Chelate-Induced Phytoextraction Potential of Brassica rapa for Soil Contaminated with Nickel

Abstract

The aim of present study is to induce for phytoextraction of Ni by Brassica rapa from contaminated soil by application of EDTA. Brassica rapa seeds were planted in pots with Ni concentrations ranging from 0 to 2000 mg/kg in the absence or presence of 10 mg/kg EDTA. After 60 days of growth, Ni concentration of plants were observed. Brassica rapa showed the remarkable resistance to Ni toxicity with no visual toxic symptoms as chlorosis and necrosis. The addition of 10 mg/kg EDTA significantly increased both the plant growth and the Ni concentration, compared with the control. Especially the addition of 10 mg/kg EDTA and 500 mg/kg Ni produced fertilizer effect and maximum dry matter achieved to 1.96 mg/plant from 0.82 mg/plant. While Brassica rapa accumulated 3763 mg/kg Ni in the absence of EDTA, the addition of 10 mg/kg EDTA increased Ni accumulation to 3942 mg/kg Ni at Ni application dose of 2000 mg/kg. Experimental results indicated that Brassica rapa is Ni hyperaccumulator plant (>1000 mg/kg in shoots) both in the absence or presence of EDTA. The bioaccumulation coefficient (BAC) for Ni by Brassica rapa was greater than 1, providing further evidence for the transport of Ni from Ni contaminated soils