RESEARCH ARTICLE Alleviation of Cadmium Toxicity in Brassica juncea L. (Czern. & Coss.) by Calcium Application Involves Various Physiological and Biochemical Strategies

Calcium (Ca) plays important role in plant development and response to various environ-mental stresses. However, its involvement in mitigation of heavy metal stress in plants re-mains elusive. In this study, we examined the effect of Ca (50 mM) in controlling cadmium (Cd) uptake in mustard (Brassica juncea L.) plants exposed to toxic levels of Cd (200 mg L−1 and 300 mg L−1). The Cd treatment showed substantial decrease in plant height, root length, dry weight, pigments and protein content. Application of Ca improved the growth and biomass yield of the Cd-stressed mustard seedlings. More importantly, the oil content of mustard seeds of Cd-stressed plants was also enhanced with Ca treatment. Proline was significantly increased in mustard plants under Cd stress, and exogenously sprayed Ca was found to have a positive impact on proline content in Cd-stressed plants. Different con-centrations of Cd increased lipid peroxidation but the application of Ca minimized it to ap-preciable level in Cd-treated plants. Excessive Cd treatment enhanced the activities of antioxidant enzymes superoxide dismutase, ascorbate peroxidase and glutathione reduc-tase, which were further enhanced by the addition of Ca. Additionally, Cd stress caused re