Abstract:

In order to provide reference basis for the vegetation restoration and reconstruction of Pb-Zn mining tailings and peripheral polluted farmland, as well as habitat improvement in Lanping County, the impact of the single and combined of Pb2+ and Zn2+ ions with different contents on the germination and seedling growth of five leguminous plants was studied in this paper. The experiment researched the tolerance of the five legumes species to Pb2+, Zn2+ and their combined pollution by solution culture and soilless culture. The results showed that: (1) Except for Cassia bicapsularis, the seed germination increased under the treatments with single Lead and Zinc at low concentration, but it could reduce when Lead and Zinc reached high concentration. Both Medicago sativa and Trifolium repens had much tolerance to Lead than the other three. Treated with combined Lead and Zinc ions, the germination of seeds could be promoted by Zinc ion at low level of Lead concentration, but it was inhibited by both Lead and Zinc when Lead reached high level concentration. (2) The impact of heavy metals on the seedling growth was as follows: being treated with single Zinc ion, there was no significant differences of growth between the five legumes species. While being treated with single Lead ion, the seedlings growth of Medicago sativa was better than the other four once Pb2+ concentration being up to 1100 mg/L. (3) When the concentration of Zn2+ was 265 mg/L, the growth of seedlings was inhibited obviously, and the inhibition increased with Pb2+ concentration increase and Pb2+ concentration was main inhibition factor. It suggested a certain concentration of Zinc enhanced the poison effect of Lead to leguminous seeds when treated with combined Lead and Zinc ions.