Volume I 117

SALINITY AND PLANT PRODUCTIVITY

D. L. Carter

INTRODUCTION

Plant productivity is limited on an estimated one third of the irrigated land in theworld or approximately 4 x 10 7 ha by soluble salt accumulations in the soil, oftenreferred to as soil salinity or salinity. As irrigated agriculture expands, more salinityproblems will develop because there are millions of hectares of potentially irrigableland that could become saline. Every year new salinity problem areas develop and areidentified. Salinity is the most important problem facing irrigated agriculture, andsolving salinity problems is one of the greatest challenges to agricultural scientists.

Much research has been conducted during the past 30 to 40 years to determine therelative tolerance of crops to salinity. Most of the salinity tolerance data availablethrough the early 1960s was compiled into useful relationships by Bernstein in 1964,and these data have been cited and applied throughout the world.' Since then, manynew salinity tolerance studies have been conducted, and many new management prac-tices have been proposed, evaluated, and some of them practiced to reclaim salt-af-fected soils for improved crop production. Recently, Maas and Hoffman evaluatedexisting salinity tolerance data for agricultural crops and presented the data graphicallyso that the relative tolerance among crops could be easily compared.'•'

THE NATURE OF SOIL SALINITY

The soil solution or the water in the soil contains soluble salts, usually as the ioniccomponents. The ions commonly present in the greatest concentrations are Na', Ca",Mg", Cl*, HCO 3 and SO 4 .— The proportions and the amounts of each vary widely.Sometimes NO; is present in significant concentrations, and K* is generally, but notalways, present in low concentrations. Some other ions are present in low concentra-tions. Total soluble salts or soil salinity generally refers to the total concentration ofall ions of the soluble salts. When the total soluble salt concentration in the soil solu-tion is high enough to limit plant growth and productivity, a salinity or soluble saltproblem exists. Soils also contain slightly soluble salts like CaCO3 , but these salts donot contribute to salinity problems.

Most arid soils contain high residual salt concentrations. These residual salts resultfrom natural weathering processes of soil parent materials, evaporation of lakes, andrainfall and evaporation over centuries. Soil salinity problems may develop in normallynon-saline areas when salts are leached from some soils and carried by water to otherareas where the water table is near the soil surface because of inadequate drainage;the salts are then left behind as the water evaporates from the soil. The source of waterfor leaching and transport of soluble salts in arid regions is generally from irrigation.Soluble salts also accumulate in soils irrigated with saline waters, particularly wheredrainage is poor or when too little water is applied to leach excess salts.

Water is transpired by plants in essentially the pure state just as it is evaporatedfrom a free water surface or from the soil. Therefore, as plants use water, the saltsare concentrated in the soil solution. When plants have used one half of the water,stored in a soil from irrigation or natural precipitation, the salt concentration in theremaining water or soil solution will be approximately twice the original concentration.When three fourths of the initial water is used, the salt concentration will have in-

118 CRC Handbook of Agricultural Productivity

creased approximately four times: All irrigation waters contain some salt, and the ef-fects of this salt as plants use water depends upon the salt concentration in the irriga-tion water. The total soluble salt concentration determines the quality of water forirrigation; such waters are classified based upon their salt concentrations.'"

SALINITY EFFECTS ON PLANTS

Excessive soluble salt concentrations or salinity affects plant growth and productionprimarily by increasing the osmotic potential of the soils solution.' Under some con-ditions,'" specific ion toxicities can also be important for some crops, particularlywoody species. The physiological effects of excess salinity are many, but visual symp-toms generally do not become evident until salinity conditions are extreme.

Plants affected by excessive soluble salt concentrations usually appear normal, butthere is a general stunting of growth, foliage may be darker green than for normalplants, and sometimes leaves are thicker and more succulent. Woody species oftenexhibit leaf burn, necrosis, and defoliation resulting from toxic accumulations of Clor Na. Chlorophyll formation is inhibited in citrus by specific ion toxicities." Occa-sionally, nutritional imbalances caused by salinity produce specific nutrient-deficiencysymptoms." 15

The osmotic effect of salinity is to increase the osmotic potential of the soil solution,thereby making soil water less available for plant uptake. Therefore, salinity-affectedcrops often appear the same as crops suffering from drought. Many plants adapt tothe increased salt concentrations by increasing the osmotic potential of the cell sap." "

As the salt concentration in the soil solution increases, both the growth rate andultimate size of most plant species progressively decrease. Salinity effects are fre-quently not recognized, even though yield reduction may be 20 to 30% because of thegeneral decrease in growth rate and plant size. Not all plant parts are affected the sameway, and any relationship between growth response and soil salinity must take thisinto account.'" " The leaf-to-stem ratio of alfalfa is affected, influencing forage qual-ity. 3 ' Vegetative production is decreased more than seed or fiber production for cropssuch as barley, wheat, cotton, and some grasses_ 2•3• " In contrast, grain yields of riceand corn may be greatly reduced without appreciable reduction in vegetative produc-tion." " Root yields of root crops are generally decreased much more than topyields."-" In contrast, top grOwth is affected more than root growth with some otherspecies.

The impact of reduced plant production caused by salinity depends upon the purposefor which the plants are grown. Total yield and quality of crops grown for sale or forfeed are generally most important. However, the survival and growth of plants usedfor landscaping and ground cover may also be important under some conditions.

MEASURING SOIL SALINITY

Soil salinity can be measured by several methods. Plant growth is primarily relatedto the osmotic potential of the soil solution in the root zone."'" Osmotic potential(P) can be measured directly by freezing point depression, vapor pressure osmometers,or thermocouple psychrometers, or it can be calculated from the electrical conductivityof soil saturation extracts (EC,) by the equation

= –0.36 (ECe )

The saturation extract is the soil solution removed from saturated soil by suction orpressure. Measuring EC, has become widely accepted because the saturation percent-

Volume I 119

age is easy to determine and reproduce in the laboratory over a wide soil textural range.Plant tolerance to salinity is generally based upon EC. values rather than osmotic po-tential or total salt concentration. Both osmotic potential and total salt concentrationare readily calculated from EC.. based upon the above formula and relationships de-veloped at the U. S. Salinity Laborabory."

Instruments have been developed recently to determine the electrical conductivity ofsoil water (EC,..) in the field. Salinity sensors permit EC... measurements at a givenpoint in the soil, and the four-electrode probe can be used to measure an average orintegrated EC,. in the field."•" The salinity sensors ark useful for measuring soil solu-tion salinity under field conditions over the ranges of soil matric potential normallyencountered in the field. The four-electrode probe is a simple, rapid, diagnostic tech-nique for determining management practices. Both methods are based upon electricalconductivity and are generally referenced to EC, values for plant productivity esti-mates. When specific ion toxicities are evident or suspected, the concentrations of theions are measured in the saturation extract.

FACTORS INFLUENCING THE EFFECTS OF SALINITYON PLANT PRODUCTIVITY

Many factors influence plant response to salinity. One factor is the growth stage.Sensitivity to salinity varies with the growth stage for many plants, particularly cerealcrops. Rice is tolerant during germination, becomes sensitive during early seedlinggrowth, and then becomes more tolerant as it matures."'" Barley, wheat, and cornare more sensitive during emergence and early seedling growth than during germinationand grain development."•"'" Sugar beets are sensitive during germination and becometolerant after that." Varietal differences in salinity tolerance have been observed withwheat, barley, soybeans and some other legumes, and many grasses. 36 - 42 Rootstocksfor tree and vine crops differ in tolerance to total salts and also exhibit a differentialsusceptibility to specific ion toxicities." ."'"

The availability of plant nutrients can affect salinity tolerance; conversely, salinityand specific ion toxicities can cause nutritional disorders. Conflicting results of somesalinity-nutrient interactions are found in the literature. Applications of P have in-creased plant production under saline conditions in some investigations but not in oth-ers. There have been reports that excess P in sand cultures may decrease salt toleranceof some crops; however, P concentrations would seldom be excessive in soils becauseP is adsorbed and precipitated in the soil. As the salt concentration increases, N re-quirements of plants generally decrease. The Literature contains information on severalother interacting effects of salinity and plant nutrients on growth and production.These are not discussed here, but references are provided." . "- 48 - 5' Published salinitytolerance lists of crops are generally based on data obtained where nutrient availabilitywas adequate.

Plant response to salinity is influenced by climatic factors. Many crops are less tol-erantw hen grown under dry, hot conditions. Relative yields of alfalfa, beans, beets,carrots, cotton, onions, squash, tomatoes, strawberry clover, and saltgrass are lowerin warm than in cool climates." High atmospheric humidity increases the salt toleranceof some crops, and benefits salt-sensitive plants more than tolerant crops."

Irri gation management influences plant productivity in several ways. As previouslymentioned, all irrigation waters contain some salt, and as the water passes into theatmosphere throu gh evapotranspiration processes, salts remain in the soil or the soilsolution. Unless extra water is added for leachin g salts from the root zone, salts willaccumulate from irrigation during the season. When the irrigation water contains mod-

4w c 2 .9:0.2 I eP-7 fe; . eV.

rIFI N 4 .4.7 g 4L;-77272

zz

Q4

00

I..t Nen en W $.0

e ri Ce. GIN

N..0 W ..0 W

ztn"

a.

P. al 0e

i,c 1,IZZ2!– •••n el el

CU

z CM1 0 0 1 0 1 0 0 0 0 10 1 0 0 0

co 00 l a f 0<a 0 .0 1 1 0N0

1.143 Z 00 0 1 0000 j e0

-'2 0 ‘4:3 000 1 0 1' 0 ° 0 i g lf17,PaZ ca

< °° Ia VI 1,1 V'f NiNNN •— n I I CCP NoI.—)u

EI en 4 4 ,c, —

1" 2 N rqz1

nr. CO 0 N F F CF F '4;7

N NI e-- N r•-•

zc1.1

0' 0.0' 80000000 I008000 a

— 8 8 8 8 8 8 8 8 8 8 8 8 8 8

[—I

Volume I 12!

ev,c,vs .., N1' W NO en

4 IE: 0- .4. vaO

NA.4 4 $.1:

. •–n .41 el .. rire, . . W • nO 0

,—. 1 en en 0,7 re, . ...ni N . 4 4 .•-. 7ES 4 2 72 e•i^

LU

z0

.? L; ‹? .1 et 4:: CI41 4.1 tt! °R c? ‹? CI el N. el Ci`r: ri ..

0E.4

U

LLB

LU

11° 0 ° 1° 0 !RI

I I 0C'C' I C'C' 1e95 I

I VO 2 0 1 00 10l

I PA `;',1 #

117-:4,71 0 ,41SI0 0.,

•ri I en he. 4-1 Fr, F F F k0

3: a

8 8 8 8 8 8 8 8 8 8 8

c I9 .2!, .g

c.I... ij ., q V.,.... toC r,- '2 ,s i l. Li9 ix ts .-..

.

.. .., •.-: -S. , • n . • St .2 .0I.) 4 ,.. .,. 0 0,4

'... --‘ k." a ..) .r" E La - : :,72' g`Z E. ., 1u .?C 4.1 2 v.,•... ,...., ... _ =2 z..a egt. ..e2,?,..d88 .2 us G EEEe

.2-3 co =, '. 6, ,g C. zl. z 6. ns t: 6, 7z06. A ,.., er, ,4 OJ 4 :--. a a 2 wc`A ' -Z. 7, 9; 9, :;,' to a I = ..:-.- q cn -,;,. q c,. !.,' ti .':'CI :P..

0 v? ,., ;., 8 "i a E -, ,4 43 ,,, E E. n LI . 0 l R .,',F., 2 4 2 E. A .2 .-,. ,, 6, g . -2..?... , •413 -., g 1,-. 2 g % .. :% g E ,g.. 2

ei: ''-' t':: cL, la. c4 c4 t.. c°4 Q-“3 Z '• C:i R Ci el: ci ct Q. a. 67: c2

00

1"

; 2 1, "g t F,GU

q — • 'A' u ,..(2 2 q t >E c. ›. 5- 1: 7

11Y.II0 1.

i 2a t8 q i .F . C b a 2•! 8 g 22 1! 2 2 D.

g

gu 0n E

E0 0 0

000

0 0 0

000

0 CO

o

74, er, •••.• el

N '0

CP,

00

f•I

122CRC Handbook of Agricultural Productivity

zz0

c4

0

1:4

c \ 2

S' R. 652N

E.nZ 0

a< 0 0

t a

1:4

tit

z

z

<• z0

• 0

Pk 0P-A 04Z

r1 (1/z

z0

<0• zVA C.)o zE-I

7

0

Lt1

Volume 1 123

0

e Ea

z

114C4

z

E-s

Z

Z0

P4

1.140

Ed4:4

z

e4-) Z

:FE

ZQJta

<

-0r:<c4 j

0Z

Uo z

o

O

r.z.1

CG

L.t.7

1

E, 7t1 di 11 •• r••

4.94 . -o ci

L '" ' •• ;-

< 0:1

r•1VI rIi.IN .n• 14.

n

ICCi C7 N 0 - N...1 IN IC0

ID nie"7 r4

.(+I n Iol..

...• •••••• IN IN 40. n417. GG i Mr•CII r,7'C.

v? O en

•-n 1•71

.rn 0 CO 0 7.7-7 unN N If N 2a a

CC 4 0 0 0 0

ek 0 0 0 0 n

*1

b M Lel C CO CO 0, 0 N

CA M

VZ M 0 0 •n•.... e'I

4,1 C.1

..i. 0, N 'C. CC xe, .r T.,• 0,N 'et r.I Vi en VI •-•n Se

0, .0 V- WI sz CO

..et •I• N 31

4r,C:+1 CC •er 0r,41 .1. VI v 4.1 rn

sr,"d•N ,0, C) N

N W N N in V.1r• E., F., 00

Fir IO •—n N 00 NCC GO 00 CC I,- c7.

087, ft,' i":;; 2,1 8

,

C

A A

g

11

C1-

.911 u Z,4N N

00

N

CP I 0 07 0

I I 1 ° ° 1 °

°

ct,

4°

n

ON I I 1 I-- I

I I I° I 1 4" IN 0

rrl g I I -7.

o M I r•-,tl m r N

soes.)en se "ri-

I g?I I '5:

'A 14

1

i

c" C, C,in

N IN..1 .-•

VIw-1. IN

71 Si I .52k 00 I.7r v-7 I A kiC

Fcl, I .5", 1,r. N

Ino I

I 44•1

C• co74, •7/.

v2r—

I pg Y] osCO r-- I •Cr 4'1

f I en 00CO Cr. 07

I F..1 '4388 1 4" 4"

so a. roC77 CI

I a-

0 0

0 0 0

0 0 CA.

IO co I•-•

`re 7,

— 8 8 I 8 3 888 18 88 888 8 8 8 8 8 8

>, -

ftr

N

....-

I I I I e' °°'=""

I I I"" e'

I IR1 :-.; l 000.e0 I N

mon

N

I

M g

„T s 14. 1400gC. yr. 4 74.

' .t. 0 4^ II ° ,,A$ 4

el 6̀1 tez =.,:p. - N n

.ten I i c,g ic,,,gz.? r4,... IM 8 rg I ra;

-I. 114,3 lc,gi.,gpp i- ,r--0. r„.61 / s13. ag d .z w

.0en 1 1 g 1 6 .r.,- 4 .,k2 f,.. .1 1 G NN [ N

•4.1 00 11 ta--= I '4 'rn S 1:--.1 ,7-: I°n -.N I

-

• :r

en

.)on

I g g 1 r,2 eg ..2 3 i cc CA •-•1 M. SO

oo 1.rmn g.8ez...ergn 1 8 trlevar47. N • cen N Ci C.

CA CA r, CA

e

N I888861* 888&D

- 8 188888888 18 8888------

124 CRC Handbook of Agricultural Productivity

n n n

0t I-- r; O n

r- 0 - n 0 - 0 0

G ,"$N

n d 6 -ter d e e- 1 IN N."' '41' N , 0 4r•i .17 .4 43 . c.; e.; . ..7 i r...• g.„ ,,,.. ,

I6.1 e .,-; "' i 1 - c, 1 o - 1 r4

- t4 - .70- b .-,.1 - - ..i, ry. 3... _ "-L ,..;F.' N.- I 1

zins

rxUz

k'N p n N r N a N en C. NN N r4 - - N N

.?..126

- 4 r. Nglau 0, IIIr

cD I °0 1 p 4 0 1 en

0100i0

nce

P4

N ItnA I A

otn.tr. -

5f.;. •-m 'PC Le,

S rze S p

10.2 Le2 p ec..2

nI

l n

n enp co co Cr.

IV, a 18 8

8 188 18 g

OOs

c E c. ilc..

. 03 4a.

4

q 8 ca. .. L s ..7 , , E .C,' Z q, ,s.1 , .- ..,.. 44 :1= :s - -. =

t.) tzt. o c-g -Q ES '74 F:i m iS" z [4. z %' g. 653 le, R 04 = L- LI - -c

41 gt --' i:' ..?.. .,- "" E. c"4 ''' iz .. 4 -2., N 0. a VS n *3 0

..r. , Li Z ♦-- _m = .7. .] *3 '' i... 0 *3 = L., -ra c ,. .,, g-,

E-. c c • - '31. , 3,5 'i' E. , 4 . ,L, .,,, 2 'C' 4 , ,5 ,,1 2 2 g E 4- . ,..4 R 3 ;.- ti .:. 1 ,y, -P.

tai 8 .t- E ;..' -E<

.-1 Fin Q a ,, c.- E.' ct El.. "2. -7-% 44 a c E 2 L.,. '' a a G- ,, ... .4 -d .4 _ r, .4 - _ ,' • 3 A E . 'a ri., .-Z `s.' ' _-

q:. `•

W .t v., U Z a. ¢ C.) v) 0. la4 G. qC) co) v) (..) v) - a4 p.r..- -a a, -a - -a

ge I FL"

E g 5 aco ,_ _›, ,,

C4 .._ x 0., ..,o-,-,. -.5. 2%5 c m 4 .- ,.c L. 5 -ty •.' .-. 0 0:1 .g •• 1 a g L. -.- 05 -° 7". -:.g & 73 335' '4.- • ,.3 a a.. w 0 c6

,,, ,./ 331 3- . . ,,,

g Ti 4 “... 11 $.3 F,- .5 ';, '7, e .8 -9, i I. 14 „ . E 0Er. x E

7 • 7 7 .c) a. a. A., A. 3:6 IX 64 r.q vsr..1 rn ,n cri ‘n {--. (--, 1--.

cisI I - a; I ez

CC

Cr.-4r

%ow

L. ....4.)>

0Pa a .0 q

Voluine I 125

r-

e;

N

71;

C3.

O

cs

0

q7a

8S

:-,

Q aaoa 0a

0

0 N

IN 0Pn

Ktel

wl .43

43 21E .E

cr. -0

ON

OcY:

C C C I

CC••••

C•n1 C C

N C en cc a

ZN

C C 0Za 0

In C N N CN

Z

ci 8g 1.1.1n1

n-4 LT4 0,

0X 4 g tn CON

Z

Z0

!X t-P<

1:3 E0E

(..)raj

OD

•-•NN

N

co• ceNO

en

N

r

IX NON

%C. I 8 NN

oz

1n1

8FU

8

.4 8

8

8

8 `cf,

8 8

— 8 8 0

us

U

0a.

<

0' On.cc ca

ON

-4)en

•cl•N

Nri

CO

t-

CON

•ct

as Cr,

C 88

8 88

8 88

_

N

en

C

;7, N

O

4'

8 f3 r

0'

8

8

8

8

8

8

ro

zvs .4

EF

Qt

F-

q

CS

00

EOC

O, 'sq

c, .0 rrs•Sc

‘ n 'Fs 2.

L14

.E•UCU

q

c4 C.)Urt3

y. or,

q ozi

1 26 CRC Handbook of Aaricultuial Producrivity

C C N N

-

N ° t 7 f 7 f N

zI CC

N

),

-7

ry °

0rs

2

5. 0

T- :4)

>•• 0..

Volume I 127

e(-4 e,

7 el I 0,

P

nN

3 __. zd O; 7 .6,

,r c' I 2 7.1 3 P.

I

I

I

I

1

I f

I I

I I

I I

I I

I

I

I

ve

I e,I '0

IN

1

C

ken

0

0

p

re,

CC

C

0

C

‘0 I o '40

1,11.4 I NID

I .7r In a,try

I IQ 0 0rn

I 4-1 .0 pp3

I2 0CO

0 ‘0.I.7 0

f•-•

I '- 0 CC 0r- 140co

I I I,' 2 CC

I » 8 F ,L7 8I g F 8 8 g • - 8 8I\ 8 I 8 8 8 8 8 8I/ 8 112 8 8 8 8 8

8 I I 8 8 8 8 8 8 8I/ 8 8 117 8 8 8 8 8

E

fi r,•

_2 2 •-••-• •-n p, P:J , "'

&I 7r.; E

=2.2 -8 • g

•=.En ""'

Ler

es •

riI 2 a

r- — r--

V;aC

Qz

to

Z

Zgt, 0

E-1Z

8q w4 a4

fox

rh Z

r;3i0 H

4.1 uz8

Pd

yW

t A t2 3

• ‘s 4,5 44

0...0 0. uE

-s E E

C.

cu

to

V

rs

UC

0

C

O

to. 0

a.

C

En

Cz

en

N

. 1 t

I I

N I 1

I I

N

N

Nen

en

00

N

00

88

128 CRC Handbook of Agricultural Productivity

U

C.0CUU

CO

to

C

e

to

gC. 7,

e O

V CT., -

u 0.o

tp "cl •

E :6 5

ro-

a) 4 a.. 6 u;g C.

7•7+ U 4 C ° 2 es

E 4E. t

n-•=u a -0..„to 12

ccE -

86% 1-'`j11a A

4, 7

^ ro o8 7

1— 1—

el

Cu

to

8.2V

to

C

ro

C

a.

U

Cro0

C.

*el

O

2

Volume 1 1 ZY

LD

ez.nr-0 1 0,—, el el

ae

.et

a

0

0

I)

CR

a

00

cci

In I ; I I

ON00

0N

8

is 4CC

00

1 3 0 CRC Handbook of Agricultin-al Productivity

c_k

0 •

4 I i

z0

1:4

-12

(4)_.to .5

Ug L°:00 E

-11: E0

CO

00

7cc.

88

88

;161

-2

1

1

888

.2.

-.A•

2

0

-0

1,3

•3

-E

o.

2 2 E 2 Etr, t4 t

7,C.4 rS

- 8—

• r; vsu 3 - t- 3 3

n

0

00

• 17

Volume I 131

REFERENCES

I. Bernstein, L., Salt Tolerance of Plants. U. S. Dep. Agric. Inf. Bull., No. 283, U.S. Department ofAgriculture, Washington, D.C., 1964, 10-12.

2. Maas, E. V. and Hoffman, G. J., Crop salt tolerance — current assessment, J. Irrig. and Drain.Div., Proc. Am. Soc. Civ, Eng., 103(1 R2), 115-134, 1977.

3. Maas, E. V. and Hoffman, G. J., Crop salt tolerance: Evaluation of existing data, in ManagingSaline Water for Irrigation, Proc. Internat. Con f, on Managing Saline Water for Irrigation: Planningfor the Future, Dregne, H. E., Ed., Texas Technical University, Lubbock. Texas, 1977, 187-198.

4. Babcock, K. L., Carlson, R. M., Schulz, R. K., and Overstreet, R., A study of the effect of irrigationwater composition on soil properties, Hilgardia. 29, 155-164, 1959.

5. Carter, D. L., Managing Moderately Saline (Salty) Irrigation Water, Univ. of Ida. Curr. Inf. Ser..No. 107, University of Idaho, Moscow, 1969, 2.

6. Rhoades, J. D., Quality of water for irrigation, Soil &I., 113, 277-284, 1972.7. Wilcox, L. F., Classification and Use of Irrigation Waters, U. S. Dep. Agric, Circ. No. 969, 1955,

9.8. Wilcox. L. 'V., Determining the Quality of Water for Irrigation, U.S. Dep. Agric. Inf. Buil. 197,

U.S. Department of Agriculture, Washington, D.C., /958, 3-4.9. Bernstein, L., Osmotic adjustment of plants to saline media. I. Steady state, Am. J. Rot., 48,

909-918, 1961.ID. Bernstein, L., Crop growth and salinity, in Drainage for Agriculture, Agronomy 17, van Schiff-

gaarde, J., Ed., American Society of Agronomy, Madison, 1974, 39-54.11. Bernstein, L., Brown, J. W., and Hayward, H. E., The influence of rootstock on growth and salt

accumulation in stone-fruit trees and almonds, Proc. Am. Soc. Honk. Sci., 68, 75-86, 1956.12. Hayward, H. E. and Bernstein, L., Plant-growth relationships on salt affected soils, Bot. Rev., 24,

584-635, 1958.13. Carter, D. L. and Myers, V. I., Light reflectance and chlorophyll and caratene contents of grapefruit

leaves as affected by Na,S0.„ NaCl, and CaCis, Proc. Am. Soc. Horde. Sci., 82, 217-221, 1963.14. Lunin, J. and Gallatin, M. H., Salinity-fertility interactions in relation to the growth and composition

of beans 1. Effect of N, P, and K, Agron. J., 57, 339-342, 1965.15. Ravikovitch, S. and Porath, A., The effects of nutrients on the salt tolerance of crops, Plant Soil,

26, 49-71, 1967.16. Bernstein, L., Osmotic adjustment of plants to saline media. I. Steady state, Ant. J. Bot., 48,

909-918. 1961,17. Bernstein, L., Osmotic adjustment of plants to saline media. II. Dynamic phase, Am. J. Bot., 50,

360-370, 1963.18. Bernstein, L. and Pearson, G. A., Influence of integrated moisture stress achieved by varying the

osmotic pressure of culture solutions on growth of tomato and pepper plants, soil Sci., 77, 335-368,1954.

19. Mehl, A. and Poljakoff-Mayber, A., Effect of various salinity regimes on growth, leaf expansionand transpiration rate of bean plants, Soil Sci., 109, 26-34, 1970.

20. Hoffman, G. .1., Maas, E. V., and Rawlins, S. L., Salinity-ozone interactive effects on alfalfa yieldand water relations, J. Environ. Qual., 4, 326-331, 1975.

21. Ayers, A. D., Brown, J. W., and Wadleigh, C. H., Salt tolerance of barley and wheat in sail plotsreceiving several salinization regimes, Agron. J.,44, 307-310, 1952.

22. Kaddah, M, T. and Ghowail, S. 1., Salinity effects on the growth of corn at different stages ofdevelopment. A gron. J., 56, 214-217, 1964.

23. Pearson, G. A., Factors influencing salinity of submerged soils and growth of Calero rice, Soil Sci.,87, 198-206, 1959.

24. Hoffman, G. J. and Rawlins, S. L., Growth and water potential of root crops as influenced bysalinity and relative humidity, ,Aron. 1,63. 877-880, 1971.

25. Bernstein, L. and Hayward, H. E., Physiology of salt tolerance. Annu. Rev. Plant Physiol., 9,25-46, 2958.

26, Bernstein, L., Tolerance of plants to salinity, J. Irrig. and Drain Div.. Proc. Am. Soc. Civ. Eng..87fIR4), 11, 1961.

27. U.S. Salinity Laboratory Staff, Determination at the properties of saline and alkali soils, in Diagnosisand Itnprosernent of Saline and Alkali Soils, Richards. L. A., Ed., U.S. Dep. Agric. Hdbk. No. 60,U.S. Department of Agriculture, Washington, D.C., 1954. 7-23.

28. Oster, J. D. and Ingvalson, R. D., In situ measurement of soil salinity with a sensor, Soil Sci. Soc.Am. Proc.31, 572-574, 1967.

29, Rhoades, J. D. and Ingvalson, R. D., Determining salinity in field soils with soil resistance measure-

ments, Soil Sci. Soc. Am. Proc., 35, 54-60, 1971.

132 CRC Handbook of Agricultural Productivity

30. Kaddah, M. T., Salinity effects on growth of rice at the seedling and inflorescence stages of devel-opment. Soil Sri_ 96, 105—III, 1963.

31. Narale, R. P., Subramanyarn, T. K., and Mukherjee, R. K., Influence of salinity on germination,vegetative growth and grain yield of rice (Oriza &viva var. Dular), Agron. J., 61, 341-344, 1969.

32. Pearson, G. A. and Ayers, A. D., Rice as a Crop for Salt-Affected Soil in Process of Reclamation.U.S. Dep. Agric. Prod. Res. Rep. No. 43, 1960, 7-10.

33. Pearson, G. A., Ayers, A. D., and Eberhard, D. L., Relative salt tolerance of rice during germinationand early seedling development. Soil Sri_ 102, 151-156, 1966.

34. Pearson, G. A. and Bernstein, L., Salinity effects at several growth stages of rice, Agron. J., 51,654-657, 1959.

35. Francois, L. E. and Goodin. J. R., interaction of temperature and salinity on sugarbeet germination,Agron. J., 64, 272-273, 1972.

36. Ayers, A. D., Germination and emergence of several varieties of barley in salinized soil cultures,Agron. J„ 45, 68-71, 1953.

37. Donovan, T. J. and Day, A. D., Some effects of high salinity on germination and emergence ofbarley ( Hardeurn vulgate L. emend Lam.), Agron. J., 61, 236-238, 1969.

38. Torres, B. C. and Bingham, F. T., Salt tolerance of Mexican wheat. 1. Effect of NO and NaCI onmineral nutrition, growth and grain production of four wheats, Soil Sci.'Soc. Am. Proc., 37,711-715, 1973.

39. Greenway, H., Plant response to saline substrates. VII. Growth and ion uptake throughout plantdevelopment in two varieties of Horde= vulgate, Aust. J. Biol. Sri., 18, 763-779, 1965,

40. Abel, G. H. and MacKenzie, A. J., Salt tolerance of soybean varieties (Glycine max. L. Merrill)during germination and later growth, Crop Sci., 4, 157-161, 1964.

41. Mitkees, A. I., Selim, M. H., and Mashaty, A., Effect of salinity on five berseem varieties in relationto their dry matter and nitrogen contents, Agric. Res. Rev.,50, 19-29, 1972.

42, Dregne, H. E., Effects of Various Salts on Barley Growth, New Mexico Agric. Exp. Stn. Res. Rep.62, New Mexico Agricultural Experiment Station, Los Cruces, 1962, 2-5.

43. Cooper, W. C., Salt Tolerance of Avocados on Various Rootstocks, Tex. Avocado Soc. Yearb.,Texas Avocado Society, Weslaco, 1951, 24-28.

44. Cooper, W. C., Toxicity and accumulation of salts in citrus trees on various rootstocks in Texas.Florida State Horde. Soc. Proc., 74, 95-104, 1961.

45. Peynado, A. and Young, R., Performance of nucellar red blush grapefruit trees on 13 kinds ofrootstocks irrigated with saline and boron-contaminated well water over a 3-year period, J. RioGrande Val. Honk. Soc., 16, 52-58, 1962.

46. Ream, C. L. and Furr, J. R., Salt tolerance of same citrus species, relatives and hybrids tested asrootstocks, J. Am, Soc. Honk. Sri., 101, 265-267, 1976.

47, Bernstein, L., Francois, L. E., and Clark, R. A.. Effect of grape rootstocks on chloride accumulationin leaves, J. Am. Soc. Manic. Sci., 94, 584-590,.9969.

48. Bernstein, L., Francois, L. 4., and Clark, R. A., Interactive effects of salinity and fertility on yieldsof grains and vegetables, Agron. 1_66,412-421, 1974,

49. Lunin, J., Gallatin, M. H., and Batchelder, A. R., Interactive effects of soil fertility and salinity onthe growth and composition of beans, Proc. Am. Soc. Hortir. Sri., 58, 350-360, 1964.

50. Ehrler, W. and Bernstein, L., Effects of root temperature, mineral nutrition, and salinity on thegrowth and composition of rice, Sot. Gaz., 120, 64-74, 1958.

51. Langdale, G. W. and Thomas, J. R., Soil salinity effects on absorption of Ititrogen, phosphorus,and protein synthesis by coastal bermudagrass, Agron. J., 63, 708-711, 1971.

52. Langdale, G. W. Thomas, J. R., and Littleton, T. G., Nitrogen metabolism of stargrass as affectedby nitrogen and soil salinity, Agron. J., 65, 468-470, 1973.

53. Langdale, G. W., Thomas, J. R., and Littleton, T. G., Influence of soil salinity and nitrogen fertilizeron spinach growth, J. Rio Grande Val. Honk. Soc., 25, 61-66, 1971.

54. Khalil, M. A.. Amer, F., and Elgabaly, M. .3., A salinity-fertility interaction study on corn andcotton. Soil Sri. Soc. Am. Proc., 31, 683-686, 1967.

55. Maas, E. V., Ogata, G., and Garber, M. J., Influence of salinity on Fe, Mn, and Zn uptake byplants, Agron. J., 64, 793-795, 1972.

56, Ravikovitch, S., Effects of brackish irrigation water and fertilizers on millet and corn, Exp. Agric.,9, 181-188, 1973.

57. Ravikovitch, S. • and Yoles, D., The influence of phosphorus and nitrogen on millet and clover grow-ing in soils affected by salinity. 1. Plant development, Plant Soil, 35, 555-567, 1971.

58. Ravikovitch, S. and Yates, D., The influence of phosphorus and nitrogen on millet and clover grow-ing in soils affected by salinity. 11. Plant composition, Plant Soil, 35, 569-588, 1971.

59. Ravikovitch, S. and Navrat, J., The effect of manganese and zinc on plants in saline sail, Soil Sri.,121, 25-31, 1976.

Volume 133

60. Magistad, 0. C., Ayers, A. D., Wadleigh, C. H., and Gauch, H. G., Effect of salt concentration,kind of salt, and climate on plant growth in sand cultures, Plant Physial., 18, 15E-166, 1943.

61. Bernstein, L., Francois, L. E., and Clark, R. A., Salt tolerance of ornamental shrubs and groundcovers, J. Am. Soc. Hortic. Sci., 97, 550-556 1972.

62. Bernstein, L., Salt Tolerance of Fruit Crops, U.S. Dep. Agric. Inf. Bull. 292, U.S. Department ofAgriculture, Washington, D.C., 1965, 3-6.

63. Wadleigh, C. H., Hayward, H. E., and Ayers, A. D., First year growth of stone fruit trees on salinesubstrates, Proc. Am. Soc. Hortic. Sci., 57, S1-36, 1951.

64. Bernstein, L., Salt Tolerance of Field Crops, U.S. Dep. Agric. lnf. Bull. 217, U.S. Department ofAgriculture, Washington, D.C.. 1960, 4.

65. Lagerwerff, J. W., Osmotic growth inhibition and electrometric salt-tolerance evaluation of plants,Plant Soil, 31, 77-96, 1969.

66. Lagerwerff, J. W. and Holland, J. P., Growth and mineral content of carrots and beans as relatedto varying osmotic and ionic-composition effects in saline-sodic sand cultures, Agron. J., 52,603-608, 1960.

67. Bernstein, L., Salt Tolerance of Vegetable Crops in the West, U.S. Dep. Agric. lnf. Bull. 205, U.S.Department of Agriculture, Washington, D.C., 1959, 3.

68. Ayers, A. D. and Eberhard, D. L., Response of edible broadbean to several levels of salinity, Agron.J., 52, 110-111, 1960.

69. Ehlig, C. F., Salt tolerance of raspberry, boysenberry, and blackberry, Proc. Am. Soc. Horric. Sci.,85, 318-319, 1964.

70. Bernstein, L., Salt Tolerance of Grasses and Forage Legumes, U. S. Dep, Agric. Inf. Bull. 194, U.S.Department of Agriculture, Washington, D.C., 1958, 5.

71. Yaron, B., Zieslin, J., and Halevy, A. H., Response of Baccara roses to saline irrigation, J. Am.Soc. Hortic. Sci., 94, 481-484, 1969.

72. Ehlig, C. F., Effects of salinity on four varieties of table grapes grown in sand cultures, Proc. Am.Soc. Hortic. Sci., 76, 323-331, /960.

73. Shalhevet, J., Reiniger, P., and Shimshi, D., Peanut response to uniform and non-uniform soil sal-inity, Agron. 1,, 61, 384-387, 1969.

74. Francois, L. E., Yermanos, D. M., and Bernstein, L., Salt tolerance of safflower, Calif. Agric., 18,12-14, 1964,

75. Bernal, C. T., Bingham, F. T., and Oertli, J., Salt tolerance of Mexican wheat. 11. Relation ofvariable sodium chloride and length of growing season, Soil Sci. Soc. Am. Proc., 38, 777-780. 1974,