Exserohilum rostratum-Mediated Synthesis of Silver Nanoparticles: A Case Study on Their Bioherbicidal Activity Against Leptochloa chinensis (L.) Nees

The interdisciplinary progress in nanotechnology has yielded environmentally friendly and cost-effective strategies to enhance bioherbicidal efficacy. This study presents the biosynthesis of silver nanoparticles (M-AgNPs) using the fungus Exserohilum rostratum, specifically targeting the Leptochloa chinensis weed in paddy fields. The M-AgNPs were characterized with an aqueous solution size of 107.9 nm and a zeta potential of -24.0 +/- 0.20 mV, and their properties were analyzed by UV-Vis spectrophotometry, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The application of M-AgNP suspension at different concentrations of 70 mu g center dot mL-1, 80 mu g center dot mL-1, and 100 mu g center dot mL-1 to L. chinensis at the 3-4 leaf stage resulted in significant herbicidal effects. These nanoparticles induced oxidative stress and significantly reduced the activities of peroxidase, catalase, and superoxide dismutase in the weed seedlings. Meanwhile, M-AgNP treatments significantly increased the activity of cell wall-degrading enzymes, including polygalacturonase and cellulase, in L. chinensis leaves and caused organelle damage in plant leaf cells. Safety assessments showed no significant impact on rice growth after treatment with M-AgNP3 (100 mu g center dot mL-1) suspension. Our results suggest that M-AgNPs represent a sustainable and eco-friendly approach to weed control that is compatible with rice cultivation, thus supporting the adoption of green agricultural practices.