Silk Fibroin Seed Coatings: Towards Sustainable Seed Protection and Enhanced Growth

Seed coating technology is vital in agriculture, enhancing seed protection and growth. However, conventional coatings often include chemical fungicides that pose environmental risks, highlighting the need for sustainable alternatives. This study explores silk fibroin (SF), a natural biopolymer with excellent film-forming properties, as a potential seed coating agent, addressing its antimicrobial limitations by combining it with the commercial agent CRUISER^® and the antimicrobial peptide Nisin. Experimental methods included solution stability analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and growth assessments of wheat seeds. Findings reveal that silk fibroin-CRUISER^® (SC) composites form stable β-sheet structures, enhancing the coating's mechanical strength. SF-based coatings improved seedling emergence rates (up to 1.65-fold), plant height (up to 1.05-fold), and root growth (up to 1.2-fold), especially under cold stress. The addition of Nisin further significantly boosted the antibacterial properties, providing sustained pathogen inhibition (p < 0.01). Identifying the optimal concentration of SF was essential for achieving a balance between protection and breathability, a key factor for industrial application. This research provides valuable insights into the development of eco-friendly seed coatings, presenting a viable and sustainable alternative to traditional chemical-based options in agricultural practices.