International Journal of Life Sciences 9 (5) : 2015; 103 - 107 Founded 2007 An Independent, Open Access, Peer Reviewed, Non-Profit Journal International Journal of Life Sciences ISSN 2091-0525 website: http://nepjol.info/index.php/IJLS/index International Journal of Life Sciences Copyright © International Journal of Life Sciences ResearchArticle Changes in Yield and Yield Components of Wheat Cultivars under Water Stress Condition 1 Amin Farnia *, Amin Tork 2 1 Assistant professor of department of agriculture, Boroujerd branch, Islamic Azad University, Boroujerd, Iran M. Sc. student of department of agriculture, Boroujerd branch, Islamic Azad University, Boroujerd, Iran 2 Article Information ABSTRACT Keywords: Commonwheat; irrigation; Yieldandyield components A field experiment was laid out in order to evaluation of effects water stress on yield and yield componentsofwheatcultivarsinLorestanprovinceinIslamicAzadUniversity,Boroujerdbranch,Iran at2014.Theexperimentwaslaidoutinasplit-plotdesignbasedonrandomizedblockdesignwith three replications. Treatments were irrigation in five levels such as 1: four period irrigation after anthesis,2:threeperiodirrigationafteranthesis,3:twoperiodirrigationafteranthesis,4:oneperiod irrigationafteranthesisand5:controlinmainplotsandthreewheatcultivars(Shiraz,Pishtazand Bahar)insubplots.Theresultsshowedthat,theeffectofwaterstress,cultivarandinteractionbetween themonallparametersweresignificantat1%level.TheheightofPishtazcultivarwastallerthanother cultivars.ThePishtazcultivarwithoneperiodirrigationafteranthesishadthehighestnumberofspike persquareandBaharcultivarwithoneperiodirrigationafteranthesishadthelowestnumberofspike per square. However, 1000- grainwas decreased in water deficit treatment. However, the Pishtaz cultivarwithfourperiodirrigationhadthehighestplantdryweightandgrainyieldandBaharcultivar nonirrigationtreatmentafteranthesishadthelowestplantdryweightandShirazcultivarinnonirrigationtreatmenthadthelowestgrainyield.Theresultsshowedthatyieldandyieldcomponentsof commonwheatdecreasedwithincreasingofwaterdeficitandforincreasingingrainyieldofwheat completeirrigationareneeded.However,Pishtazcultivarhadahighestgrainyieldanddrymatter production. Then we can increase grain yield and production of wheat with cultivation of Pishtaz cultivarandavoidofwaterstress. INTRODUCTION Wheat (Triticum aestivum L.) is the most important cerealcropintheworld(Akbar,2001;Zahidetal.,2003). Commonwheatisthenationalstaplefoodinforty-three countries.Theworlddoesnothaveenoughpotentialfor increasingthesoillevelcultivatedwithwheat;therefore in order to increase the wheat production, we have to increasetheproductivityofthefieldswhichhavebeen cultivatedwithwheat.Accordingtothestatisticsofthe food and agriculture organization (FAO), during 20082009 growing season 682 million tons of wheat were producedanditisestimatedthatupto690milliontons willbeproducedin2012-2013growingseason. The global water crisis seriously influences crop productivityparticularlyinmostoftheAsiancountries where irrigated agriculture accounts for 90% of total divertedfreshwater(Huaqietal.,2002).Environmental conditions around 20 days pre- and 10 days postanthesis are considered critical for grain yield determination (Savin and Slafer, 1991). During preanthesis, the potential grain number per unit area and potential grain weight are defined (Fischer, 1985; Calderinietal.,2001).Thefinalgrainnumberperunit areaissetimmediatelyafteranthesis,whilegrainfilling occurs during the remaining post-anthesis period (Ugarte et al., 2007) and this process affected by to numerousstressessuchaswaterstress.Environmental stressisaprimarycauseofcroplossworldwide,resulting inaverageyieldlossesofmorethan50%formajorcrops everyyear(Chavesandoliveira,2004).Droughtstressis the second important constraint of yield in crops after disease (Singh et al., 1994). Drought stress causes decelerationofcellenlargementandthusreducesstem *Corresponding author Email address: aminfarnia@yahoo.com Copyright reserved © International Journal of Life Sciences DOI:dx.doi.org/10.3126/ijls.v9i5.12707 International Journal of Life Sciences 9 (5) : 2015; 103 - 107 length by inhibiting inter nodal elongation and also checks the tillering capacity of plants (Ashraf and O'Leary, 1996). Several studies have also shown that optimum yield can be obtained with irrigation at branching, flowering and pod formation stages (Prihar andSandhu,1968). Lietal.(2004)showedthatunder recommended complete irrigation conditions and supplementary irrigation programs, plants would have higher yields compared with those without any irrigation. Limited water availability and unfavorable moisture distribution during the main wheat growing periodcanleadtoahighvariabilityinyieldandinprotein contentaffectingthebread-makingquality(Bonfiletal., 2004).Kumaretal.(2005)foundsignificantcorrelation ofgrainyieldwithleafareaindex,plantheight,spikelets perspike,1000-grainweight,andbiologicalyieldunder both environments (drought stress and rainfed condition).Blum(2005)statedthatdroughtstressmay occur throughout the growing season, early or late season,butitseffectonyieldreductionishighestwhenit occursafteranthesis.Jalotaetal.(2006)reportedthatthe anthesis to grain development period is the most sensitive stage to water stress in wheat. Therefore the aimofthisstudyisevaluationofeffectswaterstresson yield and yield components of wheat cultivars in Lorestanprovince(Khorramabadregion),Iran. MATERIALS AND METHODS FieldmaterialandExperimentaldesign This field experiment was laid out in the Faculty of agronomy and plant breeding, Islamic Azad University, Boroujerd Branch, Boroujerd, Iran (Khorramabad region) during the growing seasons 2013- 2014. The experimentwaslaidoutinordertoevaluationofeffects water stress on yield and yield components of wheat cultivarsinLorestanprovince.TheKhorramabadregion has a continental semi-humid climate with annual precipitationof512mm.About50%ofthisfallsduring thewheatandwheatgrowingperiod. Table1.Soilpropertyofexperimentsite Treatments Theexperimentwaslaidoutinasplit-plotdesignbased on randomized block design with three replications. Treatmentswereirrigationinfivelevelssuchas1:four periodirrigationafteranthesis,2:threeperiodirrigation afteranthesis,3:twoperiodirrigationafteranthesis,4: oneperiodirrigationafteranthesisand5:controlinmain plots and three wheat cultivars (Shiraz, Pishtaz and Bahar)insubplots. Soilpropertyofexperimentalfield showedintable1. Yieldandyieldcomponentsdetermination Therewere6rowsineachfrom45plot;rowswere3m longwith0.3mrowspacing.Atmaturity,twoouterrows foreachplot,50cmfromeachendoftheplots,wereleft as borders and the middle two central rows were harvested. Then yield components were calculated as standard methods with using 8 plants. To determine grainyield,biomassyieldandharvestindex,weremoved and cleaned all the seeds produced within two central rows in the field. Then grain yield and biomass yield recorded on a dry weight basis. Yield was defined in terms of grams per square meter and quintals per hectare.Replicatedsamplesofcleanseed(brokengrain andforeignmaterialremoved)weresampledrandomly and1000-grainwerecountedandweighed.Theharvest indexwasaccountedwithfollow: HI=(Economicalyield/Biologicalyield)*100 Statisticalanalysis Thestatisticalanalysestodeterminetheindividualand interactive effects of treatments was conducted using JMP 5.0.1.2 (SAS Institute Inc., 2002). Statistical significance was declared at P≤0.05 and P≤0.01. Treatment effects from the two runs of experiments followedasimilartrend,andthusthedatafromthetwo independentrunswerecombinedintheanalysis. RESULTS Plantheight:Theresultsshowedthat,theeffectofwater stress,cultivarand interactionbetweenthemonplant heightweresignificant(table2).Thecomparisonofthe meanvaluesoftheplantheightforinteractioneffectof waterstressandcultivarshowedthatBaharcultivarwith two period irrigation after anthesis had the highest (77.5cm) plant height and Pishtaz cultivar with four period irrigation after anthesis had the lowest (58cm) plant height and difference between them were significant(table3). Numberofspikepersquare:Theeffectofwaterstress, cultivar and interaction between them on number of spike per square were significant (table 2). The comparisonofthemeanvaluesofthenumberofspikeper squareforinteractioneffectofwaterstressandcultivar showedthatPishtazcultivarwithoneperiodirrigation afteranthesishadthehighest(540)numberofspikeper squareandBaharcultivarwithoneperiodirrigationafter anthesishadthelowest(98)numberofspikepersquare (table3). 104 International Journal of Life Sciences 9 (5) : 2015; 103 - 107 1000grainweight:Theresultsshowedthat,theeffectof waterstress,cultivarand interactionbetweenthemon 1000 grain weight were significant (table 2). The comparisonofthemeanvaluesofthe1000grainweight forinteractioneffectofwaterstressandcultivarshowed that Pishtaz cultivar with two period irrigation after anthesis had the highest (62g) 1000 grain weight and Bahar cultivar non irrigation treatment had the lowest (52g) 1000 grain weight and difference between them weresignificant(table3). Table2. Analysisofvariance(meansquares)foryield and yieldcomponentsofwheatcultivarsunderwaterstress ns:Non-significant,*and**:Significantat5and1%probabilitylevels, respectively. Plantdryweight:Thisresultshowedthat,theeffectof waterstress,cultivarandinteractionbetweenthemon plant dry weight was significant (table 2). The comparisonofthemeanvaluesoftheplantdryweightfor interactioneffectofwaterstressandcultivarshowedthat Pishtaz cultivar with four period irrigation had the highest plant dry weight and Bahar cultivar non irrigationtreatmentafteranthesishadthelowestplant dryweight(table3). Grainyield:Theresultsshowedthat,theeffectofwater stress, cultivar and interaction between them on grain yield were significant (table 2). The comparison of the mean values of the grain yield for interaction effect of water stress and cultivar showed that Pishtaz cultivar withfourperiodirrigationafteranthesishadthehighest (425g.m2) grain yield and Shiraz cultivar in nonirrigationtreatmenthadthelowest(74g.m2)grainyield anddifferencebetweenthemweresignificant(table3). Harvestindex(HI):Theeffectofwaterstress,cultivarand interaction between them on harvest index were significant(table2).Thecomparisonofthemeanvalues oftheharvestindexforinteractioneffectofwaterstress andcultivarshowedthatPishtazcultivarwithoneperiod irrigationafteranthesishadthehighest(47%)harvest indexandShirazcultivarinnon-irrigationtreatmenthad thelowest(13%)harvestindex(table3). DISCUSSION Thepositiveeffectofirrigationonincreaseofplantdry weightandgrainyieldofcommonwheatwasobtainedin thepresentstudy. Theresultsofthisstudyshowed,the effect of water stress, cultivar and interaction between themonallparametersweresignificantat1%level(table 2). Almost all the varieties had produced good plant height, spike length, grains per spike and 1000 grain weightincontrolhavingnormalirrigations,whileallthe parameters were significantly reduced at highest drought. The plant height of Pishtaz cultivar was most Table3.Interactioneffectofwaterstressandcultivaronyieldandyieldcomponentsofwheat Meansbytheuncommonletterineachcolumnaresignificantlydifferent(p<0.05). 105 International Journal of Life Sciences 9 (5) : 2015; 103 - 107 significantly affected at higher water stress level while Baharcultivarproducedtallerplantsinresponsetoall stresslevelsthanothercultivars(table3).Plantheight plays an important role in photosynthesis. Malik & Hassan,(2002)andKhanzadaetal.,(2001)haveearlier reported that shoot length of guar genotypes significantly reduced under water stress. Similarly Inamullahetal.,(1999)alsoobservedthatplantheightin wheatvarietiesreducedsignificantlyunderwaterstress whenitwascomparedwithirrigated. The Pishtaz cultivar with one period irrigation after anthesishadthehighestnumberofspikepersquareand Baharcultivarwithoneperiodirrigationafteranthesis had the lowest number of spike per square (table 3). Tompkins et al., (1991) reported the significant suppressive effect of water stress on number of grains perspikeandnumberofspikepersquare.Khanzadaet al.,(2001)andQadiretal.,(1999)haveearlierreported thatwaterstressthroughoutvegetativeandreproductive developmentcausedasignificantreductioninnumberof grainsperspikeandnumberofspikepersquareinwheat. Drastic decrease in 1000- grain weight was recorded (table 3) as the drought stress increased but highest reductions were found in non-irrigated treatment followed by I4. The highest 1000-grain weight was recorded in Pishtaz cultivar with two period irrigation afteranthesis.Theseresultsareinagreementwiththose of Khan et al., (2005) and Qadir et al., (1999) who observedthat1000-grainweightofwheatwasreduced mainly due to increasing water stress. However, the Pishtaz cultivar with four period irrigation had the highest plant dry weight and Bahar cultivar non irrigationtreatmentafteranthesishadthelowestplant dry weight and the Pishtaz cultivar with four period irrigationafteranthesishadthehighest(425g.m2)grain yieldandShirazcultivarinnon-irrigationtreatmenthad thelowest(74g.m2)grainyieldanddifferencebetween themweresignificant(table3).ThefindingsfromSaeidi etal.,(2010)whentheyimposedwaterdeficitatdifferent stagesofgraingrowthseparately,showedthatsignificant reductioningrainyieldproductionintheseconditions may be result of reducing the production of photoassimilates(sourcelimitation)forgrainfilling,reducing the sink power in absorbing of photo-assimilates and reducing the grain filling duration. They also reported thatprobably,theearlyprocessesofgraingrowth(cell divisionandformationofsinksize)arelessaffectedby waterdeficiency.Therefore,grainweightandgrainyield reductionunderpost-anthesiswaterdeficiencymaybe more reflects the lack of photo-assimilates supply for grainfilling.AshrafandMehmood(1990)reportedeven a short term water deficit stress can cause substantial losses in crop yield that is in agreement with our results.ThesefindingsalsoareinagreementwithEmam andNiknejad(2004),Ehdaieetal.(2006),Ahmadietal. (2009).Theharvestindexcanbeexpressedasabilityof plants to allocate photosynthetic material to produce economicyield.Intermsofthistraitundercontroland post-anthesis water deficiency stress, there was significant variation between cultivars. In the present study,thePishtazcultivarwithoneperiodirrigationafter anthesishadthehighestharvestindexandShirazcultivar innon-irrigationtreatmenthadthelowestharvestindex (table 3). Significant reduction in harvest index under postanthesiswaterdeficiencystressshowedthatwater stress. Is largely due to more significant reduction in grain yield production than biomass production (Shafazadeh et al., 2004). It means that increasing of grain weight is accompanied with increasing harvest index(Koochekietal.,2006). In final our results showed that yield and yield components of common wheat decreased with increasing of water deficit and for increasing in grain yieldofwheatcompleteirrigationareneeded.However, Pishtazcultivarhadahighestgrainyieldanddrymatter production. Then we can increase grain yield and productionofwheatwithcultivationofPishtazcultivar andavoidofwaterstressinLorestanregion. 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