Relationship of Soybean Seed Quality to Fatty Acid and C6‐Aldehyde Levels during Storage

Lipid peroxidation is thought to be an important factor in seed deterioration. This investigation was initiated to determine if changes in free fatty acids and peroxidation products are related to changes in seed quality during soybean [ Glycine max (L.), Merr.] seed deterioration. Seed lots of three soybean cultivars (Century, Pennyrile, and Pharaoh) were stored at 20, 30, and 40°C, sampled periodically, and tested for seed germination and vigor. Embryonic axes excised from deteriorated seeds were tested for contents of total and free fatty acids and C 6 ‐aldehydes. Seed vigor, as measured by accelerated aging, conductivity, and cold tests, was the first seed quality component lost in all cultivars and storage environments, followed by a decline in percentage germination. Conductivity of seed leachates increased about two‐fold during storage for all cultivars. The amount of total fatty acids in the lipid fraction did not change, while free linoleic and linolenic acids increased about two‐fold during seed deterioration. E ‐2‐hexenal increased two‐fold but hexanal did not change during storage. Both free linoleic acid and E ‐2‐hexenal content were correlated with seed quality, but little association was shown between lipoxygenase activity and seed quality. Free fatty acids may have contributed to seed deterioration by disrupting membranes and/or by toxicity of subsequent peroxidation products.