Tolerance And Accumulation Characteristics Of Cadmium, Cooper In Leucaena Glauca L.

Using phytoremediation technology for heavy metals contaminated soil become a hot topic in scientific research. However, some hyperaccumulators used to remedy the contaminated environment are not ideal for phytoremediation since they were usually small and slow growing. To choose a more suitable phytoremediation material, the Leucaena glauca L. was chose for the experimental materials. This paper researched the growth, physiological and biochemical response under cadmium(Cd) and cooper(Cu) accumulation and discussed the total nitrogen between rhizosphere and non-rhizosphere soil with the increase of concentration of Cd and Cu in both pot and plot experiments. The major results showed as follows:(1) plot experiment, the Leucaena glauca L. showed a greater tolerance for cadmium(Cd). The plant height, root length and biomass of the Leucaena glauca L. were significantly enhanced with the increase of the concentration of Cd (P<0.05), and were significantly difference under different concentrations of Cd (P<0.05). Under the stress of Cd, the photosynthetic parameters of Leucaena glauca L. were influenced in varying degrees. Its net photosynthetic rate (Pn), stomatal conductance (Cond), intercellular CO2 concentration (Ci), transpiration rate (Tr) were enhanced first and down later with the increase of the concentration of Cd. Its peroxidase (POD) and catalase (CAT) were boosted with the increase of the concentration of Cd in fitting way of quadratic equation and linearly. with the increase of the concentration of Cd, its leaves’ glutathione (GSH) contents changed little and its roots’ content presented a first after rising downward trend. The contents of malondialdehyde (MDA) in leaves had a similar variation trend with GSH. The contents of soluble protein (SP) in leaves and roots had significant differences Among various treatment of Cd (P< 0.05).The Cd concentrations in roots, stems, leaves and shoots display linear increase with the increasing Cd and Cu concentrations in soil. Under Cd and Cu stress, BCF values of roots and leaves were 0.2 to 3.01 and 0.01 to 0.22, respectively. Though Leucaena glauca L. could not be recognized the hyperaccumulator according to the former results, TF values of roots reached up to 1.62-2.98 The consequence indicated that this kind of plant would have a stronger ability in translating the Cd and Cu from plant roots to its aboveground.(2) The Cu concentrations in roots, stems, leaves and shoots display linear increase with the increasing Cu concentrations in soil. As a whole, with increasing the Cu concentrations in soil, the activities of POD and CAT of Leucaena glauca L. rose at first and lowered later. Contrast with the activities of POD, the emzyme activity of leaves was higher than that of roots. Otherwise, the emzyme activity of the roots and leaves presented a similar regularity under the stress of Cu. The MDA in the leaves and roots had no significance both under Cd and Cu (P>0.05). Nevertheless, the soluble protein (SP) in the leaves and roots showed significant difference under the Cu treatments.Under Cu stress, BCF values of roots and leaves were0.23 to 2.83 and 0.02 to 0.32, respectively. Though Leucaena glauca L. could not be recognized the hyperaccumulator according to the former results, TF values of roots reached up to 1.33-2.73. The consequence indicated that this kind of plant would have a stronger ability in translating the Cd and Cu from plant roots to its aboveground.(3) In plot experiments, Leucaena glauca L. had a great tolerance under Cd and Cu stress as they grown vigorously and showed no visible symptoms of the two metals toxicity. The Cd and Cu accumulation in the shoots and roots attained 846.06μg plant-1,111-77μg plant-1 and 5667.49μg plant-1,2734.41 p,g plant-1, respectively. Furthermore, the plants had a huge rise space, which stated that Leucaena glauca L. had a huge potential in restoring the heavy metal pollution.