evaluation of rice cultivars in drought and normal conditions based on sensitive and tolerance indices

drought stress has been well documented as an effective parameter in decreasing crop production, developing and releasing new varieties which are adaptable to water deficit conditions can be a constructive program to overcome unsuitable environmental conditions. in order to evaluate the adaptation of rice genotypes to drought stress and to identify the tolerant and sensitive genotypes, 15 genotypes were studied in two environments (stressed and non –stressed conditions) using randomized complete block design with three replications in the research farm of gonbad kavos university in 2008 growing season. analysis of variance showed that there was highly significant effect (p> 0.01) between genotypes in all traits and in both environments. mean comparison showed that the highest yield belonged to dom siah, sarkho and sangjo in nonstressed and stressed respectively. mean productivity (mp), geometric mean productivity (gmp) and stress tolerance index (sti) were the most suitable indices showing the highest correlation with yield. based on mp, gmp and sti and also biplot technique, garde, sarkho, sangjo, ir83752-b-b123, tarom mahali and tarom amiri) were determined as the most tolerant cultivars while brsbonanc graldo being the most sensitive.