Green Synthesis and Physicochemical Characterization of Zinc Oxide Nanoparticles From Medicinal Plants Leaf Extracts...

The study was aimed to synthesize zinc oxide nanoparticles (ZnONPs) by using a plant-mediated method to alleviate salinity stress. ZnONPs were synthesized using leaf extracts of Portulaca oleracea L. (ZnONPsPO), Morus alba L. (ZnONPsMA), Acacia nilotica L. (ZnONPsAN), and a combined extract of all three plants (ZnONPsCOM). The different concentrations (20, 40, 80 mg L^-1) of the synthesized nanoparticles were applied to wheat (Triticum aestivum) under induced salinity stress and their responses at physiological and biochemical levels were determined. UV-Vis spectra confirmed ZnONPs formation, while FTIR analysis revealed peaks ranging from 421.2 to 3362.1 cm^-1 indicating varying functional groups. XRD analysis revealed the structural identity of the ZnONPs to be a hexagonal wurtzite structure with a size range of 31.67-39.96 nm, and SEM showed some degree of agglomeration. Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbic peroxidase (APX) activities in wheat increased by 230%, 253.8%, 224.3%, and 205%, respectively under salinity stress, compared with the control. ZnONPscom (80 mg L^-1) also significantly elevated SOD, POD, CAT, and APX activities by 83.1%, 491.6%, 517.8%, and 363%, respectively under non-saline conditions. Conversely, malondialdehyde (MDA) content in wheat decreased in both saline and non-saline treatments relative to the control. The synergistic phytochemical composition of the combined plant extracts facilitated efficient nanoparticles synthesis and enhanced their biological efficacy, thereby improving wheat tolerance to salinity stress.