راه‌کارهای مناسب گزینش ژنوتیپ‌های متحمّل به تنش خشکی در کلزا

In this research, the possibility of applying selection index of ideal genotype (SIIG) technique for identify tolerate genotypes using the different drought tolerance indices be amended. The experiment was conducted as split plot based on randomized complete block design with three replications at the experimental farm of agricultural research institute and natural resources, Yazd, Iran in 2011-2012. Three irrigation levels consisting of irrigation after 80mm evaporation from class “A” pan as control, no irrigation from stem elongation stage until flowering and flowering stage until podding stage were applied in main plots and Subplots were six winter canola cultivars. Thirteen drought tolerance indices including stress susceptibility index, stress tolerance index, tolerance index, abiotic-stress tolerance index, stress susceptibility percentage index, stress non-stress production index, relative drought index, harmonic mean, percentage of yield reduction, yield stability index, yield index, mean productivity and geometric mean productivity and also selection index of ideal genotype were calculated. The results indicated that drought stress significantly decreased the stomatal conductivity at stem elongation and flowering stages. Tassilo genotype with the highest selection index of ideal genotype values, near to one was accepted drought tolerance genotype; also Cooper and Adriana genotypes with the lowest selection index of ideal genotype values, near to zero were accepted drought susceptible genotypes at drought stress conditions from stem elongation stage until flowering. Lilian genotype with the highest selection index of ideal genotype value, near to one, perceived as the drought tolerance genotype under drought stress in flowering stage and Cooper and Adriana genotypes with the lowest selection index of ideal genotype values, near to zero were perceived as the drought susceptible genotypes. Thus, Tassilo and Lilian genotypes may be used as the genetic sources for drought resistance.