Comparative impact of seed priming with zinc oxide nanoparticles and zinc sulphate on biocompatibility, zinc uptake, germination, seedling vitality, and antioxidant modulation in groundnut

Nanotechnology has transformative potential in agriculture by optimizing plant nutrient use. In this study, zinc oxide nanoparticles (ZnO-NPs) were synthesized using ZnSO4.7H2O as a precursor. The synthesized ZnO-NPs exhibited a particle size of 63.60 nm, stability characterized by a zeta potential, and a semispherical agglomerated shape under scanning electron microscopy (SEM). The purity of the nanomaterials was confirmed through energy-dispersive X-ray spectroscopy (EDAX). SEM-EDAX analysis of groundnut seeds primed with ZnO-NPs showed improved zinc adsorption and distribution compared to bulk ZnSO4, with no physical damage, indicating good biocompatibility. The small size and high surface area of the nanoparticles enhanced zinc uptake, as confirmed by higher zinc levels in ZnO-NP-treated seeds. ZnO-NP priming resulted in greater physio-biochemical responses, enhancing germination and the seedling vigor index at 10 days post-sowing. Biochemical analysis revealed elevated levels of chlorophyll, soluble protein, total soluble sugar, and free amino acid in the leaves of ZnO-NP-treated plants. Furthermore, ZnO-NP-treated groundnut seedlings exhibited significantly greater DPPH radical scavenging activity than control plants, indicating enhanced antioxidant potential. This study further explored the elevations in the levels of antioxidant enzymes (superoxide dismutase-SOD, catalase-CAT, ascorbate peroxidase-APX, guaiacol peroxidase-GPX and polyphenol oxidase-PPO) primed with ZnO-NPs to augment the hydration of seeds, increase antioxidant enzyme activity to neutralize reactive oxygen species, preserve cellular integrity, and promote overall plant health. These findings underscore the potential of ZnO-NPs as a sustainable nanotechnological approach for enhancing groundnut seed germination, seedling vigor, and stress tolerance, ultimately promoting crop growth and productivity.