Study On Tolerance Of Sweet Potato To Simple And Compounded Pollution Of Cadmium And Plumbum

In present study, in order to clarify the tolerance of sweet potato to simple and compounded pollution of cadmium and plumbum through researching the characteristics of accumulation and absorption of cadmium and plumbum by sweet potato, pot experiments of sweet potato with different concentrations of single heavy metal pollutants (Cd or Pb) and Cd-Pb compounded pollutants added into pot soil were carried out. Moreover, the morphological characteristics of heavy metals Cd and Pb in the pot soil under the above-mentioned experimental conditions were determined and the relationships between morphological characteristics and accumulation and absorption of cadmium and plumbum by sweet potato were analyzed. The present results would provide support data for phytoremediation of soil heavy metal pollution by sweet potato, and also give the scientific basis for the safety management of agricultural production.The major results were as followed: 1. Sweet potato leaves were regularly collected 7,14,30 and 60 days after the beginning of the pot experiments during the growth of sweet potato. The length, the average number of leaves and the concentrations of chlorophyll in sweet potato leaves were measured,counted and determinded for clarifying the effects of Cd and Pb on the growth of sweet potato. The results showed that in low concentrations of the cadmium or plumbum accelerated the growth of sweet potato, and in high levels of cadmium or plumbum inhibited the growth of sweet potato.2. Sweet potato pot soil experiments showed that under the conditions of single heavy metal pollutants (Cd or Pb), the concentrations of cadmium, or plumbum absorbed in the body of sweet potato were significantly positively related to the heavy meatals added in soil. Under the conditions of Cd-Pb compounded pollution, cadmium and plumbum levels in the body of sweet potato were mainly affected by different cadmium or plumbum concentrations added into soil and affected by a cross action of Cd-Pb secondly. The cross action of cadmium and plumbum in the absorption and transference showed that cadmium inhibited the plumbum absorption of the roots and transference to the shoots. The low concentrations of plumbum accelerated the cadmium absorption of roots and transference to shoots. On the otherhands, high concentrations of plumbum inhibied the cadmium uptaken into roots and migration for shoot. The both concentrations of cadmium and plumbum in shoots were lower than that of roots in sweet potato.3 Tessier sequential extraction analysis was used for analyzing and understanding the chemical forms of Cd and Pb in sweet potato pot soil, and the regression between the morphological characteristics of heavy metals and the heavy metals absorption of sweet potato under single and Cd-Pb compounded pollution.The results showed that under the all of concectrations in single and compounded pollutions, there were significant positive correlations between the cadmium and plumbum concentrations in sweet potato roots, stems and leaves and the available chemical forms of Cd and Pb in sweet potato pot soil. Under the compounded pollution conditions, low concentrations of plumbum accelerated the biological activity of cadmium, but the high levels of plumbum inhibited the biological activity of cadmium. Cadmium was able to restrain bioavailability of plumbum.