Lead Tolerance And Accumulation In Houttuynia Cordata Thunb

The effects of some physical chemical properties of soil and variety forms of lead on accumulation in Houttuynia cordata Thurib were discussed, the effects of lead on growth and physio-biochemical characteristics were discussed, and the absorption and tolerance of lead in Houttuynia cordata Thunb were studied especially by Filed Survey, Analysis Sampling, Pot Experiment and Hydroponic Experiment. The major results were summarized as follows:The effects of some physical chemical properties of soil on Houttuynia cordata Thunb were significant. The best distinct negative correlations between the lead adsorption of Houttuynia cordata Thunb and pH value, organic content, cation exchange capacity and content of clay, and the best distinct positive correlations between the lead adsorption of Houttuynia cordata Thunb and P, available N, available K and total N were found.The effect of different forms of lead on Houttuynia cordata Thunb absorbing lead. The main form that it absorbed is EXC, then Carb and MnO, OM and RES were not absorbed by itLead distribution in Houttuynia cordata Thunb under natural conditioa The lead concentration of it changed in the order of leaf > stem >underground stem. The Lead content in underground stem is from 0.04600 mg kg^-1 to 7.566 mg kg^-1, in stem is from 1.140 mg kg^-1 to 11.05 mg kg^-1, and in leaf is from 1.140 mg kg^-1 to 11.05 mg kg^-1. The ratio between stem Lead and underground stem Lead was from 0.1649 to 43.10,and between leaf Lead and underground stem Lead was from 1.650 to 39.10.Lead distribution in Houttuynia cordata Thunb under pot experiment The main forms that it absorbed was EXC, then OM, Carb and MnO. RES was not absorbed by it Lead concentration in Houttuynia cordata Thunb increased with the quantity of adscititious lead. The lead concentration of Houttuynia cordata Thunb changed in the order of stem >underground stem> leaf at Lead<1500 mg kg^-1,while at Lead>1500 mg kg^-1 changed in the ordered of underground stem> stem> leaf. The lead concentration of aerial parts changed in the order of stem> leaf.The effect of lead on leaf biomass and metabolism of Houttuynia cordata Thunb were significant. The plasma membrane content, the activities of SOD, the activities of POD,the activities of CAT, the MDA content, the chlorophyll content, and dry weight of leaf and underground stem were not affected at Lead< 400mg L^-1,while at Lead> 400mg L^-1, were affected significantly. The resultsindicated Houttuynia cordata Thunb was activity of membrane oxidative system at Lead> 400mg L'1.Houttuynia cordata Thunb could grow on the soils supplied with 2039mg kg'1, and could grow in water supplied with 400mg L"1 too. Analysis Sampling suggested Lead-concentration in aerial parts reached 40.02 mg kg"1. Pot Experiment suggested Lead-concentration in aerial parts reached 447.0 mg kg"1, and lead accumulation reached 107.1ug plant"1.Lead stimulated the growth of Houttuynia conktta Thunb at Lead<2000 mg kg"',while the growth was affected at Lead>2000 mg kg"1. Hydroponic Experiment suggested the effects of lead were significant at Lead> 400mg L"',while at Lead< 400mg L^were not affected, and Lead-concentration in aerial parts reached 1980 mg kg"1. Houttuynia cordata Thunb could activate soil. The mechanism as follows: underground stem could absorb much lead, higher transportation coefficient and enrichment coefficient...