A Comparative Study on Pb Tolerance and Enrichment Characteristics among Different Species of Compositae

摘要

In order to find landscape plants purifying Pb pollution of soil,a pot experiment was conducted to study Pb resistance and enrichment characteristics of six species of Compositae plants( Aster ageratoides,Rudbeckia hirta,Cosmos sulphureus,Gynura bicolor,Calendula officinalis,Bidens pilosa) in different soil Pb concentrations. The results showed that the dry weight of aboveground part in the six plants decreased with the increase of soil Pb concentration. The tolerance index( TI) of C. sulphureus,G. bicolor and C. officinalis was greater than 0. 5 in all concentrations,and the root tolerance index( RTI) was greater than 0. 9,which were better resistant to Pb stress. The maximum Pb content in aboveground part of R. hirta was 1 783 mg/kg,and the enrichment and transport coefficients were all greater than 1. When the soil Pb concentration was 500 mg/kg,the total Pb accumulation in the aboveground part of R. hirta was 2. 507 mg/plant. Finally based on the integrated observation of the enrichment coefficient,transport factor and repair potential index,it believed that R. hirta can be used to restore Pb contaminated soil at low concentration.