Mycogenic synthesis of iron oxide nanoparticles (IONPs) for managing bacterial wilt in tomato (Solanum lycopersicum) caused by Ralstonia solanacearum: disease suppression, growth promotion and soil health improvement

Abstract

Bacterial wilt caused by Ralstonia solanacearum (RS) severely affects tomato cultivation worldwide. This study investigates the efficacy of iron oxide nanoparticles (IONPs) as a novel management strategy for bacterial wilt disease. Biogenic IONPs were synthesized using fungal extracellular metabolites. The characterization of these synthesized biogenic IONPs was performed using multiple analytical techniques, revealing spherical particles with an average size of 71 nm and a crystallite size of 17.2 nm. Application of IONPs (100 ppm) to the tomato plant significantly enhanced its growth parameters in comparison to RS-inoculated controls. A substantial improvement in shoot and root development along with biomass accumulation was observed in the treated tomato plant. In addition to significant phenotypic effects, IONP treatment also reduced bacterial wilt disease incidence to only 13.09%, compared to 98.01% in pathogen-only control plants, demonstrating strong disease suppression capabilities. Furthermore, the treatment also significantly improved physiological parameters such as chlorophyll content and antioxidant enzyme activity. The soil health indicators also indicated marked enhancement following IONP application, including increases in dehydrogenase activity, nutrient availability (organic carbon, NPK), and iron content. These findings demonstrate that IONPs effectively mitigate RS infection through multiple mechanisms, including growth promotion, enhanced physiological responses, and direct disease suppression. The results of our study offer a promising nanomaterial-based approach for sustainable management of bacterial wilt in tomato cultivation. Further research is warranted on elucidating the molecular mechanisms underlying IONP-mediated disease resistance, optimizing field application methods, and evaluating long-term ecological impacts.