Effect of Drought Stress on proline content and Canola (Brassica napus L.) Antioxidants enzymes activity

To study drought stress on seedling dry weight, proline contents and evaluate of antioxidant enzymes activity in canola genotypes (Brassica napus l.), an experiment were evaluated at laboratory physiology, Shahed University. This experiment was carried out in factorial with CRD design with 4 replications in 2008. The first factor was including levels of dough stress, one without stress as check (0) and the other with stress (-0.5 ,-1 and -1.5 Mpa) and the second factor rapeseed genotypes of RGS and Modena were considered. To evaluate drought tolerance genotypes on the basis of Morphological aspects on root and stem dry weight, ascorbat peroxidase and Gayacol peroxidase activity in root and stem, change of osmolites include proline in seedling stage in growth environment with stress and comparison with control plants were computed. Analysis of variance showed that there were significant differences among drought stress, varieties and interaction drought*varieties in terms of traits under stress. Results showed significant differences among drought stress, genotypes and interaction between drought stress*genotypes with respect to all indices. The highest and the least amounts of root dry weight was related to Modena genotype in -1 Mpa stressed and RGS genotype non-stressed conditions, respectively 2.32 and 1.52g. Correlation analysis between dry weights and all enzyme indices and proline content were significant, in which the most correlation was among proline content and antioxidants enzymes activity. There were negative significant between leaf and root antioxidants enzymes activity. Correlation coefficients between dry weight and indices in drought stress and proline was significant overall, result showed that in drought stress, plants attempt to increase proline content and Antioxidants enzymes activity in relating decrease organs dry weight. Besides, the sensitivity of stem than root in response to decrease of dry weight and antioxidant enzymes activity was more.