iune SeptemberJuly August
Figure 4.4.2.5plant height.
The effects of variety on average
oOO-L------.---------.------------r-----
X102085
042C\J1
Gb 021~Cl)Cj«
000
X102 Spacing085
064
042
021
064
042
064
021
Variety
II
o Pentland CrownORecord
Physiological age
./..8- ___
Er./»:
ra-j
jOMultiOApical
____-El
030cm040cm
June July~--
August Sept.
Figure 4.4.2.6 The effects of variety, physiological age andspacing on dry weight of above ground stems (AGS).
1 I I I-: ---s- - -B- I
Id- --- -g - "El I1// ~~(Zl
I./d
Variety25
I
I20
15
10
o..!- "I _
25 Physiological age
20
15C\J 10I
6h..r:fl 5()~
0
25 Spacing
20
15
10
5
o~ ~ __June July
Figure 4.4.2.7
ISEDs
o Pentland Crowno Record
------.----------------------------- T----- --------
o Multio Apical
T------ ------------ --1
---- B"13-- -B----£J
o 30cmo 40cm
August Sept.
The effects of variety, physiological age andspaclng on dry weight of under ground stems (UGS).
2050Variety
I I I I II~~2000 I 13' Dj
-Er \ ISEDsy:r-1050 I \
\1000 ~
050~
0 Pentland Crowno Record
000
2050lPhysiological age
2DOO~
1050
1000
/050H
:§ 000
2050 Spacing
2000
1000
050
o Multio Apical
o 30cmo 40cm
JuneoOO-'-----.-----------r------------r-----
July August Sept.
Figure 4.4.2.8 The effects of variety, physiological age andspacing on leaf area index (LAI).
Varietyo SOl o Pentland Crown
050 Spacings
040 0 30cm0 40cm
030
0201
010
040
030
020
010
o SOl040
030
0201~ Di°l<,H
j 000
I II ISEDs
o Record
~--------~
Physiological age
o Multio Apical
)cl
/ "" _-f)/ a--.0Id-_ .// -s. ./
/ -s/ --~-~o-
·~-----=--'---~----·-~--r
Q/ \/ \
.0/Jd-_
/ -s../ ~~~~---~
/.0000~ ~ -. ~ ~ __
Figure 4.4.2.9
June July August Sept.
The effects of variety, physiological age andspaclng on leaf area index contributed by the axillarybranches (LAIjAB).
2050Variety
I SEDs2025 I T r I
:r :r
2000
1015rlI
bD 1050_C\],a
1025~jP-.U)
20 50~
·2025I
2000~
1015
11050j
1025
o Pentland Crowno Record
Spacing
o 30cmo 40cm
June July SeptemberAugustFigure 4.4.2.10
280l Y'I I III <, ~ I
l ~ '~
21011 J. ./'-B- -P ..._B- __ £ 8- ___
1[,0 I _0' - i3- - -8. <,
/ R~o 30cm ~'f.)
C\JI
70
The effects of variety and spacing on specificleaf area (SPLA).
I I IISEDS
o 40cm
0-'- -.._June
-----------.--------------rJuly August September
Figure 4.4.2.11 The effects of spacing on leaf number,excluding the leaves coming from the axillary branches.
2-10,I!
i-158!
1
!i!I125_:
II
8~_~
C\JI
"HQ)
§2-10__>=1
Ict--l ,
ItU IQ)
H I
158_~I
iiI
125JI
Variety
IIII o Record
o Pentland Crown
II SEDs0J./ \
)d/ \ / <,
/ \ / ':/J M 'B- - - -R ""-
I
-------1----------------------------y-----
Physiological age o Multio Apical
84
1//~" /
.G..~
'42 I e' <,
B_~I-e--
° -G:- -==- ~--June
Figure 4.4.2.12
,-------------------,-- h -------------- IJuly August Sept.
The effects of variety (V) and physiological age
(PA) on leaf number contributed by the differant types of stems,excluding the leaves coming from the axillary branches. SED onthe right side is to be used for comparing means within samelevel;:;of V or PA. Residual degrees of freedom is41.Key: ---, main stem; ----, branch stem.
1025
1000.
II
o 15~I
0501
III025
Variety
SEDsIIIIII
.0/
/./ B-- --..-0
-- e- ./
o 00-"-------·--,---·---------···---1---··--- .---.--------..-----
..s 102 5l
Physiological age.,.,Ul
IHtilQ)H
1000
050
025
000Sept.
Figure 4.4.2.13 The effects of variety (V) and physiologicalage (PA) on leaf size (leaves coming from the axillarybranches were not included). For meaning of SEDs, symbolsand residual degrees of freedom see figure 4.4.2.12.
,
I
20 10~
I104°1
i
01°1o ooJ_--~~~---'-T~~----'----~----'~-----~--'---T~'--"-~-~--------
3 050_Ii
iII
2 a 801
0'r-!+'ajH
S 3050_,OJ+'en i0 I+' I'\-i Iaj
2 0 80~OJH
II
2010JIi,iI
1040J
i
010
000
-,-,
'M- --- .";' \
\\ ..0
'13- .--- -- B- -- --e- ./
Variety
I III II
Physiological age
IIII II SEDsB - --H- - -:-
//
........... -=- - - -e- ---'& - "'"
..e---8---B---
-----~----------T· ~--._._-_.._._...._-
June July
Figure 4.4.2.14.
I ~--r--Sept.August
The effects of variety (V) and physiologicalage (PA) on leaf to stem ratio (dry weight basis). Formeaning of SEDs, symbols and residual degrees of freedomsee figure 4.4.2.12.
Pentland Crown
30 Multi
24
18
~I
~+'Ul
Multi
18_
12
6
O-'---r-----,----------,--JuJ.,y Aug.
Apical
Record30,
I Apical
24.
18
I II(2)
0._-.-July Aug.
Figure 4.4.2.15 The effects of variety (V) and physiologicalage (PA) on stem size.Key:_, main stem;for comparing means within same levels of V or PA.
branch stem. SEDs (2) is to be used
Variety I80 I
I I IB-
/ I I'10 I I_-8'- \.
f Q_ \1 I I60 I p- \/ tJ SEDs
~30.
r / 0 Pentland Crown40 I 0 Record
<. y3D
80
10.
60
50
{.o
Physiological age
o Multio Apical
3 0 _~ ~
80
'10
60
50
{.o
30_ rj
. r------ --_ ... _-_ ...._---,- ----~-- - .... -- 1
Spacing
p./
.0--
oo
/-----..~·---..-----I------ ..-----~----.--
June July Sept.August
Figure 4.4.2.16 The effects of variety, physiological age andspacing on photosynthetically active radiation (PAR) interception.
1050 Variety
eos:1'rl+>(I)
ria;ro :>s:1 H
I'rl ror:r..::r::rSEDs0
II 0
B'-'...---
0 Pentland Crown0 Record
8{'0
{'20
630
210
1050_ Physiological age-)
-El
8{'0 B./
.Er630 -:
C\J ../I
Gb .>{'20 -+>..c: /'eo 210 if''rla; ,/ 0 Multi~~ .s 0 ApicalH ~'d 0 /'
Ha;..0;:l8 1050
l Spacing0
8{,OJ -El./' 0
I»>
630 '7.0
/'
{'20/'210 -: 0 30cm
0 0 40cm
June July August Sept.
Figure 4.4.2.17 The effects of variety, physiological age andspacing on tuber dry weight.
Variety
120! I I
~ -. -El" I I I/ '8- _ -B- _ +:l- __ II/ i3---EJ
~
i90_!
I
!iI
6°-i
I
30. 0o Pentland Crowno Record
-120_ Physiological age
90.
"HOJ@ 30~HOJ
.g 08 -----------1.------ --.-- --r------- ---------r----.---
o Multio Apical
120
30
50
30 o 30cm
o 40cm
o ----TJune
-- ----------·1-----·----- -------r-July August Sept.
Figure 4.4.2.18 The effect of variety, physiological age andspacing on tuber number.
=<: SEDs[J
8
on
Key: Q,Pentland Crown; 0, Record; open symbols, apical;closed symbols, multi.
60
C\J 50IS.. •HQ)
0~~ 40H •Q)
.gE-t
30~----~~------~~----~10 15 ~g
Stem number, m25
60
C\JI
S50
..HQ)
~ 40~HQ),.0~E-t
3035 40 45 50 55
LAD/TI30
Q
•800~.------~------r-----~125 150 175 200
LAD
Figure 4.4.2.19 The relationshipbetween total stem number (SN) (main& branch) ~nd total tuber number (TN).TN = 2.86(~8.45)+2.10(~0.42)SN%variance accounted for 77.4residual standard deviation = 5.12.
Figure 4.4.2.20 The relationshipbetween leaf area duration accumulatedfor a period of 30 days from the dateof tuber initiation (LAD/TI30) andtotal tuber number (TN).TN=10.44(~4.84)+1.32(~0.10)LAD/TI30for Record andTN=18.15(~7.23)+0.38(~0.15)LAD/TI30for Pentland Crown.% variance accounted for 98.8residual standard deviation = 1.14.
Figure 4.4.2.21 The relationshipbetween leaf area duration (LAD) andtotal tuber dry weight (TW).TW= 517.57(~123.58)+2.56(~0.75)LAD% variance accounted for 60.0residual standard deviation = 55.74 •
7000
C\J •I 600E; •~0
"
!400MQ)
>0oj.)
~ TG = 205.72 (~ 74.66) + 15.82 (~ 4.42) LAD/AB• r-i 300 •Q)::t • % variance accounted for 62.8t: • residual standard deviation = 130.03.'lj
MQ).0 100e:!
o 5 10 15 20 25 30 35LAD/AB
Figure 4.4.2.23 The relationship between tuber dry weight over 57mm(TG) and leaf area duration contributed by the axillary branches(LAD/AB). For meanlng of symbols see figure 4.4.2.19.
Variety ISEDs1250I
1000 I I
I .8-- --El150 »:
./I ...BI ./500.
:t: 0 Pentland Crown250 :I
0 Record
0
1250~Physiological age
1000
150........-:
.H
500C\JI 250So
0 Multi"~
0 Apical~ 08
_-El
1250 Spacing
1000 ___ -El
150 /'-Erc--
500 --:/'"250 ./0 30cm0 40cm0 --"-----_.-
TJune July August Sept.Figure 4.4.2.24 The effects of variety, physiological age and
spacing on total dry weight (TDW).
Variety SEDs80
15
I_B--
/T/lY
'15
60L;.5
30 o Pentland Crowno Record
~-~-~-~~-~--~-r:------------.-~-
80'15
60~E--i
45Ct-i0
1j 300
1-1Q) '15,0;::!+'
* 0
Phys~ological age
o Multio Apical
80 Spacing
'15
6045l
30~15
o 30cmo 40cm
O·-l.---H=-----,r--------·T---------July August Sept.June
Figure 4.4.2.25 The effects of variety, physiological age andspacing on percentages of tubersout of total dry weight (TDW)(on dry weight basis).
The effects of mix i t::; seed tubers of differentphysio-
Log i cc.L ~tge on: i.o. of dc~:ys from 9Lmting to tube r ini ti.at-
Lou ('rI) ('rIFP)j I.o , of d.iye from emer-gence to 'El ('l'IF~);
;:0. of duys from~)l:J.ntir:g to se ne scence ; (SEI':P) main stem
number (HSTL); Br-unch stem number (JJSffiJ) j number of axillary
brunche s (I.B).
TlFP rrr.: S·'c.:D ' 'cT" Dt"''l''l~~,,Jj, ... l"l0_~ .uu -2
m m m'I'r ea tmen t
Ap i c al, 53.6'(' n.3Lt 161.00 10.15 16.05 26.03
Multi 54.00 21.00 162.6'7 1'7.59 6.58 30.33
Cold 64.00 26.00 -:61.6'/ 1'7.28 5.11 1'?63
,\+t:: 25 53.67 20.67 158.00 1'7.65 1l~.38 17.65
A+I'l ;6 53.00 19.67 156.67 14.02 10.83 22.04
A+C 25 59.33 ~7 '2:7- 160.6'7 20.41 11.37 18.23C~) • ././
i;+C 36 58.17 21.03 161.67 12.42 9.60 25.32
H+C 25 5S.83 23.56 15'7.00 22.39 4.39 29.71
l·j+C 36 SE.oo 21.6'7 159.6'/ 18.33 3.44 23.27
SED 0.7'78 1.092 3.031 1.09 1.92 5.06
In exueriment F3, 3 tubers of each treatment were dug up before
emergence to study the growth rate of snr-outs after planting. vii th
Table 4.4.3.2. The effects of physiological age arid sprouting treatments
on total sprout length after planting but before emergence (Exp.F3).
Total sprout Leng th, mm tuber -1
Date 21/4 30/4 21/4 30/4
Treatment Treatment
Apical 79.5 121 Fast 79.4 204
Multi 87.5 251 Slow 87.4 167
SED 13.68 58.1 13.68 58.1
availability of moisture and nutrients after planting, extension rate
of sprouts was increased in all treatments ('l'~ble1~.4.3.2 and Fig.4.4.1.2),
and so the initial difference in length of the largest sprout between
apical and multi of various experiments (Table 4.4.1.6 a,b) did not
affect the emergence. NumberE of main sprouts were greater in multi
and so this treatment had higher total extension rate of sprouts than
apical after planting (Table 4.4.3.2), while the higher extension rate
,of fast (Fig.4.4.1.3) was not maintained in the field (Table 4.4.3.2).As a result there was no difference in emergence due to sprouting treat-
ments (Fig.4.4.3.2). In case of multi the growth rate of sprout weight
was also higher (Fig.4.4.3.3) mainly due to a larger number of sprouts.
Due to increase in extension rate of sprouts, specific sprout weight
was decreased after planting in all treatments (Fig.4.4.3.3). Apicalhad higher specific sprout weight because sprouts were thicker than
')3
those of multi. Mixing of different physiologically aged tubers or
different seed sizes (Bxp , F2, F4) did not affect the emergence. There
was no significant difference in stem numbers between different dates
of growth ar.alyses in all the experiments, and so they were averaged
for various dates of growth analyses until the middle of August for
after that they started to die. Like experiment F1, apical increased
branch stems, compared to multi in both experiments F2 and F3
(Table 4.4.3.1 and Fig.4.4.3.2), but the proportion of increase was
more in experiment F2 compared to F3 and total stem numbers were
increased in F2 and decreased in F3. Planting at closer spacings and
using bigger seed size incre~sed total stem number per unit area
(Table 4.4.3.1 and Fig. 4.4.3.1). 'Mixing of different type of seeds
and sprouting treatments did not affect the stem number or their type
(Table 4.4.3.1 and Fig.4.4.3.1). Numbers of axillary branches (AB)
were averaged for various dates of growth analyses after they stopped
increasing in number. Cold had lower number of AB compared to multi
(Table 4.4.3.1), this may be because emergence was more homogenous in
cold (Fig.4.4.3.1). Apical, in experiment F2 decreased the number of
AB (Table 4.4.3.1) while in F3 it increased (34.9,m-2) compared to
multi (25.4,m-2), this may be explained by the f3.ct that apical increased
the total stem number in F2 and decreased in F3, thus lateral buds in
F2 may have been ~haded more. On em overall basis over 90 per cent of
the AB present were contributed by the main stems which may be due to
two reasons: firstly, branch stems were lower in number (Table 4.4.3.1
and Fig.4.4.3.2) and secondly they were smaller in size (Fig.4.4.3.26),
and thus may have emerged later, so their lateral buds were shaded and
stayed dormant. In fact most of the effect appears to be due to the
sec.ond reason because numbers of AB con tributed by the branch stems
were not in proportion to their total aumbers. For example in apical
(Exp. F2) the numbers of branch stems were more than the main still
main stems contributed aoout 85% of the totd.lAB present. This is also
supported by the fact that in case of mixing different physiologically
aged seed where cold VIas one of the compone nts , cold only contributed
23% of the AB present, because it emerged later, so its lateral buds
were shaded by the plants those emerged before it. As in 1979(Bxp , F1) a linear relationship was found bet\Veen leaf area duration
accumulated for a period of 30 days from the date of 50 per cent
emergence and the number of AB present (Fig.4.4.3.9). Data shown inthis Figure is from experiments F2 and F3 and every point is average
for 3 replicates.
4.4.3.2 Stolon growth and development
Cold and S25 increased stolon we igh t (Fig.4.4.3.4 and 4.4.3.7)
for a longer time and this may be due to delay in '1'1(Chapter 4.4.3.5).
Stolon numbers were :.I.lsohigher in these treatmen t.a. (Figs.4.4.3.5 and
4.4.3.7). Stolon gr-owth slowed down after T1 in :111 the three experi-
ments. l-lixingof differen t type of seeds and sprouting treatments did
not affect the stolon weight or their number (Figs.4.4.3.4; 4.4.3.5;
4.4.3.6; 4.4.3.7). As in 1979 (F1), a positive linear relationship
was found between LAl and stolon dry weight for all the 'three experi--1ments (Fig.4.4.3.8), until tuber dry weight of 19 plant was reached.
Data in Fig.4.4.3.8 is from all the three experiments and every point
is average for 3 replicates.
4.4.3.3 Growth :md development of stem C:l.ndLeaf,
As in the previous year ma.i.nstems were slightly longer than the
branch stems, but overall plant height ',lasnot affected by any treat-
ment (Figs.4.4.3.10; 4,4,3,11; 4.4.3.12), except that early in the
season plants were smaller in cold and 825 treatments because they
emerged later.
Due to this their stem weight was also lower early in the season
(Figs.4.4.3.12 and 4.4.3.13). Increase in stem numbers per unit area,
either by planting at closer spacing or by using bigger seed size,
increased the stem weight per unit area, while other treatments did
not affect it (Figs.4.4.3.12; 4.4.3.13; 4.4.3.14; 4.4.3.15).
Increase in stem number [{Iso increased the LAI early in the season.
(Figs.4.4.3.16 and 4.4.3.19). Cold (Experiment F2) emerged later
(Fig.4.4.3.1) so had lower LAI early in the season compared to
Apical and Mul ti when considered from the date of planting, but
there was no difference when considered from the date of 50;C; emergence,
for example after 15 days of emergence multi had LAI of 0.7 compared
to 0.99 for cold and after 30 days of emergence multi and cold had LAlof 3.32 and 3.33 respectively. 825 (Experiment F4) also had lower LAlearly in the season (Fig.4.4.3.19), compared to other treatments in
-that experiment, which was affected in two ways: firstly it emerged
late and secondly it had lower total stem numbers (Fig.4.4.3.1).
In mixed treatments where" cold or 825 was one of the two components,
LAI early in the season was lower (Figs.4.4.3.16 and 4.4.3.19).
Competition between different components within plot is presented later
(Chapter 4.4.4.). Physiological age and sprouting treatments did not
differ in experiment F3 (Fig.4.4.3.18).
After about 70 days from planting in all the 3 experiments LAI
was over 4.0 and effects due to different treatments disappeared
(Figs.4.4.3.16; 4.4.3.18; 4.4.3.19). In experiments, F2 and F3
senescence of the canopy was not significantly affected by any treat-
ment, thus there was no great difference between different treatments
in the decline of LAI. In eyperiment F4,S25 stayed green for 16 days
after other treatments had senesced wid thus had higher LAI later in
the season. For example after 149 days of planting it had LAI of 1.73
and B36 had only 0.25 (Fig.4.4.3.19). Although physiological age
(apical, multi) did not affect the LAI but the proportion contributed
by different types of stems was affected. For example in experiment F2,
main stems of apical, multi and cold contributed 62, 91 and 97}~of the
total LAI respectively. In experiment F3 these figures were 83 and 96
percent for apical and multi respectively. Difference between the
results of experiments may be explained by the different sources of
seed wh ich affected the type of stems Crable 4.4.3.1 and Fig.4.4.3.2).
Other treatments such as mixing of different types of seed (Exp. F2)
a~d sprouting (Exp. F3) did not affect the proportion of LAI contributed
by different types of stems. As in 1979, the size of AB was studied by
working out their LAI (LAI'AB) separately. LAI'AB was decreased by
cold and planting at closer spacing (Fig.4.4.3.17), these treatments
decreased the number of AB also. In Experiment F3, apical had higher
number of AB and thus had higher LAI'AB compared to multi (Fig.4.4.3.21)
while sprouting treatment showed no effect.
In gener-al,over 90 percent of the LAI 'AB in both experiments F2
and F3 was contributed by the AB present on the main stems. Number of
leaves present on the AB were proportional to LAI 'AB. Apart from leaves
coming from the AB, treatments those increased tota.l stem number also
(1/
increased leaf numbers, for example, pl an t ing at closer spacing in
Experiments F2 and F4 and use of big seed size in Experiment F4
(Figs.4.4.3.22 and 4.4.3.19). Physiological age (apical, multi, cold)
did not affect the total leaf number except that cold emerged later and
thus had lower leaf numbers early in the season; but the important
result was that the leaves contributed by different types of stems wereaffected. In apical branch stems contributed a higher proportion of
leaves, wh i.Lein multi and cold most of the leaves were contributed by
their main stems (Fig.4.4.3.23).
Size of the leaves coming from the AB was not affected by any
treatment but their size \oJasmuch smaller than those coming straight
from the main stems. Thus average leaf size for main and branch stems
presented in Figure 4.4.3.24 was calculated w i thou t including the leaves
coming from the AB. In all the treatments leaves present on the main
stems were much bigger than those present on the branch stems. Leaves
"present on the br-anch stems of cold were srnal Leat i:l s ice, Differences
in leaf size resulted in differential values for leaf to stem ratios
for different types of stems (Fig.4.4.3.25) leaf to stem ratio decreased
as the season advanced due to increase in stem length. This ratio was
higher for main stems than for branch stems apparently because the
latter were smaller in size and so wer-emore affected by interstem
competi tion. Increase in stem number-s decreased the leaf to stem ratio
(Fig.4.4.3.2(7).
Specific Leaf area in Experiment F2 was only slightly affected by
interstem competition, increased by pLan t i.ngat closer spacings andwas not affected in Experiment F3. Thus leaf dry weight was prop-
ortional to their LAI (Figs.4.4.3.18 and 4.4.3.20). In Experiment F4
due to greater difference in stem number specific leaf area was increased
with increase in stem numbers (Fig.4.4.3.19). As in Experiment F1,
the size of different type of stems was studied in Experiment F2 and
F3 and the results are presented as leaf area per stem (Fig.4.4.3. ~).
Main stems in general were much bigger than the br-anch stems, owing to
increased leaf size and the presence of higher numbers of AB. Apical
increased the size of branch stems compared to cold and multi
(Fig.4.4.3.26) and this difference was consistent throughout the season.
Mixing of different physiologically aged tubers or sprouting treatments
did not affect the size of specific types of stems.
Light interception (LVEarly in the season the effects of treatments on photosynthetically
active radiation (PAR) interception were similar to their effects on
LAI.
The relationship betweeriLAl and LI is presented later (Chapter
4.4.6). Cold and S25 intercepted less PAR early in the season because
they emerged later and had lower LAl. Increase in stem number due to
closer planting or the use of big seed increased PAR interception until·
about 65 days after planting. About 90 percent and most of the times
over 90 percent of the PAR waa intercepted by the canopy of all treat-
ments during the middle part of the growing season (65 to 120 days)
and differences dJ,leto treatments disappeured (Figs.4.4.3.27; 4.4.3.28;4.4.3.29).
4.4.3.5 Tuber growth and deveLopmerrt:
Tuber initiation (Tl) was calculated by interpolation from growth
analyses and additional sampling data, taken during early growth of the
I)')
crop. Cold and S25 delayed TI for 4 to 5 d.iys when considered from
the date of 50% emergence. Thus apr-outi.ng tubers before planting
may have increased the tuberization stimulus. TI for mixed treatments,
in which cold or S25 was one of the two components, \oI:1.S calculated
separately for the different type of plants and then averaged to obtain
a figure for that treatment. Apical or multi sprouting treatments and
mixing of different type of seeds did not affect the date of TI.
In Experiment F2, cold increased tuber number over apical and
mul,ti and the effect \>I(1S more Lmmed iateLy after TI compared to final
harvesting (Fig.1+.4.3.30). This may be explained by the fact that LA!
at the time of TI in cold (2.69) was hi3her compared to apical or
multi (1.74), thus higher numbe r of tubers initiated but this difference
did not last very long due to better growing conditions (higher rain-
fall, Fig.3.3.1). As growth rate was very high, it did not take very
long to reach LAI of 4.0 when most of the incoming radiation was being
intercepted. In apical LAI of 4.0 "IDB reached after 14 days of TI
while in mul ti 3.11dcold it reached after 12 and 8 days of TI respect-
ively. Therefore assimilates available for the development of the
tubers after 14 days of TI may be similar in all the three treatments,
but cold had initiated more tubers and so the percentage survival of
tubers was more in apical and multi compared to cold. Similarly as
in Experiment F2 ~25 had higher LAI (2.8) at the time of T! compared
to B36 (2.40) thus S25 initiated higher number of tubers but percent-
age survival \'las.more in B36. Apical and multi did not differ sig-
nific~~tly, but multi had higher number~ of tubers and this differencewas consistent throughout the season (Figs.4.4.3.30 and 4.4.3.31).
Planting at closer spacings also increased tuber numbers which may be
attributed to the greater LAI at the time of TI (Figs.4.lt.3.30 & 4.4.3.32).
1()!)
Grading of tubers showed that tubers which did not survive never attain-
ed a size of 25mm diameter and most of them did not attain the size of
10mm (Figs.4.4.3.30j 4.4.3.31; 4.4.3.32). Some wrinkled tubers and
f'ewin the process of shrivelling were found especially at the last
two harvests. As in 1979, a linear relationship between total stem
numbers (main + brwlch) and tuber numbers was found. Linear regress-
ion between them accounted 31% of the variance. S25 and cold appeared
different from other points, may be due to different physiological
s~atus of the seed.excluding only S25 from the regression, improved
the linear relationship (accounted 43.5% of the variance (Fig.4.4.3.}6) ).
Data in Figure 4.4.3.36 is from all the three experiments (F1, F2, F3)
and every point is ~~ average for 3 replicates. Since stem number do
not t3ke any account of stem size, thus regression equation between
tuber number and LAD, accumulated for a period of 30 days from the date
of TI accounted more variance (53.6%) and r-emoval,.of S25 from the
regression improved the liLear relationship (accounted 60%.variance)
(Fig.4.4.3.37). Data in Figure 4.4.3.37 is from all the 3 experiments
(F1, F2, F3) and every point is an average for replicates. Cold treat-
ment in Experiment F2 initiated tubers later than the apical and multi,
thus had lower tuber '{leight early in the season but when considered
from the date of TI there was no difference. For example after 12 days-2of TI, cold, multi and apical yielded 78.3, 88.7 al1d87.8g m respect-
ively. Similarly after 26 days of TI their yield was 352, 329.8 and-2 .326.6g m respectively. S25 in Experiment F4 also gave lower yields
early in the season, This effect was not only due to delay in TI but
this t.r-eatmen t also had a much lower LAl but then it senesced later.', than other treatments and so the final tuber yield vJUS not less.
Other treatments did not differ si.gni.f Lc.an t.Ly but planting at closer
1 U1
spacing in Experiment F2 and F4 and api ce.L in Experiment F3 gave con";
sistently higher tuber weights during the growing season (Figs.4.4.3.31j
4.4.3.32; 4.4.3.33). As in Experiment F1 (1979), tuber weight was
related to LAD, wh ich accounted30)j of the variance (Fig.4.4.3.43).
Data in Figure 4.4.3.43 is from all the three experiments and every
point is average for 3 replicates. Tuber yield per unit of LAD was
4.3, which is lower than in 1979. This may be due to higher rainfall
during 1980 which stimulated more haulm growth. Tuber yield is usually
~elatedto LAD, calculated by assuming LAI over 3.0 as 3.0 (LAD'3)
(Bremner and Radley, 1966; Bremner illldTaha, 1966; Gunasena and Harris,
1968; Choudhury, 1980). 'I'hia relationship was examined here. Linear
relationship between LAD'3 and tuber we igh t accounted only 6 percent of
the variance and "'/asnot significant (tuber weight = 1038.57Ct 343.29) +
1.81(~ 1.28) LAD'3, RSD = 90.6). This may be due to the reason that
PAR interception was still increasing with increase in LAI over 3.0
(Chapter 4.4.6). Al though there was not much increase .in PAR inter-
ception with increase in LAI after 4.0, even than assuming the LAI over 4.0
did not give the significant linear relation between tuber weight (TW)
and LAD'4(T'v1 = 982.95(:' 310.16) + 1.64(:' 0.94) LAD'4, RSD = 87.89).
This may be explained by the fact that although there was no increase
in PAR interception with increase in LAI after 4.0 conversion efficiency
of the canopy was, improving (Chapter 4.4.6).
TNber size grades are of practical importance. Percentages of
various size grades for two dates of growth analyses in addition to
final harvesting are presented for all the three experiments (Table 4.4.3.3,
Figs.4.4.3.34 and 4.4.3.35). Similar results were obtained for other
.'. dates of gr-owth analyses not presented here. For simplification in
some cases tuber weight less than 35 or 38mm is not presented as their
1U2
proportion was low (most of the time less than 2%) and there was no
difference between treatments. In Experiment F2 the cold treatment had
higher tuber numbers compared to apical and multi thus assimilates
available for the growth of individual tuber wer-e lower, and this
resulted in higher proportioLs of medium sized tubers. For examnle at
final harvesting cold had only 3.6 percent of tubers over 76mm wh iLe
this figure for apical and multi was 19.9 and 21.3 percent respectively.
The percentages of 38,57mm tubers \'Jere25.3, 7.0 Qnd 9.8 percent for
cold, apical and multi repectively. Per-centages of 5?...76mm tubers did
not differ significantly among these treatments.S25 in Experiment F4
also gave increased proportions of medium sized tubers (Fig.4.4.3.35).
Apical and multi of Experiment F2 did not differ but in Experiment F3
multi gave a higher proportion of medium sized tubers compared to
apical maybe because multi increased total stem number in Experiment F3.
Planting at closer spacing in Experiment F2 increased tuber numbers
and this resulted in a higher proportion of medium sized tubers
(Table 4.4.3.3). In Experiment F4, planting at closer spacing only
slightly increased the tuber number ill1ddid not affect the tuber size
grades. Tuber size over 76mm was related to leaf area dur3.tion con-
tributed by the AB, and linear regression between them accounted for.45% of
the variance (Fig.4.4.3.38). Data in Figure 4.4.3.38 is from experiments
F2 and F3 and every point is average for 3 replicates.
4.4.3.~ Total dry matter accumulation
Roots were not collected and those present on the stems and stolons
were removed and discarded; thus total dry wei.ght (Tm-J) figures which
are presented exclude roots. By the end of June leaves started to fall
103
off and these were not collected from the ground. TmJ figures presented
in this chapter also exclude those leaves. Cold and S25 treatments
had lower 'I'm!because they emerged later. Planting at closer spacing
had consistently higher TD\'J throughout the season, wh i.Leother treat-
ments did not affect it (Figs.4.4.3.39; 4.4.3.41; 4.4.3.42). As in
1979, (Exp, F1) the ~ercentages of various components wer-e worked out
for these experiments. Cold and S25 recorded a lower percentage of
tubers out of TD'd (Figs.4.4.3.40 and 4.4.3.42) when considered from
tbe date of planting. But when considered from the date of T1 there
was no difference. For exumple after 12 days from T1 cold had 18.7
percent .of tubers, out of 'I'DHwhile this figure for apical and multi
was 20.8 and 20.9 respectively. Similarly after 26 days from T1 cold
had 45.8 percent of tubers while apical and multi had 47.2 and 43.9
percent respectively. Other treatments did not affect the percentage
distribution of 'I'DV!but apical of Experiment F3 did record a consist-
ently higher percentage of Dlv in tubers compar-ed to multi, but the
difference was not significant on any date (Fig.4.4.3.41).
4.4.4 Competition between two components within plot.
In experiment F2 there was mo intera.ction between apical and multi,
'so results are presented as sprouted and cold (average for apical and
multi). Similarly in Experiment F4 there Vias no interaction between
2 spacings used and so the results presented for that experiment are
averaged for 2 spacings. In all the three experiments statistical
analyses were car-ried out CtS split plot design taking two components,',
(sprouted and cold) within plot as sub plot and residual degrees of
freedom (RDF) is given on the figures itself. RDF for SED No. 5,6 of
'I'abl.e 4.l~.3•.3. The ci I'e c Ls of mix.LIIG seed Lubers of different
physiologic:l!. itge or: pe r-ce n t,JGc of tubers in different
s i ze gr ..ide s out of to tal, tuber we igh t ,
D:J.;{s after 90 121 Final harvestingplanting
Size (mm) <35 35-45 <45 35-60 >60 38-57 57-76 >76'I'r-e a tmen t
A:pical (A) 2.5 15.0 82.5 11+.4 84.4 '1.0 72.9 19.9
Hulti (H) 1.lj. 18.0 80.6 211-.1 '15.3 9.8 68.7 21.3
Cold (C) 19.7 65.2 15.1 '73.6 24.7 25.3 70.4 3.6
A+E 25 4.0 14.6 81.4 42.9 56.1 17.6 72.4 9.5
1'.+1-1 36 2.6 20.1 7'1.3 24.0 75.2 7.6 75.6 16.5
A+C 25 11.3 16.7 72.0 53.7 44.5 23.6 68.7 7.0
A+C 36 10.3 18.1 '71.6 33.6 65.2 18.0 68.6 13.0
M+C 25 18.8 20.6 60.6 60.5 37.9 29.1 63.8 6.3-
N+C 36 10.1 21.1 6B.8 35.6 63.4 23.3 66.1 10.2
SED 3.28 5.94 6.22 '7.40 7.26 4.42 4.69 3.73
.'.
40_
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32~I
i
Experiment F2o Apicalo Multib Cold
i
24!-"1
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15.Ji
I TI SEDs
HDate of 50% emergenceand its SED.
C\J --lI
s
I I SEDs...1-t 4o_, F4(J) Experiment
II0 Stem number
~ 0 B36~ 0 Averaged overi s: S25 I various growthS i
(J)
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i + B+S36 III
I
241 XlI
I161
lIII
8~
0 ,-L, r7 12 17 22 27 1 6May June
"
Figure 4.4.3.1 The effects of physiological age on emergence.
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o Apicalo Multi
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Figure 4.4.3.2
fJ
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Stem numberaveraged overvarious growthanalyses.
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o
o1GJ
II
I
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9 14 19May
treatments on emergence .The effects of physiological age and sprouting
.-I 0 Apical
f-< 350_ .QJ ,0 Mu.lt ;.g+'
eo 280JS I
I
!+'ih'M 210 iQJ _,~
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~ 0~ 70~E-t I planting
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Jan. Feb. March April
Figure 4.4.3.3
QIIIII¢
o Apical
I3 0 GO, 0 Multi+ Slow*" Fast
3008.
~1 0 52~ T G-~
OJ1o ooL,___--.-- T_L~Jan. Feb. March April
The effects of physiological age and sproutingtreatments on specific sprout weight (SP8W) and the effectsof physiological age on sprout weight. Vertical bars areSEDs for last 3 dates and SE of mean for first two dates ofsmeasurements.
\0 \0 \0(Y") (Y) (Y")
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ill ' J:ClqumU uOTo,+Sc;-
Stolon dry weight8.5 8.5
SEDs6.8 6.8
C\JIEleo..5.1 5.1
+>..c::bO'r-!OJ~>. 3.4 3.4~'CJ Apical>=1
0 0 Slow0 Multirl .0 0 Fast0 1.7 1.7+>U,)
Stolon number340 340
A I.I -,300 6 -, 300
-,C\JI 260 260El..~(J)
.02 220 -, 220>=1 'b0rlo·+> 0 Apical 0 SlowtQ 180 180
0 Multi 0 FastI
140 140 6June July Aug. June July Aug.
Figure 4.4.3.6 The effects of physiological age and sproutingtreatments on stolon dry weight and stolon number (Experiment F3) .
...
oJune July Aug.
O~-------'--------r-------June July Aug.
.b- ___
- / ----- ---/ -~ - - ---- - ~._ - - - - - - - El/..... ------- ~-....;::::
// ------:_--::_
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II //
o ///x:' //
f{O-'-r---------·----··--T----··------ ----------1·-------June July August
Figure 4.4.3.7 The effects of mixing seed tubers of different Slzes onstolon dry weight and stolon numb~r (Experiment F4)
~/- 6 ./
/~
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Q)
~240
s::s:: 1600rl0+' 80UJ
Key:
C\JIStlO
I
030
015
.b-........__./_./-- IX ........__~ SEDs/' A" ~G _ -/ /,' '~... ........_ -X
/ /' / "'-_ ____....._I Y/' -_;:.---~ - - __~
/ I f{ 'X'- - - ________I~ B
/ I
:r 1/1. / I I[JIIxl
l--rI-ft.K!r--·------_··-·---------,----- -.----..--.------------ -·----T-- -----June July August
II/
/
I I
/
o ,B36; /).,825; o ,B+825; +, B+836.
-:oy = - 0.686 (~0.274) + 3.555 (~0.25l)x% variance accounted for 85.4residual standard deviation = 0.741.
LAIFigure 4.4.3.8 The relationship between LAI and stolon dry weight.
Data is average for replicates and is from experiments: F2,qF3,AF4,0.
I SEDs110
10
I0-
///
/~I#
I90
ElC)
50o Apicalo Multi
/
/1O......,_-------T----------- --- I
July
30
June August
Figure 4.4.3.10 The effects of physiological age on average plantheight (Experiment F3).
35'1Ii130 lI
C\J II IEl I
I.. 251p:j«: lt+-t
,
0
1-<. (J).0 '"~z
15120
,_)
y = 46.20 (~ 5.87) - 0.558 (~0.154)x% variance accounted for 50.2,residual
o standard deviation = 4.12
oo
o
-'--'-r ----.--r--'~~-~-T~---- ---,~--~---'I---~-I25 30 35 (,0 4'5 :SO ~):)
LAD/E30Figure 4.4.3.9 The relationship between number of axillary branches (AB)
and leaf area duration accumulated over a period of 30 days from thedate of 50% emergence (LAD/E30) . Data is from experiments: F2, 0 ; F3, J::,.
ISEDsElCJ
105_ I
!0- - --------~:-?-::----~
.~ =r:>.cy .~-- .z>: _84 ," ----... .- ,/y-- -_/ -I .'.: G /'
63 I I //~- - ~-1 /-/- /
I /~ /421 f' /1 ",,;/ ."211 tt'/
o ~ _ -----1----------------- -- ---- --I ---------- ------------------,------
C\J
1Gb
250_
200_~I!
I
t.°lII
30_J
ISEDs
20~
-----------------T-------------------T-----July Aug.
Figure 4.4.3.12 .The effects of mixing seed tubers of different
size on average plant height, above ground (AGS) and under ground
(UGS) stem dry weight. Key: O,B36; b. ,825; O,B+S25; +,B+S36
(Experiment -F4) .
en~Ji:l(f)
I
t ~ Q! ~ 0II: Ul
L '"'Q)f------lI '§I +'
f----t :>, .-0rl Q);:J bO
, t-:> alI :>,r--i rl
rl\D \0 \0I al(Y) (Y) (Y)
I o::8 u UI Q) 'r-!+ + + I § bO<r: ~ ::8I 0I t-:> rl0 0 <l L 0'r-!
I------·~··-r·-·-·--~- ---'-r - -----r-- -- ----------- -[ ------------1 Ul
0 ci 0 0 0 0 Etn 0 tn 0 tn p.,N N \' \'
+'QQ)
'"'Q)
~~'r-!.-0
bO ~;:J 0<r:
bOQ
'r-!><'r-!S:>,.-0
i 3 Qt-:> al
IC\J
Q) r:r...... bO! al +'l1'\ l1'\ l1'\ , Q(',J C\J C\JI Q) rl Q):r u u : § al S+ + l~o 'r-!< <r: ::8 'r-! '"'bO Q)
0 0 <l 0 p.,rl ><0 M,--------------,----------------T-- --- ----, ,-------1 'r-!0 0 0 0 0 0 Ultn 0 tn 0 L0 :>, +'N N " \' .c: .c:p., bO
'r-!~ Q)
0 )
Ul t>+'o .-0Q). ~
bO ~ Cf.l
.fJ Q) b~Q)
~ m+'Ul
:>,rl CV) .-0::I rl §t-:> ·CV) 0· '"'-::t bO·rl
-::t Q)al 'r-!>-tJ +' .-0
Q) 0'r-! rl rlQ Q)
~p., ;:J 0
;:J '"'<r: ::8 ut-:> ~.'0
0 0 <l 'r-!r:r..I 1 ----,-
e; ,_ _) I___l Cl 0tn 0 tn 0N N \' \'
ur:6 'SDV(;-
Ul1-1
'0f.LI
§U}
01---1,~
l-<+' Q)en '0;j §bO;j~ s:::
0
Ull-<Q)
.g» +'r-I;j '0
f-:J Q)bO
\D \D \D
Cl!(Y) (Y) (Y)
::B u u»+ + +r-I
~ ~ ::Br-I
Q) Cl!0 0 <l§ C)
'rlf-:J eo
0r-I0t.n CO \' 'rlen
(') C\J C\J»-&+'s:::Q)l-<Q)G-t
+' G-ten 'rl;j '0eo;j G-t~ 0
bOs:::'rl» ><
'3 'rlIS
f-:J'0s:::Cl!
l1'\ l1'\ l1'\(\J (\J (\J
Q)~ u U
bO+ +
Cl!~ ~ ::B
Q) al0 0 <l
§ C)
f-:J 'rlbO0t.nr-I0
(')
'rl (\Jen Ii.»..c1 +'P< s:::
Q)G-t IS0 'rl
l-<en Q)+' +' P<en C) ><;j Q) [::ijbO G-t;j G-t~ Q) +'
Q) it..c1 'rl8 Q)
~» »3 H
..::t '0r-_, r-Ir-ICl! 'rl
(Y) U)
'c) +' '0
c.?'rl r-I r-I
..::t !=>P< ;j 0
"'"~ ::B u
Q) ..::t§ IS
0 0 <lQ)
,f-:J Q) +'
S enbO'rlt.n
'-.j ("l- a Ii.(')
\'
ur 'iJ 'SDDc-
120 120
0 Apical o Slow~ 80 0 Multi 80 o Fasts~..CJl 40 40 .C,!)-<
20 20Apical 0 SlowMulti 0 Paat
~ 15 15El~..~ 10;::) 10
200Above ground stem(AGS)209
160160
o oJune July July Aug.JuneAug.
30Under ground stem(UGS)
30 .
25I SlIDe
25
5 5June July Aug. June July Aug.Figure 4.4.3.15 The effects of physiological age and sprouting
treatments on stem dry weight (Experiment F3).
\D \D \D(Y) (Y) (Y)
~+ u u+ +<:x: <:x: ~
o 0 <l
ir-, If\ tr-,
C\J C\J C\J
=f ;:' ;:'<:x: <:x: ~
o 0 <l
~-~.--[~N 0\' 0o 0
co'-Jo
1OMo
'-JNo
,---------, ...
\' 0 COo, ....1O '-JX 0 0 o o o o
'Clr-IoU
<l(])
§I-:l
·--..---~--·-·-··-T---·----I'-J NN \'
co'-Jo
CDM o
ooo o o
IV1
G-ioCIl~CJ(])G-iG-i(])
H
j
rJlH
bO QJ~ .g~
.p,I
'd:-QJeotU
» »rl rl~ rl\0 \0 lJ\f-;) tU(Y) (Y) C\J
i o:::s u u r~ or!+ + +bO~ ~ :::s0rl0 0 <l 0 C\Jor! ~f~-~-~----~ --- -- -r- --I ----T- -1 ~----------I rJl0 -,J OJ N CD 0 » .pCV) 0 r+ Ln N 0,_q s::P< QJ0 c 0 0 0 0 S\' \' .p or!s:: HQJ QJH P<QJ ><
CH I:iICH
I or!I 'df- lY!I CH ~! 0 <,
H! eo jbO s::~ or!~ ><or! rJl
S QJ,_q
'd tJs:: @
ItU
H» QJ p3 bO
i tU »lJ\ lJ\ lJ\
~
f-;) HC\J C\J C\Jrl tU~ u UtU rl+ +o rl~ c:r; :::s or! or!
QJ bO ~0 0 <lI § 0
rlr--- -- --~I I ~- ---T- --- - --1 ~---~--~~-------If-;) 0 QJ0 '-J" OJ C\J CD 0 or! ,_qrJl .pCV) 0 o- Ln N 0 »0 0 0 0 0 a ,_q »\' \' P< PCH 'd0 QJ
rJl ~.p PtJ or!QJ HCH .pCH s::QJ 0
tJQJ
bO~ ><~ QJc:r; 'ds::or!t-- rorl QJ
H» (Y) Cl!rl~ ...::t CHrlf-;) . Cl!tU or!
...::t Q)tJ .p 'drl
or! 3 rl
~ 0QJ s:::::s u
QJ
~0
0 0 <l §f-;) 'r!
.--.----.-~-- ~,-- I I -I ---~----~---~~I0 -,t CO C\1 co 0CV) (~) (-t- In (\..1 0(] u 0 0 0 0\' "
trif/IIf'I
LAl6 6
5 5
4 4 f
SEDs3 3
H
:!J2 2
0 Apical Slow0 Multi 0 Fast
o oJune July August June July August
160Leaf dry weight
160
SEDs
132
C\JI
1':1104eo"+>
~'(0 76~
t>'d~ 48cOQJN
o Apicalo Multi
7 DSlowo Fast
July
Figure 4~4.3.18 The effects of physiological age and sproutingtreatments on LAl and leaf dry weight (Experiment F3).
Hj
I
II SEDs
July I August ..--T--·-------Sept.
550,C\J II IS f. f.o,
i" I
3301~._l~ ,~ 22°1Cri I
~ 1'10 iH -
I o ....o -,
T
, // /T, / /
/ /o / J!.)(/ / /
/s
....
....
IT SEDs
o_-!~~--------~---~~----~~~~-----June July August lSept~
:r4 I\\ fr - - - - _ -b- Ir--/~___ - -_.J:idI\ 7' c B - / - B - - - -:..._-_=-= - 8 - .::.-: --a
\ I : - £/ -~-
1/// //\/k
SEDs
1--June July August
.--r- -- ------Sept.
Figure 4.4.3.19 The effects of mixing seed tubers of differentsizes on LAI, leaf number . and specific leaf area (SPLA)(Experiment F4).Key: O,B36; b. ,S25; D,B+S25;+,B+S36.
UJqI:Ll(j)
J I1
Ir-I+>
UJ::JbO::J~\0 \0 \0
(Y) (Y) (Y)
?f u u+ +
>.~ ~ ~30 0 <lt-:>
(j)
§t-:>
HI
ci-,c..) Cl C) CJ 0 0co I.II C\J Ul (J) CV),~ \~ ~
~+>UJ::JbO::J~If\ If\ ir-,
(\J (\J (\J~ u u+ + +< ~ ~0 0 <l
oDrloU
<l
,-.--------, ...- .. - ..- ......·T- ..···..- ..·-· -.,----, ....-- ..-- ..........------10000000co Ln (\J Ul (J) CV)~ ~ '\"
Cj...jcd(j)rl
s::0
UJ1-<(j)
.g+>oD(j)bOcd
>.rlrlcdo
'r-!eo0rl0'r-!UJ>.,.qp..
+>s::(j)1-<(j)
Cj...jCj...j'r-!oDCj...j0
eos::'r-!><'r-!SoD
~(l)eocd
~o
'r-!eo0rl0'r-!Ul
Ep..Cj...j0
Ul+> C\Jo Ii.(l)
Cj...j +>Cj...j s::(l) (j)s(l) 'r-!,.q 1-<E-t (l)
p..xIZ1
0(\J +>. ,.q(Y) bO
'r-!...:;t (j)
~...:;t
>.(l) 1-<1-< oD
61'r-!Ii.
0 Apical0 Multi
1035_
ii
1008JI
!I
o 81~I __ BI yri - B-I I
o 54~p::) I~ /<,
IH
;j o 21J /
oooJ/
YJ-.-----'---,-- r -~.---.-.--- -T-···----June July Aug.
0 Slow0 Fast
'1035
1n 08.j I SEDs
o 8'1_:
o 54_J ,
o 21~I
n ool ----.---.-r------------l---·····---June July Aug.
Figure 4.4.3.21 The effects of physiological age and sproutingtreatments on leaf area index contributed by the axillary branches(LAI/AB) (Experiment F3).
o A+M25o A+C25b. M+C25
450_
C\JIS
385,IiI
32011I
I
~ 190JQ) , - IH I12St.
June..---r---··------
JulyI -
Figure 4.4.3.22
]85~
o A+M36o A+C36b. M+C36
IJ20~
!II
I1)55 !G 'l
!I
190~ I
125_1~ _, --r-June JulyAug.
I I
ISEDs
,---Aug.
The effects of mlxlng seed tubers of differentphysiologically aged tubers on leaf number (Experiment F2).
54
(\J 210I S I
21G~!
Ii II152i
i!
'10SJ
5.4
Experiment F?
<,'N
-,-,
,R "/ \ -,\\\\
II SEDs
0._
//
.0./'
-:.e
./' --c-"'_./" -A---~- --7'1- ____0':--" ------- ..-_--- ·l-------------- .----T----·-·--~----
JulyJune August
Experiment F3
SEDsII
-_ -- -8-- - - - - -f=l- _ -_
---E)...... _---,-
Augusto c;:. "2"~-------Tn_u
June-'--1
July
Figure 4.4.3.23 The effects of physiological age (PA) on leafnumber contributed by the different types of stems, excludingthe leaves coming from the axillary branches. SED on the rightside is to be used for comparing means within same levels of PA.Residual degrees of freedom is 6 for experiment F2 and 8 forexperiment F3.Key: El,apical;O, multi; A,cold;--, main stem;---, branch stem.
\ \
2025_Ii
1035
II10 8 O_~
Experiment F3
"Q)N-r-i "U)
1080_] SEDs
1D 35_iI!
-------------.---------------------a-August
Figure 4.4.3.24 The effects of physiological age (PA) on leaf size of thedifferent types of stems (leaves coming from the axillary brancheswere not included). For meaning of SEDs, symbols and residualdegrees of freedom, see figure 4.4.3.23.
Experiment F2
2015
1062
o 0 0 ~---------------- --rJune
-TJuly August
Experiment F3.
~i,J 52
II1008
II II SEDe
June-----------------~----------_r
July August
Figure 4.4.3.25 The effects of physiological age on leaf to stemratio (dry weight basis) of different types of stems.For meaning of SEDs and residual degrees of freedom, seefigure 4.4.3.23.
Key: 0, apical; O,multi; 6., average for apical, multi and cold
I21J
r-l 35_I
IEl(])+"u: I
C\J IEl 28~'d
I"cd(]) Ir-.cd ICt-i 211cd(])H
II
141I
Experiment F2
SEDeII
7 I I
___ -""- __ -6- _o ~--~ _...l..-;-if!F.:..__-------------r-------------- ----------------l-----~-- ---r
June July August
Experiment F3
II II B>s
.8-_/' -
/' - _ -L,/' r-"......._/' ---B' B- --- ___
/ -- -- -- --- --- --- --- ""El/ _B-- --s./ -_
o [t-3/ ---""0:---r~--------- ----------[-------------------- --_---I ------- ------------- __ ~
June July August
Figure 4.4.3.26 The effects of physiological age on stem Slze.For meanlng of SEDs, symbols and residual degrees of freedom,see figu~e ~.4.3.23.
I1\\\ I\\\\-,-,-,
2 C(,D.) J....
IIi
I2 0 OO~
II
0
10501OJ I
~ 1000-1(j) I+' ,(f) I
050
June---'-',--'---..-...-.--·------ ..-·--·--1..--------"--'-'--'-'---'T---
July August Sept.
I
'2°i,
O-!-,r-------~~_.------_ ---r---- ---June July August Sept.
Figure 4.4.3.27 The effects of mixing seed tubers of different
SEDs
SEDs
sizes on leaf to stem ratio (dry weight basis) and photosyntheticallyactive radiation interception (PAR) (Experiment F4).Key: 0 ,B36; ~ ,S25; D,B+S25; +,B+S36.
i!
8°1II
601
1I
IIII!40.~ ':
i 9, IDI i
s:: I 'I/ /o I' /'M I 0/;.> I _j~ 2O_-q~--------~-'---r'--'"'-_'---"'-"··-··-··-··-····-r··---··----··-·-·-----T----·--···-··HQ)
;.>s::'M
80~i
60JI
;
40J
I I
I ,k\,-Q I\ c::(>.0 'r] \
C'1qh\II/'
q5'p
SEDs
I.(
o ApicalIi . 0 M1Jlti
June July August Sept.
I'
!
f{({ o Slow
o Fast
ill/'.0/ /
I ~/20_~ _
June July August Sept.
Figure 4.4.3.29 The effects of physiological age and sproutingtreatments on photosynthetically active radiation (PAR)inte~ception' (Experiment F3).
--I;UJ~['1(f)
H <1(.1 I J i:Q Ul
/) H~I (f)
!1J H s:::0
\/ / 0 Ul <0bO H I=:;j Q) ro1rrPQ t-i ~ .g H
I I \ -fJ Q)/
~r---t <1 r!) tp H <0Q)bO s:::-, '~ ro'\ :>, H
'fl cP~ 1-1 r-I :>, Q);j r-I .g\0 \0 \0
i II r;, r-I(Y) (Y) (Y) ro -fJ;2: 0 0.!;j.- $ H CJ+ + + 'r! r-I~ ~ ;2: -........ '-.- eo ro........---...'-. Q) 0 -fJ
0 0 <l .---....::.<;I-l § r-I 0B '<0 0 -fJ,------,------- ------,---- 1--------,------- r;, 'n
0 Cl) N CO <r 0 Ul H:>, 0r+ C"! 0 Cl) C"!~
ft-i\' \' \'
Cl)-fJ Hs::: roQ)
5:1U!=,+SaA.lBl{ TBU!=.if €JrJ HQ)~ft-i Ulft-i ~'n f:iI<0 (f)
QJ ft-i/ 0
I \ .:/ bOoI/ s:::
~ ~¢ bO 'n;j ~ I
\/\ ~ 'n '-'S
~~ ?:1~ <0I=: 0 C\J
1\ \ ro r-I r:r..:>,r-I Q) H -fJ
~ 0l\1 ;j bO Cl) s:::Lr\ Lr\ Lr\ r;, ro ::- Cl)C\J C\J C\J -< \ 0 s;2:' 0 0 .//
r-I 'n+ + + ::s- ----~ ro H H~ ~ ;2: CJ Cl) Cl)
-\:: : Cl) 'n~
~0 0 <l!!l .::-:::.--~ s::: bO
;j 0 f:iIr;, r-I s:::,- y--------r--------------r---------r---- 0-0 Cl) N CO -.....t 0 on H~Lt- C"! 0 Cl) C"! CIl Cl)
:>,~
0\' \' \'~ r-I
-fJH
ft-i <0 Q)0 s::: ::-
<l 00 til 0Ul
0 -fJ HCJ OJ
Y' Cl)
I ~ft-i
r4 Q) ft-iQ) s:::
-\ '-'Q) H
/ bO ..c: H OJ
Cy ~8 Q) .gQ
~-fJ
\ \ s::: H
~ ~0 0(Y) H ft-i
0 Q)
I / (Y)
~Q)
:>, H~ql r-I ..:;t -fJ tilr-I ;j 0ro 'n
\ 'i r;, ..:;t r-I~CJ -fJ <0 til CIl'n '3 r-Ils-_~ +J ~
~0 Q) 0 f:iI;2: 0 H -fJ (f),,- Cl)
So'0 0 <l § 'nr--------------!------------r-----------------,--------,----- r;, r:r..0 Cl) c\1 CO '.J 0Lt- (") Cl Cl) C"!\' \' \'
ill 'S.laqumu .la qn,r,G-
1500
t\I11:11200~..~i900
~~ 600,Q.i:
90
75
60
45
30
15
300
o
Total tuber number (TTN)Tuber number over 10mm(TN010)
oJune July Aug. June July Aug.
Figure 4.4.3.31 The effects of physiological age and sproutingtreatments on total tuber number,tuber number over 10mm andtuber dry weight (Experiment F3).
..-?---
/ 0-- _ 0- __ 0 0/// 0
1/erI
J/1d
o Apicalo Multi
Aug.
o ApicalMulti
, 90
~..-I+>III
.-4 Q)cd tr:=•.-t 11fa4
SEDs (TTN)
75
45
15 o Slowo Fast
June July Aug.
Tuber dry weight SEDeo I ~1500o
1200
900
600
300 o Slowo Fast
C\I 1700laI:VJ..1360+"
~'Q1 1020:.>..ff' 680fJ~ 340
200
160
120
80
40
200
160
120
80
40
o
/~....... I..... I SEDs/ .....__ , ,"'e-- - -_ - - - - ::...8-- ;;...:_-_A/..r--, __J"I _._ - :t::J
0-. , ca'''''' ...,4.~ __ • -- _..:: ---. __ .. __0--7 ~ ......_.--- -.,rr//
June July August sept.
I SEDs
SEnso•oJ:.
Figure 4.4.3.32 The effects of mixing seed tubers of differentsizes on tuber number over 10mm,total tuber number and tuberdry weight (Experiment F4)Key: 0 ,:836;J:. ,S25; 0 .BtS25; • ,B+8,36.
./I
June July August sept.
': ---~J:.
././
./
June July August sept.
UJ>=lfLl(f)
I---l Cl it---t I
IL ~
0. Cf.leo 1-1;:::l OJ~ .g
~
+>"dOJeo~ '"3 ~
'0 '0 '0 ~ rl(Y") (Y") (Y") rl
=f u u '"+ + o~ ~ ::;<: OJ 'rl~ bD0 0 <I ;:::l 0~ r-i
0I
--______,- ----,--- ·rl0 ci 0 0 0 0 Cf.l
0 lD N 0) -0 E[1- CV! 0 lD CV! p..\' \' \'
+>:aU"F'+S<:JA.!Bl{ ~OJ
IBU!=.i1 0 0<1 1-1OJCriCri'rl"d
Cri0
bD bD;:::l ~~ 'rl~
'rlS"d~tll
~3 OJ
l!\ l!\ l!\ bDC\J C\J C\J ~ '"=f u u
+ + rl~ ~ ::;<: tllOJ o
0 0 <I § 'rlbD
~ 0I
--!-~'.-----,- ---,----- rl0 0 0 0 0 0 00 co C\J 0) '-J 'rl
Cf.l[1- CV! 0 co CV! E\' \' \' p.. C\J
Crif.%..
O@l 0 +>~Cf.l OJ+> So 'rlOJ 1-1Cri OJCri p..OJ ~~OJ
bD .cl;:::l 8 +'~ ~
'rlOJ
(Y") ~(Y")
~ ~3 (Y")
~rl ~ ...:::t
'" 'rl . 1-1() +> "d ...:::t OJ'rl rl rl '§Pi ~ 0 OJ~ U OJ S +>0 0 <I § bD
~ 'rlf.%..
0 0 0 0 0 00 co c\1 0) '-J •[1- CV! 0 co CV!\' \' \~
11& ''+l{:a::<:J.t1.A'!P .!<:JqnJ,G-
<1
60 <1<1 <1
<1 <140
0 0 0 0 <1 <1
0 0 0 0 <1 <120 ..--•
0 0 0 0 ~ <1 ~ <l r-
• • 0 0 0 0 ~ <1 ~ ~ <l ic0
84 107 Final harvesting
+l'§,'r-! 80ID~
~"d
1-..ID'§ 60'+l
~
Fast80
Apical
40
20
o
Figure 4.h.3.34
Slow
•
Fast
Apical
o
o
Slow
Multi
o
Fast Slow
••
o 0
o 0
o 0
o 0
o
o 0
o 0
o 0
Multi
o 0
Apical Multi
•84 107
Days after planting
.---<l <1
<1 <l
<l <l
<l .<l
<l <l
Final harvesting
The effects of physiological age and sproutingtreatment on proportion of tubers in size grades (dry weightbasis). Vertical bars are the SEDs.[!] < 35mm 0 >45mm·· [§J >60mm ~ 57-76mmo 35-45mm @]35-60mm G 38-57mm lie I >76mrn
+>ib 60.r!Q)
~t: 40'd
HQ)
,D
.B 20~
80
60
40
20
oB36
80
• •• •• •
91 days afterplanting (DAP)
825 B+825 B+836
o
125o 0 0 0 0 DAP
o 0 0 0 0
o
o
B36o 0 0 0 0
825 B+825 B+836o
60
40
20
oB36
Figure 4.4.3.35
<l
[!] <35mmo 35-45mm
D >45nnn
~ 35-60mm
o >60mm
~ 38-57mm
G 57-76mm
~ >76mm
825
<l
Finalharvesting
B+825
<J
<J
B+836
The effects of mixing seed tubers ofdifferent sizes on proportion of tubers in size grades(dry weight basis). Vertical bars are the 8EDs.
average for replicates and is fromexperiments:F2, 0; F3, ~ ; F4,D . One pointencircled was not included in the
30T---'---'---'- __ 1I __ -r __~8 8 10 '11 12 13 14regression(seetext).
LAD/TI30 X 101
+:> 30 0 and leaf area duration contributed..c::bD'rl 25 by the axillary branches (LAD/AB)Q) 0~
-~ Data is for replicatest' 20 average'd and from experiments:NQ) '15 F2, 0; F3, ~.o 0~ 10
~A
53 4 5 6 '7 8 8 '10 1 '1
LAD/AB 'X101
y = 26.31 (+ 5.14) + 0.70 (+ 0.20) x% variance accounted for 43~5residual standard deviation = 5.08
50®55
°0
20 25 30 -2 35Total stem number, m
C\JIS
5055
50
y = 1.92 (+ 8.72) + 0.37 (+ 0.08) x% variance-accounted for 60residual standarddeviation = 4.27
®n
C\JI
51"~ y = -28.08 (~ 67.48) + 3.44 (+1.05)x
'te. X"" 0 '~i % v~riance accounted for 44.9 -N' J resi duaL standard~ 35 deviations=68.36o o
Figure 4.4.3.36 The relationshipbetween tuber number and total stemnumber (main + branch).Data isaverage for replicates and is fromexperiments:F2, 0; F3, A ; F4, D. One pointencircled was not included in theregression (see text).
40
Figure 4.4.3.37 The relationshipbetween tuber number and leaf areaduration accumulated for a periodof 30 days from the date of tuberinitiation (LAD/TI30). Data is
Figure 4.4.3.38 The relationshipbetween tuber dry weight over 76mm
UJqr,lCl)
r-it----1 al
+>0+>
i .eo $:l
I ;:l 0I -<
~
[I)
~ID
'§+>
:>. ror-i ID;:l bDi-;) al
:>.r-i
\D \D \D ~(Y) (Y") (Y") ID V~ U U § OM+ + bD-< -< ~ i-;) 0
r-i0 0 <I 0OM
r ---I [I)
0 0 0 0 0 0 :>...c:::0 '0 CO N CO PlCO '0 0 r-- CV)
\' \' \' +>$:lID~IDr CHCH
IOM't1
bD
I ;:l CH-< 0
~
eo$:lOM><I OMa:>. ro3 $:l
i-;) al
IDeoalIf\ If\ If\
C\J C\J C\J r-i~ 0 U ID al+ + § o-< -< ~ OM
i-;) eo0 0 <I 0
r-i0I .--- OM0 0 0 0 0 0 [I)
0 '0 CO N 1O :>.CO '0 0 r-- CV) .g.'"' '"' \' C\J
CH r>:..0
+>[I) $:l+> IDv aID OM. CH ~
bD CH ID;:l ID
~-<ID rz:l
..c::: ._..,8 ..-...
~8:>. 0\
3 (Y)· +>i-;) (Y")
~·rl -:::t OMal OM · IDV +> ro -:::t ~0r-i rl rl
~ i 0~U ID ID
§ ~ ro0 0 <I
i-;) bDOMr>:..
0 0 0 0 0 0 00 0 I,.) () Cl ()CO I.n N CD 1O CV)\' \' ,-<
u6i '11G.10-
UJ()~,jU)
H
ric0
m!--tQ)
I .g,I +''"dQ)eo
~ a:l
'3 ~I-:> rl
\D \D \D rl(Yl (Yl (Yl a:l~ () () tJ+ + + ·rl«: «: ~ Q) bO
§ 00 0 <I rl
I-:> 0·rli m
0 C\.i '0 CO 0 ~OJ ("1- In \' ..c:
P<+'s::Q)!--tQ)~'i-l·rl C\J'"d rx.'i-l +'
bO 0 s::~
Q)bO Ss:: .r-i.r-i !--t>< Q).r-i P<S ><
f;t:l'"d ..._..
~ §'3 Q) ~I-:> bO E-il{\ l{\ l{\ a:l
C\J C\J C\J
~() () fQ) rl +'+ + a:l ..c:«: «: ~ o bO
I s:: ·rl .r-i0 0 <I I~ bO Q)
0 ~rl_,--"---'---·'--1<>----. 0 t>0 N '0 co CO 0 .r-im '"dOJ ("1- \.() (") \' ~..c: rlP< a:l
+'~ 00 +'
r m ~+' 0oQ) +'
ibO'i-l ;J'i-l 0
~Q)
mQ) !--t..c: Q)E-i .g
+''i-l
0 0.:t
~ . Q)rl rl (Y') bOa:l .r-i ;J a:ltJ +' '"d I-:> .:t +'·rl '3 rl s::P< 0 .:t Q)«: ~ () tJ
!--t0 0 <I Q) Q)
Q)~ P<
§ bOI-:> .r-irx.
0 Lri 0 \.() 0 0OJ ("1- C..D '0 (") '\'
M.G.L JO q.no ' .Iaqnq. %
TDW1520 1520
1220 1220
C\JI 920 920s
b.O
"~ 620 620E-i
0 Apical I 0 Slow0 Multi 'I 0 Fast
320 320
July Aug.
90% tuber, out of TDW
90
75 75
~ 60 60E-iIH0
+> 45 45;J0
Ulf..<OJ 30 30.g
Apical 0 Slow+-, 0
* Multi 015 0 15 Fast
June July Aug.JulyAug. June
Figure 4.4.3.41 The effects of physiological age and sproutingtreatments on total dry weight (TDW) and percentages of tubersout of TDW (Experiment F3).
SEDs
SEDs
1850
1480C\JI s 1110
tU)
~6 140E-l
3'10
0
I I SEDs
-.-------...-------T-·----·-- ..---.- -r----·----------,---June July August Sept.
100
80~i:::)E-l 50~0
+-' 40::s0
.:rH 20Q)
.g+-'~ 0
:z:: SEDs
Sept.Figure 4.4.3.42 The effects of mixing seed tub-ersof different
sizes on total dry weight (TDW) and percentages of tubers,out of TDW (Experiment F4) ..Key: 0, B36; a , S25; 0 , B+S25; +, B+S36
X1011'10155
C\JI 150seo 155~+-' '150..r:::eo'MQ) -145~H 140Q)p::s+-' 135
30
o o
oo
y = 783.6(±262.5)+2.09(:!:0 ..14)X% variance accounted for 30.4residual standard deviation =7T~
·-A--r·····--·-·q-·· .._.--,--- ..-._.-r ···----r-·.--.-.---,
32 34 35 38 40 42UD X101
oo
Figure 4.4.3.43 The relationship between tuber dry weight and leaf area
duration (LAD)., Data is average for replicates and is fromexperiments: F2 (0); F 3 ( b. ); F4 ( 0 ).
Figures 4.4.4.1 and 4.4.4.2 varied for different sampling dutes, but
there is not much difference in 'I' value (Table) for the range of RDF
found, so for simplification, average (for all dates) RDF along with
range is given. In Experiment F2 the mixture never yielded signific-
antly different from the exyected yield, i.e. the average of sprouted
and cold, when grown al.one (Figs.4.4.4.1 and 4.4.4.2). Replacement
diagrams for LAI and TD\v (Figs.LI-.4.4.1 and 4.4.4.2) show that competit-
ion between 2 components within mixed plot, started after about 60 days
from planting, ,8 sprouted in mixture guve higher values for LAI and
TDW compared to s9routed in mono and cold in mixture gave lower
values for LAI and TD'v'1 compared to cold in mono (Fic;s.4.4.4.1 and
4.4.4.2). Similar results wer-e obtained for tuber weight from 90 days
of planting onward (Fig.4.lt.4.2). In Exueriment F2 at 25cm spacings
differences between sprouted and cold were the same as found at 36cm
spacings (F.'igs.4.4.4.1,4.4.4.2 and 4.4.4.3). For examp.l,eout of total
LAI for mixture, after 63, 76, 90 :~~d 105 days of planting sprouted
contributed: 68; 64; 59; 60 percent at 36cm spacing and 67; 57; 69; 64
percent at 25cm spacing respectively. Similo.r results were for TmJ
and tuber weight. In Experiment F4 where difference between cold and
sprouted Wo.s further increased by using different seed size, sprouted
contributed about 90):; of the tobl yield of mixture (Fig.4.4.4.4).
During 1980, in both -the experiments sprouted hud an advantage over
cold early in the season but both componerlts senesced at the same time
i.e. cold did not show any advantage over sprouted later in the season.
But it was found that in Cl1se of Experiment F4, where cold was suppressed
more, the proportion of oversize (>76mm) tubers were ir.creased thus it
'may not be useful to have bigger differences. So in 1981 it was decided
to use· the S3lTleseed size with difference in sprouting only. Planting
106
pattern W3.S slightly ch.mge d (Ch.ipte r 1+.3). There '..:.-J5 no interaction
between 2 pLanti.ngdates, and so the results presented are averaged
for 2 dates. Results for Experiment F5 sho\l that competition between
sprouted and cold was not affected by ch.mge in planting pattern as
results were quite similar to those obtained for Experiment F2 (Figs:4.4.4.5;
4.4.4.1; 4.4.4.2; 4.4.4.3). For ex~ple in Experiment F5 after 77, 98
and 119 days of planting (planting date tuken as aver:1ge of two plant-
ing dates), in mixture, sprouted contributed: 62; 63; 56 percent of
LAI, these figures are quite similar to those obtained for Experiment F2,
reported earlier.
4.4.5 CroD evaporation
In 1979, crop evaporat ion (ET) culculcted from the neutron probe
data \"as ah;ays lower than the potential evaporation (Penman, 1956)
(Fig.4.4.5.1). This may be rel3.ted to the lower LAI during that year
(Fig.4.4.2.8) and evapor-a t ion from soil surface may have been very
little as the soil was dry during most of the growing season (Fig.4.4.5.2).
For convenience the ratio of actual to potential evaporation (Fig.4.4.5.2)
is also presented which o.ppears to be increo.sing in favour of actual,
with a decrease in soil moisture deficit ili~da~ increase in LAI
(Figs.4.4.5.2 and 4;4.2.8). It shows that potatoes ar-e very sensitive
to drought. Another factor which may have contributed to the lower
values (calculated) of ET, is the capillary movement of ground water
\'Jhich\'Jasnot measured in the present experiments. In 1980 the field
had a slight slope, thus during he.ivy r-ai.nsdue to surface runoff and
drainage loss, ET could have been over-estimated (Fig.4.4.1.3), and
when the crop was aeneaci.ng, measured values wer-e lower than the
3 2
--.-3.0
2.0
1.0
0105 121
H
j
0.5
153
3.0
2.01.0
o
Days after planting~igure 4.4.4.1 Replacement diagrams for LAI. The scale on left hand side
1S just for one-diagram.Key: 0, Cold;O, sprouted (average for apical and multi);
• , Mixture for whole plot; 1, SED to compare between sproutedand mixed (whole plot basis); 2, SED to compare between cold and mixed(whole plot basis); 3, SED to compare between mixed and mean of coldand sprouted (whole plot basis); 4, SED to compare between sproutedand cold within plot; 5, SED to compare between sprouted (half plotbasis) and its counter part in mixed; 6, SED to compare cold (halfplot basis) with its counter part in mixed. Residual degrees offreedom are: 16 for SEDs 1,2, 3; 8 for SED 4; 21 (17-24) for SEDs 5, 6.
- --_. -- •1000- __
l?OO
750 900
500 600
C\i 250 300I
~~ 0 0"
121 139""''tb..,(l)~
t' 500'tj
~ 600(l) 200,Q 375;:J~
150 250 400100
125 20050
0 0 076 90 105
- -'-1000 --750 1110
500 740C\iI~ 250 370~"
""' 0 0fa 105 121..,&~'tj
"'itil
""'~ 40
Days after planting
600
400
200
o
Figure 4.4~4.2 'Replacement diagrams for total dry weight and tuber dryweight. For meaning of symbols, SEDs and residual degrees of freedom(RDF). see figure 4.4.4.1 except that RDF for SEDs 5 & 6 is 22(19-24) fortuber dry wt and 23(20-24) for total dry weight.
Hj
I
SEDs
"..-_..f3'";a---
//
I/JZI
/
I
I SEDs850
C\JI '150seo"+J ~\ "·7 :~~\,.qeo
'rl(])~ r")~-
:>,,_)~ U
H'd
H 180(])
.g8
0 1--------
I
1-------- ---1---
1000ISEDs
I .oI --_B'"-C\J 800 B- -I ./s ./eo :t"./
" 600 01:: /eo /-'rl(]) 400 :1:/~
'~..0-:'d 200 =r,/
rl gcd+J /'0 /'8 0 _-_"---
June July August Sept.
Figure 4.4.4.325cm spacing.Key: 0 ,sprouted (mean of apical and multi); 0, unsprouted
Growth of 2 components within mixed plot at
(cold)(Experiment F2).
1r;nn/0... ... _.o
..../ ...... 420
N / 'DNI IS 1200 / I seo /
bD
+> ;:f +> 280.t:: .t::
bDeo 800 / 'rl'rlQ) p/ Q)
~ ~
t: / :>. 140H'd 400 / 'd
M ;1 MtU 0 tU+> +>0 08 80 0
1300 ID- ---0 350 )J/ I -:
/ INN p/I ISS /bD /
bD /800
+> / +> 210.t:: .t::bD eo'rl / ·rlQ) OJ~ 0 ~
/ :>.:>. 400 / IH H'd rf 'd
H / H 70Q) OJ
,..0 / '§;:J IT8 80 0
Figure 4.4.4.4 Growth of2 components withinmixed plot (Experiment F4). Residualdegrees of freedom (RDF)is 4 except for 4th sampling for which it.is 2.'Key: 0, Big; 0" small. Vertical barsare the BEDs.
2.0
,I'0
1.50
1.0
0.5
oJuly Aug.
Figure 4.4.4.5 Growth of twocomponents within mixed plot(Experiment F5). RDF is 4.Key: 0 , apical; 0 , co.Ld .Vertical tars are the SEDs .
1(),/
Pote nt i al , which is r eLute d to dec.line in 11'.1. For- further calculations,
Potential evapor a t i.on data for 1980 and me.rsured for 1979, are used.
Evaporation for var i.ous t re a tment s of Experiment F1 (19'79) is
presented in Fig.4.4.5.1. Evupor-c.t i on Wi,S only slightly affected by
varieties. Apical t.r-eotrnent had J. slightly higher evaporation rate early
in the season but Late r on multi had hi gher compar-ed to api cal , For
example, total, evaporat i.on (HJ.i) from 4th June to 30th July and 31st July
to 7th October W:IS '78.5 and 93.2 for ,J.piccc: and 71.0 .md 101.2 for
mul ti respectively. Sp.ici.ng did not ..if'f'e c t the evupor a t ion (Fig.4.4.5.1)
except that during the L...ter par t of the growing season evapor-at i on was
slightly higher in s40. During severe drought roots of the variety
Record penetrated sligh tly deeper than those of PentLand Crown (Fig.4.4.5.3),
other treatments had no effect on rootir:g depth (data not presented).
In 1980 before the onset of he avy ra ina the soil IvJS quite dry early in
the season ar;.d roots by 11th June were extr:.tctinG·water fror:J 70-80cm
depth and there W:J.S no difference amongst the various treatments. After
that rocit penetration could not be followed as most of the time the field
was near field capacity. At the end of the season (beginning of Sept.)
it was found th:.tt roots did not go deeper th.,n SOcm.
The re~a t i orish i.p be tween crop evupora t ion and crop gr owth rate is
presented in Figure 4.4.5.4. Leaf senescence w i thin the canopy ','las
evident in 1980 .rt .n e.u-Lier date Lh.in Ln 1979, vrh i ch may have been due
to differences in humi.di ty .rnd L1\l between the year s , Consequently, the
t.otaL dry weights for 1980 were udjus ted to ...ccount for the early leaf
loss, w i th estimates of led weight loss being related to the dry weight
of senesced Leave s and number of missing Leave s , CrOiJ growth rate data
presented in Figure 4./+.5.4 is'ldjusted (roots not LncLuded ) and refer
to harvests up to 15th August in 1980 and 20th August for Record and
108
10th September for Pentland Crown in 19?9, since it vJ;J.S r::ot possible to
account for weight losses due to stem rotting after these dates. The
five points encircled on the Figure 4.4.5.4 were not included in the
regression, four were for the ye~r 1980 when ground w~s not covered
and thus Potential evaporation \HS over=e s t iraate d and one point for 1979,
Pen tLand Crown, 27th July to 8th August, a.s a lot of the leaves had
senesced during that period 'J.nd no adjustment was made. Linear re-
gression for the remaining p~ints accounted for 79.5 nercent of the
var-Lance in crop growth r:J.te ,
4.4.6 Light interception ::l..ndpot:lto growth
4.4.6.1 Led are:" index :'\Ddphotosythetic:llly active r<'_diation (PAR)
intercention.
The relu.tionship between leaf :.trea index (LAI) cmd the proportion
of P1Jt intercepted by the crop canopy is shown in Figure 4.4.6.1. Up
to LAI values around two the relationship appeared to be almost linear,
wh.iLe above four, PARinterception W"1.S relatively constant. The charact-
eristics of light transmission in crop ccnop i.es have been related to
Beerl's Law by the equation IL _ 10 e -kL wher-e IL = the irradiance on
e, hor-i zon tal, plane below a leaf are a index of L, and k ,. a light ext-
inction coefficient, assuming n homogenous canopy, which depends on the
transmission chur-ac ter-Ls t i cs of single leaves and their geometrical
arrangement (Nonte i th , 1965). The r-eLat.Lor.ahip generated by this
equation did not fit the measured d~ta over the range of LAl found in
these experiments (Fig.4.4.6.1). From the analysis it ilppeared that the
light extinction coefficient v.il.ue , k , W'clS not constant as LAl increased.
Varietyb. Potentialo Pentland Crowno Record
) ."C.~ cf._!_
,.'" .-)t::",,~ D ,~ •. )
30'15~I
~3025
']j
~ 20'15"s:: 20250
'rl~roH 10150p.,
~QJ 1025p.,0H
o 75u
Physiological age
o Multio Apical
~/' .B- -B' \
\ I1':1
-----··--J--·------···--·--r----·--- ·-------·-T--------
30 j5~ Spacing
30252075202510151025
o '15_.June
Figure 4.4.5.1
o 30cmo 40cm
I
,R
/ \\\--fj
July .I ·····------·--T-·-···----·-August September
The effects of~riety, physiological age andspaclng on crop evaporation (Experiment F1).
~ 56
090,II
Io 19,
I
o68JI
10
28,
1:]I---.-------.I-----.------.T----.-- ...--.----.-----rJune July August Sept.
I '03 5---·------·-·-·--·-r---·---·-·---.-------r---- ....-.-.---.-T
June July August Sept.
Figure 4.4.5.2 Cumulative soil moisutre deficit and ratio ofmeasured (neutron probe) to potential evaporation (ExperimentFl, average for 2 varieties).
0
0 Pentland Crown20 0 Record
Elo....c: 40+'p..(lJ
'd
eo.:.: 60.r!
+'0 \0p:;
~
80 \\b-e
100June July August Sept.
6. Potential evaporation3.75i Crop evaporation0
3.1~I
I I \~ 2.4 I ~'d
~ J. \\
I \../.:.: \0 1.8 I'r! \+'
al 6.J...t0c,al::-~ 1.1
June July August Sept.
Figure 4.4.5.3 The effects of variety on rooting depth(Experiment F1) and crop and potential evaporation during,1980 (~xperiment F2).
~I>. 20!O'0
C\JI-etJI..t3u 10
o
Y = 10.98 (!1.27) x - 2.56 (!2.48)
% variance accounted for 79.5residual standard deviation = 2.78
•
1.0 2.0-1ET, mm day
1.5 2.5
Figure 4.4.5.4. The relationship between crop growth rate andcrop evaporation (ET). Key: 0, exp , F2; ~ ,exp. F3;o ,exp. F4; • and • ,exp. F1 (Pentland Crown andRecord respectively). The points encircled were not includedin the regression (see text).
109
In these experiments, Lncr-e ased LAI was ussociated wi th crop gr-owth
as a function of time and therefore it may be expected that changes
in leaf angle, size, distribution and transmission characteristics
with leaf age 'tlouldoccur. A significant (p = 0.001) quadratic re-
lationship was found between k and LAI and could be represented by the
equation; k = 0.335 + 0.1511 - 0.013L2 (Fig.4.4.6.2) (where L = LAI).
\oIhenthese calculated values for k were substituted into the Beer's
Law equation the resulting fit to the data accounted for 9~;6 of the
variance compared with 88% when a constant k(= 0.72) was used
(FiJ.g.4.4.6.1). Thus the du t a indicated that k VIas relatively lower at
lower leaf area indices, earlier in the season. Differences in leaf
angle which may occur during the season would obviously affect the
light interception characteristics of the canopy, but such differences
wer-e probably confounded wi th other changes for example leaf distribution,
and individual effects could not be determined, from these experiments.
The PAR interception da1.;u(Fig.4.4.6.1) was obtained from all the
treatments of Experiments: F1, F2, F3, F4 and although LAI varied, the
relationship betweeriLAI and PAR interception did not vary systemat-
ically with any of the agronomic treatments.
4.4.6.2 Dry matter nroduction
Daily incoming PAR data was obtained from a site within one km. of
the experiments (courtesy of H. Bat.eman, Environmental Physics Section).
On a few occasions when instruments failed, total solar radiation CST)
values were obtained from u.neu.rby Heteorologicill Station and PAR was
calculated as PAR = 0.53 (ST), from the relationship shoi...n in Figure
4.4.6.3.
A significant Li.ne ar r-eLat ionsh i.p was found between cumulative
total dry weight (TmJ) (1'D'.1,used in the chapter is adjusted see
Chapter 4.4.5) and cumulative PAR intercepted in both years, and the
1980 data are shown in Figure 4.4.6.4. 'i/hen forced through the
origin, total dry weight ('rm-J) = 2.49 (PAR) and 3.42 (PAR) for 1979
and 1980, respectively, .indi.ca t ing t.hat conversion of light to dry
matter was more efficient in 1980. Al though such iJ.E effect may be
explained in terms of wate r stress in 1979 (Chapter 4.4.5), relation-
~hips based on cumulative data are not entirely satisfactory since
other variables, and time, m.iy be confounded with the apparerrt effect.
The photosynthetic conversion efficiency (g dry wt MJ-1 PAR
intercepted) for the canpoy W:lS cul.cul.at.ed for each gr-owth analysis
period. In gener a.l , the expe r imen'to.L treatments had no significant
effect on photosynthetic efficiency and therefore the general temporal
patterns for var-Le t ies in 1979, and individual experiments in 198o,
are shown in Figure 4.4.6.5. In general, photosynthetic efficiency
was higher in 1980 compared with 1979, probably as .':1. consequence of
differences in water stress. The variety Record had a higher con-
version efficiency than Pentland Crown, during early August, and it
may be that Record was less affected, since neutron probe data indi-
cated that Record had a slightly deeper root system. Later in August
the photosynthetic efficiency of Record vIas Lowe r than that of Pentland
Crown due to earlier C:_U10PY senescence.
Crop gr-owth rate (CGR) ~lS a function of PARinterception is shown
in Figure 4.4.6.6. A Li.near- relationship was evident for 1980, while
CGR Wi.l.S severely restricted under the drought conditions of 1979.
Calculation of intercepted PAR, assuming constant le = 0.7, from LAI
values resulted ina similar relationship between CGR u.nd PAR.
111
However the r-eLut i.onsh io vii th measur-ed PAn accounted for 91% of the
var i ance in CGR..rh iLe th.i t with calculated ?1\R intercention accounted
for 84%. The difference was due to the f',ct that k WCJ.6 not constant
throughout the season dS discussed previously.
Al though CGRand to ta.l dry m.it te r production are .impor-t an t the
factor of major COnCer!l in pot~toes is tuber yield. The relationship
between tuber yield and interceuted PAR is shown in Figure 4.4.6.7.
-1Although photosynthetic conversion efficiency (g tuber dry wt HJ PAR
i_ntercepted over the whole season) for tuber weight was slightly
different for two years: tuber dry weight = 1.97 (PAR) and 2.37 (PAR)
for 197q and 1980 respectively, but still Q significant linear relation-
ship between tuber dry weight and to t al, PAR intercepted over the whoLe
season existed CFig.4.4.6.7). Between two varieties in 1979, Record
vias 13.4% more efficient than PentLand Crown in converting light to
tubers.
4.4.7 :Sxperiment F5
Soil temperature, at 10cm depth lnd screen, max. and min. air
temperature and rainfall from April to October 1981 are given in
Figures 4.4.7.1 and 4.4.7.2.
4.4.7.1 Emergence ,md stem number
The cold treatment took 45 days to reach 5CJ;G emergence compared
to 31.7 for upi cal., :, dd ff'e r-ence bigger th:m the one f'ound for Exp, F2
C1980). This muy be exp'lairied by the difference of temperature at the
time of p.lan t i ng of two t r-ea tmen t.s in this exper-Lment , Similarly
Figure 4.4.6.1 The relationship between LAI(L) and interceptedPAR in 1979 and 1980. Each data point is the mean ofreplicates for a particular treatment. Excludes data fromlate in the 1980 season when LAI was declining and stemswere intercepting a higher proportion of radiation (totalnumber of points 278).
(a ) p. . 1 -kL h 0 2 ( )a AR lnterceptlon = -e ,were k = .7 ----residual standard deviation (RSD) = 7.90% variance accounted for 88.26.
(b)-lkLPAR interception = 1-e (----) 2
where \ = 0.335 (~0.038) + 0.151 (~0.030) L-0.013(~0.o05)L
RSD = 6.49% variance accounted for 92.1
Key: 0, Experiment F2; D. , Experiment F3; 0 , ExperimentF4; <:> , Record /Experiment F1); \l , Pentland Crown(Experiment F1).
o
o
<loo
o
o
oI>I>I>o
. I>-'80. 0c»- 1>1> I>. Rf 0I> ~ 1>0 I>OD'l-""OO~ "
I> 0~~t>\o ' 0 0
I> ,1>0I>oI>
®:>O0:I>
o o
I> 0
"o
oo
o
1O
o
If)
CV) H
j
(\)
r---r----.---,----T----r----.-----T--_.-- __ ~--_,__--_r 000 ~ W If) ~ CV) ~ 0
PAR = 0.53 (~ 0.001) ST% variance accounted for 99.9residual standard deviation = 0.20
+-----------1------- -
5--- r------ ------------ -1 - 1 -------
10 '15 20-2 -1ST, MJ m day
The relationship between photosynthetically active radiation
_ .. -.. _---o
30
Figure 4.4.6.3(PAR) and total incoming radiation (ST) on a horizontal plane. Data from144 days between May-October, 1979.
Co
X10-110_
9--,:
8:..,'1j
i5~sJ
I
k 4J 0i
3J
')\.-' -,.\"0
,,.r-,
oo
2k=O.335(~0.038)+0.151(~0.030)L-0.013(~0.005)L% Variance accounted for 42.2residual standard deviation = 0.14
+r2
rJ
r------------- -----,-------
4 5i
5L
Figure 4.4.6.2 The relationship between k and leaf area index (L).Data from experiments: Fl; F2; F3; F4. Excludes data from late lnthe season when LAI was declining and stems were intercepting ahigher proportion of radiation (total no. of points 195).
I\-t0
eo
reor-i >=:r-i 'rlCIl §~ Q)
0 ElC\J I\-t0 ~
>=: 00\' 0 Ii..X 'rl
+>0p.Q)\ o ..:t~ 0\Q)0+> tilc:
In >=: +>\'rl >=:'rlc~.~ 0C'-"
p.C '\ P-.I\-tCC\ r-i 0
CIl0 +> ~0 Q)
+>~Q)
> >=:<1 'rl+> r-iCIl CIl<J
<J-'0 r-i +>;:J 0c
§ +>( ':
()( ;til
I\-t Q)
0 +'til
>=: o0 'rl0
C\J 'rl r-iI +' P.El o Q)
>=: ~0~
;:JI\-t ~
M " CIl ere;( .:Q) til Q)c; r'·-·\
+' til tillpc:; \ \. .
P. til< \ Q) ...--.. ~P-.o ;3: Q)\ ~
~>o· Q) til
LJ\<J +>0
>=: >=:'rl CIl0 C\J<J Gl
~til,+1 0\
1 ~ ~+' 'rlt--
tb +'LJ\ C\J II'rl >=:
LJ\ .C\J
Q) 'rlCO Q
~ 0(Y) 0\ 0
P.'rl
t-+ ~ +>til0 CIl
re; +>I\-t 'rl 'ctilC\J >
r-i re;t-- re; Q)
tilQ) re;+' .r:::(Y) +> q 0 o
~ § re;',' 0 +> til \C+1 ~
~ .0 tilQ) ..:t
() re;> .CO o >=:
'rl . ..:t0 til til
+' 0of +>l_\ til CO Cl;
..:t til
i 0\ '-..:t ()
\'6j
I >=: ';jtilQ 'r-
'rl ;:JC) 'rl l\-
II ~ re;
~ 'rltil Cl;~ til
...::t +' Cl;Q) . >=: er.E-i * ~
\D Q). El er....::t 'rl r-~ C...::t Q) .c~~Q) ><F-t Q) er.
;:J~
j ~.~---r--------r-'- -----,- --'----T-------y---"----- 0 'rl,,~ ------'-,-- ----T
Ii..0 CD CD '0 N 0 CD CD '0 N 0,C\J C\J " '\' '\' '\' '\'
ill 'B ' ::P-l'B:: a1-\. A.IP 1'8'+0,1G,'"
30 CGR = -2.97 (~1. 56) + 3.85 ± 0.28) PAR% variance accounted for 91.3residual standard deviation = 2.48 0
D
r- 2I
~c
-0C\J 15I v
AS o oeo
0.. Vp::0 c0
5
00 2 3 4 5 6 7 8
PAR, MJ-2 day -1m
Figure 4.4.6.6. Crop growth rate (CGR) as a function of PAR interceptionfor three experiments in 1980 (each data point is a mean for totalnumber of plots in that experiment) and 2 varieties ln 1979 (each datapoint is a mean for 12 plots). Regression line fitted through 1980 dataonly (see text).
1700TW = 428.71 (~134.74) + 2.98 (~0.23)PAR% variance accounted for 87.9
OAresidual standard deviation = 103.03.
C\JIS
eoAD
+'..c:bO'MQ)
~»H.-0
VHQ) V.£l~E-i
80650 70
Figure 4.4.6.7PAR, intercepted MJ m -2
Total tuber dry weight produced during 1979 and 1980". as a function of PAR interception. Each data point is a mean for
replicates .
. Note: For meaning of symbols see figure 4.4.6.1.
ear Ly planting :.llso took more di_lys to r e ach 50% emergence compared
to late due to differe~ce in temper~ture. (Table 4.4.7.1.). Unlike
Experiment F2, cold took more days (8.7) from appearance of the first
stem to reach 5(J)b emer-gence compar-ed to ap i.caL (6.l,), this may be
due to the r eaaon the, tJ.pic21 in Expe r-i.ment F2 .incr-eaae d tota.l stem
number. Stem numbers were averaged for .dL dates of growth analyses,
as there was no difference be twee n different da te s and they were not
uffected by :my tr-ea tmerit (T,Jble 4.4.?1.).
4.4.7.2 Growth and develoument of stem and le.::.f.
Cold emerged later ur.d thus hnd lower LJI,I ear Ly in the season
(Fig.4.4.7.3) but when considered from the date of 505b emergence cold
had slightly higher LAl compar-ed to .ipi.cnl , For exampLe after
14, 21 and 28 days of 50}Semer gence , cold had LAl of: 0.l~2; 1.14 ;
1.65 and apical: 0.40; 0.86; 1.34 respectively. Late pLant i.ng had
lower LAl early in the season but when cons ider ed from the date of
50;:; emer-gence there was no difference. For example after 12, 19 and
26 days of 50}S emergence Lat e had LAI of: 0.53; 0.97; 1.51 and early:
0.43; 0.87; 1.54 respectively.
As found for Experiment F2, mixture gilve s ign i f i.cunt Ly lower
LAl early in the vseason cornoar-ed to .rp i cu'l , Specific leaf area
was not .rf'f'e c t.ed , thus leaf dry weight vl:AS pr-cpor t iouul. to LAL
Effects on stem weight ..us s irni.Lur to LAl. Leuf to stem ratio de-
creased during the gr-owing se ason :lS wus found in the previous two
years and w:J.snot af'f'e c t.ed by any of o'~hetreatments (data for
leaf and stem weight is not presented).
113
4.4.7.3 Tuber growth :md developmen t ,
Tuber Lni t ia t ion (TI) W.J.S cal cu'Lrted by interpolation aa in
previous years. Unlike 1980, TI was not delayed by cold (Table 4.4.7.1.)
when considered f'r-ornthe date of 50;\ emergence, but when considered from
the appe ar ance of first stet .., it vias 2.7 days La te r in cold compared
to apical; still the difference was slightly less then the Experiment
F2 (4.3 days). Tuber weight was lower in cold and early planting
(Fig.4.4.7.5) but when considered from the date of TI there was no
difference. For example af te r 5, 15, 36 and 57 days of T1 cold yielded:
6 4 41 6 -2 . 1 2 102 8 3 8 6 -23.7; 92.; +2; 51gm and ap i ca.i : 1 .1; .; 7; OOgm ,
respectively. Similarly iT: case of date of planting (data used only
from mono plots as da te of TI for mi.x tur e vlilS not worked out), after
6, 21, 37 and 58 days of TI, late plonting yielded: 33.6; 110.5; 416.5;
580.5g m-2 and early planting: 28.'7; 122.7; 422.8; 611.2C m-2 respect-
ively. As found for Experiment F2 (1980) tuber weicht in m::'xture was
significantly lower than apical ear-Ly in the season.
As far as tuber size grades ,ITe concerned cold did increase the
percentage of medi.urn size tubers (Fig.l+.1~.'7.6) but the difference was
not significant. Late planting had a higher percentage of medium sized
tubers, but maybe because it was t.r-a.i Li.ng about 4 days behind (difference
in time to rea.ch501{' emergence), early pl:mting.
As found in 1980 (Exp, F2) cold had slightly higher LA1 (1.30) at
the time of T1 then apical (0.98) and Lni t.ia ted ~l higher number of
tubers (Fig.4.4. 7.4). Planting date did not affect the tuber number-,
More tubers were found in r:Jixture compar-ed to api ca'l , maybe due to
presence of cold in the r:Jixture.
4.4.7.4 Tot3.1 dry matter ac cummul.et iou,
During this year roots present all the stolons iJnd stems were not
removed. Leave s started to falloff, by the middle of July and were
not collected. Like LAI and tuber we ight , total dry weight (TD\-l)
was also Lowe r in cold and late plan ting (Fig. 4. 4. 7.7) due to diff-
erence in time of emergence (Table 4.4.7.1.). Percentage of tubers
out of TDHwere lower in cold and Ls te p.l an t Lng (Fig.4.4.7.7) but
~hen considered from the date of TI there was no difference. For
example, after: 5; 15; 36; 5'7 days of TI cold had : 16.2; 35.3; 60.5;
68.6 percent and apical: 9.25; 32.94; 57.38; 68.3 percent tubers out
of Tm-l, respectively. Similarly in the case of date of planting after:
6; 21; 37; 58 days of TI, late planting had: 16.4; 34.5; 59.3; 67.0
percent and early planting had: 14.7; 3'7.0; 60.4; 70.6 percent tubers
out of TD\ol,rcspecti ve Ly (dab used from the mono plots only).
4.4.8 Exneriment F6
This experiment was specially designed to study the effect of
physiological age on emergence. 'I'her-e was no difference in time to
reach 50;; emergence between BODand 920D suggesting tha t once. the
sprouts had become visible (ubcu t 2 to 3mm) af te r- that Longe s t sprout
or phys i.ol ogi.cal. age has not much to do with emergence (Tables 4.4.8.1.
and 4.4.1.6.). Time between appearance of first stem and reaching
the 50;; emergence var ied from 2 to 6 days and VIas 4.0 for 4D and 5.5
for 920D.
All the plants Vlere harvested after 64 days of planting. Although
LAI vIas higher in treatment 920D it did not differ significantly from
the treatments which emerged with it (rI\~bles 4.4.8.1; 4.4.8.2.).
Similer results were obt.a.i.ned for stem wei ght , Leaf weight and total
dry weight (Tm'!) (T,',ble 4.4.8.2.). Tuber weight , tuber number and
percentage of tubers out of TD'.-J, were hi ghe r in tre a trnent 920D
(T:J.ble 4.4.8.2.) pr-obub.l.y becauae it initiated tubers earlier. But
all other treatments of those which emerged at the sarne time did not
differ significantly (T;3.ble 4.4.8.2.).
Table 4.4.7.1. The effects of physiological age and time of planting
on: stem No, , emer-gence and tuber initiation (TI).
Days be tweenTotal Days taken appearancestem to reach Days taken of 1st stem
nu~~er 50}; to TI from to reachingm er.Jergence planting 50,;6emergence
Treat-ment.
Cold 14.9 45.1'1 68.17 8.69
Apical 13.6 31.6'7 54.33 6.35
A + C 13.4 40.0
, SED 0.68 1.322 1.139 1.139
Early 13.3 1+0.?8 63.33 8.19
Late 14.'1 3?11 59.17 6.85
SED 0.55 1.088 1.344 1.139
100
60
~n
~0,,..,+'til 40+'
""""PI,,..,oQ)s-.a,
80
-
-
-
-
-
-
,-
20
o April May June July Aug. Sept. Oct.*
Figure 4.4.7.1 Monthly rainfall from April to October 1981.
*only for first 25 d~ys for October.
XBUI Has -_ -~-- --3>
"-==- -
-,.>
:<---.~ ....-~
-=---=. =::-.: :::::= --
----- ......
.>-r:... __ :::-..=.::
---- -__- ---- _)
c ~-- .:=:=
----. -=.:::=...
-. "---- "_ -_ .• -_ -_
------=- -.:::=:--..::::::: ---_ ----
-,"C-
I-=::::..::::--
--',";?
~::::::::_~~.--.-- ------
......._-- ==:::
~---- ----------. -- -- ~
'--
--~~~~--------
-----.-~~~:~~=~~ -__-
----_ .-----_ ..
1--------- r-----Q) '0N C\l
---=~--=---=:=_-----------1------ -- ----,
N Q)\~'a,:m1- B.:radUIaJ,
-r-,
..J
C\J
t--rl'ri -=tHP< -=t<:t:
Q)
H
0 Gb'rirr..
HQ)
..0o+>()
o
~IP<
Ic%
IrI
I
UlQ)
H;:J+>cOHQ)
~Q)
+>
rl'rioUl
'Tj~uJ
Q)
§i-;J
s CDEl 0\
'ri~'ri HEl cO
Q)'Tj »>=1cO Q)
~+>H0'i-t
HQ)
S ..00
El +>'ri ()>.; 0
~ 0+>~
Q) rlQ) 'riH Ho P<U) <:t:
015
I ISEDs3 n '15
- --El
-8
I./
10I
o Apicalt::.. Coldo A + C
/II \':o //
/ ;or
I/lZ1 /
/ I
I/, l_I)
1]"
'~----~~-I----
015
I-- ISEDs
.£I-:I ./
JZr//
I 0/
'/r3
'////
I ///
----0
o Earlyo Late
o 0 O,...l-.,- ~, ,_ " ~-, _'I'
June July AugustFigure 4.4.7.3 The effects of physiological age and date of
planting on leaf area index (LAI).
100 I I I SEDs100
r ISEDs80 80 I Ja._
I ' 0----0 ....,.., -.......,
C\J 60 m..... 7I !Pi .-, <, ,- ..D 60a I I' ,,-- /n
I I "Et'I /H 1 ¢OJ 40
m /s::: o Apical 0 EarlyH /OJ 20 A Cold o Late.g 20 I8 0 A + C 13-~
0 0June July Aug. June July ug.
Figure 4.4.7.4 The effects of physiological age and date of planting ontuber number.
650ISEDs ISEDsfLI 550//
1//
380I I
,
I ~ 260II 0 Apical 0 Early!Zf A Cold " 0 Late
/ I.' 0 A + C 1.30:I / '
'"
June July Aug.
520
C\J
11'1380eon
-j.J
~260·rlOJ~~~130HOJ.g8
Figure 4.4.7.5 The effects of physiological age and~te of planting ontuber dry weight.
Cold70
56
42.p
ib'r-! 28Cl)~
t; 14'0
~ 0.g.p
~ 70.po.p 56G-io~ 42oUl
,gj 28til1--<
eo 14Cl)N'r-!Ul 0*
Figure 4.4.7.6
Apical
......: t~::loo ,", .....• ~ ,0. :· : ..I :: ".",'~
:"{;.:.-..;'· :'0:;:"., ,..\:;~6
':-.:~{~\'1,' ,-
i},:.:·:.'· "f: •· .· .
24 July
<, 40mm
40-60mm
>60mm
A+C Early Late
14 August
The effects of physiological age and date of plantingon percentages of tuber size'grades out of total tuber weight(nry weight basis). Vertical bars are the SEDs.
1000 SE~DOO I SEDs
800 80 ...a,/,-
C\J,/
IS r600 60 /till.. /6
8 400 400 IApical 0 EarlyCold 0 Late
200 A+C 20
I SEDs I SEDs
6 508.~ 400
~0 30..!-tQ)
.g. 20+>
* 10
I
/1./'
1/ '
60
o Apicalo Coldt, A+C
o Earlyo Late
June July Aug. July Aug.
Figure 4.4.7.7 The effects of physiological age and date ofplanting on total dry weight (TDW) and percentages of tubersout of TDW.
•Cl>o>::Cl>eoHCl>ElCl>
s.::o
!\bcu.r--jeuo'r-!eoo'6'r-!
~-a'HotQ
oj..>
t>
~Cl>
Cl>
tl
ol!\
o.;;t.
C\IIEl
rnElCl>+Jrn.....oHCl>..0El;$Z
cor<\
or<\
coC\I
+Js.::Cl>S+J(1jCl>HE-t
r<\•o
.;;t
co•C'-
['-..
•l!\
C\I
co
co•N\'"
l!\•or
r<\•CO
l!\•l!\
l!\•C\I
co•
~
['-..
•l!\'"
o-,•l!\r
.;;t•l!\r
.;;t•l!\r
co•r<\'"
C\I•0,
U\•'"
C\I•'"
08•o
§CO
o•.;;t
r<\
C\I•l!\"
l!\•r<\r
r-,•C\I'"
r<\•C\I"
\D•
CO
()\
•C\I
l!\•C\I
116
CY,)
•r<\r<\
o•
\D,.-
r-;•l!\r
CO•..::1-'"
\D•
r<\,
C\I·r<\,.-
o•('1'"
C\I•l!\ ''''•.;;t
.;;t•l!\,
,.-•
l!\,.-
l!\•.;;t
,.-
o•C\I'"
00•()\
CO•l!\
C\I.'"
o•r<\
r<\
o•
\D,.-
.;;t•l!\,
CO•.;;t
,.-
CO•
r<\,.-
o-,·C\I,CO•0\
\D•o
§0:)C\I
l!\•.;;t
,.-
l!\•.;;t,.-
l!\·r<\,.-
C\I•r<\,
C\I•()\
.C'--
,.-•r<\
C\I
If\•.;;tr.,
CO•.;;t
,.-
o-,•C\I,.-
\D•C\I'"
o•
CO
C\I•
\D
()\
•oCO•
\D
r<\·o \D•.;;t
C\I•,
l!\•r<\r<\
,.-C\I•,.-
l!\•C\I
C\I
.;;tl!\•C\I
r<\•oC\I
C'--.;;t•C\I
o•o
C\I
C\IC'--•C\I
l!\\D•C\I
CO•CO
,.-
0,.;;t•C\I
.;;t•l!\,.-
\Dr•C\I
\DCO•C\I
C'--l!\•C\I
l!\C'--•o
11/
Table 4.4.8.2. The effects of phyad o.Logi cc.L age after 64 days of plantingon, tuber, LAI, 'l'DVJand its components.
Dry weight, g m-2Treat LAI Tuber % tuberment no~m-2 out of
Tuber Leaf AGS UGP TD\r1 TDW
4D 1.03 0.9 0.01 42.3 27.5 14.0 83.8 0.01
24D 1.26 13.5 1.9 52.4 33.5 15.6 103.4 1.8
48D 1.36 31.7 7.6 59.9 38.5 17.3 123.3 6.2
80D 1.80 23.4 10.6 73.7 47.1 21.4 152.7 5.5
128:0 1.79 35.5 21.9 75.7 47.9 21.0 166.5 11.2
184D 1.70 20.9 10.9 '71.1 45.8 18~4 146.2 6.0
232D 2.09 40.0 30.8 87.8 8'7.4 23.4 199.5 13.8
280D 1.65 26.9 11.5 72.6 4'7.1 21.4 152.5 6.0
352D 1.62 21.1 10.6 68.5 42.3 22.3 143.7 6.8
920D 2.25 52.3 4'7.6 95.0 59.3 25.8 227.7 20.4
SED 0.237 12.06 9.38 -9.67 '/.25 2.95 25.02 4.34
11~;
4.5 DlSCUS:Jlm:
4.5.1 Sorout growth during storage
Similar results were obtained over three years for sprout growth
during storage. Total sprout length per tuber as well as growth of
the indi vi dua'l sprout incre use d with i.ncr-ease in il1i t ial, tuber weight
and there wc's a s i.gni f i can t linear r eLa t ioneh i.p between total sprout
length per tuber and initial tuber weiBht. This may reflect the avail-
ability of substntes (~~orris, 1966, 1967j ;.,rurr, 1978;).). Total sprout
olength per tuber mer-eased wi th Lncr eaee in day degrees above 4 C after
dormancy break for a similar type of treatment (sprout growth rate was
different for different types of treatments e.g. ap ica.l , multi, fast
and slO\,,). '."hen lines of cumuLc t ive total sprout length per tuber as
40 'a function of cumulative day degrees above C from dor-mancy break over
three years for :.Apicdl tre,'; tmen t from the experiments: F1 (both varieties) ;
F2jF3 were compared, they differ in intercept iilld slope which was
related to initial tuber weight. Thus for these .lines multiple re-
gression was done in which day degrees above 4°c from dormancy bre ak
accounted for 70;; of the var Lance (significant, P = 0.001) in total
sprout Length per tuber .irid when tuber ve i.ght W:J.S included the variance
accounted for increased to 80% ilnd this increase due to initial tuber
weight was significant (p = 0.001). So the tobl sprout length may
be represented by the equation,
SPL = 2.25( "!: 2.08) + 0.31( t. 0.002)DD + 0.118( t, 0.023)T\O/
-1'\<Jhere, SPL = Total sprout length, mmtuber ,DD = day degrees above
4°C from dor-mancy break and T;i/ = Lni t i al tuber weight , g and residual
standard deviatioI,1 = 4.58 and residu.J.l degrees of freedom = 53.
When data from the experiment F3 w~s also included in the multiple
regression the var i auce .iccounted for decz-eased from 80},j to 7Qb; perhaps
the dormancy of this seed lot hud already broken be f'oz-eit was re-
ceived, for this seed h ad many d.unaged sprouts which Lnc reased the
number of growing sprouts arid even tu.s.l.Ly the total spr ou t length per
tuber. Increi:J.sein sprout length with iEcrease in day degrees, when
stored at different temperatures during storage immediately after
dormancy break has been reported by se veral.worker-a, Rawi, 1981; Ali,
1979; Wurr, 1978b. When tubers were under ideal conditions for
sprouting Lnmedi a'teLy after dorrn..ncy break, apical dominance established
within the sprout ~opuliltion, l~rger sprouts inhibiting the smaller
ones as reported by Goodwin (196}), for the variety Arran Pilot.
Storing tubers in cold (3 ± 1oC) stimulated more sprouts to grow, as
reported by \vurr and Allen, 1976, and tobl sprout length per tuber
per day degree increased as reported by Krijthe, ~962 and Wurr, 1978a~
Thom3s and Wurr (1976) reported .1 build up of the gibberellins in
notato tubers following cold storage for 14 days, which may have in-
creased sprout number and thus the total sprout length per tuber.
Al though to t.al,sprout length per tuber Lncr-eused due to greater number
of sprouts following cold storage the extension rate of the longest
sprout was not changed. 'Ivhentubers were stored in the dark extension
'rate 'of the sprouts was increased , this confirms the report of Rawi
(1981 ).
If the physiological st~te of the tuber is to be judged from the
state of the sprouts present then tuber weight must be taken into
consideration. If tubers were stored ~t conditions ideal for sprout
growth Lmmed i,utely after dor-m.mcy br-eak, then total sprout length or
length of the Longe s t sprou t may be a Good Lndicator of the physiological
1?()
state of the tuber. But if tubers were stored for different periods
in the cold (3 t 10C) then length of the longest sprout alone appears
to be the par-ameter for judging the phyai.o Logi cal, e ti te of the tuber.
Hean sprout leq~th_\s used by !'~orris (1966), may not be the useful
parameter es oec ia.ll.y in the cuse of ap i ca l.Ly sprouted tubers where
some sprouts stoPged growing.
Emergence
In these exoe r-Lment s the Longe s t sprout in the case of apical
trea.tment wus 7 - 16mmlonger than that of multi and in three out of
the four cases, apic:ll emerged Cl day before multi but this difference
was not s i.gni.f'dcan t and may not be of much pr-act icul, importance,
e.imiLar but slightly different results have been reported by other
workers e.g. 'vlurr and Allen (19'('6), could not find differences in time
to emerg~r:..ce in seed lots sprouted either from 15th Se;:>tember, 15th
November or 15th .Innuar y unti L planting. Ali (1979) found a difference
of 1 - 4 days in appe ar ance of 50,i£ pl:111ts in various experiments where
difference in length of the Longe s t sprout v.rr i ed from 6 - 3Omm.
Younger (1975) found 3 difference of 4 days in one ye~r (planted on
23rd April) .md 1 day Ln ano the r year (pL:mted on 3rd !.1ay) between
two treatments, LS (sprouted for 12 - 13 weeks at 120C before planting)
and SS·( sprouted for 18 daYB ut 120C before pl~ulting), in time to
reach 50% emergence. Rawi (1981), reported that 50X of plants appeared
l~ to 5 days earlier in phye i oLog ic.d.Ly old seed (longest sprout over
100mm) compared to phys io.Logi.cal.Ly young seed (longest sprout 32mmin
one exueriment 3.nd 62mmin another). However tubers with such long
sprouts may be .imnr-act i cal, to be used for commerciall)l.:mting.
121
Harvesting before emergence showed th., t af te r- plan tin..;, w i th the
availability of moisture and nutrients, the ex te ns ion rate of sprouts
increased many fold and i t 'IJc:~S 2.8mm d;;;.y-1 sprout-1 between 7 to 14
da.ys of p.Lan tLng (Experiment F3, 1980) arid this may have further in-
creased before emergence with increase in soil temperdture (Headford,
1962; Bremner and Radley, 1966; Borah, 1959). Furthermore it is not
only the longest sprout which hue to emerge and in the case of apical
sprouting some branches had already ini t isted in the store on the
main sprouts, and these developed as branch stems. Branch stems
usually emerged later than the main stems. In one experiment (F2)
where apical h ad a higher proportion of br-anch stems compar-ed to
other experiments 5Qj emergence \':,:,-s one day later th.m the multi treat-
mente Thus gr-eate r differences in emergence due to differences in the
length of longest sprouts mav not be expected especially when planting
is done late e.g. after the middle of April.
Experiment F6, which was taken for emergence showed that when at
oleast 80 day degrees above 4 C wer-e given just before pL.mting emergence
was only delayed for a day or so and the difference was not signifi-
cant but less them 80 day degrees above 4°c did sugn i f'Lcan t.Ly delay
the emergence. Depending upon the time of planting in different exp-
eriments and different treatments in the same experiment, cold emerged
'4 - 14 days later than the seed which had at least 80 day degrees above
4°C before p.lan t ing , Similar results wer-e reported by Younger, (1975).
It ';Ias seen that about 50 day degrees above 4°C wei:e required to have
sprouts of about 2.3mm in the store. About 5QS to 60;;j of the sprouts
were either removed or damaged in mech.m i cal. p.lant i.ng from seed lots
which were either stored ut 12°C for, 12 - 13 weeks or 10 days, before
planting (Younger" ~975). If further tuber development is not affected
122
(discussed later, 4.5.3), then tubers given about 50 d.cy degrees before
s tor-age may be of practiced import:mce for commercia.l p.l an ting where
mechanical hand l i.ng is nece saar-y , ..:tlthough emergence m:.lybe delayed
for about 2 to 3 days , Results may v::'..ryfrom one varie ty to another
as in Experiment F1, where two vo.rieties had little difference in
sprout length but Record started emerging ten days L:l.ter than Pentland
Crown. Similar results were obto.ined in 1980, when f'ew tubers with
similar .physiolot:;ic.:U state of t\>10var i.ei ties were planted to see
the effect on emergence. Th3 period oetween plantinG :J.nd emergence
reduces as p.l an t i ng is deLuyed (Bremner and Radley, 1966). The variety
Pen tland Crown took 24 days in 1979 (plan ted on 1st lfi;a.y)and 33 to 34
days in 1980 and 1981 (planted on 15th or 16th April) from planting
to reach 5aJ~ emergence. Simili~r results were found by Younger (1975).
These resul ts were confirmed by da te of plan ting experiment (F5)
in 1981.
Tuber growth and development
T\ew tubers may form on mother tubers during lonGer storage period
in the dark without foliage being produced (ClaveI', 1975; van Staden
and Dimalla, 1977). Van Loon and Houwing (1981) reported reduction in
'incubation period (peiod between the appearance of the first sprout
on the tuber and formation of tu'gers on the snrout when stored in
darkness (ClaveI', 1951) ) by storing at 120C ocompared to 4 C. Rawi
(1981), reported f a.i.Lur-e in emergence due to 'little po t a to ' disorder
in physiologically very old seed. In the present experiments no diff-
erence between tuber initiation (TI) or La te r tuber growth was found
among apical, multi" f'us t and slow t.reu tmen ts of various experiments,
1?3
but cold (seed stored a t 4°C ur.t iL .. d."y before p.Lunti.ug ) , did deLay
the TI even whe~ considered from emer~ence. This confirms the report
of Raquf (19?9). LAI 1 t t.he t i.me of 'I'I \VU.!3 higher i:l cold compar-ed
to apical and r.u.lt i '-1.S found by Raquf , (1979). 'I'hom.csand \tJurr (1976),
reported an il1cre:J.se in sibberellins following cold storage for 14 days.
\\furr et i.J~., (1980), found hi.gher- concentrations of cytokinin and
gibberellins in 'little potato' comnared to normal tubers and further
they s ta ted that 'little potato' initiation may huve occurred at low
gi.bber-eLl Lns levels but tha t gibbez-el l i.n v.c t ivi ty subsequently increased
vii th tuber growth. It may be t.hut during storage at 120C concentrations
of cyto~inins in the sprouts may have increased while in cold stored
tubers concentrations of gibberellins were increased, so the ratio of
cytokinins and unknown tuber i zc.t i.on stimulus to gibberel1ins may have
been more in sprouted tubers (o.pic;,l or mult i ) compar-ed wi th unsprouted
(cold) at the time of emergence. 'I'h i s resulted in dif'f'ez-ence s in time
to TI (Chapter 2.5). A: though there wer-e differences in phy s i.o.l.ogi ca.L
age be tween ap i cuL and multi t r-e.rtment.s , TI ·.vasnot ;,ffected. Possibly
the ratio of cytokinins ~ld the unknown tuberization stimulus to
gibberelli1".s increase at higher rates immediately on trc:nsfer to warm
conditions (12oC) f'ol.Low.i.ngcold s torsge and after that it increases
. at a s l.ower rate, thus differences may not have been big enough between
ap ical. and multi to affect the '1'1. It appears that cer tai,n aspects of
tuberization are var Leta.l, char-ac ter-Ls t i cs as Record took less time to
initiate tubers and further it ctllocated more assimilates to the tubers,
compared to Pen t l and Cr-own;
In the apicsl treatment L< slightly higher per-cent.age of assimilates
were allocated to the tubers compar-ed to the multi tr-eatrnenta in Exp-
eriments F1 and F3,but not .ir. Exper i.ment F4, although this was not
significan t , This effec t .rooenr-s to oe due to compet i tion between
stems rather thanphysiologic:.::.l 1:,ge, :'lS total stem number were higher
in multi of Expe r-Emer; ts F"l and F3 «nd de cr-e..lse in sp·.lcings between
plan ts did slightly de cr-ease the pe r cer t,)ge of '~lssirnilates a.lLocat ed
to the tubers. ro difference .in pe r-cen t age of tuber by wei.ght out of
total dry weigh t vIas found be tween cold .ind :tpic',_l or mul ti when COTl-
sidered from thw dite of TI. So it apDeurs that once the TI had occurred
the effect of phyai.o.Logi co.l age di s.ippeur-ed and major f ac to.r affecting
the tuber growth may then h.ive been the environment. An effect of
photoperiod could not be detected i.l.S the difference in emergence between
early ~U1dLate planting of Experiment F5 was only four days and day
length, dur Lng mi d-Nay , when p.Lant s wer-e emerging, was increasing at
the rate of 20 minutes per week. It iG accepted that there is a balance
be tween gr-owth of tubers and rest of the pl.:..tnt anything which favours
the growth of one will retard the gr-owth of others Oloorby,. 1978;
Ivins and Bremner, 1965). II: 19'79 due to \'nter-strcGG h.iu lrn growth was
reduced and tLis resulted in eJ.lloco.tion of ,cl higher percentage of
assimilutes to the tubers compared to very we.:t ye'J.r of 1980. For
example after 36 and 47 days of 50% emergence percentage of tuber dry
weight out of tot al, dry weigh t Wd.S 36 and 53% in 1979; (average of apical
. and multi for Pentland Crown only) 28 and 47/~ in 1980 (Experiment F2,
aver-age of apic.:.U and mul ti); 30 and 48'){,in 1981 (Experiment F5, for
ap i.cal , average of two da te s of planting) respectively. Although a
higher percentage of assimilates was ulloCdted to tubers in 1979 the
overall growth of the cr-op was very much reduced (4.5.4 q, v.) which
reduced the bulking rate per unit ar ea , For examp.Le af te r- 36, 47, 57,
-269 and 81 days from 50}{ emergence tuber weight gm was 107, 227, 362,
432 and 525 in 1979·,(mean of apical and mul ti for PentLand Crovm); 154,
125
349, 557, 795 and 1091 in 1980 (mean of apical and multi for Exp. F1)
and 88, 234, 359, 503 :md 637 for 1981 (for apical, mean of two plant-
ing dates, Experiment F5) respectively. These figures appear to be
related to rainfall d~ta for three years (Figs.3.3.1 and 4.4.7.2).
Similar resul ts were found by Chowdhur-y, 1980. Llewelyn (1967) in-
creased tuber bulking by irrigation. HcDermott and Ivins (1955),
found a linear relationship between total tuber yield and the May -
September rainfall over eight years (1947-54). There was increase in
yield of 1.4T/ha for each cm of rainfall, which Harris (1978), states
is similar to yield responses found in irrigation experiments in
Britain. Hixing of two type of seed tubers did not affect the bulking
rate as their yield was not significantly different from that expected
i.e. average of two types of seeds when grown alone. But sprouted seed
had the advantage over cold early in the season as found by Chowdhury
(1980). In general senescence (4.5.4 q.v.) was not affected by any
trentments w ithi,n 'CltX1)eriment,50 f inal. yield did not differ due to
treatments, but final yields of 1979 were much lower than 1980, as the
crop was affected by drought in 1979. Significant linear relationship
was found between final tuber yield and leaf area duration (LAD) as
reported by several workers (e.g. Gunasena and Harris, 1968, 1969, 1971).
Several workers (e.g. Gunasena and Harris, 1968, Bremner and Radley,
1966; Bremner and TahL.t,1966) have reported improvement in the relation-
ship between LAD and tuber yield, when leaf areCl.indices above three
were assumed as three, but this was not the case in the present in-
vestigation even assuming LAI over 4.0 as 4.0 did not give any relation-
ship with tuber. Probably light interception increases with increase
in LAI over 3 and further efficiency of the canopy was increasing with
increase in LAI (4.5.4 q.v.). In f'act Lu ter- Gun;).senaand Harris (1971)
126
also could not improve relationship be tween LADand tuber yield by
assuming leaf ar-ea indices over 3 as 3 or over 4 as 4 or over 4.5 as
4.5. A Ld.near' relutionship be tween tuber number cl.ndtot a.l stem number
was found as reported by Allen, 1972jlOosey, 1962j \'!urr, 1974. Since
stem number does not toke ::..nY:.l.ccount of the s i ze of different types
of stems the relationship between LADuccumul.at ed over & period of
30 days from the date of TI accounted for more var-Lance , This confirms
the mechanism discussed in Chupte r 3.5 th a t tuber numbers which develop
depend upon the assimilates available at the time of TI LU1dCl. period
after that. Sizes of the tubers depend upon the tot3.l assimilates
available for their growth from TI until harvesting. Since LADwas
much greater in 1980, there were higher percentages of bigger sized
tubers in 1980 compared to 1979. The number- of axillary branches
(AB) decreased w.i. th an increase in stem numbers per uni t area
(Ifenkwe, 1975), which in the oresent investigation were related to
leaf area duratior~ (LAD) for a period of 30 days from emergence (i.e.
speed of ground cover). Tuber numbers increased with decreilse in
spacing so their average size decr-eased (Ifenkwe, 1975) thus the pro-
portion of bigger sized tubers may be related to the AB. In the
present investigation tuber yields of relatively bigger sized tubers
were significantly_ linearly related to the LADcontributed by the
axillary branches.
1?,?
General cro,) groi.,rth
Stem number is now considered as the unit of population in the
potato crop (Allen and Deem, 19'18). Api ca.l tre atrnen t increased the
proportion of br-anch stems compar-ed "Ii th multi and cold treatments in
all the experiments as earlier found by Younger (1975). Main stems
were much bigger them their counterpartbranch stems. It may be that
because br-anch stems emer-ged later they were suppressed by the main
stems. Hence the type of sprouting treatment given to the seed tubers
must be taken into consideration when calculating plant populations.
iv'ater stress may inhibit the formation of new Leuves (Nunns and Pearson,
1974; Zaag and Burton, 19'18) and so may reduce the LAI (Boyer, 1976;
Hunns and Pearson, 1974). II' the present experiments due to more rain
fall in 1980, stems were much longer them those in 1979 and leaf numbers
were increased. This resul ted in higher LAI values when compared with
1979 ill1d1981. Increase in LAI or ground cover with irrigation has
been reported by Llewelyn, 196'1; Hohindra.,. 1975. In the absence of
any appar'en t water stress, higher LAI in 1980 resul ted in higher rad-
iation interception and thus total crop growth was higher in 1980 when
compared \vith the other two years. It muy become more clear if light
interception und crop eVCJ.pora.tion are taken into consider.::ttion. In
general different tre'J.tments within a purticular year did not differ
in their photosynthetic efficiei1cy or evaporation rates thus the results
are discussed in general for two different years.
The fraction of r-adi.at ion intercepted by a canopy depends mainly
on LAI (Shibles and 'weber, 1966; Horie and Udayawa, 1970), and trans-
mission of Lndi v.i.du.d. leaves and their geometrical urrangements. Light
interception (LI) i·li'creCl.sedlinearly until LAI was about 2.25 and
12B
thereafter L1 Lncz-e aaed at ,1 dim .n iah ing r! te, due to in ter-leaf shading.
Furthermore, Lea f ang.le 1<1::-\yvd.ry w i th (A.ll Lr.cr-ease in Lea f size and so
may affect the geometr-Lcal, :.:l.rr_Elgrnentl'li thin the CJ.}lO?Y. IE the present
investigation these cornbi r.e d effects were de te c ted cis a ch.inge in k as
LAI increased. The efficiency of conversion of light to dry matter
can be estimated from the Ldne.rr relationship betwee n accumulated total
dry weight and ac cumu'la te d .inte r ceo ted T:).diation (Littleton et &1.,
1979; !Jlilford et al., 1980)..vhen forced through the origin (Smillie,
1966), the r-eI.ationships found here .indi ca ted that for every 1.OMJ of
PAR intercepted, the crop produced 3.42g of dry weigh t ill 1980 and 2.49g
in 1979. 'I'he 1980 results are compar-able with results reported for
other crops, for exampl e ; 3.2g;MJ PAR for barley and whea t grown at
Sutton Bonington and Rothamsted (G:.illagher and Biscoe, 1978); 3.5g,MiJ PAR
for sugarbeet (Biscoe, and Gallagher, 1977). The conversion efficiency
in 1979 was much lower than tha t in 1980, probably because 1979 was a
dry year. Reduction in photosynthetic efficiency due to water stress
has been reported for potato (Shekhar- and Iritani, 1979; Chapman and
Loomis, 1953; ;';oorby_ et ell., 19'75), barley (Legg et· ..tl., 1979; Biscoe
et al., 1975j Gallagher and Biscoe, 1978), maize (Verdun and Loomis,
1944), appl e (Schneider and Childers, 1941), soybeans (Schibles and
~veber, 1966) and whea t (Gall:.igher '..ind Biscoe, 1978). A reduction in
wate r supply will frequently cause s tom.itu.l closure (Hoorby et al.,
1975) and thus increase the resistance to C02 uptake. Also decreased
crop evaporation may result in higher respiration rates, associated withhigher leaf temperatures and consequently ne t photosynthesis may be
decreased (Lomas et al., 1972), (evd.poration mesurements for the presentinvestiga.tion are discussed later). Another factor which may have
affected the photosynthetic efficiency of the canopy is the irradiance
129
level in relutioll to the light sdtur~tion point of individual leaves.
Changes in LAl result .in differences in the degree of ill ter-leaf
shading and consequently alter the irradiance level required to saturate
the leaf cano:;JY. Individuul leaves may be light satur.J.tedat irradiance-2 8 -2 -1of 100w m for whea t (}brsh.:llarid .3iscoeI 19'77)or 50 UEH S for
potatoes (Ku et ,11.,1977). Howe ver , although incident irradiance may-2 -1reach 2000 UEl'] S ,in summer, the canopy as a whoLe is seldom light
saturated. In 1980, in the absence of any apparent water stress, the
pbotosynthetic efficiency of the cdnopy iLcreased slightly with in-
creasing LAI, up to LAl values of around 5 (Figs.4.4.6.5j 4.4.3.16 ;
4.4.3.18; 4.4.3.19). Further evidence for increased photosynthetic
efficiency of the canopy with increasing LAl comes from the relation-
ship between CGR and mean leaf ar-ea index (L) (Fig.4.5.1). Up to LAl
values of 2.5 - 3 the relationship between CGR and L was similar to
that between light interception and LAL However at v<.:iluesof LAI
gr-eat.er than 3 tot.i l Light in terception increased at u slower rate than
CGR i~e. the conversion of light to dry matter was more efficient per
unit area when LAl was higher than 3. Puckeridge and Ratkowsky (1971)
reported a similar effect in wheut u.lthough the values of LAI were
higher due to the characteristics of a grass type canopy.
At LAl values of 4 or more around 95%of the incoming radiation
was intercepted and it muy be eXlJected thdt for some of the lower leaves
the rate of respiration would exceed gross photosynthesis. However at-2these vulues of LAl the total dry weight of the CiJ.IlOpywas over 1000g m
and:consequently the contribution to total cunopy respiration, by the
minor proportion of Lower Leaves, woul.d have been smalL, As has been
shown in other crops (e.g. Ga.lLagher and Biscoe, 1978), crop growth
rate was found to be,linearly related to PAR intercepted by the leaf
130
canopy. The relationship was clearly influenced by water stress as in
1979. Although the efficiency of light conversion to total dry matter
was much reduced by water stress in 1979 the percentages of tuber dry
matter out of total dry we igh t wer-e increased (4.5.3 q.v.). A linear
relationship between tuber dry weiGht and total PAR intercepted over
the whole season was found for both years data as reported by Scholte
Ubbing (1959).
Soil moisture studies of the present investigation showed that in
1979 due to water stress and lower LAI crop evaporation viasmuch lower
than the potential evapor-at i.on (Penman, 1956). 'I'he se differences were
grei:\ter.than the differences detected for pei:l.s(Dawkins, pers. comn.)
for the same year but the peas were planted earlier than the potatoes
and so they were better established than potatoes by the commencement
of the dry spell. Fulton (1970) described potatoes as much more
ser...sitive to water stress than maize or tomatoes. Burrow (1969) demon-
strated that the rati,oof actual to po ten t ial, evapor-at ion fell more
rapidly in potatoes compar-ed to sugarbeet. Shepher-d (1972) reported
a greater reduction in crop evaporation of potntoes compared to mixed
crops of grass and clover. He related this to the greater sensitivity
of potato leaf diffusion resistance to'etdecrease in leaf water potential.
Fuehring et al., (1966) reported considerable reduction in crop evapor-
Cition if irrigation was not given at 75% available soil moisture.
Potatoes are consider-ed to have shal.Low root systems compared to other
crops e.g. sweet corn, tomato, sugarbeet and barley (Corey and Blake,
1953; Durrant et aI., 19'73). In the present investigation roots extracted
water from a depth of 90cm in one year and 80cm in another i.e. in the
orders found by French, et al., 1972; Durrant et al., 1973. Ark;Ley(1963)
showed that there WaB a linear relationship between the amount of dry
131
matter produced and the umoun t of w:~ter evnpor-ated, Penman (1963)
related tuber bulking to the adjusted potenti~l evaporation. In the
present investigation crop growth rate VIas linearly related to the crop
evaporation. Although there was a difference betweeriyears, wi thin any
year, physiological age or storing tubers in the durk before planting
did not affect the overall to ta.l gr-owth of the crop when considered
from the date of 5(},l;emergence. However the proportion contributed by
different types of stems WelS different for different physiologically
aged tubers" as apical,treatment increased the number of branch stems.
When total stem number were increased either by decreasing spacing or
using bigger seed, LAI and total dry weight were increased early in
the season, and this resulted in more tubers being initiated. The
average tuber size was reduced as found by Ifenkwe, 1975. General
growth of the mixed plots, where two types of seeds (i.e. sprouted and
unsprouted) were mixed within rows was not different from expected
(i.e.').verage of sprouted (apical or multi etc,) and unsprouted (cold)
when gr-own alone). Sprouted occupied more space than allocated to it,
this confirms the report of Chowdhury (1980) but both treatments sene seed
at the same time.
One way of increasing the interception of total radiation is by
increasing the longevity of the crop. In 1979 senescence of the crop
was not affected by the physiological age or spacing but the variety
Record senesced after 138 days of p.lanti.ngand PentLand Crown after 160
days of planting. In the case of Pentland Crown it \'JaS observed that
small seed (34g) emerged later and senesced later than bigger seed
(62 or 105g). In 1980 there was no difference in senescence among the
various treatments of Experiments F2 and F3j all senesced after 162
days of p.Lant i.ng, 'I'r-e atment 025 of Exce rimcn t F4 sencsccd 16 days
132
later than other treatments of that expe r i.ment .ind 12 days later than
the Experiment F2 or F3. Differences in LAI due to different treat-
ments of Experiment F5 (1981) disc.tppe'J.red from the middle of July and
ligh t interception measurements showed that about 93% of the incoming
radiation \VUsbeing intercepted on 30th. September and 90X on 13th.
October, w i th no difference between treatments. It now appears that
senescence in 1979 1:J:J.S affected due to water stress. As large seed
emerged first it may have been affected more by the water stress than
the later emerging small seed. This hypothesis agrees \'lith Bagley
(1971) who foung than an eu.rly developing crop suffered more from the
drought ·in July than the less advanced crop. Younger (1975) reported
that cold treated seed emerged later and senesced later than the sprouted
seed. Sene ac ing in 1980 was affected by the very humid weuther- as stems
were over a metre long, lodging occurred and rotting of stem tissues
was observed from the middle of August onwar-ds, Another f ac to.r could
be the depletion of nutrients especially the IJ (Ivins, 1963; Ivins and
Bremner, 1965; Gunasena and Harris, 1969, 1971), as crop grew at a very
fast rate. Due to higher stem numbers total dry wei.ght of all treat-
ments of Experiment F4 but S25 was higher than the treatments of Experi-
ments F2 or F3, so they might have depleted the soil before others.
Another factor vrhich may have affectc-d the senescence is the transmission
of wavelengths above 700nm (Holmes .md Snith , 197'7; Scott et al., 1968),
which may have affected the physiological status of the plants as LAI
was very high in that year. Another evidence for this come from
Chapter 3, where the pp333 treated plot in 1980 had a close canopy
compared to other treatments and this F.iayhave af'f'e c te d the transmission
and it senesced before others. It caL not be the temperature as some
individual guard pLHltS were aee n green for itt least ten days after
133
the crop had senesced. ;JO\"I, since 1981 has been the medium year for
rainfall and LAl did no\;reach above 3.5 and growth rate has been much
Lowe r' than 1980, thus soil may not have been depleted for nutrients
and as there was no severe drouGht like 1979 the crop did not senesce
until the middle of October.
For delaying leaf senescence in :...we t year, application of nitrogen
later in the season may be helpful (Gunase n« and Harris, 1969, 1971).
Later application of N may slightly affect the bulking r-ate, but if
L~r of over 3 or so is maintained during September and the middle of
October could be very useful as due to short days most of the assimilates
produced may be used for tuber growth only. In a dry year like 1979,
if irrigation is given in such a way that crop does not suffer from
drought and LAr stays around 4.0, may be helpful in increasing the
duration of the crop.
Any of these techniques to ext.end leaf persistence by delaying
leaf senescence could be frustrated by blight disease Ci.ndof course
blight control in itself extends leCJ.fpersistence und the period of
tuber bulking.
4U
3S
+ + + 2CGR = 2.03 (-0.98) + 8.09 (-0.89) L - 0.67 (-0.16) L
% variance accounted for 76.6residual standard deviation = 4.65
30 0 Experiment F21::. Experiment F30 Experiment F4 0
[:;
ne:: °0 0(_,.._; -------_...-_..----
/-
/'/' 0/'
r< / [:;I
>0 / 0III /'0 2JN CJIE
//
/
0' /0..~o /U /0
15 // [:;
[:;
10uj/
5
o~
O-t-----r-------.------,----------,------- ---,-----,------,2 J 4 5 5-1 J 1
Mean leaf area index (L)Figure 4.5.1. The relationship between crop growth rate (CGR) and mean
leaf area index for all experiments in 1980. Each data point is anav~rage fdr number of plots in that experiment.
134
SUMMARY AND CONCLUSIONS
In the majority of the field experiments, final tuber yields
were not significantly different over a wide range of treatments
which included (a) different physiological ages (b) different
sprout growth rates at planting time (c) different stem populations
obtained by adjusting plant spacing and seed tuber sizes
(d) a mixture of seed tubers of different physiological ages
or even (e) the two different varieties. In 1979 drought in
early summer affected all treatments but there was some recovery
when rain fell later, but because of this all yields were lower
than in 1980. The photosynthetic conversion efficiency of the
canopy (g dry weight MJ-l PAR intercepted) was 2.49 in 1979
compared with 3.42 in 1980 when there was no apparent water
~tress •
Final yields are multiples of tuber numbers and mean tuber
weights. and these two components, together with stem numbers,
were significantly different with different plant spacings,
seed tuber sizes and storage treatments. Record produced
mqre tubers than Pentland Crown. The relationship between seed
tuber numbers and stem numbers was linear and significant.
In treatments which gave higher stem numbers in the crop
L.A.I. and general 'crop growth rate were higher early in the
season but other treatments caught up later. PAR interception
increased linearly with increases in L.A.I. up to LAI ~ 2.25
when over 70% of the incoming radiation was intercepted.
135
Above LAI = 2.25 the rate of PAR interception slowed down until
LAI = 4.0 when around 95% of the incoming radiation was
intercepted. F~nal tuber yields were significantly rQlated to
the PAR intercepted by the canopy over the whole season.
No treatment other than varietal differences hastened
leaf senescence which was later than anticipated and this
probably explains why final tuber yields were not significantly
different for several different treatments. Growth analysis
studies showed how different aspects of plant growth were
affected, but in each case it appears that the crops arrived
at similar final yields but by different pathways, i.e. bulking
rates x duration. Growth analysis results also showed that
had the crops been burned off or lifted earlier for final yield
then the different effects of many treatments would"have been
much larger. Hence seed treatments are of vital importance with
early crops and probably second early crops where lifting
occurs before mid-August. However, with maincrops which are
allowed to mature late, by favourable environment, absence
o~ blight and by production treatments such as irrigation or
higher N levels, then a great dea~ of catching up takes place
a'ndat final harvest there are not likely to be great differences
in yield from a range of seed treatments. The major effects
are likely to be on tuber numbers and sizes which can have
implications for quality for various purposes.
Drastic effects on leaf growth resulted from treatment with
a growth regulator pP333. Although this investigation was no
136
more than observation plots with no replication, it was evident
that leaf area per plant was reduced and higher tuber yields
resulted. It proved possible to plant closer without enhancing
interplant competition and PP333 appeared to increase the
allocation of assimilates to the tubers. The result was
more medium sized tubers. This preliminary trial suggests
that there might well be a future for plant growth regulators
with the -potato crop and gives encouragement for further
investigations to be carried out.
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APPENDICES
Appendix A
John Innes potting compost number was prepared by mixing loam:
peat: Grit; 7:3:2 (volume basis). 372g of J.I.B (5% N,
7.2% P205 soluble, 1% P205 insoluble and 10% K20) fertilizer
and 70g of chalk was added per 100Kg of mixed compost.
Appendix B
Seed used for experiments: GR1 (growth room); F1; PP333 trial
1979, was obtained from UCW, Aberystwyth, where it was grown
at Rhayader, Powys, from Scottish FS3 (Pentland Crown) and
FS2 (Record) stocks. It was planted on 10 May, defoliated on
4 August and harvested on 5 September
Appendix C
Seed used for experiments: GR2 (growth room); GH1 (glasshouse);
F2 was also obtained from UCW, Aberystwyth, where it was grown
at Dyfed, near Llanarth from a once-grown Scottish VTSC stock
(Multiplied in 1978 at high altitude seed site near Rhayader,
Powys). It was planted on 22 May, defoliated on 10 August and
harvested on 17 September.
Seed used for experiments: F3; F4; PP333 trial 1980 was grown
at Bunny (University of Nottingham Farm) from Scottish AA1.
It was planted on 7 May, defoliated by the end of August and
harvested from middle to end of October.
Appendix D
Seed used for experiments F5 and F6 was obtained from uew,Aberystwyth, where it was grown at Dyfed near Llanarth. It was
planted on 17 April, defoliated on 21 July and harvested on
4 September.
Appendix E
Main stem The stems directly originating from the mother
tuber.
Branch stem - The stems originating from the underground stem
i.e. not straight from the mother tuber.
Axillary branches The stems originating from the leaf-
axis above ground.
Main stolons The stolons originating straight from the stems.
Branch stolons The stolons originating from another stolon
i.e. not straight from the stem.
(Block Capitals) (Surname) (Forenames)
ADDRESS ~..
FACULTY AND DEPARTMENT IN WHICH REGISTERED ••••••••••••••••••••••
.. .~~v..M\."}.. ~.~.... ~.~Q:":\~.~~;\>,~. ~""",;"",TITLE OF THESIS ••• ~Q:\.~ -X. 0 .•••• c,R..O ~":\ h\ ~ ~ b .
~. E:vEo \...Q£~.N\~. ~ ::y \~ .~ ~ 1.-.""""5.\Q ~ •• J':Q ....••
...~~.\;.h~ .DEGREE FOR WHICH SUBMITTED •••• ~ ~ .•j). ~ .YEAR OF AWARD OF DEGREE .. .\.~~ L ..
I agree that photocopies of the above-named thesis may be supplied onrequest on the understanding that such copies will be single copies made forstudy purposes and that they will be subject to the usual copyright condi tions.
Signed.... ~~;{~ .....•..
Date •••• :i.~:~: ~:'\.~} .April 1979
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