Direct Application of Green Synthesized Silver Nanoparticles Enhances Growth and Physiological Performance in Wheat

Green synthesized silver nanoparticles (AgNPs) offer potential applications as eco-friendly biostimulants in agriculture. This study evaluated the effects of direct applications of neem (Azadirachta indica) flower extract-mediated AgNPs on early growth and physiological responses of wheat (Triticum aestivum L.) seedlings. The AgNPs were characterized using UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), and Field-emission scanning electron microscopy (FESEM), confirming their successful formation, surface chemistry, morphology, and particle size. The nanoparticles exhibited diameters ranging from 37.50 to 63.10 nm, with an average size of 49.32 ± 7.3 nm. Three-day-old wheat seedlings were treated with 20, 40, and 80 mg L−1 AgNPs to assess their growth parameters, photosynthetic pigments, soluble protein, secondary metabolites, oxidative stress markers, antioxidant enzyme activities, and stomatal and epidermal cell characteristics. ICP-MS analysis showed a dose-dependent increase in total root-associated Ag, reaching a maximum of 1460.34 mg kg−1 dry weight at 80 mg L−1. AgNP treatment improved growth, pigment accumulation, stomatal traits and antioxidant response, indicating enhanced physiological activity during early seedling development. These findings provide insights into the relationship between Ag accumulation and the physiological, biochemical and structural responses of wheat seedlings, contributing to a better understanding of plant–AgNP interactions. Furthermore, neem flower-mediated AgNPs show potential as an environmentally compatible nanomaterial for improving early wheat seedling establishment and performance, highlighting their prospective application in sustainable agricultural practices.