This study aimed to examine changes in seed vitality and physiological mechanisms under natural aging conditions in winter wheat, to analyze how different storage durations affect seed germination vitality, root growth, and antioxidant capacity, and to identify key physiological indicators of seed aging, so as to provide a basis for breeding winter wheat varieties with improved storability.
The newly bred winter wheat cultivars, including Annong1589 (AN1589), Annong1687 (AN1687), and Annong179 (AN179), were used as experimental materials. The seeds were stored at room temperature to simulate natural aging condition. Samples were taken from seeds stored for 6 months, 18 months, and 30 months to measure seed vigor indices, such as germination rate, germination potential, germination index, vigor index, field emergence rate, and seedling root characteristics. Additionally, those key physiological indicators during the seed and seedling stages were analyzed, including electrical conductivity (Con), malondialdehyde (MDA) content, proline (Pro), superoxide dismutase (SOD) activity, catalase (CAT) activity, peroxidase (POD) activity, and the content of soluble sugars and soluble proteins in the seeds.
Genotype had a significant effect on seed vigor and physiological indicators within the same storage period, with the interaction of cultivar and aging time having a notable impact on seed vigor. As storage time increased, the germination potential and root vigor of winter wheat seeds significantly declined. Germination index, vigor index, field emergence rate, and seedling stage indicators such as seedling height, fresh weight, and root fresh weight also showed a decreasing trend. Germination potential decreased most rapidly, with all three cultivars maintaining over 90% germination potential after 6 months of storage. After 18 months, the germination potential of AN1589, AN1687, and AN179 declined to 85.88%, 81.70%, and 88.58%, respectively. After 30 months of storage, the germination potential of all cultivars dropped below 80%, to 75.42%, 74.04%, and 79.17% of AN1589, AN1687, and AN179, respectively. This indicated a significant decline in seed vigor during natural aging. The study found that as the aging process progressed, the three cultivars continuously accumulated MDA and Pro, indicating increasing oxidative damage to the seed cell membranes. The initial MDA content in AN1589 was the lowest among the three cultivars, at 0.0427 μmol·g-1. Moreover, AN1589 had the smallest increase in Pro content after 30 months of storage, at 22.43%. The activities of antioxidant enzymes of SOD, CAT, and POD, as well as the contents of soluble sugars and soluble proteins, decreased with increasing aging, indicating a gradual loss of antioxidant capacity and consumption of internal substances to support seed germination and seedling growth.
Under natural aging conditions, the vigor of winter wheat seeds gradually decreased, closely related to the consumption of internal substances, increased oxidative damage, and weakened antioxidant capacity. The increase in MDA content and changes in antioxidant enzyme activity were important physiological indicators reflecting seed aging. AN1589 exhibited relatively stable vigor and physiological indicators under natural aging conditions, indicating strong storage tolerance.