evaluation of drought tolerance in some of winter canola cultivars

in order to evaluate terminal drought tolerance in different canola cultivars based on drought tolerance indices, an experiment was conducted based on randomized complete block design (rcbd) with three replications at experimental field of seed and plant improvement institute (spii), karaj in 2008-09. results using stress tolerance index (sti), geometric mean productivity (gmp) and mean productivity (mp) indices revealed zarfam, talaye and gkh305, were as cultivars with highest yield in both optimum irrigation and terminal drought conditions. high and positive correlation between sti, gmp and mp indices with yield in optimum and drought conditions indicated that they were as the best indices for introduction and characterization of drought tolerant canola cultivars. biplot graph showed that mp, gmp and sti indices had high correlation coefficient with each other, and tolerant genotypes were located near tolerance indices. also results of three dimensional scatter plot indicated that cultivars zarfam, gkh 305 and tassilo were recognized as tolerant genotypes to drought stress, and cultivars es astrid, gk helena, modena and okapi were identified as sensitive genotypes.