Abstract: A pot experiment with soybean cultivar Nannong 996 was conducted to study its growth and C and N metabolism at seedling and flowering stages under the stress of different duration of waterlogging. Waterlogging inhibited the soybean growth. The plant biomass, leaf area, leaf pigment content, and photosynthesis rate all decreased significantly, and the leaf malonyldialdehyde (MDA) content had a significant increase. The change ranges of the physiological indices increased with increasing waterlogging duration. After the release of the stress, the plants had some recovery. The recovery capability in treatment waterlogging for 10 d was stronger than that in the treatment waterlogging for 20 d. The leaf soluble C and N and key enzymes had different responses to waterlogging. Soluble sugar content and glutamine synthease and sucrose synthease activities all increased, but soluble protein content decreased. The influence of waterlogging on the plant biomass, leaf area, and MDA content was smaller at seedling stage than at flowering stage. It was suggested that the shorter the waterlogging duration was, the lesser damage the soybean plant suffered, and the stronger the recovery capability was. Soybean plant could recover itself after waterlogging for 10 d.  

Key words: soybean, waterlogging, C and N metabolism, photosynthetic rate, seedling stage, flowering stage.