Evaluation of drought tolerance in selected soybean lines

In this study,drought tolerance of advanced soybean lines has been investigated. In this study,14soybean lines Along with two control cultivars of Saba and Kowsardar were separately carriedout in two experiments of a randomized complete block design with three replications in two years of2015-2016 in Karaj.These lines have been superior in preliminary experiments indicting in different regions.Both experiments were similarly irrigated until seedling establishment and the emergence of the V4-V5 stage,which coincided with the full development of the fourth to fifth leaves.Afterthat, the first experiment was irrigated weeklyand the second one aweek in between(50-55-and120-100-mm evaporation from ClassA evaporation pan,respectively).Different tolerance and sensitivity indices were used to evaluate the stress response.Indices were grouped by using principal component analysis and genotypes were grouped byusing biplot.Also,grouping wasperformed byusing SIIG indexand the resalt genotypes cluster was comparedwith Fernandez index.The resultsof mean comparison showed that three lines ColumbusxKrasnodar778(L.45),CrafordxLan(L.44)and WilliamsxKatool(L.3)in numberof pods perplant, numberof seeds per pod and1000-seedweight andseedyield had the highest value andwere superiorto both sensitiveand tolerant control cultivars.Bioplate diagram showedthat lines WilliamsxKatool(L.3).NemahaxSavoy(L.3),ColumbusxKrasnodar778(L.45)andSaba and Kosarcultivars were located near the vectorsof important drought resistance indices.Lines WilliamsxKatool(L.3)andCrafordxLan(L.44)tended tobe relatedto the yeildvector under stressconditions,indicating that the high values forthe drought tolerance index in these lines were mostly dueto its high yeild under stress conditions.Accordingto the SIIG index,the line WilliamsxKatool(L.3)was themost tolerant ofdrought stress.The results showedthat in each four methods,Sumof ranking,principal component analysis andSIIG index and fernandez diagram,linesWilliamsxKatool(L.3),CrafordxLan(L.44)andColumbusxKrasnodar778(L.45)werethe most tolerant and linesWilliamsxKatool(L.8),RVBxKatool(L.13)and were the most sensitive to drought stress.Therefore,using rankings for less complication can be effective in selecting tolerant genotypes.