Effects Of 9 Typical Paddy Herbicides On Tobacco Growth And Their Degradation Dynamics

In the process of tobacco production,herbicides plays an important and irreplaceable role in controlling the weeds in tobacco fields and protecting the production of tobacco leaves.But tobacco is particularly sensitive to herbicide,In recent years,the phenomenon of tobacco affected by herbicide phytotoxicity is frequently crops up in rice and tobacco rotation area,which seriously restricts the sustainable development of tobacco leaf production.To reduce or avoid the damage caused by herbicide residues to tobacco leaf production,the influence of 9 kinds of commonly used herbicides in paddy field on tobacco growth and their degradation dynamics in the field soil were studied in this paper.This study will provide reliable theoretical basis and specific practical measures for the smooth progress of tobacco leaf production in rice and tobacco rotation area.It has important theoretical and practical significance for the tobacco safety production in tobacco-crop rotation areas,the healthy development of the tobacco industry,and increase the income of farmers who suffered from herbicide injury in rice and tobacco rotation area.The main findings are as follows:(1)A method was developed to detect residues of quinclorac,bensulfuron methyl,pyrazosulfuron-ethyl,acetochlor,metolachlor,butachlor,2,4-D butyl,bentazone and bispyribac-sodium in soils and tobacco leaves useing liquid chromatography-tandem massspectrometry(LC-MS/MS).The results showed that the average recoveries of the above 9 kinds of herbicides in this study were between 75.0%-120%,with the relative standard deviations(RSDs)between1.0%-8.3%.The proposed method meets the requirements of pesticide residue detection methods,and the results are reproducible and feasible.(2)The degradation dynamics of this 9 kinds of herbicides were detected using the builted method,The results showed that the higher the application concentration,the higher the herbicide residue,the longer the half-life in potting soil.(3)There is a significant dose-effect relationship between the dosage of herbicide and the growth condition of tobacco in pot experiment,the higher the dosing dose,the stronger its inhibition to tobacco height and leaf area.The inhibitory effect of quinclorac on the plant height and leaf area of tobacco was the most obvious,even the 1/2 times recommended dose treatment group had obvious herbicide damage.The affected tobacco leaf margin curled to the back,and it becomes more and more serious with the growth of tobacco,and eventually only the main leaf veins were remained.Besides,Bensulfuron methyl,pyrazosulfuron-ethyl,bentazone,2,4-D butyl ester and bispyribac sodium also inhibition the growth and development of tobacco.The inhibitory effect of acetochlor,metolachlor and butachlor on the growth and development of tobacco is relatively low.(4)During the identification of field phytotoxicity symptoms,no obvious symptoms of damage in tobacco were find caused by acetochlor,metolachlor and machete.quinciorac showes the most obvious symptoms of drug injury,the main symptoms including leaf curling,leaf edges are serrated,blades thicken and darken,leaf blade clustering,dwarfing serious,pitch became shorter.bensulfuron-methyl,pyrazosulfuron ethyl,2,4-butylate,bentazone and bispyribac sodium treatment group also had different symptoms of drug damage.(5)The degradation of quincloric acid in soil is slow,the final residue in the soil is 0.391 mg/kg,and the theoretical half-life is 27.7days.The final residue of bensulfuron methyl,pyrazosulfuron-ethyl,acetochlor,metolachlor,machette,2,4-D butyl ester,bentazone and bispyribac-sodium in field soils were 0.058,0.011,0.235,0.899,0.254,0.420,0.014 and 0.032 mg/kg,The theoretical half-lives are16.1,16.9,15.1,16.5,13.6,13.3,15.4 and 17.3 days.(6)In this experiment,the critical concentrations of quincloric,bensulfuron methyl,pyrazosulfuron-ethyl,acetochlor,metolachlor,machette,2,4-D butyl ester,bentazone and bispyribac-sodium that cause tobacco poisoning in soils are 0.052,0.020,0.035,1.927,2.801,2.102,3.013,0.012 and 5.224 mg/kg.The safety intervals for quinclorac,bensulfuron methyl,pyrazosulfuron-ethyl,acetochlor,metolachlor,machette,2,4-D butyl ester,bentazone and bispyribac-sodium were 159,102,56,29,54,33,53,57 and 85 days respectively.