Study On The Difference Of Sedimentation And Residue Dynamics Of Commonly Used Pesticides In Paddy Fields On Rice

Rice is one of the most serious food crops in China that suffer from pests and diseases.It is also one of the crops with the most pest control in China.Therefore,the residue dynamics of commonly used pesticides on rice are studied,the relationship between pesticide residues and control efficacy is clarified,and rice is guided.Scientific reduction of medication is particularly important.This dissertation mainly focuses on the following three aspects:1.Compare the difference in the amount of the same pesticide(Imidacloprid and Azoxystrobin)produced by different manufacturers on rice,and provide basis for establishing rice pesticide application limit standard;2.Indoor pot experiment was used to study the pesticide residue dynamics of pymetrozine and thiadicarb on rice plants;3.Field trials were conducted to study the application of pymetrozine,thiadicarb,Azoxystrobin,and Imidacloprid in rice plants and brown rice.The final residue on the chaff.The main test results are as follows:Analyzed by high performance liquid chromatography In all the different formulations of Imidacloprid tested,the Imidacloprid water dispersible granules produced by Jiangsu Evergreen Biotech Co.,Ltd.had the highest deposition rate on rice,which was 2.61 ?g/g.In Azoxystrobin,the suspension agent Hebei Weiyuan Biochemical Pesticide Co.,Ltd.had the highest deposition rate on rice at 1.02 ?g/g.The above two agents were applied in the field to study field rice residue dynamics.A high performance liquid chromatography-mass spectrometry method for the determination of pyometrozine residues in rice plants was established.The pot dynamics of pymetrozine on rice plants was determined by pot experiment with an effective composition of 90 g/hm2 pymetrozine.Applied to rice plants,the application of quantitative spray method once,the original deposition of 6.81 ?g/g,residual degradation consistent with the first-order kinetic equation y = 6.3139e-0-236x,the determination coefficient R2 = 0.9733,the half-life of 2.9d.A high performance gas chromatographic method for the determination of thiadicarb residues in rice plants was established.Thioferamide was applied at an effective composition of 82.80 g/hm2.The original deposition was 1.27 ?g/g,and the residual degradation of thiadiramide on rice plants was consistent.The first-order kinetic equation is y = 1.0295e-0.088x,the determination coefficient is R2= 0.9574,and the half-life is 7.88 d.Field experiments have studied the residual dynamics and final residues of pymetrozine,thiadicarb,Azoxystrobin and Imidacloprid in rice plants.The results showed that the application amount of 25%pymetrozine in rice tiller stage was 24g/mu,and the original deposition amount on rice plants was 1.69?g/g.The dynamic equation for digestion was:y = 0.7836e-0.405x,R2=0.8785,the half-life is:T1/2 = 1,7 d.The final residue on brown rice is:0.0011 mg/L,which is far lower than the maximum residue safety value(MRL)specified by China and the European Union in brown rice.No residue of pymetrozine was detected on the rice hull.In the same application amount,application method,and application time,the original deposition amount detected in the indoor test was larger and the half-life was longer.Applied 30 days before harvest,residue on the plant:0.012 ?g/g,residue in brown rice:0.003 ?,g/g,residue in rice husk:0.022 ?g/g,lower than China's maximum residue The safety limit value,but the residue on rice hulls is higher than the EU's maximum residue safety limit value.In a high-performance gas chromatograph,Thiadiamide was applied once at an effective dose of 82.80 g/hm2.Using quantitative spray,the dynamic equation for the digestion of 240g/L Thiendomide on rice plants was:y = 0.5716e-0.177x,R2 = 0.6794 The half-life is:T1/2 = 4.13 d.The final disability on rice in this test was:0.05 mg/L,and the final residue on the chaff was 0.07 mg/L,which was far below the maximum residue safety limits set by Japan and Korea.Therefore,the application of thiadicarb once during the period from turning green to tillering of rice is not more than 23 g/hm2,which is very safe for rice production.250g/L Azoxystrobin was applied in rice tillering stage with 150g/hm2 active ingredient.Once applied,the original deposition amount on rice plants was 0.93?g/g.The dynamic equation for digestion was:y = 0.8999e-0.146x,R2=0.9585 The half-life is:.T1/2 = 4.75 d.The final residue on the plants was 0.04?g/g,and no Azoxystrobin residue was detected in the brown rice and chaff of this experiment.Azoxystrobin was applied once during rice tillering,and the application amount was not more than 150 g/hm2 of the active ingredient,which was very safe for rice production.70%Imidacloprid water dispersible granules were applied once at 30 g/hm2 of active ingredient in rice tillering stage.The dynamic equation in rice plants was:y = 2.2154e-0.09x degradation,determination coefficient R2 =0.9235,and half-life of 7.70d.The final residue on the plants was 0.04 ?g/g.The maximum safety limit for Imidacloprid in rice was 0.05 ?g/g in China.Imidacloprid residues were not detected in the brown rice of this experiment,and the final residue in rice husk was 0.018 ?g/g is lower than the maximum safety residue limit of Imidacloprid in rice in China..The application of Imidacloprid during the tillering stage of rice once,the application rate is not more than 3g/mu of the application amount of the formulation,and it is very safe for rice production.