EVALUATION OF GRAIN YIELD OF WHEAT GENOTYPES USING STRESS TOLERANCE INDICES

Drought has unfavorableimpactsonthesuccessofagricultureinmanypartsoftheworld.unfavorable impacts on the success of agriculture in many parts of the world. ProvidingfuturepopulationswithenoughfoodwouldobviouslyrequiretheevaluationofProviding future populations with enough food would obviously require the evaluation of cropyield,higherpotentials,andtheprovisionofyieldstabilityindroughtcrop yield, higher potentials, and the provision of yield stability in drought --affectedaffected rregions.Inthisresearch,thedroughtegions. In this research, the drought--toleranceofwheatgenotypeswasstudiedinatolerance of wheat genotypes was studied in a randomizedcompleteblockdesignandinathreerandomized complete block design and in a three--replicationexperimentundernormalreplication experiment under normal anddroughtstressconditions.Intwoconsecutivegrowingseasons,themeasurementsand drought stress conditions. In two consecutive growing seasons, the measurements werewere aimedatevaluatingthestresssusceptibilityindex(SSI),droughttoleranceindexaimed at evaluating the stress susceptibility index (SSI), drought tolerance index (TOL),meanproductivity(MP,stresstoleranceindex(STI,harmonicmean(HARM),(TOL), mean productivity (MP, stress tolerance index (STI, harmonic mean (HARM), yieldindex(YI,andgyield index (YI, and genomicmeanproductivity(enomic mean productivity (GMPGMP).Theseparametersdescribedthe). These parameters described the yieldsyields ofdifferentgenotypesfortwoyearsandunderbothnormalandstressconditions.of different genotypes for two years and under both normal and stress conditions. ThecombinedanalysisofvarianceshowedthattheenvironmentsignificantlyaffectedThe combined analysis of variance showed that the environment significantly affected grainyield.Themeanvaluesofparametersbythedroughtstressconditionwerelessthagrain yield. The mean values of parameters by the drought stress condition were less thann thoseofthenonthose of the non--stresscondition.stress condition. Stressintensity(SI)was46%and43%inthefirstandStress intensity (SI) was 46% and 43% in the first and secondyear,respectively.second year, respectively. Inbothyears,In both years, MP,GMP,STIandHARMindicescorrelatedMP, GMP, STI and HARM indices correlated significantlywithgrainyieldunderstressandnormalconditions.Basedonathrsignificantly with grain yield under stress and normal conditions. Based on a threeee-dimensionaldiagramoftheseindices,thepishgamanddimensional diagram of these indices, the pishgam and wsws--8282--9genotypeswere9 genotypes were consideredasmostsuperiorinthefirstyear(bothconditions)..Furthermore,thepishgam,considered as most superior in the first year (both conditions).. Furthermore, the pishgam, alvand,andohadigenotypeswereconsideredassuperiorinthesecondyear.Accordinalvand, and ohadi genotypes were considered as superior in the second year. Accordin gtog to thebithe bi--plotdiagramandbasedonthefirsttwomajorcomponents,thesegenotypeswereplot diagram and based on the first two major components, these genotypes were moretoleranttodroughtstress.Ingeneral,itissuggestedthatthepishgamshowsahighermore tolerant to drought stress. In general, it is suggested that the pishgam shows a higher levelofyieldsustainability.Itwasfoundtobethegenotypewiththelevel of yield sustainability. It was found to be the genotype with the highestyieldunderhighest yield under bothnormalandstressconditions.Itsgrainyieldandresistanceindiceshaveincreasedboth normal and stress conditions. Its grain yield and resistance indices have increased during80yearsofbreedingandselection. during 80 years of breeding and selection.