Evaluation of Drought Tolerance of someWinter Wheat Genotypes

Drought stress is one of the main limiting factors crop production in arid and semiarid regions. In this study, drought tolerance of 19 wheat genotypes were evaluated by using UPGMA cluster analysis. To this end, the effect of drought stress on a number of related agronomic and physiological traits of wheat genotypes, belonging to three groups of sensitive, intermediate and drought tolerant, under three conditions of normal, moderate and severe drought stress were studied. A factorial experiment based on completely randomized design with three replications was performed. Traits like plant height, shoot fresh weight, spike length, awn length, shoot dry weight, seed yield and relative water content of genotypes were measured. Analysis of variance showed that the effects of drought on all traits except awn length were significant. Most of the traits were negatively affected by drought stress. Highest reduction was observed in grain yield. Cluster analysis grouped genotypes exposed to drought stresses in to three categories. Genotypes numbering 15, 13, 12, 16 and 17 expirienced low means in all of traits under study. The results also showed that the second and third groups, resulting from cluster analysis, were in agreement with the results of previous researches reported. The first cluster, however, was found to be inconsistent with their initial introduction grouping under severe drought stress conditions. Therefore, the initial grouping was consistent especially in most of sensitive and tolerant genotypes under severe drought stress conditions.