Evaluation of drought resistance in safflower (Carthamustinctorius L.) genotypes under field conditions

In order to evaluate drought resistance indices in eight safflower (Carthamus tinctorius L.) genotypes were evaluated in a split plot design with three replications in two levels of irrigation, one with stress and the other without stress at the Islamic Azad University of Shoushtar, Iran, research farm in the year 2014. To evaluate drought tolerance genotypes on the basis of yield performance in stressed (ys) and non-stressed (yp) environments, quantitative measures of drought tolerance i. e. mean productivity (MP), stress tolerance (TOL), geometric mean productivity (GMP), stress susceptibility index (SSI) and tolerance index (STI) were computed. The analysis of variance showed that the genotypes had significant differences in all the traits. Drought had highly significant difference on all of the studied traits except number of seeds per capsule. The highest and lowest means of grain yield were 356s6 (787 kg/ha) and 376 (362.2 kg/ha), respectively. The highest values of SSI were observed in 357s6 and 27-N and the lowest values of SSI were observed in Pi-258 and KW 13. These genotypes could be proposed as tolerant genotypes to drought stress. Pi-258 and KW 13 with a smaller value of TOL were identified as the most tolerant genotypes, while 44 and 376 with the highest TOL value were the most sensitive genotypes.The results indicated that MP, STI and GMP had a significant (P<0.01) positive correlation with yield under non-stress and stressed conditions indicating that these indices are suitable criteria for screeningdrought tolerant genotypes.