Selenium Increases Photosynthetic Pigments, Flavonoid Biosynthesis, Nodulation, and Growth of Soybean Plants (Glycine max L.)

This study aimed to investigate the physiological roles of selenium (Se) in the photosynthetic pigment, antioxidant metabolism, flavonoid biosynthesis, nodulation, and its relationship with soybean production. The treatments consisted of five doses of Se (0 mu g kg(-1), 7.5 mu g kg(-1), 15 mu g kg(-1), 30 mu g kg(-1), and 45 mu g kg(-1)) applied via soil and in the form of sodium selenate at the V-2 phenological stage of soybean. The concentration of chlorophyll b and carotenoids, the activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase), and the concentration of total sugars in soybean leaves increased in response to Se fertilization. In addition, Se increased ureide concentration in leaves and activity of nitrate reductase, resulting in greater bioavailability of amino acids and proteins in the leaves, generating greater stimulation of plant growth and root dry weight, but did not increase yield. The number of nodules and the synthesis of rutin and genistein in the roots were significantly increased by the Se application. Se also stimulated the translocation of amino acids from leaves to the nodules and of ureides from nodules to leaves, increasing efficiency in biological nitrogen fixation. This study presents fundamental new insights regarding Se effect on nitrogen metabolism, flavonoid synthesis, antioxidant metabolism, and nodulation of soybean that can be helpful in increasing the crop tolerance to abiotic stress.

Automated summary

This study aims to investigate the physiological roles of selenium in soybean and its relationship with soybean production through exploring its effect on chlorophyll, antioxidant enzymes, flavonoid biosynthesis, and nodulation. The results show that selenium fertilization can increase the concentration of chlorophyll and carotenoids, boost antioxidant enzyme activity, and increase total sugar content in soybean leaves. Additionally, it enhances ureide concentration and nitrate reductase activity, leading to improved bioavailability of amino acids and proteins in the leaves, promoting plant growth and root dry weight. It also increases the number of nodules and synthesis of rutin and genistein in the roots, facilitating nitrogen fixation. This study provides valuable insights into the role of selenium in soybean physiology, which can be beneficial in improving crop tolerance to environmental stress.