EDTA and nitric acid responses on nickel uptake, translocation factor and pigments on <i>Spinacia oleracea</i> L. replanted seedlings in hydroponic solution

Abstract

The effects of Na₂EDTA and HNO₃ on Ni²⁺ uptake by Spinacia oleracea seedlings replanted inhydroponic culture in a greenhouse was investigated. Eight week old seedlings, were exposed to various doses of Ni²⁺ (0, 1000, 2000, and 4000 mg/L) as N_iSO₄, at (0, 500 and 3000 mg/L) Na₂EDTA and ( 0, 500 and 3000 mg /L) HNO₃ in different combinations. There was a substantial increase in nickel uptake in chelated treatments (p < 0.05) compared to unchelated treatments of same concentrations of Ni²⁺. So, chelation enhanced Ni²⁺ uptake in S. oleracea. During the exposure, antioxidant defense system helped the plant to protect itself from the damage. Due to increasing nickel  uptake by the plant, the photosynthetic pigments (i.e chlorophyll a, chlorophyll b and Caretenoids) gradually declined. In this study, Spinacia oleracea Seedlings and contents of the photosynthetic pigments (chlorophyll a, chlorophyll b and Caretenoids) of both chelated and unchelated hydroponic treatments were investigated. Changes in photosynthetic pigments was significant (p < 0.05) with respect to addition of EDTA and HNO₃ at different concentration to different concentrations of Ni²⁺ compared to unchelated treatments of same concentrations of Nⁱ²+. The Nⁱ²+ induced translocation factor was also determined which increased significantly (P < 0.05) with increasing Ni²⁺ concentrations.