Evaluation of sorghum genotypes under drought stress conditions using some stress tolerance indices

Seven genotypes of sorghum (Sorghum bicolour (L.) Moench) were studied in both drought and normal conditions. In each condition, the genotypes were evaluated using a split plot based randomized complete block design with three replications. Drought tolerance indices including stability tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), stress susceptibility index (SSI), tolerance index (TOL) were calculated for each genotype. The maximum value of STI (0.687), MP (658.95) and GMP (624.94) were recorded for genotype KGS 3. Correlation coefficients revealed that MP index had the highest value in two conditions with grain yield. Thus, tolerance index including MP is suitable for screening of tolerant genotypes in drought stress condition. Cluster analysis by method Ward classified seven genotypes in two groups in drought stress condition.