Enhancing the role of biopolymer-based composites as cost-effective biostimulants and bioactive coating systems for sustainable agriculture: preparation, characterization, and optimization

Abstract

Herein, biopolymer-based composite coating systems using cellulose gum (CMC) and gum acacia (GA) as polymeric biostimulants were developed. Micronized beer spent grain waste (BW) and montmorillonite (MT) were used as filler materials. Salicylic acid (a model bioactive phytohormone) was added to various gel formulations, which were applied as coatings on Lupinus angustifolius (Boregine lupin) seeds. The composite coatings were characterized by Fourier transform infrared spectroscopy (FTIR), surface morphology analysis (SEM), and compression tests for mechanical stability. A factorial optimization design was applied to evaluated the effects of MT: BW ratio, salicylic acid concentration, and coating layers on germination rate (GR%), germination potential (GP%), germination index (GI), and vigor index (VI). Results demonstrated that using 0.5 g/kg salicylic acid yielded maximum GR%, GP%, GI, and VI values of over 75%, 30%, 3%, and 5%, respectively. The biopolymeric composite coatings exhibited significantly improved germination and early growth in the coated seeds as compared to the uncoated seeds. In conclusion, the developed composite coatings show promise for enhancing early plant growth, while promoting facile and cost-effective sustainable agricultural practices through the use of biopolymers.