▎ 摘　　要

The present study investigated the impact of sulfonated graphene (SG) on the growth of maize seedlings at a concentration range of 0-500 mg L-1. Stress-related parameters including reactive oxygen species (ROS), intracellular Ca2+, antioxidant enzyme activities, lipid peroxidation, membrane leakage, cell death and rootmorphology were examined to reveal the potential mechanisms. The results indicate that SG induced a hormesis effect on plant height, i.e., low-concentration (50 mg L-1) stimulation and high-concentration (500 mg L-1) inhibition. The hormesis effect of SG on plant height was directly correlated with ROS levels in roots. A low concentration (50 mg L-1) of SG promoted ROS scavenging, alleviated oxidative stress, enhanced the soluble protein (SP) content, and decreased intracellular Ca2+ and cell death in the roots. At a higher concentration (500 mg L-1), SG stimulated the generation of ROS in the roots, decreased SP content in the leaves, increased antioxidant enzyme activities, intracellular Ca2+, electrolyte leakage and cell death in the roots, and increased the malondialdehyde (MDA) content in both roots and leaves. Different changes were observed for root morphology at SG concentrations of 50 and 500 mg L-1, and a larger amount of SG was deposited onto the root surface at a concentration of 500 mg L-1 compared with 50 mg L-1. (C) 2016 Elsevier B.V. All rights reserved.