Effect of EDTA on the tolerance and accumulation of nickel in Calendula tripterocarpa Rupr

It has been demonstrated that chelators such as EDTA affect the tolerance and accumulation of metals in plants. Therefore, in a greenhouse experiment, the effect of different concentrations of EDTA (0, 0.5, 1, 2, g/kg soil) were investigated on Calendula tripterocarpa Rupr .plants exposed to various concentrations of nickel (0, 100, 150 mg/kg) in soil and relative growth index , the content of photosynthetic pigments, lipid peroxidation and the activity of antioxidant catalase and superoxide dismutase enzymes was evaluated in roots and leaves. Results showed that increasing EDTA concentrations decreased relative growth index of root and shoot and the content of total chlorophyll and increased the content of malondialdehyde in leaves and roots. Application of 0.5 g/kg EDTA increased carotenoid content in leaves, the activity of catalase and superoxide dismutase enzymes in leaves and roots and nickel concentration in roots and shoots. Interestingly, application of 1 and 2 g/kg EDTA, reduced nickel concentration in roots and shoots and the activity of catalase and superoxide dismutase and increased the content of malondialdehyde. In conclusion, application of 0.5 g/kg EDTA enhanced phytoremediation ability of this species but high concentrations of EDTA was toxic for plant growth and reduced nickel accumulation and therefore, the application of high dose of this chelate is not recommended for enhancing the tolerance and accumulation of nickel in Calendula tripterocarpa