Engineering Seeds for a Food-Secure World: Optimizing Alginate-Based Seed Coatings to Improve Germination in Saline Soil

Overview

Soil salinity is a major environmental stress that limits plant growth by reducing water availability, causing osmotic stress, and interfering with early metabolic processes required for seed germination. As drought conditions and the salinity of soils increase worldwide, developing strategies to improve crop growth under stress is necessary for food security. This project tested whether engineered alginate-based hydrogel seed coatings could improve germination performance and early seedling growth of mung beans (Vigna radiata) under saline and non-saline conditions, and whether coating composition and short-term storage influence effectiveness. The research question asked how plain alginate (C1), foamed alginate (C2), and bentonite-alginate (C3) coatings compare with uncoated seeds (C0) in their effects on germination speed, final germination percentage, and seedling vigor index (SVI). I hypothesized that coated seeds would outperform uncoated seeds under salt stress, with C3 showing the strongest overall performance because of its improved water retention and microenvironment stabilization abilities. Seeds were coated with calcium-crosslinked hydrogel formulations and tested with either distilled water (0 mM NaCl) or salty water (75 mM NaCl). Germination, as determined by a radicle length of at least 2 mm, was recorded twice daily until no new germination was observed (about 10 days) to calculate time to 50% germination (T₅₀), cumulative germination percentage, and SVI. Root and shoot lengths were measured at the end to quantify early growth. Coating durability and storage stability after seven days was also tested. Soil mass, moisture content, planting depth, location, and light exposure were standardized across all treatments. Salt stress significantly decreased T₅₀, final germination percentage, and SVI (p < 0.05). All coatings significantly improved germination compared to C0 under saline conditions, including after storage (p < 0.05). C2 outperformed C1 under salt stress, likely because of increased porosity enhancing water diffusion, but showed slightly reduced performance under non-saline conditions. C3 consistently produced the highest germination percentages, fastest T₅₀, and greatest SVI across fresh and stored trials. Overall, results support the hypothesis and show that optimized bentonite-alginate hydrogel coatings can help with salt-induced germination stress and improve early seedling vigor, with applications in sustainable agriculture for salt-affected soils.

Competition history

• CSEF 2026 Plant Biology (Junior Division) · Entry J-18-02

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