Antifungal efficacy of Aloe vera-mediated silver nanoparticles in different concentrations and application methods against Fusarium oxysporum in Cucurbita pepo

ABSTRACT Fusarium wilt seriously threatens Cucurbita pepo L. production worldwide. Plant-based nanotechnology antifungals offer a promising and eco-friendly control strategy. This study investigated the antifungal efficacy of Aloe vera (L.) Burm. f.-mediated Ag nanoparticles (Ag-NPs) against Fusarium oxysporum. Biogenic Ag-NPs were synthesized using A. vera leaf extract with an average crystallite size of 15.22 nm and a surface plasmon resonance peak at 413 nm. In vitro, Ag-NPs at 2.5, 5, 10, and 15 mg L⁻¹ generated dose-dependent inhibition zones (0.5-2.0 cm). The concentration 15 mg L-1 produced the largest inhibition zone (2.0 cm) and the greatest reduction in colony diameter. In vivo greenhouse trial, Ag-NPs were tested at 2.5, 5, 10, and 15 mg L⁻¹ by foliar spray or soil drench (pre-planting) on Fusarium-inoculated plants vs. uninoculated and inoculated controls. Fusarium infection severely reduced plant growth (47%-155%), photosynthetic pigments (47%-58%), and mineral elements (30%-80%) compared to the uninoculated control (T1). However, Ag-NPs applications displayed strong antifungal agents and plant biostimulants. In particular, 15 mg L⁻¹ foliar Ag-NPs (T5) displayed the significant improvement in leaf number (43.1%), shoot length (42.9%), biomass (68.0%-154.5%), chlorophyll a and b (112.5% and 100%), phenols (40.0%), sugars (14%), and minerals Ca/Mg/Na/K (42.9%, 150.0%, 150.0%, and 42.9%) compared to the inoculated control. Moreover, increasing Ag-NPs concentration mitigated oxidative stress in infected plants by enhancing activities of catalase, superoxide dismutase, polyphenol oxidase, and peroxidase. Multivariate analyses (principal component analysis and heatmap) showed that high-dose Ag-NPs were associated with improved growth and mineral traits, antioxidant and osmoprotective metabolites.