Research Article Comparative Performance of Hybrid and...

Research ArticleComparative Performance of Hybrid and Elite Inbred RiceVarieties with respect to Their Source-Sink Relationship

Md Moinul Haque1 Habibur Rahman Pramanik2 Jiban Krishna Biswas3

K M Iftekharuddaula4 and Mirza Hasanuzzaman5

1Department of Agricultural Botany Sher-e-Bangla Agricultural University Dhaka 1207 Bangladesh2Department of Crop Botany Bangladesh Agricultural University Mymenshing 2202 Bangladesh3Plant Physiology Division Bangladesh Rice Research Institute Gazipur 1701 Bangladesh4Plant Breeding Division Bangladesh Rice Research Institute Gazipur 1701 Bangladesh5Department of Agronomy Faculty of Agriculture Sher-e-Bangla Agricultural University Dhaka 1207 Bangladesh

Correspondence should be addressed to Mirza Hasanuzzaman mhzsauagyahoocom

Received 26 July 2014 Revised 10 December 2014 Accepted 5 January 2015

Academic Editor Chad C Chase Jr

Copyright copy 2015 Md Moinul Haque et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Hybrid rice varieties have higher yield potential over inbred varieties This improvement is not always translated to the grain yieldand its physiological causes are still unclear In order to clarify it two field experimentswere conducted including two popular indicahybrids (BRRI hybrid dhan2 and Heera2) and one elite inbred (BRRI dhan45) rice varieties Leaf area index chlorophyll statusand photosynthetic rate of flag leaf postheading crop growth rate shoot reserve translocation source-sink relation and yield andits attributes of each variety were comprehensively analyzed Both hybrid varieties outyielded the inbred However the hybrids andinbred varieties exhibited statistically identical yield in late planting Both hybrids accumulated higher amount of biomass beforeheading and exhibited greater remobilization of assimilates to the grain in early plantings compared to the inbred variety Filledgrain () declined significantly at delayed planting in the hybrids compared to elite inbred due to increased temperature impaired-inefficient transport of assimilates Flag leaf photosynthesis parameters were higher in the hybrid varieties than those of the inbredvariety Results suggest that greater remobilization of shoot reserves to the grain rendered higher yield of hybrid rice varieties

1 Introduction

Rice (Oryza sativa L) is the main food crop of more thanone-half of the worldrsquos population and grows worldwideRice production has to be increased 1 per annum todeliver sufficient rice for an evergrowing population ofrice-consuming countries [1] According to the Food andAgriculture Organization (FAO) hybrid rice technology isthe key approach for the increase of global rice production[2] It has a 15ndash30 advantage in yield over modern inbredrice varieties [3ndash5] but does not frequently exhibit higheryield potential [3 6ndash11] Higher grain yield of hybrid rice is anintricate outcome of genotype and environment interaction

Higher dry matter accumulation before heading longerleaf area duration higher LAI and higher photosyntheticcapability at the grain filling period are the essentials for

achieving higher yield of rice [6 12ndash15]However the findingsof previous studies on hybrid rice suggest cross talk about thephysiological causes of its higher yield Many investigatorsreported that greater biomass accumulation before headingand higher shoot reserve translocation are the decisive factorsof higher yield in hybrids [16ndash21] On the other hand Yan etal [22] andYang et al [8] reported that hybrid rice had higherproductivity after heading but translocation of assimilateswas inefficient (source use efficiency) Separately Lafarge andBueno [1] stated that higher yield of hybrid was the result ofbetter sink regulation

Poor grain filling is the cause of poor grain yield inhybrids [8 10 23] Chlorophyll content reflects the intensityof plant photosynthetic capacity and the extent of leaf senes-cence [24] Slow senescence and stronger photosyntheticcapability of flag leaf higher LAI at grain filling period

Hindawi Publishing Corporatione Scientific World JournalVolume 2015 Article ID 326802 11 pageshttpdxdoiorg1011552015326802

2 The Scientific World Journal

and higher postheading-CGR are the prerequisites for higheryield in hybrid rice [25ndash28] The postanthesis decline inleaf area at specially the ripening stage was higher in thehybrid compared to the inbred [17] Whereas some inves-tigators mentioned that the hybrid has the lower single-leaf photosynthetic rate throughout the whole growth periodand greater LAI contributes to the heterosis in biomassproduction and grain yield [3 29 30] So the availableinformation on photosynthetic capability of flag leaf theroles of shoot reserve translocation and postheading cropgrowth rate to higher grain yield of hybrid rice varieties arestill controversial Therefore it is imperative to clarify thiscontroversy on hybrid rice varieties

Keeping the above facts inmind the present investigationwas undertaken to study source-sink relation shoot reservetranslocation source activity and yield attributes of hybridrice varieties at gradually rising temperature environmentsin order to clarify whether the greater accumulated biomassinduced-higher remobilization or postheading photosyn-thetic capability plays a key role in the higher yield of hybridsIn addition to this the physiological characteristics of flag leafin hybrid and elite inbred rice were also studied

2 Materials and Methods

21 Experimental Sites Design and Crop Husbandry Thefield experiments were conducted with two hybrids (BRRIhybrid dhan2 and Heera2) and one elite inbred (BRRIdhan45) rice varieties at the Experimental Farm of Sher-e-Bangla Agricultural University Dhaka (23∘771015840N 90∘371015840Eand altitude of 9m) and Bangladesh Rice Research InstituteGazipur (23∘991015840N 90∘391015840E and altitude of 84m) Bangladeshin dry (Boro) seasons (December to May) of 2008-2009 and2009-2010 respectively Four planting dates weremaintainednamely 20 December 5 January 20 January and 5 FebruarySoil of the experimental plots was medium highland withupper-middle range fertility Properties of the top soil (0ndash15 cm) of the experimental plots are summarized in Table 1The experiments were laid out in a split-plot design withthree replications placing planting dates in the main-plotsand varieties in the subplots The unit plot size was 20m2(50m times 40m) One seedling (30 days old) was transplantedper hill maintaining 25 cm times 15 cm spacing A single plot wascomprised of 20 lines and each line contained 26 hills Abuffer (levee) of 05m 05m and 10m was kept in betweensubplots main-plots and blocks respectively Cow-dung wasapplied 10 t haminus1 and chemical fertilizers as urea triplesuperphosphate muriate of potash gypsum and zinc sul-phate were applied 270-130-120-70-10 kg haminus1 respectively[31] Cow-dung was applied 15 days before land preparationAll the fertilizers were applied as basal except urea which wasapplied as top dressing in 3 equal installments at 15 days aftertransplanting (DAT) tillering stage (30 DAT) and panicleinitiation stage (45 DAT) Climate of both experimental sitesis similar Temperature solar radiation and sunshine hoursgradually increase from January to April Rainfall is scantyor absent in early dry season (December-January) Weatherconditions of the experimental seasons are shown in Table 2

Table 1 Physical and chemical properties of the initial soil of theexperimental plots

Characteristics Site 1alowast Site 2blowast

Valuetype Valuetype Sand 2997 1308 Silt 5486 4425 clay 1528 4247Textural class Silty loam Silty clayPH 587 670Organic matter () 143 120Total N () 008 013P (120583gg soil) 558 749S (120583gg soil) 789 725B (120583gg soil) 016 012Cu (120583gg soil) 015 027Fe (120583gg soil) 280 435Mn (120583gg soil) 074 163Zn (120583gg soil) 043 034Exchangeable K (meq100 g soil) 010 017Ca (meq100 g soil) 143 240Mg (meq100 g soil) 035 087aDepartment of Soil Science Sher-e-Bangla Agricultural University Dhaka1207bSoil Science Division Bangladesh Rice Research Institute (BRRI) Gazipur1703lowastRed brown terrace soil type

22 Plant Materials The BRRI hybrid dhan2 is a popularindica hybrid rice variety developed by Bangladesh RiceResearch Institute (BRRI) in 2008 It is recommended forcultivation in both dry seasons of Bangladesh The Heera2(HS-273) is the most popular indica hybrid rice varietyimported fromChina and occupied about 70 of total hybridrice cultivated area in Bangladesh Both hybrids mature in140 to 145 days during the dry seasons (December to May)[31] Also BRRI dhan45 is a high yielding inbred varietyfor dry season and was developed by BRRI in 2005 throughcrossing between BRRI dhan2 and TETEP Originally thisvariety was developed from the breeding line BR5778-21-2-3and its duration of growth ranges from 140 to 145 days

23 Sampling and Measurements Five plants were sampledat 10-day intervals starting from 20 DAT up to maturity Atfirst sampling hills were selected from the third rows andthe next two rows or three hills were left for subsequentsampling to minimize the border effect Leaf area (LA) wasmeasured by an automatic leaf area meter (Model LI-3100Li-COR Lincoln NE USA) just after removal of leaves toavoid rolling and shrinkage and transformed into leaf areaindex (LAI) according to Yoshida [32]

Ten plants were sampled from each plot at heading andat maturity All the plant samples were separated into rootleaf blades (leaf) culm and sheath (stem) and panicles Drymatter of each component was determined after drying at72∘C for 3 days to have constant weightThe preanthesis shoot(stem + leaf) reserve translocation was calculated by net loss

The Scientific World Journal 3

Table 2 Temperature relative humidity (RH) total rainfall solar radiation and total sunshine hours of the experimental sites during dryseasons (DecemberndashMay) in 2008-2009 and 2009-2010 respectively

Monthsyears Air temperature (∘C)c RH at 2 pm()

Total rainfall(mm)

Solar radiation(Cal cm2)

Total sunshine(h)Min Max Av

a1st season (2008-09)Dec 2008 1690 2557 2124 705 0 2570 121Jan 2009 1484 2592 2038 677 0 2373 148Feb 2009 1731 2979 2355 630 1 3479 178Mar 2009 2152 3328 2745 581 43 3964 184Apr 2009 2586 3558 3072 688 13 4101 255May 2009 2519 3458 2989 722 163 3984 244

b2nd season (2009-10)Dec 2009 1440 2529 1985 749 0 2130 148Jan 2010 1181 2428 1804 698 0 2350 164Feb 2010 1449 2905 2181 718 15 3399 194Mar 2010 2189 3471 2830 758 17 4053 236Apr 2010 2502 3529 3016 703 58 3944 215May 2010 2453 3387 2921 726 207 3941 232

aSher-e-Bangla Agricultural University (Bangladesh Meteorological Department Climate and Weather Division) Sher-e-Bangla Nagar Dhaka 1207bPlant Physiology Division Bangladesh Rice Research Institute (BRRI) Gazipur 1703cMonthly average of daily temperatures

in dry weight of vegetative organs between preanthesis andmaturity [33]

Flag leaves were sampled frommain tillers at 2 9 16 and23 days after flowering and a 20mg segment from middleportion of the flag leaf was used for chlorophyll analysis Flagleaf chlorophylls were extracted using 80 acetone solutionand were estimated with a double beam spectrophotometer(Model U-2001 Hitachi Japan) according to Witham et al[34] Flag leaves from the main tiller of five representativeplants of each plot were used to measure photosyntheticrate with a portable photosynthesis analyzer (Model LI-6400 Li-COR Inc USA) at 2 9 16 and 23 days afterflowering under clear sunshine from 1100 am to 1230 pmwhen photosynthetically active radiation at the top of thecanopy ranged from 1300 to 1400 120583molmminus2 sminus1Then the fivereadings were averaged for the plot

Plants of 12 hills fromeach plotwere harvested atmaturityto record the yield contributing components Plants from thecentral 6m2 undisturbed area in each plot were harvested atmaturity and grain yields were recorded

Postheading crop growth rate as an index of plant pro-ductivity in grain filling period was calculated as the increaseof plant dry matter per unit time and measured by takingthe total dry matter at heading and at maturity [35] Ratio ofspikelets number to leaf area (at heading) and ratio of yieldsink to leaf area (at heading) were calculated according toZhao et al [36]

Ratio of spikelets no to leaf area (cmminus2)

=

Spikelets numberLeaf area at heading

Ratio of yield sink to leaf area (mg cmminus2)

=

Yield sinkLeaf area at heading

(1)

Ratio of accumulated grain dry matter from current pho-tosynthate (GDMCPn) to average leaf area (heading tomaturity) was estimated using the following formula

Ratio of GDMCPn to LA (mg cmminus2)

=

Yield sink minus (panicle wt at heading + remobilization)Leaf area (heading to maturity)

(2)

Current photosynthate accumulation panicleminus1 (CPA) wascomputed using the following formula

CPA panicleminus1 (g)

= Av panicle wt at maturity

minus (av panicle wt at heading

+av remobilization panicleminus1)

(3)

24 Statistical Analysis Collected data were put to analysis ofvariance (ANOVA) technique and the means were comparedby the Duncan multiple range test (DMRT) using the statis-tical computer package programMSTAT-C [37] Correlationand regression analyses were done using Microsoft Excelsoftware


Table 3 Yield and its attributes of hybrid and inbred rice varieties at different dates of planting in dryseasons 2008-2009para and 2009-2010parapara

Variety times planting date Panicles mminus2 Spikelets panicleminus1 Filled spikelets () 1000-grain weight (g) Grain yielda (t haminus1)2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10

BRRI hybrid dhan220 December 2785 2704 1380 1319 7904ab 795ab 2653 2684 742ab 678ab05 January 2653 2472 1327 1333 7873ab 755bcd 2693 2676 684bc 610bc20 January 2465 2351 1336 1301 7623b 702ef 2706 2643 606cd 566cd05 February 2394 2167 1313 1310 6649c 664fg 2696 2688 534de 444f

Hybrid Heera220 December 3105 2848 1302 1318 7900ab 783abc 2661 2693 803a 731a05 January 2850 2569 1397 1364 7770ab 752cd 2739 2604 765ab 621bc20 January 2904 2486 1254 1335 7867ab 726de 2703 2654 728ab 559cd05 February 2607 2413 1288 1223 6481c 632g 2721 2714 512e 437f

Inbred BRRI4520 December 3223 3089 1011 952 8140ab 817a 2586 2554 616cd 552cd05 January 3038 2787 1052 9708 8239a 807a 2554 2516 574de 523de20 January 2929 2767 993 9851 8128ab 788abc 2605 2522 562de 477ef05 February 2835 2699 968 945 8099ab 782abc 2533 2536 550de 457ef

Variety lowastlowast lowastlowast lowastlowast lowastlowast lowastlowast lowastlowast lowastlowast lowastlowast lowastlowast lowastlowast

Planting date lowast lowastlowast NS NS NS lowastlowast NS NS lowastlowast lowastlowast

CV () 871 930 664 880 413 331 386 306 824 742Within a column for each site means followed by the same letters are not significantly different according to DMRT at 5 level of significance parasite SAUparaparaDhaka site BRRI GazipurNS nonsignificant at 5 level of significancelowastSignificant at 5 level of significancelowastlowastSignificant at 1 level of significancea14 moisture contained in yield

3 Results

31 Grain Yield and Its Attributes The grain yield and itsattributes of the tested varieties at different planting dateshave been shown in Table 3 In both the years the maximumgrain yield for all varieties was achieved at early plantingdates (20 December) and there was a gradual decreasingtrend observed in delayed planting An almost similar trendwas found in the case of panicle numbers mminus2 Grain yieldranged from 444 to 742 t haminus1 for BRRI hybrid2 437 to803 t haminus1 for Heera2 and 457 to 616 t haminus1 for inbred BRRIdhan45 for all planting dates in both the years The hybridsHeera2 produced significantly higher grain yield over inbredBRRI dhan45 at all planting dates except 5 February plantingand an almost similar trend was observed for BRRI hybriddhan2 The hybrids exhibited significantly lower numberof panicles mminus2 and on average 3395 higher number ofspikelets panicleminus1 compared to the tested inbred irrespectiveof planting date Higher yield of Heera2 and BRRI hybriddhan2 was attributed to the greater number of spikeletspanicleminus1 alongwith larger and heavier grain sizeThe studiedhybrid and inbred varieties produced statistically similargrain yield at delayed planting (5 February) in 2008-09 and2009-10 which was associated with rapid reduction of thenumber of filled grain percentage in hybrid varieties Filledgrain percentage of inbred BRRI dhan45 was more or lessstable at different planting dates This may be due to intrinsic

genotypic characters or the well adaptability of the inbredBRRI dhan45 to the environment

32 Flag Leaf Chlorophyll Content and Its Chlorophyll a bRatio The studied hybrid varieties synthesized significantlyhigher amounts of chlorophyll andmaintained higher chloro-phyll a b ratio in their flag leaf over inbred BRRI dhan45(Table 4) Flag leaf chlorophyll content and chlorophyll a bratio gradually decreased in the hybrid and inbred varietieswith advanced maturity Reduction of chlorophyll content at23 days after flowering compared to 2 days after floweringwas 33 and 36 in hybrids and inbred respectively Plantingdates had little influence on flag leaf chlorophyll contentChlorophyll a b ratio of the flag leaf was higher in boththe hybrids However environmental influence on totalchlorophyll content of flag leaf was relatively small

33 Flag Leaf Photosynthetic Rate Photosynthetic rate offlag leaf at 2 9 16 and 23 days after flowering is presentedin Table 5 There was no significant difference among thetested hybrid and inbred varieties with respect to flag leafphotosynthetic rates at different days after flowering except at23 days after flowering Photosynthetic rate of flag leaf rangedfrom 3329 to 3475 120583molCO

2mminus2 sminus1 among the varieties

and from 3225 to 3525120583molCO2mminus2 sminus1 among different

planting dates at 2 days after flowering The photosyntheticrate gradually decreased with the advance of grain filling


Table 4 Comparison of flag leaf chlorophyll content and chlorophyll a b ratio among hybrid and inbred rice varieties at different dates ofplanting in dryseason 2009-2010para

Varietyplanting date Total chlorophyll (mg gminus1) Chlorophyll a b2DAF 9DAF 16DAF 23DAF 2DAF 9DAF 16DAF 23DAF

HybridsBRRI hybrid dhan2 265b 253a 216b 177b 318a 297a 241b 209Heera2 280a 257a 229a 187a 322a 288a 251a 213Inbred BRRI dhan45 205c 180b 149c 130c 288b 263b 239b 199

Planting dates20 December 242 232 205 171a 315 290 248 21405 January 252 228 202 165ab 316 285 251 20520 January 252 233 197 167a 307 277 239 20605 February 253 228 189 156b 297 277 237 205

InteractionVariety times planting date NS NS NS NS NS NS NS NSCV () 621 573 730 669 501 579 393 665

Within a column means followed by the same letter(s) are not significantly different at 5 level of probability by DMRT parasite BRRI GazipurNS nonsignificant at 5 level of significanceDAF days after flowering

Table 5 Comparison of flag leaf photosynthetic rate among hybridand inbred rice varieties at different dates of planting in dryseason2009-2010para

Varietyplanting date Photosynthetic rate (120583molCO2 mminus2 sminus1)

2DAF 9DAF 16DAF 23DAFVariety

BRRI hybrid dhan2 3414 2883 2159 1501aHeera2 3475 2922 2128 1523aInbred BRRI dhan45 3329 2897 2055 1302b

Planting date20 December 3225b 3040a 2226 147505 January 3412ab 3011a 2168 151920 January 3460a 2925a 2099 140805 February 3525a 2627b 1963 1363

InteractionVariety times planting date NS NS NS NSCV () 464 550 973 614

Within a column means followed by the same letter(s) are not significantlydifferent at 5 level of probability by DMRT parasite BRRI GazipurNS nonsignificant at 5 level of significanceDAF days after flowering

period At 23 days after flowering Heera2 and BRRI hybriddhan2 showed significantly higher photosynthetic rate thanBRRI dhan45 but the studied hybrid and inbred varietiesexhibited decreasing trend of photosynthetic rate of the flagleaf at 9 16 and 23 days after flowering in all planting datesThe Heera2 and BRRI hybrid dhan2 showed considerabledecrease in flag leaf photosynthetic rate 9 days after floweringin the 5 February planting This shows the poor performanceof Heera2 and BRRI hybrid dhan2 for the delayed plantingdates

34 Shoot Reserve Translocation Dry matter accumulationat heading and its remobilization to the grain of the testedhybrid and inbred varieties at four planting dates for twoyear have been shown in Table 6 In each year dry matteraccumulation of hybrid Heera2 and BRRI hybrid dhan2 atthe heading stage was higher than that of elite inbred BRRIdhan45 but the dry matter accumulation decreased 28 and175 in the studied hybrids and inbred at 5 February plant-ing compared to 20 December planting The shoot reservetranslocation () to grain varied among the different plantingdates and gradually decreased with delayed planting Studiedhybrids exhibited 75 higher shoot reserve translocation tograin over inbred BRRI dhan45 at all planting dates except 5February planting and themagnitude of decreasing assimilateremobilization rate to grain was steeper in hybrids and wasin the order of Heera2 (60) gt BRRI hybrid dhan2 (41) gtinbred BRRI dhan45 (19)

35 Leaf Area Index Leaf area index (LAI) increased grad-ually in all the tested varieties in all the planting dates upto heading and in most of the cases the differences arenonsignificant Thereafter the reduction of LAI is greater ininbred than that of hybrids (Figure 1) As an outcome thehybrid varieties sustained higher LAI after heading to matu-rity over inbred BRRI dhan45 regardless of planting datesDays to heading decreased gradually with delayed plantingand the magnitude of reduction was almost similar in thehybrid and inbred varieties However the maximum LAI wasrecorded from Heera2 (636) at heading stage followed byBRRI hybrid dhan2 (594) while it was significantly lower inBRRI dhan45 (510) at 20 December planting of 2008-09Themaximum value of LAI gradually decreased in hybrid andinbred varieties with delayed transplanting due to reductionof vegetative phase The leaf area development of studiedvarieties at different planting dates in 2009-10 was more or


Table 6 Preanthesis dry matter accumulation in shoot and its translocation to the grain of hybrid and inbred rice varieties at different datesof planting in dryseasons 2008-2009para and 2009-2010parapara

Variety times planting datesShoot dry matter atpreanthesis (gmminus2)

Shoot dry matter atmaturity (gmminus2)

Changes in shootdry matter (gmminus2)

Shoot reservetranslocation ()

2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10BRRI hy dhan2

20 December 84695 72992 69199 57555 15495ab 15537a 1823a 2110a05 January 80736 71306 66239 58756 14518ab 12550ab 1796ab 1776bc20 January 64959 66162 54486 55751 10473cd 10410b 1614b 1578c05 February 58434 55951 51055 49848 7379de 6103cd 1251c 1084d

Hybrid Heera220 December 92537 78471 74650 63706 17887a 14765a 1939a 1868ab05 January 82757 73106 66604 60529 15853ab 13387ab 1953a 1823bc20 January 74176 66203 60325 59238 13851bc 6965c 1868ab 1057d05 February 61554 60253 59545 56061 5343e 4192cd 812d 700e

Inbred BRRI4520 December 70836 59602 62257 53409 8576de 6193cd 1085cd 1029d05 January 72969 56971 64089 50780 6181e 618cd 1211c 1103d20 January 61048 54982 54034 51347 7014de 3634d 1132c 654e05 February 55794 51873 50282 48191 5512e 3682d 1001cd 703e

Variety lowastlowast lowastlowast lowast lowastlowast lowastlowast lowastlowast lowastlowast lowastlowast

Planting date lowastlowast lowast lowastlowast NS lowastlowast lowastlowast lowastlowast lowastlowast

CV () 882 806 897 659 1952 2111 1269 1150Within a columnmeans followed by the same letter(s) are not significantly different at 5 level of probability byDMRT parasite SAUDhaka paraparasite BRRI GazipurNS nonsignificant at 5 level of significancelowastSignificant at 5 level of significancelowastlowastSignificant at 5 level of significance

less similar to the previous year This result revealed thathybrid rice varieties maintained significantly greater LAIfrom heading to maturity stage compared to the inbred

36 Source-Sink Relation and Postheading Crop Growth RateRatio of spikelets number to leaf area (at heading) yield sinkto leaf area (at heading) and grain dry matter accumulatedfrom current photosynthetic assimilation to leaf area (averagefromheading tomaturity)were reflected the source-sink rela-tion in the studied hybrid and inbred varieties (Table 6) TheHeera2 and BRRI hybrid dhan2 varieties had considerablylarger sink and produced higher yield sink per unit leaf areaover BRRI dhan45 Inbred BRRI dhan45 exhibited higherratio of grain dry matter accumulated from current pho-tosynthetic assimilation to leaf area (average from headingto maturity) compared to both hybrids In delayed planting(5 February) yield sink per unit leaf area was significantlydecreased in tested varieties Both the studied varieties andthe different planting dates showed almost similar trendsin postheading crop growth rate as that of yield sink perunit leaf area Interaction effect of variety and planting datewere nonsignificant in all the cases These results indicatedthat BRRI dhan45 has the genotypic superiority over thetested hybrids with respect to postheading photosyntheticassimilation per unit leaf area

4 Discussion

Flag leaf is the main and most active photosynthetic sourceof grain yield in rice [32 38 39] Chlorophyll contentindicates photosynthetic efficiency of leaves [24 40] Tanget al [41] reported that hybrid rice contains higher amountsof chlorophyll in their leaves Islam et al [42] found novariation in leaf chlorophyll content between hybrid andmodern inbred varieties at Boro season (December to May)but in Aman season (July to December) recorded higher leafchlorophyll content in hybrids over inbred rice varieties Inthe present investigation flag leaf of the tested hybrid varietiescontained higher amounts of chlorophyll and maintainedhigher chlorophyll a b ratio over elite inbred BRRI dhan45Fluctuation in flag leaf chlorophyll content was small amongthe different planting dates It indicated that higher flag leafchlorophyll content was the inherent characters of the studiedhybrids In this study there was no significant difference inflag leaf photosynthetic rate between the studied hybrid andinbred rice varieties irrespective of planting dates Cheng etal [25] Poshtmasari et al [27] and Tang et al [41] reportedhigher photosynthetic capability of flag leaf in hybrid riceHowever Sinclair and Horie [29] and Peng et al [3] reportedthat hybrid had lower single-leaf photosynthetic rate at grainfilling phase as compared to inbred Studied hybrid ricevarieties showed slightly higher photosynthetic rate in flag


Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Boro season 2008-09 Boro season 2009-10

(a)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(b)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(c)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

BRRI hybrid2Heera2BRRI45


(d)

Figure 1 Leaf area index (LAI) of hybrid and inbred varieties at different DAT in dry seasons 2008-09 and 2009-10 respectively (a) 20December planting (b) 05 January planting (c) 20 January planting and (d) 05 February planting Vertical bars represent standard error(119899 = 3) Arrows indicate start of heading stage


Table 7 Source-sink relation and postheading crop growth rate of hybrid and inbred rice varieties at different dates of planting in dryseasons2008-2009para and 2009-2010parapara

Varietyplanting datesRatio of spikelets number

to LAa (cmminus2)Ratio of yield sinkto LAa (mg cmminus2)

Ratio of GDMCPnto LAb (mg cmminus2)

PostheadingCGR (gmminus2 dminus1)

2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10Variety

BRRI hybrid dhan2 062a 068a 1237ab 1378a 1003b 1070b 1505b 1557Heera2 065a 066a 1305a 1345a 1030b 1033b 1621a 1548Inbred BRRI dhan45 056b 061b 1203b 1231b 1156a 1219a 1442b 1477

Planting date20 December 063a 069a 1333a 1418a 1075 1140 1591ab 1615a05 January 063a 066ab 1271a 1328a 1070 1093 1609a 1576a20 January 061ab 065ab 1257a 1345a 1075 1123 1510b 1527ab05 February 057b 061b 1087b 1182b 1033 1069 1390c 1390b

InteractionPlanting date times variety NS NS NS NS NS NS NS NSCV () 990 883 831 797 936 709 827 1026

Within a columnmeans followed by the same letter(s) are not significantly different at 5 level of probability byDMRT parasite SAUDhaka paraparasite BRRI GazipuraAt headingbAverage from heading to maturityNS nonsignificant at 5 level of significanceLA leaf areaGDMCPn grain dry matter from current photosynthate

leaf at 23 days after flowering This may be due to the slowsenescence of flag leaves and plants of the hybrids Higherchlorophyll content in the flag leaves and its slow reductiontoward maturity delayed senescence of the hybrid rice vari-eties (Table 4) This observation was partially consistent withPeng et al [3] Therefore it seems consistent that higher flagleaf chlorophyll content and chlorophyll a b ratio of hybridsplay a significant role to increase photosynthetic rate duringgrain filling period

In early plantings (20 December and 5 January) studiedrice varieties took longer in the vegetative phase Due tovigorous vegetative growth at the middle growth stage testedhybrid varieties accumulated significantly higher amounts ofdry matter at heading over the inbred Accumulated largerdry matter triggered better assimilate remobilization at thegrain filling stage Both the hybrids Heera2 and BRRI hybriddhan2 clearly superseded the elite inbred BRRI dhan45 inrespect of assimilate remobilization from shoot reserve inearly planting (Table 6) A similar result was reported byseveral other investigators [1 17 19 20 43 44] Dry matteraccumulation was steeper in Heera2 and BRRI hybrid dhan2at early planting due to the low temperature induced-longervegetative duration and efficient source activity That meansdry matter accumulation in the studied hybrid varietiesbefore heading was highly thermosensitivity Photosyntheticefficiency of the same genotypes varied markedly duringdifferent growth stages [45 46] The present study suggestedaccumulation of more dry matter before heading and itshigher translocation into the developing grain during fillingstage resulting in higher yield of hybrids over the moderninbred This result was at par with the findings of Laza et al[18] Jeng et al [19] and Yang et al [20] The shoot reserve

translocation was negatively correlated with the temperatureof grain filling period Hybrid rice varieties exhibited higherdegree of sensitivity to temperature rising in regard to shootreserve remobilization to grain compared to the inbred Forrising average daily temperature 1∘C from 29∘C shoot reserveremobilization to the grain decreased at the rate of ca 102and 24 in the tested hybrid and inbred rice varietiesrespectively (Figure 2 Table 7)

In the case of early planting higher biomass accumula-tion and rapid expansion of leaf area of the tested hybridsproduced higher LAI just after heading and developed anefficient sink (large panicles) This higher leaf area indexcontributed to the supply of higher amount of photosynthateto the grain at the filling stage and finally contributed tothe higher grain yield of hybrid Heera2 and BRRI hybriddhan2 The ratio of grain dry matter accumulated fromcurrent photosynthate to average leaf area (from headingto maturity) was almost similar in hybrid and inbred ricevarieties indicating that leaves other than the flag leaf ofstudied hybrid rice varieties had the lower photosyntheticcapability at grain filling stage than inbred BRRI dhan45This situation was aggravated by the rising temperature indelayed plantings Besides these shorter vegetative durationreduced dry matter accumulation and rising temperatureimpaired shoot reserves translocation As a consequenceyield of hybrid varieties decreased rapidly compared to theinbred under delayed planting Both the hybrid varietiesshowed relatively higher postheading-CGR at early plantingdue to their higher LAI at the grain filling period Postheadingphotosynthetic dry matter accumulation panicleminus1 in boththe hybrids exhibited higher degree of thermosensitivityPhotosynthate accumulation panicleminus1 decreased at the rate

The Scientific World Journal 9Tr

anslo

catio

n (

)

Average temperature (∘C)

y = minus75131x + 24045

R2 = 0829

R2 = 09135

5

10

15

20

25

30

35

285 290 295 300 305 310


y = minus24009x + 80906

y = minus12735x + 3975

R2 = 07692

Figure 2 Relationship between the shoot reserve translocation per-centage and average daily temperature from flowering to maturityAverage data of two dry seasons 2008-2009 and 2009-2010 used R2calculated as 5 level of significance


CPA

pan

icleminus1

(g)

12

14

16

18

2

285 290 295 300 305 310


y = 00192x + 08016

y = minus015x + 61125

y = minus02638x + 95203

R2 = 04997

R2 = 06985

R2 = 0672

Figure 3 Relationship between current photosynthate accumula-tion (CPA) panicleminus1 and average daily temperature from floweringto maturity Average data of two dry seasons 2008-2009 and 2009-2010 used R2 calculated as 5 level of significance

of ca 02 g in the hybrids for rising average daily temperature1∘C from 29∘C while this reduction rate was negligible inthe inbred rice variety (Figure 3) It might be due to theintrinsic genetic trait or well adaptability of inbred BRRIdhan5 to environmental conditions These results suggestedthat modern inbred BRRI dhan45 was efficient in sourceutilization at the grain filling stage under higher temperature

Grain filling is a deposition of starch from two sourcescurrent photosynthate (60ndash100) and remobilization (rest)from the reserve pool [23 32 47] Grain filling index reflectsthe source-sink relationship [36] Efficient assimilate supplyto the grain from the source and the capacity of the sink toreceive it determines the higher yield (grain filling percent-age) and these processes depend highly upon environmentalconditions [48 49] The percent of fertile spikelets graduallydeclines when daily mean temperature exceed 29∘C [50]or 296∘C [51] Chakrabarti et al [52] reported that pollensterility gradually increased above 33∘C In spite of prevailingnormal temperature one week before and after of flowering(data not shown) and normal appearance of spikelets thenumber of filled grain as a percentage declined rapidlyin studied hybrid varieties than in inbred BRRI dhan45at delayed planting This poor filled grain percentage wasassociated with lower postheading crop growth rate and alsorelated to failure of assimilates supply to the spikelets due torising temperature Kobata et al [48] reported that highertemperature limits the assimilate supply to meet the demandof grains The photosynthetic rate of flag leaf significantlyincreased at flowering and then decreased rapidly in delayedplanting (Table 4) It reveals that translocation of dry matterfrom shoot to grain was relatively inefficient for hybrids indelayed planting This result confirms the findings of Yanet al [22] Yang et al [53] Yang et al [8] and Wu et al[28] reported that the more dry matter in the vegetativeorgan at heading contributes little to the grain due to poortransportation and remobilization of stored assimilates andthese account for poor grain filling rather than sourcelimitation in super- and intersubspecific hybrids Large sinksize or sink strength of hybrids creating higher demandfor photosynthetic assimilates increased photosynthetic ratein flag leaf initially at delayed planting Individual grainweight remained unchanged in hybrids at delayed plantingindicating that physiological activity of the sink was notaffected significantly due to rising temperature However thestudied hybrids were more vulnerable to rising temperaturein respect to assimilate translocation to grain than that ofthe inbred variety To avoid the adverse effect of highertemperature the hybrid varieties should be transplanted atthe onset of the dry season

5 Conclusion

It is concluded that the tested hybrid rice varieties accu-mulate higher amount of dry matter before heading andmaintain large LAI at the grain filling period comparedto the inbred variety irrespective of growing temperatureHowever relatively high temperature impaired slow rate ofremobilization and transportation of assimilates ultimatelycauses rapid reduction of the percentage of filled grain in thehybrids compared to the inbred variety

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper


Acknowledgments

The authors are grateful to the Ministry of Science andTechnology of Bangladesh for their financial support (Grantno B S 6536 for 2008-2009 date May 01 2009) and also tothe laboratory staffs of Plant PhysiologyDivision BangladeshRice Research Institute (BRRI) Gazipur-1701 Bangladesh fortheir experimental support

References

[1] T Lafarge and C S Bueno ldquoHigher crop performance ofrice hybrids than of elite inbreds in the tropics 2 Does sinkregulation rather than sink size play a major rolerdquo Field CropsResearch vol 112 no 2-3 pp 238ndash244 2009

[2] S S Virmami ldquoShifting the yield frontier with hybrid ricerdquoin Increasing Rice Production in BangladeshmdashChallenges andStrategies S I Bhuiyna and A N M R Karim Eds pp 35ndash52 International Rice Reseseach Institute and Bangladesh RiceReseseach Institute 1999

[3] S Peng K G Cassman S S Virmani J Sheehy and G SKhush ldquoYield potential trends of tropical rice since the releaseof IR8 and the challenge of increasing rice yield potentialrdquo CropScience vol 39 no 6 pp 1552ndash1559 1999

[4] A W Julfiquar M J Hasan A K Azad and A M NurunnabldquoResearch and development of hybrid rice in Bangladeshrdquo inHybrid Rice in Bangladesh Progress and Future Strategies pp9ndash19 Bangladesh Rice Research Institute Gazipur Bangladesh2002

[5] A W Julfiquar ldquoBRRI research and development of hybridricerdquoThe Guardian vol 19 no 3 p 33 2009 Regd no DA 816

[6] T Horie I Lubis T Takai et al ldquoPhysiological traits associatedwith higher yield potential in ricerdquo in Rice Science Innovationsand Impact for Livelihood Proceedings of the InternationalRice Research Conference 16-19 September 2002 T W MewD S Brar S Peng D Dawe and B Hardy Eds pp 117ndash145 International Rice Research Institute Chinese Academy ofAgricultural Sciences Beijing China 2003

[7] J Ying S Peng Q He et al ldquoComparison of high-yield rice intropical and subtropical environments I Determinants of grainand dry matter yieldsrdquo Field Crops Research vol 57 no 1 pp71ndash84 1998

[8] J Yang S Peng Z Zhang ZWang RM Visperas andQ ZhuldquoGrain and dry matter yields and partitioning of assimilates injaponicaindica hybrid ricerdquo Crop Science vol 42 no 3 pp766ndash772 2002

[9] B C Nayak B B Dalei and B K Choudhury ldquoResponseof hybrid rice (Oryza sativa) to date of planting spacing andseedling rate during wet seasonrdquo Indian Journal of Agronomyvol 48 no 3 pp 172ndash174 2003

[10] H J Ao S H Wang Y B Zou et al ldquoStudy on yield stabilityand dry matter characteristics of super hybrid ricerdquo ScientiaAgricultura Sinica vol 41 pp 1927ndash1936 2008 (Chinese withEnglish abstract)

[11] A A Abou Khalifa ldquoPhysiological evaluation of some hybridrice varieties under different sowing datesrdquo Australian Journalof Crop Science vol 3 no 3 pp 178ndash183 2009

[12] Q H Lin ldquoStudies on lsquograin-leaf ratiorsquo of population andcultural approaches of high yield in rice plantsrdquo in Quality ofCrop Population pp 101ndash140 Shanghai Science amp TechnologyPress Shanghai China 2000 (Chinese)

[13] R K Dutta M A Basir-Mia and S Khanum ldquoPlant archi-tecture and growth characteristics of fine grain and aromaticrice and their relation with grain yieldrdquo International RiceCommission Newsletter vol 51 pp 51ndash55 2002

[14] J E Sheehy P L Mitchell and A B Ferrer ldquoBi-phasic growthpatterns in ricerdquo Annals of Botany vol 94 no 6 pp 811ndash8172004

[15] K Katsura S Maeda T Horie and T Shiraiwa ldquoAnalysis ofyield attributes and crop physiological traits of Liangyoupeijiua hybrid rice recently bred in Chinardquo Field Crops Research vol103 no 3 pp 170ndash177 2007

[16] Z Yan ldquoStudies on the production and distribution of drymatter in high-yielding populations of hybrid ricerdquo Acta Agro-nomica Sinica vol 7 pp 11ndash18 1981 (Chinese)

[17] M N A Khan S Murayama Y Ishimine E Tsuzuki KMotomura and INakamura ldquoGrowth and yield in F

1

hybrids ofrice ( Oryza sativa L)rdquo Japanese Journal of Tropical Agriculturevol 42 pp 263ndash271 1998

[18] M R C Laza S Peng S Akita and H Saka ldquoContribution ofbiomass partitioning and translocation to grain yield under sub-optimumgrowing conditions in irrigated ricerdquoPlant ProductionScience vol 6 no 1 pp 28ndash35 2003

[19] T L Jeng T H Tseng C S Wang C L Chen and J M SungldquoYield and grain uniformity in contrasting rice genotypes suit-able for different growth environmentsrdquo Field Crops Researchvol 99 no 1 pp 59ndash66 2006

[20] W Yang S Peng R C Laza RMVisperas andM LDionisio-Sese ldquoGrain yield and yield attributes of new plant type andhybrid ricerdquo Crop Science vol 47 no 4 pp 1393ndash1400 2007

[21] S Chen F Zeng Z Pao and G Zhang ldquoCharacterization ofhigh-yield performance as affected by genotype and environ-mentrdquo Journal of ZhejiangUniversity of Science B vol 9 pp 363ndash370 2008

[22] J M Yan H Q Zhai R X Zhang D M Jiao B S Chenand H S Zhan ldquoStudy on characteristics of photosynthesis andassimilates transportation in heavy ear hybrid rice (Oryza sativaL)rdquo Acta Agronomica Sinica vol 27 no 2 pp 261ndash266 2001(Chinese)

[23] J Yang and J Zhang ldquoGrain-filling problem in lsquosuperrsquo ricerdquoJournal of Experimental Botany vol 61 no 1 pp 1ndash5 2010

[24] R F Wang Y H Zhang L S Qian L H Wu and Q N TaoldquoStudies on diagnostics of nitrogen in rice using chlorophyllmeterrdquo Journal of Zhejiang Agricultural University vol 25 pp135ndash138 1999

[25] S H Cheng L Y Cao S G Chen et al ldquoConception of late-stage vigor super hybrid rice and its biological significancerdquoChinese Journal of Rice Science vol 19 pp 280ndash284 2005(Chinese)

[26] T Takai S Matsuura T Nishio A Ohsumi T Shiraiwa and THorie ldquoRice yield potential is closely related to crop growth rateduring late reproductive periodrdquo Field Crops Research vol 96no 2-3 pp 328ndash335 2006

[27] H K Poshtmasari H Pirdashti M Nasiri and M A Bahman-yar ldquoStudy the effect of nitrogen fertilizer management on drymatter remobilization of three cultivars of rice (Oryza sativaL)rdquo Pakistan Journal of Biological Sciences vol 10 no 19 pp3425ndash3429 2007

[28] W-G Wu H-C Zhang Y-F Qian et al ldquoAnalysis on drymatter production characteristics of super hybrid ricerdquo RiceScience vol 15 no 2 pp 110ndash118 2008


[29] T R Sinclair and T Horie ldquoLeaf nitrogen photosynthesis andcrop radiation use efficiency a reviewrdquoCrop Science vol 29 no1 pp 90ndash98 1989

[30] M R C Laza S Peng A L Sanico RMVisperas and S AkitaldquoHigher leaf area growth rate contributes to greater vegetativegrowth of F

1

rice hybrids in the tropicsrdquo Plant ProductionScience vol 4 no 3 pp 184ndash188 2001

[31] BRRI Adunik Dhaner Chash (Modern Rice Cultivation) vol 7Bangladesh Rice Research Institute Joydebpur Bangladesh 6thedition 2008 Booklet No 5

[32] S Yoshida ldquoPhysiological analysis of rice yieldrdquo in Fundamen-tals of RiceCrop Science pp 48ndash269 International RiceResearchInstitute Los Banos Philippines 1981

[33] G D Bonnett and L D Incoll ldquoThe potential pre-anthesis andpost-anthesis contributions of stem internodes to grain yield incrops of winter barleyrdquo Annals of Botany vol 69 no 3 pp 219ndash225 1992

[34] H Witham D F Blaydes and R M Devlin Exercises in PlantPhysiology PWS Publishers Boston Mass USA 2nd edition1986

[35] D A Choudhury H Hamid G U Miah and M M HaqueldquoPhenology growth and yield ability of modern and old ricecultivars of different maturity groupsrdquo Bangladesh AgronomyJournal vol 8 pp 47ndash52 1998

[36] B H Zhao P Wang H X Zhang Q S Zhu and J C YangldquoSource-sink and grain filling characteristics of two-line hybridrice Yangliangyou 6rdquo Rice Science vol 13 pp 34ndash42 2006

[37] D F RussellMSTAT-C Package Program Crop and Soil ScienceDepartment Michigan State University East Lansing MichUSA 1986

[38] S Q Cao Y Q Zhao J L Wen S A Wang and R X ZhangldquoStudies on photosynthesis in flag leaves and its relation to grainfilling course of high yield wheatrdquo Scientia Agricultura Sinicavol 33 no 6 pp 19ndash25 2000 (Chinese)

[39] S D Reo ldquoFlag leaf a selection criterion for exploiting potentialyields in ricerdquo Indian Journal of Plant Physiology vol 25 pp265ndash268 1997

[40] K M Hotta K Satoh and S Katoh ldquoRelationship betweenphotosynthesis and chlorophyll content during leaf senescenceof rice seedlingsrdquo Plant and Cell Physiology vol 28 no 7 pp1321ndash1329 1987

[41] W-B Tang G-L Zhang Y-H Xiao et al ldquoPhysiological andbiochemical characteristics in flag leaves of the C Liangyouseries of rice hybrid combinations at late growth stagesrdquo RiceScience vol 17 no 4 pp 319ndash325 2010

[42] M S Islam M S U Bhuiya S Rahman and M M HussainldquoEvaluation of SPAD and LCc based nitrogen managementin rice (Oryza sativa L)rdquo Bangladesh Journal of AgriculturalResearch vol 34 no 4 pp 661ndash672 2010

[43] C H Qi ldquoAnalysis on source-sink relationship and its regula-tion techniques of hybrid rice combinationsrdquo Journal of JiangxiAgricultural University vol 15 pp 1ndash5 1993 (Chinese withEnglish abstract)

[44] S Peng J Yang F V Gracia et al ldquoPhysiology-based cropmanagement for yieldmaximization of hybrid ricerdquo inAdvancesin Hybrid Rice S S Virmani E A Siddiq and K MuralidaranEds pp 157ndash176 IRRI 1998

[45] MA Z Sarker SMurayama Y Ishimine and E Tsuzuki ldquoHet-erosis in photosynthetic characters and dry matter productionin F1

hybrids of ricerdquo Nippon Sakumotsu Gakkai Koenkai YoshiShiryoshu vol 211 pp 48ndash49 2001

[46] J J Tang H Chen and S Katsuyoshi ldquoVarietial differences inphotosynthetic characters and chlorophyll fluorescence induc-tion kinetics parameters among intergeneric progeny drivefrom Oryza x Sorghum its parents and hybrid ricerdquo Journal ofZhejiang University of Science B vol 3 pp 113ndash117 2002

[47] S O P B Samonte L TWilson AMMcClung and L TarpleyldquoSeasonal dynamics of nonstructural carbohydrate partitioningin 15 diverse rice genotypesrdquoCrop Science vol 41 no 3 pp 902ndash909 2001

[48] T Kobata M Sugawara and S Takatu ldquoShading during theearly grain filling period does not affect potential grain drymatter increase in ricerdquo Agronomy Journal vol 92 no 3 pp411ndash417 2000

[49] T Kobata andNUemuki ldquoHigh temperatures during the grain-filling period do not reduce the potential grain dry matterincrease of ricerdquo Agronomy Journal vol 96 no 2 pp 406ndash4142004

[50] I Oh-e K Saitoh and T Kuroda ldquoEffects of rising temperatureon growth yield and dry-matter production of rice grownin the paddy fieldrdquo in Proceedings of the 4th InternationalCrop Science Congress Poster no 271 Brisbane AustraliaSeptemberndashOctober 2004

[51] S V K Jagadish P Q Craufurd and T R Wheeler ldquoHightemperature stress and spikelet fertility in rice (Oryza sativaL)rdquoJournal of Experimental Botany vol 58 no 7 pp 1627ndash16352007

[52] B Chakrabarti P K Aggarwal S D Singh S Nagarajan andH Pathak ldquoImpact of high temperature on pollen germinationand spikelet sterility in rice comparison between basmati andnon-basmati varietiesrdquo Crop and Pasture Science vol 61 no 5pp 363ndash368 2010

[53] J C Yang Q S Zhu Z Q Wang and Y Z Liang ldquoPho-tosynthetic characteristics dry matter accumulation and itstranslocation in inter-sub-specific hybrid ricerdquo Acta Agronom-ica Sinica vol 23 pp 82ndash88 1997 (Chinese)

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom

International Journal of

Volume 2014

Zoology


Molecular Biology International

GenomicsInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


BioinformaticsAdvances in

Marine BiologyJournal of



Signal TransductionJournal of


BioMed Research International

Evolutionary BiologyInternational Journal of



Biochemistry Research International

ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Genetics Research International


Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational



Enzyme Research



Microbiology


and higher postheading-CGR are the prerequisites for higheryield in hybrid rice [25ndash28] The postanthesis decline inleaf area at specially the ripening stage was higher in thehybrid compared to the inbred [17] Whereas some inves-tigators mentioned that the hybrid has the lower single-leaf photosynthetic rate throughout the whole growth periodand greater LAI contributes to the heterosis in biomassproduction and grain yield [3 29 30] So the availableinformation on photosynthetic capability of flag leaf theroles of shoot reserve translocation and postheading cropgrowth rate to higher grain yield of hybrid rice varieties arestill controversial Therefore it is imperative to clarify thiscontroversy on hybrid rice varieties

Keeping the above facts inmind the present investigationwas undertaken to study source-sink relation shoot reservetranslocation source activity and yield attributes of hybridrice varieties at gradually rising temperature environmentsin order to clarify whether the greater accumulated biomassinduced-higher remobilization or postheading photosyn-thetic capability plays a key role in the higher yield of hybridsIn addition to this the physiological characteristics of flag leafin hybrid and elite inbred rice were also studied

2 Materials and Methods

21 Experimental Sites Design and Crop Husbandry Thefield experiments were conducted with two hybrids (BRRIhybrid dhan2 and Heera2) and one elite inbred (BRRIdhan45) rice varieties at the Experimental Farm of Sher-e-Bangla Agricultural University Dhaka (23∘771015840N 90∘371015840Eand altitude of 9m) and Bangladesh Rice Research InstituteGazipur (23∘991015840N 90∘391015840E and altitude of 84m) Bangladeshin dry (Boro) seasons (December to May) of 2008-2009 and2009-2010 respectively Four planting dates weremaintainednamely 20 December 5 January 20 January and 5 FebruarySoil of the experimental plots was medium highland withupper-middle range fertility Properties of the top soil (0ndash15 cm) of the experimental plots are summarized in Table 1The experiments were laid out in a split-plot design withthree replications placing planting dates in the main-plotsand varieties in the subplots The unit plot size was 20m2(50m times 40m) One seedling (30 days old) was transplantedper hill maintaining 25 cm times 15 cm spacing A single plot wascomprised of 20 lines and each line contained 26 hills Abuffer (levee) of 05m 05m and 10m was kept in betweensubplots main-plots and blocks respectively Cow-dung wasapplied 10 t haminus1 and chemical fertilizers as urea triplesuperphosphate muriate of potash gypsum and zinc sul-phate were applied 270-130-120-70-10 kg haminus1 respectively[31] Cow-dung was applied 15 days before land preparationAll the fertilizers were applied as basal except urea which wasapplied as top dressing in 3 equal installments at 15 days aftertransplanting (DAT) tillering stage (30 DAT) and panicleinitiation stage (45 DAT) Climate of both experimental sitesis similar Temperature solar radiation and sunshine hoursgradually increase from January to April Rainfall is scantyor absent in early dry season (December-January) Weatherconditions of the experimental seasons are shown in Table 2

Table 1 Physical and chemical properties of the initial soil of theexperimental plots

Characteristics Site 1alowast Site 2blowast

Valuetype Valuetype Sand 2997 1308 Silt 5486 4425 clay 1528 4247Textural class Silty loam Silty clayPH 587 670Organic matter () 143 120Total N () 008 013P (120583gg soil) 558 749S (120583gg soil) 789 725B (120583gg soil) 016 012Cu (120583gg soil) 015 027Fe (120583gg soil) 280 435Mn (120583gg soil) 074 163Zn (120583gg soil) 043 034Exchangeable K (meq100 g soil) 010 017Ca (meq100 g soil) 143 240Mg (meq100 g soil) 035 087aDepartment of Soil Science Sher-e-Bangla Agricultural University Dhaka1207bSoil Science Division Bangladesh Rice Research Institute (BRRI) Gazipur1703lowastRed brown terrace soil type

22 Plant Materials The BRRI hybrid dhan2 is a popularindica hybrid rice variety developed by Bangladesh RiceResearch Institute (BRRI) in 2008 It is recommended forcultivation in both dry seasons of Bangladesh The Heera2(HS-273) is the most popular indica hybrid rice varietyimported fromChina and occupied about 70 of total hybridrice cultivated area in Bangladesh Both hybrids mature in140 to 145 days during the dry seasons (December to May)[31] Also BRRI dhan45 is a high yielding inbred varietyfor dry season and was developed by BRRI in 2005 throughcrossing between BRRI dhan2 and TETEP Originally thisvariety was developed from the breeding line BR5778-21-2-3and its duration of growth ranges from 140 to 145 days

23 Sampling and Measurements Five plants were sampledat 10-day intervals starting from 20 DAT up to maturity Atfirst sampling hills were selected from the third rows andthe next two rows or three hills were left for subsequentsampling to minimize the border effect Leaf area (LA) wasmeasured by an automatic leaf area meter (Model LI-3100Li-COR Lincoln NE USA) just after removal of leaves toavoid rolling and shrinkage and transformed into leaf areaindex (LAI) according to Yoshida [32]

Ten plants were sampled from each plot at heading andat maturity All the plant samples were separated into rootleaf blades (leaf) culm and sheath (stem) and panicles Drymatter of each component was determined after drying at72∘C for 3 days to have constant weightThe preanthesis shoot(stem + leaf) reserve translocation was calculated by net loss




Total rainfall(mm)











=



=


(1)



=


(2)






(3)











3 Results































2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10BRRI hy dhan2









4 Discussion



Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120


(a)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(b)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(c)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120



(d)








2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10Variety










anslo

catio

n (

)


y = minus75131x + 24045

R2 = 0829

R2 = 09135

5

10

15

20

25

30

35

285 290 295 300 305 310


y = minus24009x + 80906

y = minus12735x + 3975

R2 = 07692



CPA

pan

icleminus1

(g)

12

14

16

18

2

285 290 295 300 305 310


y = 00192x + 08016

y = minus015x + 61125

y = minus02638x + 95203

R2 = 04997

R2 = 06985

R2 = 0672




5 Conclusion





Acknowledgments


References


















1
















1

































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




Total rainfall(mm)











=



=


(1)



=


(2)






(3)











3 Results































2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10BRRI hy dhan2









4 Discussion



Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120


(a)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(b)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(c)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120



(d)








2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10Variety










anslo

catio

n (

)


y = minus75131x + 24045

R2 = 0829

R2 = 09135

5

10

15

20

25

30

35

285 290 295 300 305 310


y = minus24009x + 80906

y = minus12735x + 3975

R2 = 07692



CPA

pan

icleminus1

(g)

12

14

16

18

2

285 290 295 300 305 310


y = 00192x + 08016

y = minus015x + 61125

y = minus02638x + 95203

R2 = 04997

R2 = 06985

R2 = 0672




5 Conclusion





Acknowledgments


References


















1
















1

































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology










3 Results































2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10BRRI hy dhan2









4 Discussion



Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120


(a)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(b)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(c)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120



(d)








2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10Variety










anslo

catio

n (

)


y = minus75131x + 24045

R2 = 0829

R2 = 09135

5

10

15

20

25

30

35

285 290 295 300 305 310


y = minus24009x + 80906

y = minus12735x + 3975

R2 = 07692



CPA

pan

icleminus1

(g)

12

14

16

18

2

285 290 295 300 305 310


y = 00192x + 08016

y = minus015x + 61125

y = minus02638x + 95203

R2 = 04997

R2 = 06985

R2 = 0672




5 Conclusion





Acknowledgments


References


















1
















1

































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology
























2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10BRRI hy dhan2









4 Discussion



Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120


(a)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(b)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(c)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120



(d)








2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10Variety










anslo

catio

n (

)


y = minus75131x + 24045

R2 = 0829

R2 = 09135

5

10

15

20

25

30

35

285 290 295 300 305 310


y = minus24009x + 80906

y = minus12735x + 3975

R2 = 07692



CPA

pan

icleminus1

(g)

12

14

16

18

2

285 290 295 300 305 310


y = 00192x + 08016

y = minus015x + 61125

y = minus02638x + 95203

R2 = 04997

R2 = 06985

R2 = 0672




5 Conclusion





Acknowledgments


References


















1
















1

































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120


(a)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(b)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

(c)

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120

Days after planting

LAI

0

2

4

6

8

20 40 60 80 100 120



(d)








2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10Variety










anslo

catio

n (

)


y = minus75131x + 24045

R2 = 0829

R2 = 09135

5

10

15

20

25

30

35

285 290 295 300 305 310


y = minus24009x + 80906

y = minus12735x + 3975

R2 = 07692



CPA

pan

icleminus1

(g)

12

14

16

18

2

285 290 295 300 305 310


y = 00192x + 08016

y = minus015x + 61125

y = minus02638x + 95203

R2 = 04997

R2 = 06985

R2 = 0672




5 Conclusion





Acknowledgments


References


















1
















1

































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology







2008-09 2009-10 2008-09 2009-10 2008-09 2009-10 2008-09 2009-10Variety










anslo

catio

n (

)


y = minus75131x + 24045

R2 = 0829

R2 = 09135

5

10

15

20

25

30

35

285 290 295 300 305 310


y = minus24009x + 80906

y = minus12735x + 3975

R2 = 07692



CPA

pan

icleminus1

(g)

12

14

16

18

2

285 290 295 300 305 310


y = 00192x + 08016

y = minus015x + 61125

y = minus02638x + 95203

R2 = 04997

R2 = 06985

R2 = 0672




5 Conclusion





Acknowledgments


References


















1
















1

































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


anslo

catio

n (

)


y = minus75131x + 24045

R2 = 0829

R2 = 09135

5

10

15

20

25

30

35

285 290 295 300 305 310


y = minus24009x + 80906

y = minus12735x + 3975

R2 = 07692



CPA

pan

icleminus1

(g)

12

14

16

18

2

285 290 295 300 305 310


y = 00192x + 08016

y = minus015x + 61125

y = minus02638x + 95203

R2 = 04997

R2 = 06985

R2 = 0672




5 Conclusion





Acknowledgments


References


















1
















1

































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


Acknowledgments


References


















1
















1

































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




1

































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology








Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

Research Article Comparative Performance of Hybrid and...

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