Screening for Terminal Drought Tolerance in Iranian and Exotic Safflower Genotypes Using Drought Tolerance and Susceptibility Indices

This research was conducted to evaluate drought tolerance of safflower genotypes (Carthamus tinctorius L.) at the research farm of Isfahan University of Technology، Isfahan، Iran during growing season of 2012. One hundred genotypes including 81 foreign genotypes along with 19 Iranian genotypes were evaluated under normal and moisture stress conditions according to a simple lattice design with two replications. Drought tolerance and sensitivity indices including mean productivity (MP)، geometric mean productivity (GMP)، stress tolerance index (STI)، tolerance (TOL) and stress susceptibility index (SSI) were studied. Results of this study indicated that genotypes were significantly different for grain yield in both moisture conditions. Among all indices، MP، GMP and STI were identified as the best indices that can be used to determine tolerant genotypes. Based on MP، GMP and STI and also principal component analysis PI 369847 (Tajikistan)، CART 56 (USA)، PI 657820 (Jordan)، PI 305527 (Soudan) were determined as the most tolerant genotypes and PI 537652 (Mexico)، CART 131 (Prague)، PI 470942 (Bangladesh)، PI 209286 (Romania) and CART 32 (German) as the most sensitive ones. Results also indicated that the biplot of principal component analysis is a powerful technique to discriminate genotypes based on the measured indices. The superior safflower genotypes can be used in future breeding programs.