Synergistic impact of Trichoderma-mediated, green-synthesised zinc oxide nanoparticles and Rhizobium on mungbean crop to develop an advanced nanobiofertilizer for long-term sustainability

Metal-based nanoparticles are known for their ecotoxicological and phytotoxic effects, impairing plant growth and development. However, several nanoparticles, including those of zinc, are essential for proper plant growth and could be beneficial at low concentrations. Compared to other metal-NPs, zinc oxide (ZnO) nanoparticles are less harmful to plants and advantageous to soil microflora. Bioinoculants are also very helpful for plant growth and development. Therefore, biofertilizer combined with ZnO NPs can be used to create nano-biofertilizer. In this study, was utilized for the green synthesis of ZnO nanoparticles. The filtrate obtained from was incorporated with zinc sulfate salt (1mM) to synthesize ZnO NPs. The formation of a white precipitate confirmed that zinc oxide nanoparticles had been synthesised. Several analytical methods were employed to characterize the ZnO nanoparticles, such as UV spectroscopy (352 nm), particle size analysis (100 nm), and Fourier Transform Infrared Spectroscopy (ZnO stretching between 600 − 450 cm-1). Energy dispersive X-ray analysis indicated the presence of, Zn (76.3%) and O (55%), confirming ZnO NPs presence. Afterwards, the interaction of ZnO nanoparticles with MB17a was examined. The interaction showed that the growth of increased when ZnO NPs were applied up to a 10 mM concentration, along with increases in all plant growth-promoting rhizobacteria (PGPR) activities. Integrated application of ZnO nanoparticles and rhizobium enhanced the grain yield of the mung bean crop. Thus, co-application of strain and ZnO nanoparticles could be a breakthrough for the stability of bioinoculants and sustainable agricultural production.