Tomato root rot, caused by Rhizoctonia solani , is a major disease that severely affects tomato yield. Therefore, sustainable and effective management to control this disease is strongly needed. This study reports the green synthesis of cuprous oxide nanoparticles (Cu 2 O NPs) deposited on silica-rich rice husk ash (RHA), using a mango seed kernel suspension as a bio-based reductant. The formation of Cu 2 O crystals was confirmed by X-ray diffraction. The Cu 2 O NPs exhibited average sizes of 27.9 and 17.5 nm, as determined by scanning and transmission electron microscopy, respectively, and were uniformly distributed on the porous RHA. The Cu content in Cu 2 O NPs/RHA, as analyzed by energy dispersive X-ray spectroscopy, was ~1%. The application of Cu 2 O NPs on tomato plants demonstrated their role as an elicitor that activates the plant’s induced defense system, increasing the activities of defense-related enzymes, including chitinase and the peroxidase (POD), thereby contributing to improved resistance of tomato plants against Rhizoctonia solani , the causal agent of root rot. Specifically, in vivo antifungal assays, the soil application of Cu 2 O NPs/RHA at 45–75 mg Cu/kg soil for tomato plants controlled the disease with 84.87%–90.76% efficacy at 14 days post inoculation (dpi), while increasing chitinase and POD activities up to approximately 1.9-fold at 4 and 2 dpi, respectively, compared to the positive control. The utilization of agricultural by-products to synthesize Cu 2 O NPs/RHA offers an effective approach for managing soil-borne plant diseases, aligning with the principles of the circular economy and sustainable agricultural development. • Green synthesis of Cu 2 O NPs on RHA using MSK suspension as a bio-reductant. • Polycrystalline Cu 2 O NPs (27.9 nm) distributed on porous RHA. • Cu 2 O NPs/RHA effectively controlled tomato root rot caused by R. solani . • Cu 2 O NPs/RHA enhanced chitinase and POD enzyme activities in tomato plants. • Promising eco-friendly alternative for controlling soil-borne phytopathogens.
Tran et al. (Sun,) studied this question.