Physiological and Biochemical Responses of Allium mongolicum Regel Seeds to Drying Treatments at Various Temperatures

This study investigated the mechanism and feasibility of drying Allium mongolicum Regel seeds to different moisture content (MC) levels for storage.The seeds were dehydrated to five MC levels ranging from 1.5% to 6.0% and stored at -20, 20, 35, and 50C for up to 420 days.Seed vigor and various physiological and biochemical indicators were subsequently evaluated.Both germination and vigor were significantly influenced by the storage temperature and MC.Seeds dried to a moderate MC level (4.5-6.0%) and stored at 20-35C showed higher germination percentages compared to non-dehydrated or over-dehydrated seeds.Moreover, extreme storage temperatures (-20C or 50C) suppressed germination vigor and antioxidant enzyme activity while increasing the accumulation of harmful metabolites, thereby accelerating seed deterioration.Germination percentage was positively correlated with soluble protein and proline contents, as well as polyphenol oxidase (PPO) and catalase (CAT) activities; it was negatively correlated with glutathione peroxidase (GPX) activity, the malondialdehyde (MDA) content, and the superoxide anion (O 2 -) production rate.These correlations were especially evident in seeds with 4.5-6.0%MC.Therefore, drying seeds to 4.5-6.0%MC and storing them at 20-35C for 180-360 days is recommended for the optimal preservation of A. mongolicum germplasm resources.