Effect of paraquat on soil bacteria diversity in a young eucalypt plantation
百草枯对巨桉人工幼林土壤细菌多样性的影响

To understand the effect of paraquat on soil bacterial community, the diversity of soil bacterial community were investigated after paraquat application in a young eucalypt (Eucalyptus grandis) plantation by Polymerase Chain Reaction Denature Gradient Gel Electrophoresis (PCR-DGGE) method. Soils were sampled after the application at initial, the 1st, the 2nd, the 4th, the 8th, the 15th, and the 31st day. The results showed that the richness of soil bacteria significantly decreased on the 1st day after paraquat application, but increased on the 2nd day. After that, the richness of soil bacteria continually reduced to an obvious valley value on the 15th day, and then increased on the 31st day. Moreover, paraquat application reduced Shannon-Wiener index but increased Simpson index of soil bacterial community, indicating that paraquat could inhibit even kill some parts of the bacteria. According to the analyses of clones and DNA sequence on the advantage bands, Sphingobacteriaceae and Acidobacteria were always present in all soil samples from different days after paraquat application, but Burkholderiales and Gamma proteobacteria disappeared on the 1st day and appeared on the 2nd, the 4th and the 8th day. Further, Burkholderiales, Alphaproteobacteria and Gamma proteobacteria disappeared on the 15th day after paraquat application, and Gamma proteobacteria was also not detected on the 31st day. These results provided basic data to understand the effects of herbicides like paraquat on soil microbial community in a young eucalyptus plantation in West China.