We examined the effects of Cd on growth, lipid peroxidation, reactive oxygen species (ROS) accumulation, antioxidant enzymatic activity, and lignin content in the roots of two varieties of Vicia sativa. Treatment with Cd decreased plant growth and increased ROS and lipid peroxidation levels to a greater extent in the Cd-sensitive variety ZM than in the Cd-tolerant variety L3. Most hydrogen peroxide (H2O2) and superoxide anion (O-2(center dot-)) were accumulated in the cell walls and extracellular spaces in response to Cd treatments. Chemical assays and experiments using inhibitors showed that larger increases in H2O2 and O-2(center dot-) production in ZM than in 13 were probably attributed to elevated Cd-induced nicotinamide adenine dinucleotide-peroxidase (NADH-POD) activity. Cd treatment increased the accumulation of lignin and the guaiacol peroxidase (GPOD) activities in the apoplast more significantly in ZM root than in 13. Howerver, root laccase activity was higher in 13 than in ZM. Thus Cd toxicity induced significant lignification in the roots of V. sativa, and increases in H2O2 accumulation and apoplastic GPOD activity were likely responsible for this effect. (C) 2015 Elsevier B.V. All rights reserved.