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生态学报  2011 

Effect of chlorothalonil on soil microbial communities of Larix artificial shelter-forest

Keywords: chlorothalonil,soil microbial community,Biolog-Eco detecting method,principal component analysis

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Chlorothalonil is considered to be a non-selective fungicide and used commonly to control a broad spectrum of plant diseases. Hence, it is important to study its impact on ecological safety. In this study, the recommended dosage of chlorothalonil was sprayed on the soil of larch artificial shelter-forest to evaluate the impact of the fungicide on soil microbial communities. At the same time, analysis of correlations between soil diversity and propertities showed that it can provide basic data of the influence to soil microbial community and thus, provide basic foundings of scientifical usage and crisis managament for the pesticide. Using dilution-plate method, data of culturable microbial populations, soil properties and microbial functional diversity indexes were collected before spraying fungicide, 0 MAT, 2 MAT, 4 MAT and 12 MAT respectively. The results showed that bacterium was the dominant species among soil microbes whose number directly affected the dynamics of total soil microbial amount of larch artificial shelter-forest. As a whole, chlorothalonil had inhibitory effect on the proliferation of the soil bacteria. The inhibition occurred mainly in both the surface and the upper-layer (0-10cm) soils on 0 day after spraying.Moreover, the inhibitory effect on the bacteria in surface soil was significantly different from that in upper soil two months after spraying and the difference reached the climax four months later. At the time of both 0 MAT and 2 MAT, chlorothalonil facilitated the proliferation of the fungi in both the surface and the upper-layer (0-10cm) soils. Nevertheless, it showed little influence on the under layer soil fungi populations. Although the actinomycetes amount in both the surface and upper layer(0-10cm) soils were decreased as a result of the applicaton of chlorothalonil, the inhibition was weaker than those on bacterial populations. Correlation analysis between three main groups of microbial populations, soil propertities and diversity indices showed that the contents of both the effective phosphorus and available potassium in the soil were significantly positively correlated to the numbers of soil actinomycetes. The bacterium count was correlated positively to the content of soil hydrolysable nitrogen as well, whereas not to the soil microbial community diversity. Biolog-Eco Plate detecting showed that, 2 MAT, chlorothalonil had no significant effect on the carbon conversion ratio of the surface soil microbes while significant to that of the upper-layer microbes. And there was significant difference on the carbon conversion ratios of the under-layer microbes between two experiments tested on two months and four months after spraying respectively. Nevertheless, there was no significant difference between different soil layers. Principal component analysis of 31 carbon sources showed that the ability of single carbon conversion ratio of soil microbial community strikingly improved after chlorothalonil spaying. Furtherm


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