Abstract:

The change of growth and microbial community characteristics in the rhizosphere of four types of poplars under pentachlorophenol contamination were investigated with a potting experiment in a green house. The results showed that the height and basal diameter of tested poplars were significant different when treated with different pentachlorophenol concentrations. Concentration of microbial biomass carbon in the rhizosphere soil of poplars, detected by the chloroform fumigation, decreased with increasing pentachlorophenol concentration, which suggested microorganisms were poisoned by high concentration of pentachlorophenol in the soil. Data collected by Biolog measurement demonstrated that the value of average well color development (AWCD) of microorganism in the soil treated with pentachlorophenol was always higher in the rhizosphere of poplars than in the control, and principal component analysis also showed that carbon used by microorganisms in the rhizosphere of poplars was influenced by polluted soil with pentachlorophenol. These results preliminarily implied that the physiological metabolic activity of some specific microbial communities in the rhizosphere soil was enhanced under the integrated effect of a certain range of pentachlorophenol concentration and root exudates in the rhizosphere, which resulted in increasing utilization of carbon source. The indexes of Shannon, Simpson and McIntosh of microbial communities were higher in the rhizosphere soil of poplars than in the control. The richness, evenness and superiority of microbial communities were enhanced, and the stimulated effect of microorganism in response to pentachlorophenol was increased with increasing pentachlorophenol concentration.

Key words: pentachlorophenol, poplar, height, basal diameter, rhizosphere microorganism, Biolog