GREEN SYNTHESIS OF ZINC OXIDE NANOPARTICLES (ZNO-NPS) USING ACACIA MODESTA EXTRACT AND THEIR APPLICATIONS IN SUSTAINABLE AGRICULTURE

Abstract

Green synthesis of zinc oxide nanoparticles (ZnO-NPs) using Acacia modesta extracts represents an environmentally compatible approach for developing nano-enabled materials with potential applications in sustainable agriculture. In this study, an aqueous leaf extract of wheat (Triticum aestivum L.) was used as a phytochemical-rich medium to synthesize ZnO-NPs. We characterized the synthesized nanoparticles using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and UV–visible spectroscopy. SEM analysis indicated predominantly near-spherical to irregularly spherical nanoparticles with some degree of aggregation, while EDX confirmed Zn and O as the principal elements. XRD analysis revealed the characteristic hexagonal wurtzite structure of ZnO, with an estimated crystallite size of approximately 24.6 nm. FTIR spectra indicated the presence of surface-associated plant-derived functional groups together with characteristic Zn–O vibrations, whereas TGA demonstrated the progressive loss of moisture and residual organic constituents. UV–visible analysis showed a characteristic absorption maximum near 372 nm, corresponding to an estimated optical band gap of approximately 3.33–3.34 eV. The agricultural application component evaluated foliar ZnO-NP treatments at 0, 25, 50, and 100 mg L⁻¹ in wheat subjected to Cd–Cu stress. Increasing ZnO-NP concentration was associated with improved plant growth and physiological performance, reduced MDA and H₂O₂ accumulation, enhanced POD activity, and lower Cd and Cu concentrations in plant tissues. The 100 mg L⁻¹ treatment showed the strongest response within the tested concentration range. Overall, the findings indicate that Acacia modesta -extract-mediated ZnO-NPs have potential as a nano-enabled Zn source and as a component of strategies for improving crop tolerance to heavy-metal stress. However, optimization of nanoparticle dose, evaluation of grain metal accumulation and environmental fate, assessment of soil and microbial effects, and field-scale validation are required before practical agricultural application.