Guangdong nongye kexue (Oct 2022)
Effects of Imazapic on Soil Microbial Communities and Soil Enzyme Activities in Paddy Fields
Abstract
【Objective】The study was conducted to monitor the effects of imazapic on the number of culturable microorganisms, the number of herbicide-resistant microorganisms and soil enzyme activities of rice fields in Guangdong area, aiming to provide a reference basis for the effects of herbicide application on soil ecology in agricultural fields.【Method】The number of culturable microorganisms and herbicide-resistant bacteria in paddy field soil under water direct-seeding and dry direct-seeding modes were monitored by plate counting method. Activities of soil urease, phosphatase, peroxidase and peroxidase were determined by sodium phenol-sodium hypochlorite colorimetric method, sodium phosphate colorimetric method, o-phenylene triol-ether extraction method and potassium permanganate titration method.【Result】After planting one crop of rice, the application of imazapic enhanced soil peroxidase activity significantly by 30% under water direct-seeding mode, and increasing soil acid phosphatase and urease enzyme activities significantly by 136.2% and 9.6% respectively under dry direct-seeding mode. Under both direct-seeding modes, the imazapic had no significant influence on the number of culturable fungi. However, under water direct-seeding mode, the number of bacteria and imazapic-tolerant bacteria decreased by 28.7% and 29.5%, respectively. The total number of actinomycetes and imazapic-resistant actinomycetes decreased by 24.2% and 40.7%, respectively. Under the dry direct-seeding mode, imazapic treatment had little effect on bacteria. The total number of actinomycetes decreased by 26.7%, and the number of herbicide-tolerant actinomycetes decreased by 45.9%.【Conclusion】The application of imazapic was effective in enhancing soil peroxidase activity under water direct-seeding mode, and enhancing the enzyme activities of soil acid phosphatase and urease under dry direct-seeding mode. Compared with manual weeding treatments, application of imazapic under water direct-seeding mode inhibited the growth of soil bacteria, and the application of herbicide inhibited the growth of soil actinomycetes under both water- and dry direct-seeding modes.
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