Evaluating the Impact of Seed Nano-Priming with Green-Synthesized Copper Oxide Nanoparticles Using Mimosa pigra Leaf Extract on the Germination and Seedling Growth of Tomato (Solanum lycopersicum)

Abstract

This study explores the impact of seed nano-priming with green-synthesized copper oxide nanoparticles (CuO NPs) using Mimosa pigra leaf extract on the germination and seedling growth of tomato (Solanum lycopersicum). CuO NPs were synthesized through a plant-mediated green synthesis approach, where phytochemicals in M. pigra extract reduced Cu²⁺ ions and stabilized the nanoparticles. The resulting nanoparticles were characterized using UV-vis spectroscopy and SEM, revealing a surface plasmon resonance (SPR) peak at 224 nm and a nanoscale morphology with an average size of 108 nm. XRD analysis confirmed a crystalline monoclinic structure, with an average crystallite size of 30.68 nm. FTIR spectra showed characteristic Cu-O bond vibrations and plant-related functional groups, confirming successful nanoparticle synthesis. Seed germination experiments evaluated the effects of CuO NPs across a concentration gradient (0–1000 ppm). Results demonstrated a biphasic effect on germination and seedling growth. Low concentrations (5–100 ppm) enhanced germination percentages and growth metrics, while higher concentrations (≥500 ppm) inhibited these parameters. The 50 ppm treatment exhibited the highest germination rate, whereas 1000 ppm significantly suppressed seed germination and seedling growth. Statistical analysis indicated significant differences in root and shoot lengths across treatments, with oxidative stress and genotoxicity attributed to higher CuO NP concentrations as key inhibitory factors.These findings highlight the dual role of CuO NPs, emphasizing the potential of green-synthesized nanoparticles as bio-enhancers at optimal concentrations, while cautioning against their phytotoxic effects at elevated levels. This research underscores the need for further studies to optimize nanoparticle applications in agriculture and mitigate environmental risks.