Synthesis and characterization of Curcuma Caesia plant root extract-mediated ZnO nanoparticles: efficacy as soil conditioner and plant growth promoter

Green synthesis of metal oxide nanoparticles is emerging as potential application for sustainable farming. Zinc oxide nanoparticles (ZnO NPs) were successfully biosynthesized by Curcuma caessia rhizome extract as a reducing and stabilizing agents in the present investigation and they were applied to test their role as a soil conditioner and growth promoter for Abelmoschus esculentus. Characterization of the synthesized ZnO NPs was carried out by UV-Vis spectroscopy, FTIR, XRD, SEM, AFM, dynamic light scattering and ζ-potential analysis. The UV-Vis absorption spectrum exhibited an absorbance at 340 nm, indicating the formation of ZnO and the crystalline nature of this product was confirmed by XRD measurements with average size along (002) plane equals 43 nm. The hydrodynamic size of the nanoparticles was shown to be 217 nm with a ζ-potential of -22.1 mV, reflecting an acceptable colloidal stability. Field and germination studies revealed that seed germination, vegetative growth, flowering, and yield parameters were significantly improved in ZnO NP-treated plants compared to control ones in a dose-dependent manner. Additionally, ^1H-NMR metabolomics of okra pods indicated changes in primary and secondary metabolite profiles, indicating possible modulation of metabolic pathways by ZnO NP. The findings of the study revealed that Curcuma caesia - synthesized ZnO NPs acted as an eco-friendly nanomaterial to modulate plant growth and metabolic performance suggesting its possible use toward sustainable farming.