Assessment of drought tolerance in some bread wheat genotypes using drought resistance indices

The aim of this study was to assessment of drought tolerance in genotypes of bread wheat (Triticum aestivum L.). For this purpose twenty genotypes were evaluated in research field of Razi University using randomized completely block design with three replications in both rain-fed (stress) and irrigated (normal) conditions. Eight drought resistance indices including Stress Tolerance Index (STI), Tolerance Index (TOL), Stress Susceptibility index (SSI), Mean Productivity (MP), Geometric Mean Productivity (GMP), Yield Index (YI), Yield Stability Index (YSI) and Harmonic Mean (HAM) were calculated for each genotype based on grain yield under stress and normal conditions. Result of combined analysis of variance revealed significant differences between genotypes for grain yield. Drought stress reduced grain yield of investigated genotypes, significantly. Result of correlation analysis between grain yield in both conditions and calculated drought resistance indices showed that STI, GMP and HAM were the best indices for identifying high yielding genotypes in both conditions (drought tolerant genotypes). Based on STI, GMP and HAM and biplot analysis, genotypes No. 9, 12, and 14 comparatively identified as drought tolerant and genotypes No. 10 and 13 identified as susceptible genotypes.

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