Biogenic iron oxide nanoparticles enhance antioxidant defense and soil nutrient dynamics under lead stress in rice

Lead (Pb) contamination of agricultural soils pose a severe threat to crop productivity and food security. This study investigated the potential of Enterobacter cloacae-mediated biosynthesis of iron oxide nanoparticles (IONPs) to mitigate Pb stress in rice plants.Query The synthesized IONPs were characterized using UV-vis spectroscopy, DLS, SEM, EDX, FTIR, and XRD, revealing crystalline structures with sizes ranging from 50 to 100 nm. In silico toxicity predictions demonstrated the toxicity of lead nitrate at 853 mg/kg (LD50). Greenhouse experiments showed that 100 ppm IONPs significantly improved plant growth parameters under Pb stress compared to untreated Pb-stressed plants, including enhancement in shoot length (118.6%), root length (115.6%), and total chlorophyll content (131.0%). The IONPs treatment further enhanced the antioxidant defense by increasing SOD activity (35.0%) and reducing proline levels (43.2%) relative to pb stressed plants. The soil health parameters showed marked improvement, with an increase in dehydrogenase activity (112.45%) and organic carbon content (406.26%). Furthermore, the application of IONPs significantly enhanced both macro-and micronutrient availability, with notable enhancements in nitrogen (70.21%), phosphorus (90.62%), potassium (289.17%), iron (368.15%), manganese (341.07%), copper (292.39%), and zinc (400.07%) contents. The present study suggests that E. cloacae-mediated synthesis of IONPs mitigates Pb stress and enhances the growth of rice plants under Pb stress.