| Fast-growing plants for phytoremediation can improve the efficiency of heavy metal contaminated soil repair. In order to investigate the tolerance, accumulation characteristics and phytoremediation potential of two Eucalyptus species which are Guanglin 9 (Eucalyptus grandis× Eucalyptus urophlla, Gn9) and Eucalyptus grandis 5 (Eg5) under Cd, Cu, Pb and Zn stress, all of the pot, plot and field mining area experiments are taken. The main results were showed as follows:(1) In pot experiments, both of the Eucalyptus species showed good tolerance characteristics of Cd, Cu, Pb and Zn. The plant height, root length of two species increased with the increase of Cd concentration and their root and aboveground biomass display significant linear relationship with the concentration of Cd treatment (P<0.001). But the plant height, root length, the biomass index and photosynthetic parameters were significantly by different degree of inhibition under the stress of Cu, Pb, zinc. In general, the activities of peroxidase (POD) and catalase (CAT) of Gn9 and Eg5 rose at first and lowered later while their SP content increases with the increase of the concentration of heavy metals.In pot experiments. Eg5 and Gn9 showed good tolerance characteristics of Cd and Pb while Gn9 just had certain ability of Cu and Zn. The heavy metal concentrations in roots and aboveground display quadratic increment or linear increase with increasing soil Cd, Cu, Pb and Zn concentrations. Both of the Eucalyptus species showed good accumulation characteristics in the low concentrations of Cd, Cu, Pb treatment and in the high concentrations of Zn. Under Cd stress, Cd concentrations and accumulations in aboveground of Gn9 and Eg5 reached their maximum of 15.93,13.31 mg kg-1 and 1005.66, 721.17 μg pot-1, respectively, at soil added Cd of 120 mg kg-1. Their BCF and TF are 0.16 to 1.18,0.13 to 1.00 and 0.27 to 0.73,0.35 to 1.00, respectively. Under Pb stress, Pb concentrations and accumulations in aboveground of Gn9 and Eg5 reached their maximum of 275.20,243.00 mg mg kg-1 and 12.10,7.86 mg pot-1, respectively, at soil added Pb of 1200,600 mg kg-1, respectively. Their BCF and TF are 0.36 to 0.87,0.40 to 0.88 and 0.10 to 0.63,0.09 to 0.65 respectively. Under Cu stress, the concentrations and accumulations of Gn9 in aboveground were 60.65 mg kg-1 and 1.08 mg pot-1. Their BCF and TF are 0.06 to 0.30 and 0.21 to 0.48. Under Zn stress, concentrations and accumulations in aboveground of Gn9 reached their maximum of 802.99 mg kg-1 and 27.66 mg pot-1, respectively, at soil added Zn of 1500 mg kg-1. Their BCF and TF are 0.25 to 0.61 and 0.45 to 0.75, respectively.(2) In plot experiments, Gn9 and Eg5 had great tolerance of Cd, Cu, Pb, Zn stress because they grown vigorously and showed no visible symptoms of heavy matel toxicity in the plot.The maximum biomass reached 858.70 g. Their accumulations in aboveground of Eg5 and Gn9 were 6.03,13.60,25.50 and 2.52,6.95,15.44,29.18 mg, respectively.(3) In field mining area experiment, both of Eg5 and Gn9 not only can adapt to bad environment in mines,but also have strong phytoremediation potential. Gn9 can adapt to the soil barren field while Eg5 can adapt to high altitude mining area of low temperature. |
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