Effects of waterlogging at different growth stages on physiological characteristics and seed yield of winter rape (Brassica napus L)

A study on physiological and yield effects of waterlogging of rape plants at different stages of growth was conducted in specially designed experimental tanks. Waterlogging at seedling and floral bud appearance stages significantly decreased leaf chlorophyll content, superoxide dismutase and catalase activities, the accumulation of leaf malondialdehyde and ethylene production, and leaf photosynthetic rate and root oxidizability. The experiment confirmed that the physiological function of rape plants was retarded during the time of waterlogging, and its adverse effect remained afterwards. Also, plant height, stem width and the number of primary branches per plant were significantly decreased by waterlogging at seedling and floral bud appearance stages. Pods per plant and seeds per pod were also significantly reduced, giving 21.3% and 12.5% decrease of seed yield from the control for treatments at the seedling and floral bud appearance stages, respectively. No significant difference in yield components and seed yield was observed between the control and treatments applied at flowering and pod formation stages. The paper also analyses the relationships between the physiological reactions of waterlogging, morphological characteristics, and yield components and discusses ways to alleviate waterlogging damage in plants.