Biogenic Synthesis of Ag, ZnO and SiO2 Nanoparticles by Pseudomonas fluorescens for Improved Rice Growth and False Smut Management

Abstract

Rice is among the most crucial food grain crops cultivated globally, including in India. A field study was carried out in Kharif 2023–24 and 2024–25 to assess the impact of various concentrations of nanoparticles synthesized from Pseudomonas fluorescens on rice growth inducer under pathogen stress. The treatments comprised silver (Ag NPs), zinc oxide (ZnO NPs), and silicon dioxide (SiO₂ NPs) at different concentrations, in addition to a standard fungicide (copper oxychloride) and control samples. Of all treatments, Ag NPs at 300 ppm (T₃) consistently showed the best results, significantly improving shoot length (46.58–107.45 cm), fresh shoot weight (65.45–185.20 g/plant), fresh root weight (20.95–25.95 g/plant), dry shoot weight (30.25–71.59 g/plant), and dry root weight (8.65–12.35 g/plant) in comparison to control and inoculated control. ZnO NPs at 300 ppm (T₇) and copper oxychloride (T₁₃) exhibited moderate enhancements, whereas the lowest growth metrics were observed in inoculated (T₁₄) and untreated controls (T₁₅), underscoring the harmful impact of Ustilaginoidea virens infection. The findings show that Ag NPs synthesized from P. fluorescens at 300 ppm not only reduced pathogen effects but also enhanced vegetative growth and biomass development. These results indicate that bio-synthesized nanoparticles may act as efficient, eco-friendly substitutes for chemical fungicides in boosting rice yield during disease stress situations.