Jyoti Kumari, Kamal Khilari, Prasant Mishra, Digvijay Singh, Neelesh Kapoor and Uday Pratap Shahi
Abstract
Rice sheath blight, caused by Rhizoctonia solani, is a major fungal disease responsible for substantial yield losses in rice production. The present study evaluated the antifungal efficacy of commercially available zinc oxide nanoparticles (ZnO NPs) against R. solani under in vitro and pot conditions. The experiment comprised five concentrations of ZnO nanoparticles (50, 100, 150, 200 and 250 ppm), Mancozeb 75% WP @200 ppm as a positive control and an untreated control. Under in vitro conditions, ZnO nanoparticles significantly inhibited the mycelial growth of R. solani in a concentration-dependent manner. Among the nano particle treatments, ZnO nanoparticles at 250 ppm recorded the lowest mycelial growth (18.43, 35.90 and 59.50 mm) and the highest percent inhibition (39.37, 38.21 and 32.84%) at 24, 48 and 72 h, respectively, whereas Mancozeb @ 200 ppm exhibited the highest antifungal activity with 62.73-63.87% inhibition. Under pot conditions, ZnO nanoparticles significantly reduced both disease incidence and disease severity of rice sheath blight. The lowest disease incidence (13.33%) was recorded at both 200 and 250 ppm, while the minimum disease severity (11.40%) was observed at 250 ppm, which was statistically at par with 200 ppm (12.00%). The untreated control recorded the highest disease incidence (83.33%) and disease severity (43.50%). The ZnO nanoparticles exhibited a concentration-dependent suppressive effect against R. solani with 200 and 250 ppm proving to be the most effective concentrations. These findings suggest that ZnO nanoparticles have considerable potential as an eco-friendly component of integrated rice sheath blight management; however, further field validation is required before their large-scale application.