Enhancing Cadmium Tolerance in Common Bean Plants by Potassium Application

Cadmium (Cd) is one of the most toxic metals for plant growth and productivity. In the present study, we investigated the possible role of potassium (K) application (0, 200 and 400 mg K kg(-1) soil) in reducing the Cd toxicity (0 and 100 mg Cd kg(-1) soil) in common bean (Phaseolus vulgaris L.). Results revealed that Cd stress markedly decreased plant height, shoot, root, and total dry weight and leaf area, which was associated with increased Cd uptake and reduction of the chlorophyll value, stomatal conductance (g(s)), net photosynthetic rate (P-n) and relative water content (RWC) as well as induced oxidative stress. Moreover, lipid peroxidation (malondialdehyde, MDA content), proline content and activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were also elevated with Cd treatment. However, supplementary K lowered Cd toxicity and improved growth attributes through reducing Cd uptake and increasing the chlorophyll value, g(s), P-n, and RWC, further enhancing the proline content and antioxidant enzymes activity as well as lowering the MDA content. Both K levels (200 and 400 mg kg(-1) soil) were effective in Cd stress tolerance. Our findings clearly indicated that application of K as a cultivation method could be used for Cd detoxification in common bean plants.