The effects of different concentrations (10(-6) M, 10(-5) M and 10(-4) M) of K2Cr2O7Cr(VI) on some minerals (Mn, Fe, Cu and Zn), lipid peroxidation, activities of antioxidant enzymes, photosynthetic function, and chlorophyll fluorescence characteristics were investigated in hydroponically grown Amaranthus viridis L. Results indicated that chromium was accumulated primarily in roots. In the roots and shoots, the Cr content increased with the increasing Cr(VI) concentrations, and induced decrease of Mn, Fe, Cu and Zn. Chromium Cr(VI) induced oxidation stress and lipid peroxidation in A. viridis L. shown by the increased concentration of NIDA. The increased activities of POD and SOD indicated that they could serve as important components of antioxidant defense mechanisms to minimize Cr induced oxidative injury. The net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO, concentration were reduced only by high Cr(VI) treatments (10(-5) M and 10(-4) M). The chlorophyll fluorescence parameters F-V/F-m, F-v'/F-m', Phi PSII and q(P), decreased in Cr(VI)-treated, but q(N) and NPQ showed an increase in Cr(VI) treated plants. (C) 2007 Elsevier Ltd. All rights reserved.