Nanoparticles of Fe₃O₄ Loaded with Azoxystrobin and Pectin to Enhance Resistance of Rice to Sheath Blight

The enhancement of pesticide utilization efficiency for improved biological activity, while promoting crop growth to enhance disease resistance, holds significant importance in agricultural production. In this study, we developed an enzyme-responsive azoxystrobin (AZOX) delivery system using iron-based mesoporous materials as porous carriers and pectin (Pec) as an encapsulation agent to manage rice sheath blight. The resultant AZOX-AFS-Pec nanoparticles (NPs) exhibit high loading capacity and could intelligently release AZOX in acidic conditions in the presence of pectinase. Notably, AZOX-AFS-Pec NPs demonstrated improved wetting and adhesion properties on rice blades, thereby augmenting AZOX utilization. Furthermore, AZOX-AFS-Pec NPs enhanced fungicidal activity against rice sheath blight, with pot experiments revealing comparable control efficacy on rice sheath blight to AZOX suspension concentration (SC). Specifically, AZOX-AFS-Pec NPs exhibited superior prevention and prolonged protection against rice sheath blight compared to AZOX SC. Additionally, continuous release of Fe 2+ and Fe 3+ by AZOX-AFS-Pec NPs increased chlorophyll content and promoted rice growth. Moreover, these NPs increased salicylic acid (SA) levels in rice plants, fortifying disease resistance. Importantly, AZOX-AFS-Pec NPs demonstrated over a 2-fold reduction in acute toxicity to earthworms compared to AZOX SC. Therefore, stimuli-responsive AZOX-AFS-Pec NPs show great promise for enhancing pesticide effectiveness against pathogens, improving crop traits, and fortifying disease resistance.