Study On Pb-Zn Accumulation Characteristics And Physiological Mechanism Of Carex Gentiles Franch

The dissertation taked the dominant herbaceous plant species from the Putuo mountain lead-zinc mine of Hanyuan county in Sichuan province as riddling object, through the field survey and measurement of different herbages, it was found that Carex gentiles Franch. was a accumulator for lead(Pb) and znic(Zn). Furthermore, its accumulation characteristics and physiological mechanisms were studied in this paper.The major results were summarized as follows:1.In the nature condition, the average Pb, Zn concentrations of Carex gentilis Franch.were 1013.23mg/kg, 91.85mg/kg in shoot respectively, the Pb, Zn transportation coefficients werel.961 ,0.996respectively. The correlation analysis between the heavy metal concentrations of soils and plants suggested that there were significant positive correlations between the Pb concentrations in root and shoot and the extractable ones of soils, the correlation coefficients were 0.765* and 0.717* respectively .while there were significant positive correlation between the Zn concentrations in root and the total and extractable ones of soil, the correlation coefficients were 0.753* and 0.817* respectively. The plant had the great ability of accumulation and translocation in Pb, also had the characteristics of Pb accumulators.2. Under the Pb, Zn stress, the highest Pb concentrations in root and shoot of Carex gentilis Franch. were 1395.96mg/kg, 1834.17mg/kg respectively, while the highest Zn concentrations were 483.93mg/kg and 416.23mg/kg respectively. The highest Pb, Zn accumulation coefficients were 3.1, 4.76 respectively in the plant, while the highest Pb, Zn translocation coefficients were 9.9, 1.99 respectively. There were highly significant positive correlations between the different Pb concentrations and the accumulation in roots and shoots.The correlation coefficients were 0.814** and 0.844** respectively. However, the correlation coefficient of Zn was not significant, it meant that the Zn had an positive effect on the Pb accumulation in the plant. Thus, Carex gentilis Franch. was thought as a new Pb hyperaccumulator.3. The dissertation also studied the physiological change of Carex gentilis Franch. under the stress of Pb and Zn. The result showed that the Pb and Zn had a significant effect on the chlorophyâ…¡content of Carex gentiles Franch. By the correlation analysis, there were negative correlations between the Pb concentrations and the soluble carbohydrate content and soluble protein content in roots and leaves. While there was significant positive correlation between the Zn concentrations and the soluble carbohydrate content and soluble protein content in roots and leaves. It indicated that the Pb inhibited the carbon and nitrogen metabolism.4. Through the research of protections enzyme in plant under stress of Pb and Zn, it was found that the content of MDA increased with the concentration of Pb and Zn increasing, and the contents of MDA in leaves were higher than that in roots. The partial correlation analysis between the heavy metal concentrations and the contents of MDA in roots and leaves suggested that there was highly significant positive correlation between the Pb concentrations and the contents of MDA in leaves, and not significant correlation between the Zn concentrations and the contents of MDA in roots and leaves. With the concentrations of Pb and Zn increasing, the SOD, POD and CAT activity changed as follows: the activity of POD and CAT constantly rised shortly and dropped sharply, but the activity of SOD rised in a long time relatively. And the activity of SOD, POD and CAT in leaves higher than that in roots, it was possible related to the translocation coefficient of Pb and Zn in plant. By partial analysis, there was positive correlation between the Pb concentrations and the activity of SOD, POD in leaves and roots, and negative correlation between the Pb concentrations and the activity of CAT in leaves and roots, while there was highly significant positive correlation between theZn concentrations and the activity of SOD in roots, and not significant correlation between the Zn concentrations and the activity of SOD in leaves and the activity of POD in roots. In the research of the POD and CAT isozymes pattern in the leaves, the POD isozymes pattern was not remarkable difference under the single stress of Pb, Zn. The POD always produced two isozymes patterns: P-1, P-2. While the activity of isozymes patterns embodied significant difference during different concentrations of Pb or Zn. Especially, with the increase of Pb concentrations, the activity of P-2 was weak firstly and then strong and weak again. Compared with the activity of P-2, the activity of P-1 was more stable. The activity of P-2 in the Zn treatment was in opposition to that in the Pb treatment. The CAT isozymes performance was not significant difference, and showed a isozymes patterns." C-1. The activity of C-1 was weakest when the concentration Pb, Zn was 800mg/L, 250mg/L respectively. It meant that the isozymes performance was consistent with the activity of enzyme.