The Study On Some Nutrition Characteristics And As-accumulating Mechanism Of Pteris Vittata L.

Pteris vittata L., an indicator plant for calcareous soils, is an As-hyperaccumulator newlydiscovered by Chen et al. in China. This finding may bring a hope to phytoremediate As-contaminated soils. The effects of As and Ca on the growth of P. vittata L. and As uptake by P. vittata L. were studied under sand culture condition. The interaction of As and Ca on concentration and distribution of metals including K, Mg, Mn, Fe, Zn and Cu in it were also investigated. In addition, the As, P, Ca subcellular distribution in it were elucidated. The results are as follows:P. vittata L. has a strong tolerant capability to high As concentration in the medium. There was no significant difference in biomass between adding As and CK treatments. But the dry matter production decreased markedly with increasing Ca concentration. Especially P. vittata L. grew much badly under the condition treated with 5.0 mmol/L Ca.The effects of As and Ca concentration in culture solution on As content in P. vittata L. were much significant. As uptake by each part of P. vittata L increased obviously with elevating As level and the ratio of pinna As concetration to root As concentration increased gradually. As concentration in root was not affected markedly by Ca levels, while that of petiole increased and that of pinna decreased significantly. Adding As was benefit to take up Ca by P. vittata L. in the roots and pinnae. Ca concentration in the plant strongly increased followed by enhancing Ca level in solution compared to 0.03 mmol/L Ca treatment. But the obvious difference about Ca content in P. vittata L. between middle and high Ca level treatments was not found except that in the petiole. Applying As reduced P concentration in the root, but that in the frond was not affected significantly. The Ca levels had a great influence on P concentration in the root and petiole.It is shown that the concentrations of K, Mn, Fe and Cu in the pinnae were not influenced by enhancing the As in addition to Fe and Zn. When treated with high As level, Pteris vittata L. could maintain its normal nutrition metabolism. The results showed that the accumulations of Fe, Zn and Cu were not significantly affected by Ca levels, but the concentration and translocation of K, Mg and Mn were depressed by Ca. The interaction of metals wasenhanced gradually from the roots to leaves, and the effect of the Ca level on other metal elements was very obvious. There was no significant relationship between the Ca concentration and other metals concentrations in the roots. But the positive correlation between Ca and Fe concentrations hi petioles was very significantly. The K, Mg, Mn and Zn concentrations in pinnae decreased as the Ca concentration increased.The results showed that As distributed mostly in cell walls in the case of 0 mmol/L As, moreover the percentage of Ca content in cell walls was higher, which might inhibit As influxing cell. As concentration mostly existed in cytoplasmic supernatant when applying As in the medium. And the distribution percentage of As in cytoplasmic supernatant increased gradually from root to frond. The Ca percentage in cytoplasmic supernatant followed the same trend as As.