Assessment of Variability for Drought Tolerance Indices in Some Wheat (Triticum aestivum L.) Genotypes

Estimation of nine yield-based drought tolerance indices was studied in ten wheat genotypes and identification of best index and best drought tolerant genotype. Nine drought tolerance indices comprising stress tolerance index (STI), tolerance index (TOL), stress susceptibility index (SSI), geometric mean productivity (GMP), mean productivity (MP), harmonic mean (HAM), yield index (YI), yield stability index (YSI) and drought resistance index (DRI) were each estimated based on yield under non-stress (Yp) and stress condition (Ys). The results of the genetic analysis for all drought tolerance indices studied demonstrated that GMP, MP and HAM had less variation between phenotypic coefficients of variability and genotypic coefficient of variability corresponded to high heritability. GMP, MP and HAM were nominated as the best useful indices that looking for drought tolerant genotypes. Also, they had positive correlation with Yp and Ys. The genotypes 1, 6 and 10 were considered drought tolerant while genotypes 3, 4, 5, 7 and 9 as drought susceptible. Genotype 8 was identified as highly drought susceptible. The studied genotypes showed considerable variation in performance and tolerated various drought conditions that could be exploited in further investigation.