Study of concentration changes of proline and potassium for two varieties of pinto beans under cadmium stress

ABSTRACT: The accumulation of heavy metals in soil causes environmental pollutions and is considered as a serious threat to humanʹs health. This study has been carried out with the purpose of studying the toxic effects of cadmium on the concentration changes of proline and potassium in the shoots of two commercial varieties of pinto beans (Talaash and local Khomein). Experimental treatments included three levels of cadmium [0 (control), 25 and 50 mg. kg-1) and three levels of potassium (Control, 157.6, 300 and 600 mg. kg-1) and two varieties of pinto beans (Talaash and local Khomein) were examined at four different times (14, 28, 42, and 56 days). The results revealed that the interaction effects of the cultivar and cadmium on the proline of the shoot became significant (P < 0.05). The highest concentration of proline was observed in the treatment of cadmium control and also in 300 mg. kg-1 potassium treatment in local Khomein variety after 28 days. With increasing the concentration of cadmium in the soil, the concentration of this element increased in both of the cultivars and the highest concentration of cadmium in the shoot (18.48 mg. kg-1) was measured in the treatments of 50 mg. kg-1 cadmium and 300 mg. kg-1 potassium in Talaash variety after 56 days. In general, local Khomein variety showed more resistance against the toxicity of cadmium than Talaash variety.