Physiological Response To Lead Stress And Phytoremediation Of Lead Contaminated Soil By Impatiens Balsamina L.and Tegetes Eresta L.

In order to choose the plants that are tolerant to heavy metal lead and for the case of phytoremediation of soils that were polluted by lead, the research was carried out by the methods of soil-planting in green-house and outdoor. The study chooses two species of plants Impatiens balsamina L. and Tegetes eresta L, observing the germination percentage of two species of seeds and development and physiological and biochemistrical response of the accumulators, improving-impact of accumulators on lead and examining the effect of nutrient elements(N,K) on the lead uptake. The major results are as follows:1. Germination percentage of two species of seeds increased with the increased concentration of lead treatment, but they declined at 800mg/L, root length shortened and the content of chlorophyll of seedlings declined with the increased of concentration of lead.2. The results showed that the content of the Biomass and chlorophyll in two species of plants increased first and then declined, content of MDA increased at all treatment. Three enzymes increased with the increasing concentration of Pb at low concentration, but declined with the increasing concentration at high concentration, the declining degree and lasting of SOD and POD activities are related to Pb concentration, but the time of Pb stress is not obvious to CAT activities.3. The sequence of lead content in two species of plants was Tegetes eresta L.> Impatiens balsamina L, in this study, two species of plants could transport the lead from roots to the above-ground parts, lead content of the root was higher than leaves.4. A little amount of Nitrogen and Potassium can accelerate the contents of chlorophyll and plant dry weights, advance the lead uptake of accumulators. But with the increasing of Nitrogon and Potassium concentration, the lead uptake of plants dropped, and chlorophyll and dry weights rose constantly. The little different effect of Nitrogen and Potassium on lead uptake was that the negtive impact of the former was more significant than the latter.