Heavy Metal Stress On The Influence Of Robinia Pseudoaeaeia-rhizobia Symbiosis System Root Exudate And Rhizosphere Soil Microbial Diversity

With the industry development, the problem of heavy metal pollution is becoming more and more serious. In heavy metal pollution, nitrogen deficiency is a major limiting factor revegetation. Rhizobium legume symbiotic nitrogen fixation system have the strongest biological nitrogen fixation ability,and especially it plays an important role in accumulation heavy metal, and it promote the nitrogen cycle and nutrients. Root exudates contact plants and rhizosphere microorganisms, promoted the research in the field of ecology rhizosphere micro. so,in recent years, it has a important theoretical and practical significance to research the relationship between root exudates and rhizosphere microorganisms, and it is also a major direction in the field of rhizosphere micro-ecology. This articleselects the plants tree(Robinia pseudoaeaeia) and rhizobia symbiosis system for the study, under heavy metal stress, by the matrix culture cultivation, with distilled water extraction and colletion the root exudates for each different treatments, root exudates composition and content of qualitative and quantitative was analysised and by DGGE method to study rhizosphere soil microbial diversity.The main experimental results are as follows,1. Under heavy metal stress, Rhizobium inoculation can significantly improve plant biomass;Make the N content of plant increased by 16.3%- 71.76%, and the nitrogen content of ground parts and underground part showed a larger difference, difference can reach 55%;2. Through to analysis of the plant and soil heavy metal of Cu2 + and Zn2 +, the results showed that heavy metal amount increased with the locust plant adsorption of Cu2 + and Zn2+ metal concentration increases, which the plant root and stem portion of Cu2 + and Zn2 + adsorption capacity exists significant differences. the plant root adsorption amount 72.7%-72.7% and stem adsorption quantity 72.65%, on the adsorption of Cu2 + and Zn2 + ability exist obvious differences;Soil heavy metal content decreased by 43.59%- 43.59%, the inoculation plants for the enrichment of Cu2 + and Zn2 + ability is significantly higher than control, and Cu2 + with more significant;3. Under different metal stress, rhizobia symbiosis secretion the different type, content of root exudates, which is a manifestation of the different responses of plants to different stresses.Moreover, the number of root exudates of the amount that is not the relationship between soil microorganisms, proportional nor proportional and rhizosphere microorganisms slso.4. By PCR- DGGE analysis, high levels of pollution in the soil strain bands detected is less than that of lightly polluted soil, shows a DGGE bands of their own, severe pollution in the soil is mainly made of Sphingomonas, lightly polluted soil Myxococcales as the main genera.