evaluation of drought tolerance and finding suitable cultivars of mustard under cold dryland condition of oroumieh

indian mustard is one of the most drought tolerant crops within brassica genus which could be used in semi dry areas of iran. 20 cultivars and lines of indian mustard were studied as complete blocks design with three replications in two different humidity regimes in oroumieh research station during 2013-2014 growing season. analysis of variance showed that the most studied agronomic characteristics were significantly different in the rainfed and irrigated field. comparing the means showed decreasing of grain yield and yield components under stress condition. cultivar bard-1 and line 14 (dari-4-2) were superior regarding grain yield and related yield components. grain yield in the both irrigation regimes showed significant correlation (p<0.01) with plant height, number of pods and number of seeds per pod however, there was significant relationship between yield and thousand kernel weight under rainfed condition, as well. cluster analysis based on all studied traits in the both trials divided lines to two clusters where genotypes in the first cluster showed higher values. based on the mean productivity (mp), geometric mean productivity (gmp) and stress tolerance (sti) indices which were selected as most suitable indices in this study, cultivar bard-1 and line 14 (dari-4-2) were identified as the most drought tolerant mustard in oroumieh.