Green Synthesis of Selenium Nanoparticles Using <i>Equisetum diffusum</i>: Characterization, Antibacterial Potential, Effects on Plant Growth

This study explores the green synthesis of selenium nanoparticles (SeNPs) using Equisetum diffusum D (ED) aqueous extract and evaluates their nanofertilizer and antibacterial potential. The synthesized SeNPs were characterized by UV-Vis spectroscopy, FTIR, XRD, SEM, EDX, DLS, TGA, and DSC, confirming their stability, spherical morphology, and high purity. The UV-Vis spectrum established a peak at 371 nm, and SEM analysis revealed an average particle size of 18.66 nm. The zeta potential measurement of -52.34 mV indicated excellent dispersion stability. The impact of SeNPs on plant growth was assessed through a five-week experiment with tomato plants. Plants treated with low and medium concentrations of SeNPs (Group 3 and 4) showed significant improvements in growth parameters, with 120.75 % and 120.03 %, respectively, compared to 101.37 % in the negative control. Leaf length and width also demonstrated notable enhancements. The antibacterial activity of SeNPs was tested against phytopathogens, Xanthomonas spp Citrus limetta and Solanum lycopersicum, along with human pathogens, Listeria monocytogenes, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. The SeNPs exhibited substantial inhibitory effects, with zones of inhibition measuring 26, 21, 31, 24, 36, and 24 mm, respectively. The MIC values ranged from 20 to $30~\mu $ L, and MBC values ranged from 30 to $40~\mu $ L. These results show the potential of biogenic SeNPs as effective nanofertilizer that enhance crop productivity and as antibacterial agents, offering a sustainable and environmental friendly alternative for agricultural and microbial management applications.