Short-term interactive effects of copper and cadmium on barley growth, metal uptake, and oxidative damage

Abstract The present study aimed at investigating the response of spring barley (Hordeum vulgare L.) across different endpoints (morphological, physiological, and biochemical) to short-term single and combined copper (Cu) and cadmium (Cd) exposure. Barley seedlings were exposed for 5 days to Cd and Cu (0.1–100 mg L−1) individually and in binary combinations. Binary mixture toxicity was evaluated using the concentration addition concept and toxic unit approach. Single metal treatment reduced barley height and biomass, altered the content of photosynthetic pigments, and induced lipid peroxidation. Plant growth (measured as plant height and biomass) and lipid peroxidation showed high sensitivity to combined Cu–Cd treatment and Cu–Cd mixture induced greater than additive effect on these endpoints. The uptake and accumulation of Cu and Cd were considerably influenced by the interaction among these metals. Cu reduced Cd accumulation in plants, while Cd had no influence on Cu accumulation in barley roots and shoots. Analysis of mixture effects across different endpoints revealed that mixture effects are endpoint dependent and different types of interactions were manifested. Overall, the present study shows that the same test design for single and mixture toxicity assessment for several endpoints cannot always be used to predict mixture effects and type of interaction.