Nano-priming with Nickel Oxide Nanoparticles Enhances Seed Germinationand Early Seedling Physiology in Black Gram (Vigna mungo L.)

Introduction: Nano-priming with metal oxide nanomaterials is an emerging strategy for improving seed germination and early seedling vigour. This study evaluates the effect of nickel oxide (NiO) nanoparticle priming on germination and early physiology traits of Black gram (Vigna mungo L., VBN 8). Methods: NiO nanoparticles were synthesised using a solution combustion method with ascorbic acid as fuel and nickel nitrate as precursor, followed by calcination at 500 °C for 1 hour. Characterisation was performed using XRD, UV–Vis spectroscopy, FTIR, and FESEM-EDAX. Seeds were primed with NiO Nanoparticle suspensions at 10, 15, 25, 50, and 100 ppm; distilled water served as the control. Germination was assessed for 7 days, and parameters including germination percentage, Mean Emergence Time (MET), root and shoot length, Seedling Vigour Index (SVI), moisture content, biomass, and water uptake were recorded. Results: All NiO treatments enhanced germination and early seedling growth compared with the control. The 50-ppm treatment resulted in the highest water uptake (27.6%) and moisture content (68.3 %). The 100-ppm treatment produced the highest SVI (1945) and biomass, demonstrating superior seedling vigour. NiO nano-priming did not induce toxicity even at 100 ppm. Discussion: Enhanced physiological responses appear to result from improved water absorption, metabolic activation, and surface-hydroxyl-mediated hydration associated with NiO nanoparticle priming. Conclusion: NiO nano-priming at 50-100 ppm significantly improved germination and early seedling performance in Vigna mungo, offering a safe and cost-effective approach for sustainable seed enhancement.