Physiological response of spring soybean leaves under osmotic stress

Osmotic stress has an important impact on the growth of soybean. In this study, Heinong44 (HN44) and Heinong65 (HN65) were used as the research objects and cultured in sand culture, four different stress levels were set to explore the response mechanisms of antioxidant enzymes, osmotic adjustment, membrane lipid system and agronomic traits of soybean seedlings under osmotic stress. The results showed that: (1) With the extension of osmotic stress intensity and treatment time, the antioxidant activity in soybean leaves increased first and then decreased. The antioxidant activity and osmotic adjustment substance content of HN44 were higher than HN65, and the malondialdehyde (MDA) content was lower than HN65; (2) Membrane lipid peroxidation gradually increased and reached its peak on the 7th day of severe drought treatment; (3) With the aggravation of drought and the extension of drought time, the relative water content of soybean gradually decreased, and the increase of plant height slowed down, while the change of HN65 was more obvious than that of HN44; (4) Correlation analysis showed that when osmotic stress was severe, there was a significantly positive correlation between the activities of different antioxidant enzymes, and there was a significantly positive correlation between soluble sugar and soluble protein content, and there was a significantly positive correlation between soluble sugar and MDA content; (5) Through the fitting analysis of antioxidants system, the experimental results showed that superoxide dismutase would lead to the cascade reaction of antioxidant enzyme system.