The Security Of Mesosulfuron-methyl On Foxtail Millet And The Residue Analysis

The field weeds severely affected the yield and quality of millet, but there is no better herbicide available except for the Guyou in the present market. Mesosulfuron-methyl is developed by Bayer Crop science Co. Ltd, Germany, belongs to the conductive triazine, sulfonylurea herbicides. It has high efficence to the main grass weeds and is widely used because of its low used amout, low biological toxicity to human and natural.so the research on the security of mesosulfuron-methyl on foxtail millet and the residue analysis has certain theoretical and practical value. In this paper, the security of mesosulfuron-methyl on hybrid cultivar "Zhangzagu 10" and common cultivar "Jingu 21", and the herbicide residues in plants, seeds and soils were studied.The experiment were conducted in the field, used the random complete block design studied the influence of mesosulfuron-methyl to two kinds of millets, including their development, Lipid Peroxy Compounds and Photosynthetic Characteristics. Through the comparison of extraction solvent, purification methods, to determine the condition of pretreatment, mobile phase system, preliminary establish mesosulfuron-methyl’s detection and analysis method; In the text of dynamics of pesticide residues, plant was spayed with recommended concentration and soil was spayed with two high dose in a open space, to determinate the residue and the simulation of a chemical kinetic equation and calculate its half-life period; Finally we adopted two concentration and measured their residue in straw, grain and soil in the millet harvest. The main results are as follows:1. Mesosulfuron-methyl sprayed with a quarter of the recommended dose (3.13 g ai hm-2) was harmful to the two varieties of foxtail millet. Plant height, leaf length, leaf width, leaf area and fresh weight were severely reduced after spraying 15 days. There was no significant difference between the treatment concentrations. Compared with the control, the chlorophyll content of leaves decreased and SOD, POD enzyme activity increased with the increased concentration of mesosulfuron-methyl, and began to decline after 15 days. The content of MDA showed a rising trend at three stages. Different concentrations of mesosulfuron-methyl reduced the chlorophyll content of millet leaf, lead to the ability of the photosynthetic system to capture and use of light energy decreased. Fv/Fo, Fv/Fm, PS, ETR and qP of Photosystem Ⅱ decreased, NPQ increased, resulted in the leaves absorbed too much light energy and dissipation in the form of heat, so the activity of the photosystem Ⅱ reaction center decreased and led to the photosynthetic rate of leaves decreased, photosynthetic capacity decreased eventually.2. Through the exploration of liquid pretreatment conditions and liquid phase conditions, we initially established a technology of pesticide residue detection of mesosulfuron-methyl. Plant and soil samples were extracted by acetonitrile/water, then through the GCB purification with the mobile phase acetonitrile-phosphate (O.Olmol/L) (V:V; 50:50), at last lOul of sample to detect. The minimum detectable concentration of the method in plants was 0.02mg/kg, the soil was 0.008mg/kg, The minimum detectable quantity was 2.0 X 10-10g. The fortified recoveries of three concentrations in plant, soil and grain were in 91.99%～98.17%, RSD in 2.2%～12.4%.3. Using external standard method detected the residues in plants, soils of mesosulfuron-methyl after sprayed. Through the results of degradation dynamics, mesosulfuron-methyl’s degradation in plant and soil were accorded with the first-order chemical reaction equation, C=Coe-k1. Its half-life period in plant was 6.41 days and it was digested more than 80% after 7 days; Its half-life in soil was 16.67 to 18.78 days and it was digested more than 60% after 7 days, so mesosulfuron-methyl is an easy degradation pesticide. Finally, the test results showed that, under the dose of 13.5g ai hm-2, there were no residues can be detected in plant, soil and grain in the period of harvest.