The effect of biogenic silver nanoparticles on the germination and phenophase of soybean (Glycine max (L.) Merr.) var. Anjasmoro

Silver nanoparticles (AgNPs) have gained considerable attention in agriculture for their potential to enhance plant growth and productivity. However, their application may also induce phytotoxic effects, depending on factors such as concentration, particle size, plant species, and mode of exposure. In this study, AgNPs were biosynthesized using Diospyros discolor leaf extract and applied to soybean ( Glycine max (L.) Merr. var. Anjasmoro) to evaluate their effects on seed germination and plant development through nanopriming and foliar spray treatments. In the first experiment, soybean seeds were soaked with AgNPs at concentrations of 20, 40, and 60 mg/L. The effects on germination rate, shoot and root length, seed vigor index, and chlorophyll a and b content were evaluated on the seedlings after 7 days. In the second experiment, 20 mg/L AgNPs were applied through seed nanopriming, foliar spray application, and a combination of both methods, then their effects were evaluated up to 78 days after sowing and spraying. Their effects on plant height, leaf number, root length, biomass, chlorophyll content, phenological stages (flowering and fruiting time), and oxidative stress markers (hydrogen peroxide and total phenolic content) were assessed. The results showed that germination rates remained above 95% across all AgNP treatments. Specifically, 20 mg/L AgNPs significantly enhanced shoot elongation and seed vigor, while 60 mg/L reduced root length. Chlorophyll a and b contents increased significantly at 40 and 60 mg/L, respectively. In mature plants, the combined application of nanopriming and foliar spray led to reductions in vegetative growth parameters, accompanied by elevated hydrogen peroxide and phenolic content, indicating oxidative stress. However, foliar and combined treatments effectively accelerated the flowering and fruiting phases. These findings demonstrate the dual role of biogenic AgNPs in stimulating physiological processes while potentially inducing oxidative stress, depending on the dose and application method. • Biogenic silver nanoparticles (AgNPs) synthesized using Diospyros discolor leaf extract at 20 mg/L enhanced shoot length and seed vigour without affecting germination percentage (>95%) on soybean seed nano priming. • Higher concentrations (60 mg/L) reduced root length and triggered oxidative stress indicators based on hydrogen peroxide and phenolic content. • Foliar spray and combined applications promoted early flowering and fruiting in soybean plants. • AgNP effects on soybean were dose- and application-method dependent, emphasizing the need for careful application.