Toxic effects of graphene on the growth and nutritional levels of wheat (Triticum aestivum L.): short- and long-term exposure studies

Increased use of graphene materials might lead to their release into the environment. However, only a few studies have investigated the impact of graphene-based materials on green plants. In the present study, effects of graphene on plant roots and shoots after 48 h or 30 days of hydroponic culture were evaluated to determine its phytotoxicity. Results showed that although exposure to graphene (250, 500, 1000 and 1500 mg L-1) significantly improved root elongation, root hair production was impaired. These observations might be associated with graphene induced-oxidative stress (indicated by nitroblue tetrazolium (NBT) and Evans blue staining, malondialdehyde (MDA) estimation, and antioxidant enzyme activity assay). After 30 days of graphene exposure, shoot biomass, chlorophyll content, PSII activity and levels of several nutrient elements (N, K, Ca, Mg, Fe, Zn and Cu) were reduced, indicating that graphene inhibited plant growth and photosynthesis, and caused an imbalance of nutrient homeostasis. Based on these findings, we conclude that graphene has growth-limiting effects on plants, including root hair reduction, oxidative burst, photosynthesis inhibition, and nutritional disorder. (C) 2016 Elsevier B.V. All rights reserved.