Determining rapeseed tolerance to waterlogging at seedling stage in the Yangtze River basin

To determine rapeseed tolerance to waterlogging and to screen its proper evaluating indicators, 32 rapeseed (Brassica napus L.) genotypes were used in a simulated waterloging field experiment. The results showed waterlogging increased proline content, and decreased root activity, chlorophyll and protein contents, and root and plant dry weight of rapeseed. The waterlogging resistance of different rapeseed genotypes varied showing a great hereditary difference. “Zhongyou 821”, “Qianyou 18”, “Zhongshuang 11”, “09L553×L559”, “Zhongshuang 9” and “SWU 7” were classified as strong tolerance genotypes, and accounted for 18.75% of the total tested genotypes. “Chuanyou 58”, “Xianyouza 2” and “Chuanyou 20” were classified as weak tolerance geneotypes, and accounted for 9.38% of the total tested genotypes. The rest were medium tolerance genotypes. Correlation analysis indicated significant to extremely significant correlation between single and comprehensive wet-damage indices. Correlations among most single indicators wet-damage indexes were significant to extremely significant. Root vigor, total dry weight and proline content contributed a total of 79.41% to comprehensive wet-damage index. These indicators were effective for determining rapeseed tolerance to waterlogging.