Screening of Drought-tolerant Brassica napus L. Varieties and Analysis on Their Physiologic and Biochemical Variations under Drought Stress

Objective] The aim of this study was to screen drought-tolerant Brassica napus L. germplasm resources by analyzing their physiological and biochemical changes under drought stress. Method] Forty varieties of B. napus varieties were cultured under PEG-6000 osmotic stress and extreme drought stress in pots, re- spectively. Then, the contents of chlorophyll, carotenoid, proline, malondialdehyde （MDA）, soluble sugar, soluble protein, and the activities of superoxide dismutase （SOD）, catalase（CAT）, peroxidase（POD） were measured under drought stress. Result] Sever- al drought-tolerant varieties of B. napus were screened out： YAU200908, Xiangyou No.15, YAU200903, YAU200907, YAU200906 and YAU200904. Physiological and biochemical analysis showed that, the contents of chlorophyll and carotenoid de- creased with drought stress increasing; the contents of proline, soluble sugar, solu- ble protein, MDA and the activities of SOD,CAT, POD raised with drought stress in- creasing. Conclusion] In the rapeseed varieties with stronger drought tolerance, the decrease in carotenoid content and the increase in proline content, soluble sugar content, MDA content, SOD activity, CAT activity were more obvious, so all these physiological and biochemical indices can be used to evaluate the drought tolerance of rapeseed.