Effect of fungicide iprodione on soil bacterial community

The effect of the fungicide iprodione on soil bacterial communities was studied by treating two kinds of soils with different concentrations of iprodione. Degradation rates of iprodione in sterile and unsterile soils were also investigated. Residues of iprodione were measured by using high-performance liquid chromatography (HPLC) and a change of bacterial communities was performed with denaturing gradient gel electrophoresis (DGGE) by counting the 16S rDNA band on DGGE patterns. The degradation rate of iprodione was slower in sterile soil than in unsterile soil in both Da-Hu sandy loam and Kuan-Shi loam. After treatment with fungicide, soil bacterial communities were changed and recovered rapidly to the original status when incubated at a lower temperature (15°C) and a lower iprodione concentration (5 μg/g). At the same temperature but with more iprodione (50 μg/g) added, the soil bacterial community increases slowly and regains the original status slowly. However, when incubated at the higher temperature (30°C), the soil bacterial community is more complex than that at the lower temperature. The response of the soil bacterial community to the iprodione is faster at the higher than at the lower temperature. At 30°C and with 50 μg/g iprodione, the amounts of soil bacterial communities increased quickly but cannot be reduced to the original status after incubation for 23 days.