Effects of Lead and EDTA-Assisted Lead on Biomass, Lead Uptake and Mineral Nutrients in Lespedeza chinensis and Lespedeza davidii

The ability of Lespedeza chinensis G. Don and Lespedeza davidii France of the family Fabaceae for Pb tolerance and accumulation in the presence and absence of the chelating agent EDTA was studied. Plants were cultured in soils containing different concentrations of Pb and Pb plus EDTA for 75 days. In the absence of EDTA, Pb supplement had no negative influence on plant growth of both species, however, stimulated the increase of shoot and root biomass of L. chinensis and L. davidii. Correspondingly, Pb accumulation in plants was low, and most of Pb was accumulated in roots, even though high doses of Pb had been supplied in soils. In the presence of EDTA, the Pb accumulation in all parts of both species was promoted, especially the translocation from roots to leaves. Regarding the influences of Pb and Pb plus EDTA treatment on the mineral nutrients, such as Mg, K, Ca, Fe, Mn, Cu and Zn in plants, Pb supplement resulted in both increase and decrease of mineral nutrients in L. chinensis and L. davidii in the absence of EDTA. In the presence of EDTA, the accumulation of mineral nutrients in plants was facilitated with the exception of Mn. The present results indicate that L. chinensis and L. davidii are Pb tolerant. Both plants can be used as potential species for chelate-assisted Pb phytoremediation. L. davidii has greater potential for phytoremediation of Pb than L. chinensis.