Study On Degradation Of Soybean Herbicide Residues With Aspergillus Niger

Applications of herbicides have become one of the important operations of modernagriculture. The residues of herbicides exist in soil for a long time and have endangered nextsensitive crop, groundwater, and drinking water, and therefore are harmful for human health.The herbicide pollution of soil.becomes increasing concern for the public and academicresearchers.Herbicide fomesafen was studied as the object of this thesis. Herbicide-contaminatedsoil from Heilongjiang Province was screened for fungi that might use the hebicide residuefor its nutrient. Fungi were cultured only in fomesafen and screened. The fungus was isolatedand identified. A strain S7was selected for its higher degradation rate of fomesafeas residue,and identified as Aspergillus niger. The growth of Aspergillus niger strain S7in the differentmedium ingredients in different proportions was observed and the degradation rate tofomesafen was measured. The fomesafen degradation rate was also measured in the sterilesoil, non-sterile soil, and in an ideal culture under the laboratory condition. Chinese cabbageAspergillus niger strain S7effect sensitive crops was observed in the rate of germination,height, and weight.The maximum growth was observed for Aspergillus niger strain S7in the initial pH of7.0, culture temperature28℃, oxygen partial pressure100mL/250mL, and5%for inoculationvolume. The more carbon content was added, the better growth of the strain S7was gained.The better growth of the strain S7was observed for lower fomesafen concentration. Thestrain S7degraded fomesafen in1.0%of carbon concentration, the initial pH of6.0,100μg/mL of fomesafen concentration,28℃for culture temperature, oxygen partial pressureas100mL/250mL, and5%for inoculation volume. The degrade rate reached to59.8%in49days in the non-sterilized and51.4%in the sterilized soil. The degradation rate64.1%tofomesafen was obtained with the strain S7at the soil pH of6.0, the moisture of70%,30℃,5%of inoculation volume in49days.The fomesafen degradation rate depended on the growth and activity of the strain S7.The degradation rate was higher for the more growth and high activity of the strain S7. The fomesafen degradation faster in the non-sterilized soil than in sterilized soil. There might be alot of different types of microorganisms in the non-sterilized soil, the synergy among themmight accelerate the degradation of fomesafen. The rate of germination of Chinese cabbagewas inhibited obviously with fomesafen. The rate of germination had been improved foraddition of the straitn S7to the soil containing fomesafen. The inhibition of fomesafen on thegrowth of Chinese cabbage seedling was reduced for the height and weight of Chinesecabbage seedling increased with the strain S7in the fomesafen containing soil.