Copper oxide nanoparticles: an effective suppression tool against bacterial leaf blight of rice and its impacts on plants

Background: To address the challenges of food security for the ever-increasing population, the emergence of nanotechnology provides an alternate technology of choice for the production of safer pesticides which serves as a substitute for conventional fertilizer. The antidrug resistance of Xanthomonas oryzae pv. oryzae (Xoo) and build-up of chemicals in the environment has made it necessary to find alternative safe techniques for effective disease management. Hence, in this study, copper oxide nanoparticles (CuONPs) were produced by green synthesis using a Hibiscus rosa-sinensis L. flower extract.

Results: The characterization of CuONPs using ultraviolet-visible spectrophotometry, scanning electron microscopy with an energy-dispersive spectrum profile, Fourier transform infrared spectroscopy, and X-ray diffraction ascertained the presence of CuONPs, which were nanorods of 28.1 nm. CuONPs significantly obstructed the growth and biofilm development of Xoo by 79.65% and 79.17% respectively. The antibacterial mechanism of CuONPs was found to result from wounding the cell membrane, giving rise to an exodus of intracellular content and generation of oxidative reactive oxygen species that invariably inhibited Xoo respiration and growth. A toxicity study under greenhouse conditions revealed that CuONPs significantly increased growth variables and the biomass of rice, and reduced bacterial leaf blight. Application of CuONPs on Arabidopsis improved the chlorophyll fluorescence parameters; the ΦPSII was significantly increased by 152.05% in comparison to the control.

Conclusion: Altogether, these results suggest that CuONPs in low concentration (200.0 μg mL^-1 ) are not toxic to plants and can serve as nano-fertilizers and nano-pesticides. © 2023 Society of Chemical Industry.