Effects Of Flooding Stress On Growth And Physiological Charcteristics Of Soybean

Soybean is an important oil crop, which could not adapt to waterlogging and flooding. Waterlogging and flooding not only affects morphological characteristics and physiological characteristics of soybean, but also affects its production and quality. In this study, soybean (Glycine max var. Nannong99-6) was used to study the effect of flooding stress of different development stages and different flooding time on growth, physiological characteristics and yield of soybean, thus providing theoretical basis and technical support for the cultivation of soybean flooding resistance. The results were as follows:1 Soybean was used to study the effects of long-term flooding stress on growth and yield. The results showed that flooding stress inhibited the growth of soybean. The main roots and lateral roots of soybean gradually decayed with prolonging flooding time. Adventitious roots produced from the flooded part of stem, which make it possible for soybean to adapt to flooding environmental conditions. Biomass, leaf area, photosynthesis rate (Pn), and other photosynthesis parameters increased within 0-10 days, but they decreased with flooding stress time developing. While malonyldialdehyde (MDA), hydrogen peroxide (H2O2), sucrose and soluble sugar contents increased with prolonging flooding time, and were significantly higher than those of control. As a result, pod number per plant and yield decreased. In sum, photosynthetic parameters, MDA and H2O2 contents, etc., had no significant differences as compared with control within 0-10 days. It could be concluded that 10 d might be the critical time of flooding for this soybean cultivar.2 Soybean was used to study the effects of flooding stress on physiological characteristics at seedling and flowering stages. The results showed that flooding stress inhibited the growth of soybean at seedling and flowering stages. Biomass, leaf area, chlorophyll content, protein content all decreased, while malonyldialdehyde (MDA), glutathione (GSH), soluble sugar, glutamine synthetase (GS) and sucrose synthase (SS) all increased. Physiological indexes had a certain recovery upon termination of flooding stress, which amplitude was smaller, and had significant differences as compared with control. Especially the recovery capability of soybean was limited with flooding stress time developing. In sum, the recovery capability of soybean was stronger because of vigorous vegetative growth, which led to be smaller of physiological indexes at seedling stage. At flowering stage, the major nutrient of plant met the reproductive organs because the reproductive growth was dominated, while the nutritional deficiency of leaves caused by flooding can not be replenished timely, which led to be greater of impact on the flowering stage.