Effects On Physiological Characteristics And Accumulation Of Three Poplar Clones Inoculated With Bacteria D14, Z14 To As Stress

Growth status and accumulation characteristics of three poplar clones LH05-17, LN05-16, NH05-20 inoculated with bacterium D14, Z14 to arsenic stress were investigated in sterilize and unsterilize soil. Meanwhile the antioxidant enzyme activity of roots, stems and leaves and the contents of chlorophyll, soluble protein, soluble sugar, malondialdehyde (MDA) and proline (Pro) of leaves were investigated, as well as the changes of arsenic concentration and pH value of the soil. Results are as follows:(1) According to the growth status in 200 days, three poplar materials’resistance to arsenic stress are as follows:LH05-17> LN05-16> NH05-20. inoculated with bacterium D14, the poplar growth significantly better than the control and inoculated with bacterium Z14. The growth of three poplar clones were inhibited obviously with the rising of the stress of arsenic.(2)The dry weight of LH05-17 was highest in three poplar clones. It was obviously different from the other two clones. The upper part and underground part of three poplar clones’dry weight were declined with the increasing concentration of arsenic. Inoculated with bacterium, the dry weight of upper part and underground part were increased obviously. The LH05-17’s dry weight increased most after inoculated with D14.(3) In the 200 days’growth, the three clones absorbed arsenic and accumulated it constantly with the prolonging of the treatment’s time. The concentration of arsenic in roots, stems and leaves were declined with the rising of the stress of arsenic. The concentration of arsenic in roots was higher than stems and leaves. Inoculated with the two different bacteria, the absorbance of arsenic was both increased. Especially, inoculated with D14, the arsenic content of LH05-17 in treatment of non-arsenic was higher than that in treatment of arsenic stress with no bacterium. The arsenic concentration of roots in sterilize soil was obviously lower than that in unsterilize soil.(4) the relative chlorophyll content of LN05-16 was the highest in the three poplar materials. The bacterium D14 could increase the relative chlorophyll content. The relative chlorophyll content in poplar leaves were declined with the rising of the stress of arsenic.(5) The soluble protein of LN05-16 in stems and leaves was the highest in the three poplar clones. And the roots’soluble protein of LH05-17 was the highest. Moreover, the soluble protein in leaves was obviously higher than that in stems and roots. The soluble protein in plant was declined with the rising of the stress of arsenic. The bacterium’s inoculation could increase the soluble protein in plant.(6) The SOD and CAT activity of LH05-17 was the highest one in the three poplar clones. But the POD activity was lower than LN05-16、NH05-20. the sequence of antioxidant enzyme activity of roots, stems and leaves were as follows:Leaves> Stems> Roots. The change trend of the three enzymes was the same, followed by Increase with the arsenic concentration. SOD activities of plant increased firstly, followed by decline with the increase of arsenic concentration. CAT activities declined with the rising of the stress of arsenic. Whereas, the opposite change trend were observed POD. Different from the declined trend of POD activity followed by the rising of the arsenic stress, the SOD and CAT activity of the plant were increased inoculated with D14. Inoculated with Z14, the CAT activity of plant was declined in somewhat. Whereas it could increase the SOD and POD activity in leaves and stems. Soil sterilization had a greater impact on the enzyme activity of plant roots.(7) The contents of MDA and Pro in plant were increased with the rising of the stress of arsenic. The declined trend was showed in the content of soluble sugar. Compared to the increase of soluble sugar, the MDA and Pro were declined effectively inoculated with bacterium. But the effect of reducing MDA content was not obvious inoculated with Z14. Soil sterilization’s impact was merely on the content of soluble sugar.(8) The pH value and the arsenic concentration in soil of three poplar materials declined gradually in the 200 day treatment’s time. The pH value and the arsenic concentration in soil varied with different poplar clones after 200 day treatment. The arsenic concentration in soil of NH05-20 and LN05-16 were obviously higher than LH05-17. Whereas, the pH value in soil of NH05-20 was higher than LN05-16 and LH05-17. The pH value and the rest arsenic content in soil were increased with the rising of the stress of arsenic. In somewhat, the rise of pH value and the arsenic concentration in soil was mitigated inoculated with bacterium. The pH value and the arsenic concentration in unsterilized soil were decline obviously.So LH05-17 has the strongest resistance to As pollution in three popular clones. And inoculated with bacterium D14 can enhance the resistance to As to protect the plant.