Starch-Based Film Coatings as a Strategy to Preserve Seed Viability during Storage.

Seed viability progressively declines during storage, and many existing coating strategies either impair germination or rely on synthetic, nonbiodegradable materials. In this work, we present a sustainable, starch-based film coating as a proof-of-concept strategy to preserve seed viability under monitored ambient storage conditions. Corn starch films plasticized with glycerol and urea were prepared and screened, leading to the selection of two formulations (A3 and A8) with distinct physicochemical properties. Tomato seeds were used as a sensitive model system and evaluated after 60, 150, and 240 days of storage. Both coatings effectively mitigated the pronounced decline in germination and vigor observed for uncoated seeds. The more compact and thermally stable A3 formulation provided superior long-term protection, while the more hydrophilic A8 film exhibited faster dissolution, promoting early seedling development. Physicochemical characterization indicates that the coatings act as semipermeable barriers during storage, reducing water and oxygen diffusion, followed by hydration-driven swelling and partial dissolution during germination. Although demonstrated at laboratory scale, these results highlight the feasibility of tuning starch-based film properties to balance storage protection and functional dissolution. This work establishes a biodegradable, low-cost, and environmentally friendly platform for the development of next-generation seed coating systems with potential applicability across diverse crop species.