Chitosan and its Derivatives for Agriculture Applications: A Review

Chitosan is a semi-synthetic natural polysaccharide derived from the deacetylation of chitin, which is found in the exoskeletons of crustaceans and the cell walls of fungi. The primary attributes that characterize the chitosan biopolymer are its molecular weight and degree of deacetylation. It also has certain unique properties such as biocompatibility, nontoxicity, biodegradability and antimicrobial activity, making it a promising material for various applications, particularly in agriculture. These characteristics can be tuned and optimized depending on the intended application of the chitosan biopolymer. The conjugation of primarily three reactive functional groups in chitosan has led to the development of its many derivatives. The article discusses about the properties, derivatives and applications of chitosan by highlighting its use as a chelating agent, controlled-release fertilizer, plant biostimulant, antimicrobial agent and in post-harvest storage of fruits and vegetables. It is an active molecule that finds many possible applications in agriculture with the aim of reducing or replacing more environmentally damaging chemical substances. Chitosan hydrogels serve as effective soil amendments by facilitating the manufacture of controlled-release fertilizers through both physical coating and chemical encapsulation, which improve the chemical kinetics of the fertilizers and their water absorption capacity. It also increases the nitrogen and calcium nutritional levels in the soil. The cationic characteristics of chitosan render it as an excellent medium for delivering supplementary vital nutrients. The paper highlights the promising feature of chitosan-based materials in sustainable agriculture, which safeguard crops from numerous biotic and abiotic stress factors, hence enhancing crop productivity and reducing reliance on synthetic non-degradable polymers.