| Aiming at the present serious situation of soil heavy metals contaminatin in Baiyangdian wetland,we would like to screen plant resources with hyperaccumulation of heavy metals that can be used in phytoremediation technology.In the present study,26 plant species growing in Baiyangdian wetlands and rhizosphere sediments were collected at different seasons,and the Cd,Pb,Cu,Zn enrichment characteristics were analyzed.We investigated the effects of arbuscular mycorrhiza fungi on growth,Pb enrichment characteristics,photosynthetic system and antioxidant enzyme system plant rhizosphere soil microbial comprehensive influence of community structure and metabolic characteristics,the associated with Solanum nigrum under different Pb2+(0,30,80,150mg/kg)treatments by using PLFAs and biolog ecoplate methods.1.Characteristics of heavy metals enrichment in plant species growing in Baiyangdian wetlandsThe results showed that Solanum nigrum presented notable capacity to absorb Cd from wetland sediment,and had good effect in the remediation of Cd pollution,being ideal plant for the bioremediation of Cd-polluted soil in Baiyangdian wetland.Inula japonica was considered as potential Cd-hyperaccumulator being able to be selected as candidates for the bioremediation of wetland soil Cd pollution.I.japonica was treated as Pb-hyperaccumulator,S.nigrum was Pb-accumulator.Xanthium sibiricum performed notable capacity to absorb Cu from wetland soil.For Zn accumulation,Chloris virgata and Kochia scoparia had acceptable effect in the remediation of Zn pollution.In conclusion,P.hydropiper is the ideal species for Cd and Cu accumulation,while I.japonica for Pb and Zn.Moreover,Cluster analysis is effective in the classification of plant species for metal accumulation and identification of potential species for phytoextraction.The results provided that the foundation for phytoremediation technology in Baiyangdian wetlands.2.The effect of arbuscular mycorrhizal fungi on growth and Pb enrichment characteristics of Solanum nigrum L.under Pb stress(1)Solanum nigrum L.could establish a good symbiotic relationship with AMF structure under the stress of Pb.(2)Inoculation with AMF could significantly improve biomass,Pb2+ concentration in aboveground and underground parts,significantly improved stomatal conductance and transpiration rate,but have no significant impact on net photosynthetic rate.3.The effect of arbuscular mycorrhizal fungi on mycrobial community structure from rhizosphere soil of Solanum nigrum L.under Pb stress(1)Bacteria content is biggest in mycrobial community structure from rhizosphere soil of Solanum nigrum L.,and then is actinomycetes,fungi content is the smallest.(2)Concentration of total,bacterial,Gram-positive bacterial,Gram-negative bacterial,actionomycete,fungal of rhizosphere soil of Solanum nigrum L.with no-inoculated AM fungi took on the diversification of "drop-ascend" with increasing lead concentration.While Concentration of total,bacterial,Gram-positive bacterial,Gram-negative bacterial,actionomycete,fungal of rhizosphere soil of Solanum nigrum L.with inoculated AM fungi took on the increased diversification with increasing lead concentration.(3)Inoculation with AM fungi could increased ratios of bacterial/total and fungal/total of mycorrhizal Solanum nigrum L.under high concentration(150 mg/kg)of Pb2+.(4)Gram-positive bacterial and Gram-negative bacterial were sensitive microbial groups which lead to microbial structure diversity difference under different treatments.4.The effect of arbuscular mycorrhizal fungi on metabolic characteristics of mycrobial community from rhizosphere soil of Solanum nigrum L.under Pb stress(1)The average well color development(AWCD)inoculated or no-inoculated AM fungi took on the diversification of "drop-ascend-drop" with increasing lead concentration.The AWCD at the medium treatment of Pb2+(80mg/kg)were higher than that at the low(30 mg/kg)and high concentration(150mg/kg)of Pb2+.(2)Inoculation with AM fungi could improve AWCD value under different lead concentrations,but had not significant difference in medium concentration.The utilization ability of soil microbes to four kinds of carbon substrates inoculated without AM fungi was the highest under medium concentration.While the utilization ability of soil microbes to four kinds of carbon substrates inoculated with AM fungi was higher under medium concentration than under low(30mg/kg)and high concentration(150 mg/kg)of Pb2+,but lower than no-inoculation.(3)Lead stress had no significant effect on microbial diversity index.However,AM fungi could significantly increase the number of microbial community species and dominance of common species under low concentration and medium concentration.(4)Sugars and their derivatives,metabolic products were sensitive carbon sources which lead to microbial function diversity difference under different treatments.(5)The use of microbial carbon sources was mainly regulated by the Pb2+ concentration,but AM fungi played a leading role under lead-free stress.This study provided the basis for making full use of AM fungi to strength phytoremediation technology. |
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