Impact Of Root Exudates Of Carex Cinerascens On Iron Plaque Formation And The Rhizosphere Under Lead Stress

Rhizosphere is a special ecological environment. It is a micro-domain soil,wherethe plant root grows and acts. Under heavy metal stress, plant root exudates, soilproperties, soil ecological environment (soil microorganisms, enzymes) are impacted.In this paper, Carex cinerascens from Poyang Lake was studied based ondifferent concentrations of Lead with pot experiment. Organic acids is effecton onCarexi iron. The results showed in the following:Used GC-MS, the main root exudates of Carex cinerascens are lipids andhydrocarbons. Their are59.44%and14.86%. Used HPLC, organic acids of Carexcinerascens is oxalic acid.Under Lead stress, the organic acids of Carex are oxalic acid, malic acid, citricacid by HPLC. With the rising of Lead concerntration, the total content of these threeacids are applied. Oxalic acid, malic acidin the proportion of total acid are increased,but citric acid is declined.(3) The inhibition of organic for the root iron plaque order is: citric>oxalic>malic. Collected root exudates were as follows:the promotion of low concentrationCarex iron plaque formation, high concentrations inhibited; Organic acids and rootexudates iron film formed on Carex have desorption and desorption size are followed:at5uolm/l concentrations, oxalic acid>citric>malic acid>root exudates, at20umol/lconcentrations of citric acid>oxalic>malic acid>root exudates, at100umol/lconcentrations of citric acid>malic acid>oxalic>root exudates.(4) With the rising of Lead concerntration, the pH is decreased in rhizo bagexperiments using. The pH, organic matter and moisture content of rhizosphere arelower than in the non-rhizosphere soil. But conductivity is higher than in thenon-rhizospher soil. Lead forms of reducible, acidextractable, oxidizable areincreased, but residual is declined.(5) With the rising of Lead concerntration,the impact of catalase, invertase,urease, activities in rhizosphere and non-rhizosphere are different. When the Pb2+concerntration are100mg/kg and500mg/kg in soil, catalase activities in the rhizosphereand and non-rhizosphere soil are more higher. The activation of a non-rootis higher than rhizosphere. Invertase activities in rhizosphere soil are higner than inthe non-rhizosphere soil. Under Lead stress, the rhizosphere soil invertase inhibitionare more than in non-rootrhizosphere soil. When the Pb2+concerntration are100mg/kg, urease activities is higher. When the Pb2+concerntration are1000mg/kg,urease activities is lower.(6) With the rising of Lead concerntration, the number of rhizospheric andnon-rhizosphere bacteria in soil are different. When the Pb2+concerntration are100mg/kg, the bacteria in soil is higer. When the Pb2+concerntration are1000mg/kg,the bacteria in soil is lower. The number of ctinomycetes in soil is decline. Thenumber of fungi in soil is the same as ctinomycetes.