Screening Drought-Tolerant Genotypes in Chickpea using Stress Tolerance Score (STS) Method

Objective: In order to study genetic variation and effect of drought stress on grain yield and some morphological traits in chickpea, an experiment was conducted on 64 genotypes during 2013-2014 cropping season at deputy of Kermanshah Sararood Dry Land Agricultural Research Institute, located on the western part of Iran. Methods: The experimental design was a randomized lattice design with tow replications under two complementary irrigation and dryland conditions. Six drought tolerance indices including stress tolerance index (STI), geometric mean productivity (GMP), mean productivity index (MP), stress susceptibility index (SSI), tolerance index (TOL), harmonic mean productivity (HMP),  were calculated and adjusted based on grain yield under drought (Ys) and irrigated conditions (Yp). Results: Results of ANOVA under two complementary irrigation and dryland conditions revealed significant differences among genotypes for YLD, NPMP and NSPP. In dryland condition all of tolerance indices except SSI*TOL have significant negative correlation with SSI index and the rest of indices except TOL*YS, HMP*TOL and YI*TOL show positive correlation. The first two components explained 95.8% of total variation between the data. Based on biplot the genotypes 40 and 63 were superior genotypes under both stress and non-stress conditions. These genotypes had stable performance in the circumstances of low sensitivity to drought stress. Genotypes 29, 55, 56, 57, 45 and 16 had a relatively low yield and they are sensitive to drought stress. In conclusion, this study showed that the effect of drought stress on grain yield was varied which suggested genetic variability for drought tolerance in this materials. Therefore, breeders can select better genotypes based on indices and a combination of different methods of selection.