Potencial multifuncional da quitosana em fertilizantes de liberação controlada: sinergia entre nutrição nitrogenada, bioestimulação e proteção antimicrobiana

Abstract

The increasing pressure for global food security intensifies the use of conventional nitrogen fertilizers, such as urea, whose application is marked by low agronomic efficiency and severe environmental liabilities, such as nitrate leaching and greenhouse gas emissions. Although controlled-release fertilizers (CRFs) seek to mitigate these losses, the use of synthetic polymers in their coatings generates the accumulation of microplastics in ecosystems, a phenomenon known as white pollution. This work investigates the technological potential of chitosan as a multifunctional and biodegradable biopolymeric matrix, analyzing, through a systematic review and compilation of case studies, its ability to integrate nutrition, biostimulation, and phytosanitary protection. The text details how the deacetylation process and the polycationic nature of the biopolymer regulate nitrogen release kinetics via multi-stage diffusion and swelling, synchronizing the nutritional supply with the physiological demand of crops. The compiled results demonstrate biomass gains exceeding 264,26% in stem length and 366,72% in stem diameter in Chinese cabbage, evidencing that the use of these matrices allows for a 25% reduction in the mineral fertilizer load without loss of productivity. The findings further indicate an increment of 469.21% in total amino acid contents and 103.51% in Vitamin C, proving the optimization of plant metabolic pathways. In the phytosanitary scope, chitosan achieved 100% inhibition against the bacterium Bacillus cereus and reduced mortality from Fusarium oxysporum by more than 90%, acting both through direct action and as an elicitor of systemic resistance. In the mitigation of abiotic stresses, the treatment reduced sodium toxicity by up to 51.52% in tomato plants under salinity, preserving the photosynthetic apparatus. In the soil, bacterial diversity (Shannon index) increased by 23.55%, with increases in the activities of the enzymes urease (46.54%) and acid phosphatase (14.94%), consolidating a more resilient rhizospheric environment. It is concluded that chitosan transcends the function of a physical barrier, consolidating itself as an intelligent platform that aligns high productivity with the principles of green chemistry.