The Study On Degradation To Soybean Herbicide By Pseudomonas Fluorescens

The herbicide residue in the soil has a serious chemical damage on the afterreap crops.The soil recovery seems to be very important for the rotation crop. Nutrition for Pseudomonasfluorescens using60～80kinds of carbon sources is simple and diverse. It might be aeffective way to use Pseudomonas fluorescens strain to degrade herbicide residue in the soil.Six different kinds of herbicides that have a long term effect were choosen as thesubstrates in the culture for Pseudomonas fluorescens that were induced and enriched, andisolated. And then an effective degrading herbicide strain was identified after Pseudomonasfluorescens was cultured with containing high concentration of herbicide. The temperture,humidity, imazethapyr concentration, pH, and noculation rate for the growth of imazethapyrwere observed in the laboratory. The conditions for degradation of imazethapyr in soil werealso observed, and therefore, the ideal condtions for the identified strain were determined.A mutant QS induced by a chemical method from Pseudomonas fluorescens was isolated.QS could grow with imazethapyr as its nitrogen source while it could utilize many differentcarbon-containing materials though mannitol was the best. When pH, temperature andimazethapyr concentration were6,28℃and100mg/L respectively,89%of imazethapyrcould be degraded within72h determined with reversed–phase high performance liquidchromatography (RPHPLC). When humidity, temperature and imazethapyr concentrationwere50%,25℃and50mg/kg respectively,75%of imazethapyr could be degraded by a5%inoculation rate of QS within2weeks.The results showed that imazethapyr concertration was rather the most important factorsin the degradation of imazethapyr with QS than other growth conditions. The combined actionof soil microorganisms might affect on the degradation of imazethapyr. The Strain QS couldbe used and developed into bacterial manure to degrade soil imazethapyr residue.