Indian Journal of Plant Physiology

A relationship between Cu²⁺ ion toxicity and oxidative stress was investigated in Brassica juncea L. seedlings by treating with different concentrations of copper (0.2, 0.4 0.6 and 0.8 mM). A uniform decrease in germination, biomass, root and shoot elongation with increasing concentrations marked as the primary signs of copper injury. Seed germination was completely inhibited at 0.8 mM copper. An increasing concentration of copper treatment showed an uniform decrease in chlorophylls and â-carotene composition with a significant accumulation of free proline suggesting an osmoprotection from copper. Copper stress resulted, an increase in lipid peroxidation with increasing copper concentrations. The increase in total peroxide content was accompanied by a decrease in catalase (CAT) and superoxide dismutase (SOD) activity at 0.4 and 0.6mM copper. However, peroxidase (POX) and glutathione reductase (GR) activities increased with increasing copper concentrations. The glutathione, ascorbate and polyphenol contents showed a decrease at a higher metal concentration. These results suggested an induction of oxidative stress in Brassica juncea L. seedlings under copper toxicity.