Effects of Graphene Oxide and/or Cd2+ on Seed Germination, Seedling Growth, and Uptake to Cd2+ in Solution Culture

With increasing graphene oxide (GO) applications in industry and biomedicine, effects of GO on microorganisms, animals, and human health have been frequently studied; however, direct and indirect effects of GO on plants are seldom concerned. In this study, effects of GO and/or Cd2+ on seed germination, seedling growth, and uptake to Cd2+ were investigated in solution culture. The results showed that GO could quickly adsorb Cd2+ in solution, and the higher the GO concentration was, the lower the residual Cd2+ concentration was in solution. Rice seed germination, seminal root length, and bud length decreased with increasing GO and Cd2+ concentrations respectively, while the presence of GO could alleviate the inhibitive effects of Cd2+ on seminal root and bud growth compared with the single Cd2+ treatment. In maize seedling, fresh weights of shoot and root showed similar responses to the presence of Cd2+ and/or GO. Compared with the single Cd2+ treatment, root Cd concentrations were generally increased by GO in high Cd2+ solution (20 mg/L), while were slightly affected by GO in low Cd2+ solution (5 mg/L) independent of GO concentrations except for 100 mg/L GO. Shoot Cd concentrations were decreased by low GO (100 mg/L) while were increased by high GO (> 500 mg/L) independent of Cd2+ concentrations in solution. Moreover, significant interactive effects of GO and Cd2+ on root and shoot Cd concentrations were observed. This study indicates that GO can change the effects of Cd2+ on seed germination, seedling growth, and uptake to Cd2+ in solution through its adsorption on Cd2+.