Evaluation of Drought Tolerance in Safflower Genotypes Based on Drought Tolerance indices

Abstract

Among the different environmental stresses, drought is the constraint that induces a highly negative effect on crop production. In order to identify drought tolerant genotypes, an experiment was conducted in a randomized complete block design with three replications under rainfed and irrigated conditions during 2011-2012 cropping season. Seven 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) and Yield Stability Index (YSI) were calculated for each genotype based on grain yield under stress and normal conditions. Analysis of variation showed significant difference among genotypes in the terms of grain yield under rainfed and irrigated conditions. Result of correlation analysis between grain yield in both conditions and calculated drought resistance indices revealed that STI, MP, GMP and YI were the best indices for identifying high yielding genotypes in both conditions (drought tolerant genotypes). Gabriel Biplot Multivariate chart showed that ‘Syrian’, ‘PI-537530’ and ‘PI-537636-S’ genotypes relatively identified as drought tolerant and ‘Hartman’, ‘Gila’, ‘PI-537636’, ‘PI-537598’, ‘LRV-51-51’ and ‘Yenice’ genotypes identified as susceptible genotypes. Cluster analysis based on grain yield and drought tolerance indices recognized the genotypes into four clusters, so that this result was consistent with biplot analysis.