Evaluation of Grain ed and Oil Yields in Spring Genotypes of Oilseed Rape (Brassica napus L.) under Different Water Deficit Levels

Evaluation of drought effects on some physiological traits relevant to drought tolerance, seed and oil yields, yield components and recognizing tolerant oilseed rape genotypes were the goals of research. The experiment was conducted as split plot based on a randomized complete block design with three replications in East Azarbaijan Research and Education Center for Agriculture and Natural Resources during 2015.The experimental factors were drought stress with three levels: non-stressed and drought stress from flowering and pod formation stages and genotype in 5 levels: RGS003, Zafar, Sarigol, Zarfam and Dalgan. Occurring drought from flowering and pod formation stages led to significant increase in leaf temperature and significant decrease in leaf relative water content, stomatal conductance, pods per plant, 1000 seeds weight, seed and oil yields. But the effects of drought from flowering stage were too hard. In case of water resources limitation, irrigation during flowering stage will be more important than pod formation stage. The existence of significantly negative correlation among leaf temperatures and significantly positive correlations among leaf relative water content, stomatal conductance with the pods per plant, 1000 seeds weight, seed and oil yields showed that, these traits can indicate drought effects on spring oilseed rape. Also the existence of significantly positive correlations among the pods per plant and 1000 seeds weight with seed and oil yields, showed that, drought reduced yields via decreasing these components. All of studied genotypes indicated similar performance under non-stressed condition. But under drought conditions, RGS003 indicated higher seed and oil yields.