NANO-ENGINEERED SEED COATINGS: ELECTROSPUN NANOFIBRES FOR SMART DELIVERY, VIGOROUS GERMINATION, AND STRESS TOLERANCE

Abstract

Seed quality determines crop establishment, and enhancement technologies increasingly aim to improve germination, vigour, and stress tolerance under variable environments. Conventional seed coatings, including film coating, pelleting, and hydrogel-based systems, enable dose-controlled delivery of nutrients, biostimulants, and inoculants, but face persistent limitations such as non-uniform component distribution, phytotoxicity from concentrated salts, and restricted gas exchange. Nanotechnology-based approaches, including nanoparticle and nanogel priming, improve nutrient uptake and stress tolerance but show inconsistent, sometimes phytotoxic effects and raise concerns over bioavailability and regulatory standardization. Electrospun nanofibres offer a distinct alternative, comprising continuous, nanoscale-diameter fibres with high surface-area-to-volume ratio, tunable porosity, and mechanical robustness. This review synthesizes evidence on nanofibre fabrication, polymer selection, electrospinning parameters, encapsulation and release of nutrients, phytohormones, and microbial inoculants, and agronomic and rhizosphere effects across several crops. Natural polymers such as chitosan and alginate provide biocompatibility and functional groups for encapsulation but lack water stability, whereas synthetic polymers such as PVA, PVP, and PCL provide mechanical strength and reliable spinnability; blended composite systems increasingly combine both classes. Polymer concentration, molecular weight, viscosity, conductivity, and surface tension jointly govern fibre morphology, which dictates porosity, adhesion, and release kinetics. Direct evidence shows nanofibre coatings improving germination, seedling vigour, nutrient-use efficiency, and yield relative to uncoated or conventionally coated seeds, and enabling microbial inoculant delivery with extended viability and enhanced rhizosphere colonization. However, mechanistic biochemical evidence remains sparse, seed-surface interaction is poorly characterized, and scale-up, storage stability, and cost remain unresolved. Nanofibre-based seed coating therefore represents a promising, functionally superior niche technology for localized input delivery at the earliest stage of crop establishment, rather than a validated replacement for existing seed treatments.