Biostimulatory Effects of Chitosan from Freshwater Prawn (Macrobrachium rosenbergii, De Man 1879) on Seed Germination and Seedling Growth

Abstract

The present study investigates the extraction and characterization of chitosan from Macrobrachium rosenbergii shell waste and evaluates its potential as a biostimulant in seed germination. Chitin and chitosan were extracted using a sequential chemical process involving deproteinization, demineralization, decolorization, and deacetylation, employing sodium hydroxide, hydrochloric acid, and sodium hypochlorite. From 100 g of shell waste, the yields of chitin and chitosan were 29.0 ± 2.71% and 24.37 ± 3.38%, respectively. The extracted chitosan exhibited an off-white appearance with a particle size of 809.33 ± 49.66 µm, solubility in 1% acetic acid of 94.33 ± 2.19%, and a water-binding capacity of 775.17 ± 76.50%. The ash content (0.20 ± 0.10%) and moisture content (9.22 ± 3.89%) confirmed high purity and effective demineralization. Structural analysis via Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) validated the molecular and morphological integrity of the extracted chitosan. Seed priming with chitosan (1–2 mg mL⁻¹) significantly enhanced Oryza sativa germination by reducing the mean germination time and promoting shoot and root elongation. Treated seeds exhibited superior seedling vigor, demonstrating chitosan’s efficacy as a natural agricultural biostimulant. These findings suggest that M. rosenbergii-derived chitosan holds promise for sustainable crop enhancement strategies.