Biogenic Zinc Oxide Nanoparticles: Advances in Green Synthesis, Characterization, and Agricultural Applications

Abstract

Biogenic zinc oxide nanoparticles (ZnO-NPs) have attracted increasing attention as sustainable nanomaterials for agricultural applications because zinc is an essential micronutrient and nanoscale delivery may improve nutrient availability. This review examines advances in the green synthesis, characterisation and agricultural use of ZnO-NPs derived from plants, bacteria, fungi and agricultural wastes. It also summarises major analytical approaches used to confirm nanoparticle formation and properties, including UV-visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and particle size analysis. The reviewed evidence indicates that biogenic ZnO-NPs can support seed germination, seedling vigour, plant growth, nutrient uptake, photosynthetic performance and tolerance to abiotic stresses when applied under suitable experimental conditions. Their antimicrobial and photocatalytic properties also suggest potential roles in disease management and environmental remediation. However, responses vary according to biological source, synthesis conditions, particle size, dose, crop species and application method. The review further identifies standardisation, scalability, environmental persistence and risk assessment as key challenges for translating experimental findings into safe agricultural practice. Overall, the article highlights the relevance of biogenic ZnO-NPs to nanofertiliser development and precision agriculture while emphasising the need for standardised synthesis protocols, reproducible characterisation, long-term field evaluation and biosafety assessment before wide agricultural adoption.