Exogenous application of chelants is a common way to enhance the phytoextraction of heavy metals. A pot experiment was conducted to investigate the influences of cadmium (Cd), lead (Pb), Cd and Pb, L-glutamic acid N, N-diacetic acid (GLDA) and ethylene diamine tetraacetate (EDTA) on the growth, Cd and Pb accumulation of Sedum hybridum 'Immergrunchen'. The results showed that Sedum hybridum 'Immergrunchen' had a high tolerance to Pb treatment, followed by Cd-Pb treatment. The plant was sensitive to Cd stress. EDTA treatment was more harmful to plant growth than that of GLDA treatment. The optimal Cd concentration of shoot and root reached 27.6 mg·kg-1 and 32.6 mg·kg-1, 757 mg·kg-1 and 1,025 mg·kg-1for Pb accumulation at 100-1,500 mg·kg-1. The maximum Cd and Pb phytoextraction from 3 mmol·kg-1 GLDA treatment were 1.40 and 1.73 times as much as that of the control, 1.21 and 1.02 times under 6 mmol·kg-1 EDTA treatment. Therefore, the enhanced phytoremediation of GLDA to Cd and Pb co-contaminated soil was better than that of EDTA. GLDA-assisted phytoextraction of Cd and Pb by Sedum hybridum 'Immergrunchen' can be considered as a promising way to phytoremediate Cd and Pb co-contaminated soil.
Keywords: Chelating agent; Sedum hybridum ‘Immergrunchen’; co-contamination; hyperaccumulator; phytoextraction.
Sedum hybridum ‘Immergrunchen’, characterized by strong resistance to waterlogging, draught, salt and zinc, high propagating rate, long green period and high ornamental value, was used as the experimental material. Here, we investigated the best phytoremediation effect of Sedum hybridum ‘Immergrunchen’ to Cd-Pb stress, GLDA and EDTA assisted phytoremediation potential of Sedum hybridum ‘Immergrunchen’ for Cd and Pb contaminated soil under the best phytoremediation concentration. The results indicated that Cd and Pb phytoextraction under 3 mmol·kg−1GLDA treatment increased by 39.8% and 73.4% compared with the control, while increased by 21.0% and 1.80% under 6 mmol·kg−1EDTA. More importantly, Pb concentration of shoot in Sedum hybridum ‘Immergrunchen’ reached the criteria of hyperaccumulators under 3 mmol·kg−1 GLDA treatment.