Positional effects on soybean seed composition during storage.

This investigation was conducted in order to determine the degree of biochemical changes during natural ageing of soybean seeds borne on different positions on stem axis. Biochemical analysis of field grown soybean seeds revealed significant differences in their oil and protein contents as a function of nodal positions. Both oil and protein content decreased after 180 days of storage (DOS) at all the nodal positions. Proportions of membrane lipids in seeds were less in basal as compared to apical positions and their proportion in stored seeds also decreased with increasing storage periods. The content of starch, total soluble sugars and reducing sugars in seeds decreased during storage for 180 days but it didn't show positional variations in their contents. The extent of lipid peroxidation increased during storage was associated with the corresponding decrease in the activities of antioxidant enzymes viz catalase and peroxidase in seeds. Seeds at basal positions showed higher rate of lipid peroxidation and lower peroxidase activity as compared to apical positions. Results suggest that soybean seeds collected from basal positions showed higher deteriorative changes during storage in comparison to apical positions that might be related to higher lipid content in seeds from basal portion of soybean stem axis as compared to apical portion.