Zhang JinFang

Consistency of different indices in rapeseed (Brassica napus) may predict the waterlogging tolerance.

Different waterlogging tolerance indices between 15 rapeseed (Brassica napus L.) cultivar materials were investigated after seed germinating and field waterlogging, in order to research the consistency of different methods, as well as the effects of waterlogging on yields. The results showed significant variation between the 15 materials. Anoxic germination under room condition resulted in great differences in kinds of waterlogging tolerant indexes, such as vigor index, survival rate, relative seedling length, relative root length and fresh weight; in the fields, plant growths were repressed seriously under waterlogging stress: root fresh weight, root length, aerial parts fresh weight, plant height, plant fresh weight, aerial parts dry weight, root dry weight and root/shoot ratio were decreased by various degrees. Meanwhile, physiological indicators like contents of soluble sugar, soluble protein, malondialdehyde (MDA) and proline, as well as activity of superoxidase (SOD) increased; on the other hand, plant height, number of effective branches, number of pods per plant, number of seeds per pod, yield per plant decreased significantly. Especially, the number of effective branches decreased by 31.81%~78.02% compared with control. 1000-seed weights were increased in some materials. Waterlogging tolerance capabilities varied between materials, but generally, waterlogging tolerant plants showed less genotype reduction. Correlation analysis showed that waterlogging tolerant indices of germinating seed in the room were significantly correlative to those physiological and morphological data in the fields, as well as the final yield characters. Unit conductivity was found significantly negatively correlated with yield per plant, while the relative vigor index was significantly positively correlated with yield per plant. This consistency demonstrated that different methods of determining waterlogging tolerance in rapeseed have the same conclusion. Moreover, it helps predicting the waterlogging tolerance of rapeseed cultivars in the lab conditions so that the breeding of the waterlogging tolerant cultivars can be accelerated in the future.