| In this study, we chosed Rumex nepalensis Spreng from8dominant species living in the lead-zinc mining area of the Tanbao mountain as material, because of its a lead-tolerant plants whtch greatest ability to translocation coefficient lead. Rumex nepalensis Spreng was planted in pots in growth chambers.25treatments from five lead, five zinc levels and their interactions (Omg/L,100mg/L,300mg/L,500mg/L,700mg/L) were arranged in a completely randomized design. Every treatment was applied to three replicates. So,75pots were set in total. In order to investigate whether Rumex nepalensis Spreng was good at the restoration of lead-zinc polluted soil, its physiological responses to lead and zinc were studied in this study, and the following indexes were determined:plant lead and zinc content, Physiological and biochemical(i.e. Antioxidant Enzyme Systems, Carbon and nitrogen metabolism, Subcellular fractions). Results follow as below:1. In the preliminary experiment, the lead and zinc content in Rumex nepalensis Spreng were87.24mg·kg"’and189.72mg-kg-1respectively. Lead and zinc translocation coefficient were1.80and2.64. Rumex nepalensis Spreng hold the most amount of lead in plant compared with the other7dominant species, with9.60g in roots and8.36g in above-ground part.2. Rumex nepalensis Sprenis is not only the best lead-enrichment species in this area but also tolerant to zinc. In this study, Rumex nepalensis Spren hold849.53mg/kg and2086.17mg/kg lead in shoots and roots at most. All enrichment indexes of above-ground were more than1, with2.65the most. All enrichment indexes of root were more than2.53, with12.07the most. The greatest transport ratio of the Rumex nepalensis Sprenis is1.19.3. Biomasses of the Rumex nepalensis Spreng decreased with increases of of lead and zinc concentration. The Rumex nepalensis Spreng had the least biomass when lead and zinc concentrations were500mg/L and700mg/L respectively, with21.88g in aboveground and7.31g in roots,42.87%and68.45%less than the controlled check. Root activity and chlorophyll content in Rumex nepalensis Spreng increased with increases of lead and zinc, maximizing (234.99μgTTF/(g-h) and2.53mg/g-WF respectively) when lead and zinc concentration were500mg/L and700mg/L,190.00%and78.17%more than the controlled check.4. Totally, contents of antioxidant enzymes (SOD、POD、CAT) and malondialdehyde (MDA) increased with increases of lead and zinc concentrations. In detail, SOD activity decreased with lead and zinc contents increases at lower concentrations, but increased at higher concentrations; POD activity always showed positive correlations with lead and zinc contents; CAT and MDA first increased and then decreased with lead and zinc increases.5. lead and zinc at low concentrations (100mg/L、300mg/L) positively affected plant soluble sugar content, while higher concentrations (500mg/L、700mg/L) of lead and zinc exerted negatively influences on plant soluble sugar. Moreover, additions of lead and zinc led to increases of protein content in above-ground part, and decreases in roots. In the P2Z4treatment, The Rumex nepalensis Spren presented the least soluble protein content in above-ground part (96.12mg/g.WF), which is31.24%less than the controlled treatment. Lowest soluble protein of root was presented in P2Z1(44.40mg/g.WF),39.82%less than the controlled.6. Concentrations of lead in subcellular followed the below order: cell wall> cell membrane and organelles> soluble materials in cell. The concentrations of lead in cell wall first increased and then decreased with increases of lead, while vice versa in cell membrane, organelles and cell soluble materials, showing a trend that first increase and then decrease. In comparison, concentration order of lead in root subcellular was the following: cell wall> soluble materials in cell> cell membrane and organelles, while those in above-ground was:soluble materials in cell> was cell wall> cell membrane and organelles at lower lead and zinc concentrations and cell wall> cell membrane and organelles> soluble materials in cell at higher lead concentrations.In conlusion, Rumex nepalensis Sprenis is not only the best lead-enrichment species in this area but also tolerant to zinc. It is promising in the restoration of lead-zinc poluted soil in dry-hot valley in western Sichuan, because it’s increasing root activity, the activity of antioxidant enzymes and enhancing the level of carbon nitrogen metabolism of plants to most of the lead and zinc curing in the cell wall, thus reducing the zinc inflicting damage. |
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