Chitosan–Cnidium monnieri fruit extract coating improves germination, antioxidant defense, and antifungal protection of maize seeds during summer storage

This study evaluated the efficacy of a chitosan-Cnidium monnieri fruit extract composite coating (0.5–2.0 % w/v extract concentrations) for preserving maize seed quality during 45-day summer storage. The coating was prepared using chitosan (≥85 % deacetylation) dissolved in 1 % acetic acid (1.0 % w/v solution) supplemented with 0.5–2.0 % (w/v) lyophilized C. monnieri extract, with seeds immersed for 5 min before air-drying. Compared to untreated controls, the 1.0 % extract-optimized coating significantly improved both initial germination rate (95.39 % vs 82.29 % radicle emergence) and normal seedling rate (89.79 % vs 74.19 % developed seedlings with intact coleoptile and primary root), while reducing insect damage (9.38 % vs 21.63 %). The treatment enhanced activities of key antioxidant enzymes - superoxide dismutase (SOD: 45.75 U·mg⁻¹), catalase (CAT: 24.68 U·mg⁻¹), and peroxidase (POD: 27.11 U·mg⁻¹) - while reducing malondialdehyde (MDA) levels by 45 %, indicating reduced oxidative stress. The coating showed potent antifungal activity with minimum inhibitory concentrations (MIC) of 0.5 mg/mL against Trichoderma spp. and 0.75 mg/mL against Aspergillus spp., corresponding to reduced incidence rates (17.12 % and 21.21 %, respectively) and 9.40 mm inhibition zones. These results demonstrate that the chitosan-C. monnieri coating provides effective protection against storage-related deterioration through synergistic antioxidant and antimicrobial mechanisms.