The effect of heavy metals and different combination of planting beds on antioxidant enzymes in pinto bean (Phaseolus vulgaris L. cv. Sadri)

In order to investigate of heavy metal effect on antioxidant enzymes in pinto bean (Phaseolus vulgaris L. cv. Sadri) under different combination of planting beds, a greenhouse experiment was conducted as a factorial based on CRD design with three replications in Yasouj University, 2013. The first factor included of five levels of heavy metals (control, Cd(NO3)2, Pb(NO3)2, Ni(NO3)2 and CuSO4 with 50 mg kg-1 soil concentration) and the second factor included of four levels of different combination of planting bed (control, compost, vermicompost and sawdust). Results showed that maximum enzymes catalase and superoxide dismutase activity were related to the application of Sawdust that compared to control respectively 21.36 and 11.94% increased; But with the addition of compost and vermicompost these two enzymes activity decreased. All levels of heavy metals increased the peroxidase activity: but soluble protein content decreased and the polyphenol oxidase activity reduced in levels of lead nitrate. Heavy metals reduced seed weight compared to control (without heavy metals) except Pb nitrate. Most of the seed weight at the level of Pb nitrate and cadmium nitrate were the lowest. In general, the use of compost and vermicompost as organic fertilizers rich in macro and micro elements could play a positive role in modulating the effects of heavy metals and to reduce the toxic effects of heavy metals leads to a reduction in the activity of antioxidant enzymes.