Abstract
Different concentrations (1 to 100 mg L-1) of copper oxide nanoparticles (CuO NPs) were imposed to rice (Oryza sativa L. cv. Giza 177) plants to assess their toxicity in terms of oxidative damage biomarkers as foliar H2O2, modulation of antioxidative enzymes (peroxidase APX, catalase CAT, superoxide dismutase SOD, glutathione reductase GR, and total ascorbate ASA) and photosynthetic performance. Photosynthetic parameters, stomatal conductance, and photosynthetic pigments were significantly reduced at all CuO NPs treatments. On the contrary, an increase in H2O2 and malondialdehyde accumulation was observed. Moreover, their concentrations increased with the increasing concentrations of CuO NPs. Likewise, there was a gradual increase in APX, CAT, SOD, and GR activities with the increasing doses of CuO NPs. However, the concentration of ASA decreased with the increasing metal concentration. The present study indicates that exposure to CuO NPs caused oxidative injury to rice plants above 50 mg L-1, while lower concentrations had no significant effects on the physiological and biochemical traits of rice.