Effects of silver-graphene oxide on seed germination and early growth of crop species

Due to its excellent material properties, silver-graphene oxide (Ag-GO) is being studied for diverse applications, such as antimicrobial agents, catalysts and absorbents. Such use of Ag-GO may lead to its release into terrestrial ecosystems, but little is known about the impact of Ag-GO on plants. In the present study, we determined the effects of Ag-GO on seed germination and early growth of crop species by analyzing the germination rate, growth of roots and shoots, hydrogen peroxide (H₂O₂) accumulation, and the uptake of Ag in alfalfa, radish and cucumber treated with 0.2-1.6 mg mL^-1 of Ag-GO. Ag-GO treatment increased the shoot growth of radish at 0.2-1.6 mg mL^-1 but decreased that of cucumber at 0.8 mg mL^-1. In addition, Ag-GO enhanced the root elongation of radish at 0.2 mg mL^-1 but inhibited that of alfalfa at 0.2, 0.8 and 1.6 mg mL^-1. Ag-GO treatment induced H₂O₂ production in alfalfa, radish and cucumber in a concentration-dependent manner. Larger amounts of Ag accumulated in the seedlings as the concentration of Ag-GO increased, and such accumulation suggests that Ag may be transferred to higher trophic levels when plants are exposed to Ag-GO in ecosystems. Our study can, thus, serve as an important basis for setting guidelines for the release of nanomaterials into the environment.