Impact of Biologically and Chemically Synthesized Zinc Oxide Nanoparticles on Seed Germination and Seedlings' Growth

Zinc oxide nanoparticles have gained attention in the last decades due to their versatile applications; in agriculture, they have been used for their multiple benefits. In this study, the effects of zinc oxide nanoparticles, obtained via chemical and biological synthesis and of 70-80 nm in size, on the germination and seedling growth of Capsicum annuum and Solanum lycopersicum seed were determined. The physiological parameters, photosynthetic pigments, the content of total phenols, total flavonoids, as well as the antioxidant capacity of 2,2-diphenyl-1-picrylhydrazyl (DPPH), and the enzymatic activity of catalase, peroxidase, and polyphenol oxidase were evaluated. The results indicated that treatment with zinc oxide nanoparticles obtained via green synthesis improved seed germination rate, while chemically synthesized nanoparticles at higher concentrations decreased germination percentage. In general, the parameters of enzymatic and nonenzymatic antioxidants in treated plants showed significant differences with respect to the control. However, the treatments with the bionanoparticles resulted in more beneficial parameters. Zinc oxide nanoparticles obtained via green synthesis are more effective in generating bioactive compounds and activating the enzyme defense system due to being more biocompatible.