Effect of Calcium and Potassium on Antioxidant System of Vicia faba L. Under Cadmium Stress

Abstract: Cadmium (Cd) in soil poses a major threat to plant growth and productivity. In the present experiment, we studied the effect of calcium (Ca²⁺) and/or potassium (K⁺) on the antioxidant system, accumulation of proline (Pro), malondialdehyde (MDA), and content of photosynthetic pigments, cadmium (Cd) and nutrients, i.e., Ca²⁺ and K⁺ in leaf of Vicia faba L. (cv. TARA) under Cd stress. Plants grown in the presence of Cd exhibited reduced growth traits [root length (RL) plant⁻¹, shoot length (SL) plant⁻¹, root fresh weight (RFW) plant⁻¹, shoot fresh weight (SFW) plant⁻¹, root dry weight (RDW) plant⁻¹ and shoot dry weight (SDW) plant⁻¹] and concentration of Ca²⁺, K⁺, Chlorophyll (Chl) a and Chl b content, except content of MDA, Cd and (Pro). The antioxidant enzymes [peroxidase (POD) and superoxide dismutase (SOD)] slightly increased as compared to control under Cd stress. However, a significant improvement was observed in all growth traits and content of Ca²⁺, K⁺, Chl a, Chl b ,Pro and activity of antioxidant enzymes catalase (CAT), POD and SOD in plants subjected to Ca²⁺ and/or K⁺. The maximum alleviating effect was recorded in the plants grown in medium containing Ca²⁺ and K⁺ together. This study indicates that the application of Ca²⁺ and/or K⁺ had a significant and synergistic effect on plant growth. Also, application of Ca²⁺ and/or K⁺ was highly effective against the toxicity of Cd by improving activity of antioxidant enzymes and solute that led to the enhanced plant growth of faba bean plants.