Deterioration of Soybean (Glycine max (L.) Merr.] Seed Stored under Low and High Relative Humidity : changes in Germination, Vigor, Membrane Permeability and Growth of Storage Fungi

Abstract

Understanding the cause of soybean (Glycine max (L>) Merr.] sed deterioration during storage will aid us in devising to investigate early deteriorate changes of stored soybean seeds. To explore the machanism of ageing, high quality seeds of the cultivarr SJ5 harvested at physiological maturity were stored at room temperature with 5 moisture contents (6, 8, 10, 12% and variable moisture). Seed quality (germination and vigor), leakage conductivity, water absorption, staining with Evans blue and triphenyl tetrazolium chloride (TTC) and fungal infection were measured every 300 days during storage. Gemination and vigor remained high only in seeds containing 6% moisture content throughtout storage, where as seeds with 8% showed small changes in the qualigy. Conductivity of seed leakage and water uptake increased for all seed moisture contents; however, this increment occurred early during storage prior to changes in seed quality of 6% seed moisture content. Staining seeds with Evans blue and TTC encouraged the changes in membrane integrity causing seed leaeage which preceded measurable declines in seed quality. In addition, increase of fungi invasion did not associate with loss of seed quality. These results indicate that changes in membrane integrity appeared to be the first stage in seed deterioration.