Study On The Efficacy Of Metamitron Against Weed And Dissipation Dynamics In Beet Field

Sugar beet is a root sugar and feed cash crop belonging to the genus Chenopodaceae.Beet leaves are rich in several nutrients such as fiber,vitamins,and folate.Beet tubers are rich in sugar and can be used to produce sugar and alcohol,as well as dyes and medicines.Sugar beets are susceptible to weeds during the planting process,and weeds will compete with sugar beets for nutrients and water in the soil,resulting in sugar beets not getting enough nutrients and water,thus affecting their normal growth and development.Secondly,too many weeds can block the entry of sunlight and air,causing beet leaves to yellow,grow slowly,and even die.Therefore,the use of herbicides in sugar beet fields is one of the keys to ensure sugar beet growth and yield.metamitron is a triazinone herbicide pioneered by Bayer,which is mainly used to control weeds in sugar beet fields.Therefore,based on the study of the effect of metamitron on weed control in sugar beet fields,this paper established the residual analysis method of metamitron on sugar beet and its digestion dynamics in sugar beet plants and soil.The results are as follows:1.According to the test guidelines of herbicide for weed control in sugar beet field,the control effect of 58%metamitron suspension on weeds in sugar beet field and its safety on sugar beet were studied,as well as the appropriate application dose.The results showed that 58%metamitron suspension at different application doses had good control effects on weeds in sugar beet fields,and the total control efficacy and fresh weight of weeds 45 days after application were 82.89%～94.34%and 84.20%～94.59%,respectively.Compared with the blank control,all the treatments had a yield increase effect,and the yield increase rate was more than 88%,among which,when the dose of metamitron was 300 m L/667m~2,the color of beet leaves was yellowed and curled,and the yield increase rate was slightly lower than that of other treatments,so the recommended dose of metamitron was 150～200 m L/667m~2.2.The Qu ECh ERS method combined with HPLC–MS/MS was optimized to detect metamitron residue analysis method in sugar beet tubers,plants and soil.Optimized for chromatographic conditions,mass spectrometry conditions and selection of purifiers.The results showed that under the optimized HPLC–MS/MS detection method,the average recovery rates of metamitron in sugar beet tubers,plants and soil were 82.9%～96%,90.4%～99.6%and84.6%～99%,and the relative standard deviations were 1.6%～4.8%,2.5%～5.0%and3.1%～8.2%,respectively.In the concentration range of 0.01～1 mg/kg,the concentration of metamitron had a good linear correlation with the peak area,and the correlation coefficient(r)was greater than 0.9967.The results show that the optimized analytical method is used to detect metamitron in the analysis sample,which can meet the requirements of pesticide residue detection and analysis.3.In this study,digestion dynamics and final residue test of 58%metamitron suspension in sugar beet field was carried out in Erguna City,Inner Mongolia in 2022,and the drug was administered once at 1740 m L a.i./ha(prepared dose 200 m L/667m~2).The experimental results showed that the digestion dynamics of metamitron in sugar beet plants and soil conformed to the first-order kinetic equation,and the half-lives were 2.8 d and 4.4 d,respectively,both less than30 d,indicating that metamitron was an easily degradable pesticide in sugar beet plants and soil.The final residues of metamitron in sugar beet tubers,plants and soil were<0.01 mg/kg、0.222～0.360 mg/kg and 0.119～0.148 mg/kg,respectively.The residue of metamitron in sugar beet tubers did not exceed the MRL(0.1 mg/kg)value of metamitron in sugar beet tubers formulated in China,but the residue of beet plants as animal feed should be concerned.