HerbicideToxicology2010年，生產(chǎn)農(nóng)藥234.2萬(wàn)噸（折100%），同比增長(zhǎng)18.8%。其中殺蟲劑84.5萬(wàn)噸，占31.9%；殺菌劑19萬(wàn)噸，占7.1%；除草劑108.9萬(wàn)噸，占45%。

1除草劑毒理學(xué)HerbicideToxicologyPartI:Introduction,definition

FactorsaffectingitsactivityAbsorptionandTranslocationHerbicideMetabolismPartII:ModeofAction2除草劑毒理學(xué)PartIIntroductionAherbicideisapesticideusedtokillunwantedplants.Herbicidesarechemicalsthatinhibitorinterruptnormalplantgrowthanddevelopment.Weedicide

3除草劑毒理學(xué)PartIIntroductionHerbicidescanprovidecost-effectiveweedcontrolwhileminimizinglabor.Understandinghowherbicidesworkprovidesinsightintohowtousethechemicalsandhelpsdiagnoseperformanceproblemsandrelatedinjurysymptoms.4除草劑毒理學(xué)PartIIntroductionWeedsareproductofhumansociety.Primitiveman,thegathererandhunter,wasnotconsciousofweedsinthemodernsense.Contemporarymanhascreatedtheconceptofweedasaplantinaplacewhereitisnotwanted.5除草劑毒理學(xué)HerbicideSelectivitySelectivity:Thepotentialforaherbicidetokillcertainplantswithoutinjuringothersiscalledselectivity.SelectiveherbicideNon-selectiveherbicideContactherbicideSystemicherbicide6除草劑毒理學(xué)HerbicideSelectivityHerbicidesthatkillorsuppressthegrowthofmostplantspeciesarerelativelynonselective.Glyphosateandparaquathistoricallyhavebeenconsiderednonselectiveherbicides.7除草劑毒理學(xué)HerbicideSelectivityHowever,glyphosateisahighlyselectiveherbicidewhenusedinconjunctionwithcropsthathavebeengeneticallyengineeredwithresistancetoglyphosate8除草劑毒理學(xué)HerbicideSelectivityMostherbicidesusedincropproductionareselective.Herbicideselectivityisrelativeanddependsonseveralfactors,includingplantbiology,environment,herbicideapplicationrate,applicationtiming,andapplicationtechnique.9除草劑毒理學(xué)HerbicideSelectivityHerbicideselectivitymaybebasedonherbicideplacement,differentialsprayretention,absorption,translocation,metabolism,oraninsensitivesiteofaction.10除草劑毒理學(xué)1.FactorsaffectingherbicideactivityFactorsinfluencingherbicideactivityincludeapplicationrate,applicationtechnique,plantmaturity,andenvironmentalconditions.Inaddition,soilcharacteristicscanaffectsoil-activeherbicides.11除草劑毒理學(xué)1.FactorsaffectingherbicideactivityMoistureandtemperatureareenvironmentalfactorsthatinfluenceactivityofsoil-appliedherbicides.12除草劑毒理學(xué)1.Factorsaffectingherbicideactivity1).SoilmoistureSoilmoistureisimportantbecauseitinfluencesherbicideadsorptiontosoils.Therefore,theherbicideisunavailableforplantuptake.Adsorptionoccurswhenherbicidemoleculesadheretosoilparticlesandorganicmatter.Whileadsorbed,herbicidemoleculesareunavailableforabsorptionbyplants.13除草劑毒理學(xué)1.FactorsaffectingherbicideactivityWatermoleculescompetewithherbicidemoleculesforadsorptionsitesonsoilparticlesandorganicmatter.Therefore,herbicideadsorptionishighestunderdrysoilconditions,andlowestinmoistsoils.Consequently,weedcontrolisgenerallybestwithmoistsoilconditionsbecausemoreherbicideisavailableforplantuptakeinthesoilsolutionorgaseousphase.14除草劑毒理學(xué)1.Factorsaffectingherbicideactivity2).TemperatureTemperatureaffectstheactivityofsoil-appliedherbicidesprimarilybecauseofitsinfluenceontherateofseedgermination,emergence,andgrowth.15除草劑毒理學(xué)1.Factorsaffectingherbicideactivity2).TemperatureSeedlingplantstendtobemoresusceptibleto

soil-appliedherbicidesundercoolconditionsthan

underwarmtemperaturesbecauseplantemergence

isdelayedandmetabolismisslowed.Ontheother

hand,extremelyhightemperaturessometimes

increasecropinjurysimplybyplacingtheplant

undermultiplestresses.16除草劑毒理學(xué)1.Factorsaffectingherbicideactivity3).SoilcharacteristicsSoilcharacteristicsaffectingherbicideactivityaretexture,organicmatter,andpH.17除草劑毒理學(xué)1.Factorsaffectingherbicideactivity3).Soilcharacteristics：Soiltexture:Herbicide

adsorptionisgreaterinfine-texturedsoilshighin

organicmatter

thanincoarse-texturedsoilslowin

organicmatter.Thus,alowerproportionof

herbicide

isavailableinthefine-texturedsoils,soahigher

herbicideapplicationrateisrequiredtoprovidethe

samelevelofweedcontrolasinacoarse-textured

soil.18除草劑毒理學(xué)1.Factorsaffectingherbicideactivity3).Soilcharacteristics：Soiltexture:Atthesametime,thechanceofcropinjuryisgreateroncoarse-texturedsoilslowinorganicmatterbecauseahigherproportionoftheappliedherbicideisavailableforplantuptake.Soil-appliedherbicideratesmayneedtobeadjustedaccordingtosoiltextureandorganicmattercontent.19除草劑毒理學(xué)1.Factorsaffectingherbicideactivity3).Soilcharacteristics：SoilpH:SoilpHinfluencestheavailabilityandpersistenceofcertainherbicidesinthesoil.SoilpHcanaltertheionicnatureoftheherbicidemolecule,whichinfluencesadsorption,solubility,andrateofherbicidebreakdown.20除草劑毒理學(xué)1.Factorsaffectingherbicideactivity3).Soilcharacteristics：SoilpH:Thetriazineherbicides(atrazine莠去津)andsomeofthesulfonylureaherbicides(Amber醚苯磺隆,)aremoreactiveandmorepersistentinhighpHsoils(>7.0)thaninlowpHsoils.21除草劑毒理學(xué)1.Factorsaffectingherbicideactivity4)EnvironmentalconditionsEnvironmentalconditionscanhaveatwo-foldeffectontheperformanceofpostemergenceherbicides.Higherhumidityandfavorabletemperaturesgenerallyresultingreaterherbicideabsorptionandactivityinplants.22除草劑毒理學(xué)1.FactorsaffectingherbicideactivityEnvironmentalsoinfluencesherbicideefficacy

byaffectingplantgrowth.Plantsaregenerally

mostsusceptibletopostemergenceherbicideswhen

activelygrowing.Extremeenvironmentalconditions

thatslowplantgrowthandthickenleafcuticlesoften

increaseplanttolerancetoaherbicide.23除草劑毒理學(xué)1.FactorsaffectingherbicideactivityCropinjuryfromaherbicide,however,canincreaseduringpoorgrowingconditionsbecauseofslowermetabolismanddetoxificationoftheherbicide.24除草劑毒理學(xué)1.FactorsaffectingherbicideactivityThus,ifcroptoleranceisbasedontheabilityofthecroptorapidlymetabolizetheherbicide,thepotentialforcropinjurymayincreaseandweedcontroldecreaseifaherbicideisappliedwhenplantsarenotactivelygrowing.25除草劑毒理學(xué)1.FactorsaffectingherbicideactivityForthisreason,mostherbicidelabelscautionagainstapplicationduringextremeenvironmentalconditions.26除草劑毒理學(xué)1.Factorsaffectingherbicideactivity5)PlantsAnnualplantsareusuallymoresusceptibletoherbicideswhentheyaresmallthanwhentheyaremature.Astheymature,plantsdevelopthickerwaxlayersonleafsurfaces,reducingherbicideabsorption.27除草劑毒理學(xué)1.Factorsaffectingherbicideactivity5)PlantsEstablishedperennialweedstendtobemoresusceptibletoherbicidesifappliedduringtheearlyfloweringstageofgrowthortoactivelygrowingplantsinthefall,probablybecauseapplicationatthesetimesresultsinthegreatesttranslocationoftheherbicidetotheroots.28除草劑毒理學(xué)2.Absorption,TranslocationA)Foliarabsorption:cuticlewax(lipophilic):no-polarCuticlecutin(角質(zhì),hydrophilic):polarPectin(膠質(zhì)):hydrophilic29除草劑毒理學(xué)Foliarabsorption30除草劑毒理學(xué)Foliarabsorption31除草劑毒理學(xué)a).FoliarabsorptionAbsorptionoffoliar-appliedherbicidesviathestomata(氣孔)canalsobeanimportantrouteofentry.32除草劑毒理學(xué)a).FoliarabsorptionSprayadjuvantsoradditivesoftenimprovesprayretentionandabsorptionbyplantfoliagebyreducingthesurfacetensionofthespraysolution,allowingthespraydroplettospreadmoreevenlyovertheleafsurface.33除草劑毒理學(xué)a).Foliarabsorption34除草劑毒理學(xué)a).FoliarabsorptionHerbicideabsorptionmaybefurtherenhancedbyinteractingwiththewaxycuticularlayerontheleafsurface.35除草劑毒理學(xué)a).FoliarabsorptionSprayadjuvantscanincreaseweedcontrol,butpotentiallycanreduceselectivitybyincreasingthesprayretentionandherbicideabsorptionbythecropmorethanbytheweed.Thus,sprayadjuvantsshouldbeusedonlyifrecommendedontheherbicidelabel.36除草劑毒理學(xué)b).TranslocationinplantsContactherbicidesarenottranslocated.Contactherbicidesgenerallyareineffectiveforlong-termperennialweedcontrol.Systemicherbicidescanbetranslocatedtootherpartsoftheplanteitherinthexylem(木質(zhì)部)orthephloem37除草劑毒理學(xué)b).TranslocationinplantsThexylemisnonlivingtissuethroughwhichwaterandnutrientsmovefromtherootstotheshootsandleavesofplants.Translocationinthexylemisonlyupwardandoutwardinplantsfromtherootstotheleavesandleafmargins.Phloemisaliving,conductingsysteminwhichmaterialscanmovebothupwardanddownward.38除草劑毒理學(xué)Translocation39除草劑毒理學(xué)b).TranslocationinplantsHerbicidescanbetranslocatedinthexylem,thephloem,orboth.Herbicidestranslocatedonlyinthexylemaremosteffectiveassoil-appliedorearlypostemergencetreatmentsbecausetranslocationisonlyupward.Atrazine(莠去津)isagoodexampleofaherbicidethatistranslocatedonlyinthexylem.40除草劑毒理學(xué)b).TranslocationinplantsPhloemtranslocatedherbicidesthatmovedownwardandsuppressrootandrhizome(根莖)growth,aswellastopgrowth,providethebestperennialweedcontrol.2,4-Disexampleofsystemicherbicidesthatwilltranslocateinthephloemandprovidegood,long-termcontrolofcertainperennialweeds.41除草劑毒理學(xué)3.HerbicideMetabolismMetabolismisoneofthemostimportantwaysaplantcanescapethetoxiceffectsofaherbicide.Herbicide-tolerantplantsoftenhavetheabilitytometabolizeorbreakdownthechemicaltononactivecompoundsbeforeitcanbuilduptotoxiclevelsatthesiteofaction.42除草劑毒理學(xué)3.HerbicideMetabolismSusceptibleplantsareunabletodetoxifyherbicides.Selectivityofmanyherbicidesisbasedondifferingratesofmetabolism.Metabolismcanbereducedincertainenvironmentalconditionssuchascoldweather.Reducedmetabolismofanherbicidecanbethecauseofcropinjury.43除草劑毒理學(xué)4.AlteredSiteofActionAnalteredsiteofactioncanresultindramaticresistancetoaherbicide.Analteredsiteofactionreferstogeneticallydifferentplantbiotypesthathaveastructurallyalteredsiteofactionthatpreventsherbicidebindingandactivity.44除草劑毒理學(xué)4.AlteredSiteofActionAtrazine(莠去津)isineffectiveonresistantbiotypebecauseaconformationalchangeinthechloroplastpreventsitfrombindingatthesiteofaction.45除草劑毒理學(xué)PartII:HerbicideModeofActionHerbicidescanworkatvarioussitesinplants.Theygenerallyinterferewithaprocessessentialfornormalplantgrowthanddevelopment.Herbicidescanbeclassifiedbysiteofactionbasedonhowtheyworkandtheinjurysymptomstheycause.46除草劑毒理學(xué)PartII:HerbicideModeofActionTobeeffective,herbicidesmust1)adequatelycontactplants;2)beabsorbedbyplants;3)movewithintheplantstothesiteofaction,withoutbeingdeactivated;4)reachtoxiclevelsatthesiteofaction.47除草劑毒理學(xué)PotentialSitofActionPhotosynthesis(food)Respiration(energy)Aminoacids(proteins/growth)Lipids(cellmembranes)Pigments(energy/lightcapture)Mitosis(celldivision)48除草劑毒理學(xué)PartII:HerbicideModeofAction1).PhotosynthesisInhibitors2).PigmentInhibition3).AminoAcidSynthesisInhibition4).LipidSynthesisInhibition5).CellMembraneDisruption6).GrowthRegulators7).SeedlingGrowthInhibitors49除草劑毒理學(xué)50除草劑毒理學(xué)1.PhotosynthesisInhibitorsPhotosyntheticinhibitorherbicidescontrolmanybroadleafandsomegrassweeds.Plantsarenotaffectedbytheherbicideuntilaftertheyemergeandbeginphotosynthesis.51除草劑毒理學(xué)1.PhotosynthesisInhibitorsPhotosynthesisinhibitorsshutdownthephotosynthetic(foodproducing)processinsusceptibleplantsbybindingtospecificsiteswithintheplant'schloroplasts.Inhibitionofphotosynthesiscouldresultinaslowstarvationoftheplant.52除草劑毒理學(xué)1.PhotosynthesisInhibitorsHowever,theplantexperiencesamorerapiddeaththatisbelievedtobeduetotheproductionofsecondarytoxicsubstances.Susceptibleplantstreatedwithaphotosyntheticinhibitordiefromabuildupofhighlyreactivemoleculesthatdestroycellmembranes.53除草劑毒理學(xué)1.PhotosynthesisInhibitorsa、阻斷電子由QA到QB的傳遞：取代脲類，三氮苯類b、抑制光合磷酸化：苯氟磺胺c、截獲電子到NADP+的傳遞：百草枯。54除草劑毒理學(xué)1.PhotosynthesisInhibitorsPhotosystemII,siteATriazine:atrazine莠去津

simazine西瑪津PhotosystemII,siteB:Phenylurea:linuron利谷隆

PhotosystemII,siteCbromoxynil溴苯腈,Bentazon苯達(dá)松55除草劑毒理學(xué)1.PhotosynthesisInhibitorsTheselectiveactionoftriazine(三嗪類,如莠去津)herbicidesisprimarilydeterminedbydifferentialmetabolism.Plantspeciessuchascornandsorghumpossesstheglutathione-S-transferase(GST)enzymeandcanselectivelymetabolizetriazineherbicidesintonontoxicsubstances.56除草劑毒理學(xué)1.PhotosynthesisInhibitorsSymptomologyInterveinalorveinal(葉脈)yellowingfollowedbydeathofplanttissuefromleafmarginsinwardPostemergenceapplicationscauserapidburningofplanttissueCropstoleranttopostappliedPI’smayexhibitspottedleafyellowingorbronzing57除草劑毒理學(xué)1.PhotosynthesisInhibitorsSymptomBladex草凈津;百得斯

Cotoran58除草劑毒理學(xué)1.Symptom59除草劑毒理學(xué)2.PigmentInhibitionThepigmentinhibitorherbicidesinterferewiththeproductionandprotectionofphotosyntheticpigments.Ultimately,chlorophyllproductionisinhibited,andplantfoliageturnswhite.Carotenoid類胡羅卜素60除草劑毒理學(xué)2.PigmentInhibitionPigmentinhibitorspreventplantsfromformingphotosyntheticpigments.Asaresult,theaffectedplantpartsbecomewhitetotranslucent.ThenewlydevelopedfoliageofmanyplantspeciesissosensitivetoCommand(廣滅靈)thatverysmallamountscanwhitennewplantgrowth.61除草劑毒理學(xué)2.PigmentInhibitionTheseherbicidescausethegreenpigments(chlorophyll)inplantstobedestroyed.Withoutchlorophyll,plantscannotphotosynthesizeandwilldie.Theseherbicidesareprimarilyxylemtranslocated,sotheyaremosteffectiveaspreemergencetreatments.62除草劑毒理學(xué)Chlorophylsynthesisinhibition63除草劑毒理學(xué)2.PigmentInhibitionProtoporphyrinogenoxidase(原卟啉原氧化酶PPO)inhibitorAcifluorfen(雜草焚),fomesafen(虎威),Oxadiazon(惡草靈,農(nóng)思它)Sunlightisnecessaryfortheseherbicidestokillorinhibitweeds.64除草劑毒理學(xué)2.PigmentInhibitionPigmentinhibitorscausewhitefoliage(“albinogrowth”)insusceptibleplantsNewgrowthwillnotcontainthenormalgreenpigmentationnecessaryforphotosynthesisAlbino（白化）growthmaybeobservedwithinveinsandbetweenveins(primarilywithCommand)65除草劑毒理學(xué)2.PigmentInhibitionCommandZorial66除草劑毒理學(xué)3.AminoAcidSynthesisInhibitionTheseherbicidesinhibitaminoacidsynthesiswhichisnecessaryfortheformationofplantproteins.67除草劑毒理學(xué)3.AminoAcidSynthesisInhibitionTheaminoacidsynthesisinhibitorsincludethefollowingherbicidefamilies:sulfonylureas(磺酰脲類),imidazolinones(咪唑啉酮類),sulfonamide(磺胺類),andaminoacidderivatives.Aminoacidsynthesisinhibitorsactonaspecificenzymetopreventtheproductionofspecificaminoacids,keybuildingblocksfornormalplantgrowthanddevelopment.68除草劑毒理學(xué)3.AminoAcidSynthesisInhibition69除草劑毒理學(xué)3.AminoAcidSynthesisInhibition(1)Theacetolactatesynthase(ALS乙酰乳酸合成酶)inhibitingherbicideshaveabroadspectrumofselectivityandareusedatlowratesassoil-appliedorpostemergencetreatmentsinavarietyofcrops.TheseherbicidesinhibittheactivityoftheALSenzyme,whichisinvolvedinthesynthesisofbranchchainaminoacids(leucine亮氨酸,ioleucineandvaline纈氨酸).70除草劑毒理學(xué)3.AminoAcidSynthesisInhibitionAminoacidsareessentialbuildingblocksinproteinsandarerequiredforproductionofnewcells.ALSherbicidesarereadilyabsorbedbybothrootsandfoliageandtranslocatedinboththexylemandphloemtothesiteofactionatthegrowingpoints.Selectivityisbasedondifferentialmetabolismandsiteexclusion.71除草劑毒理學(xué)3.AminoAcidSynthesisInhibition(2)TheEPSP(烯醇丙酮酰-莽草酸-磷酸合成酶)inhibitorherbicidesarereadilyabsorbedthroughplantfoliageandtranslocatedinthephloemtothegrowingpoints.TheseherbicidesinhibittheEPSPenzyme,whichisinvolvedinthesynthesisofthearomaticaminoacids(芳氨酸)(tyrosine酪氨酸,tryptophan色氨酸,andphenylalanine苯丙氨酸)72除草劑毒理學(xué)3.AminoAcidSynthesisInhibitionGlyphosate(草甘膦,EPSP抑制劑)isarelativelynonselectivepostemergenceherbicidethatisinactiveinthesoilbecauseofadsorption.GlyphosateresistantcropswithanalternativeEPSPenzymehavebeendevelopedthroughgeneticengineering.73除草劑毒理學(xué)3.AminoAcidSynthesisInhibition(3)Liberty(草銨磷,glufosinate)isabroad-spectrumpostemergenceherbicidethathasnosoilactivity.Libertyinhibitstheactivityoftheglutaminesynthetaseenzymethatisnecessaryfortheplanttoconvertammoniaintoothernitrogencompounds.74除草劑毒理學(xué)3.AminoAcidSynthesisInhibitionConsequently,ammoniaaccumulatesandglutaminelevelsdecrease.Plantdamageprobablyoccursduetothecombinedeffectsofammoniatoxicityanddeficiencyofaminoacidsrequiredforothermetabolicprocesses.Libertyhaslimitedtranslocation,sothoroughspraycoverageofsmallweedsgenerallyprovidesthebestperformance.75除草劑毒理學(xué)3.SymptomologyInjurysymptomsongrassincludestunting,purplecoloration,andinhibitedrootsystemswith“bottle-brush”appearanceBroadleafplantsymptomincludesformationofredorpurpleleafveins,yellowingofnewleaftissueandblackeningofterminalgrowthInitialyellowingfollowedbydeathofaffectedtissue76除草劑毒理學(xué)3.SymptomologyCadre“yellowflash”77除草劑毒理學(xué)3.Symptomology78除草劑毒理學(xué)4.LipidSynthesisInhibitionTheseherbicidesactbydisruptinglipidbiosynthesisingrassplants.Plantcellsandcellularorganellesallcontainlipidmembranes.Therefore,theseherbicidesaffectcellmembraneintegrityinthemeristematic(分生組織的)areas.79除草劑毒理學(xué)4.LipidSynthesisInhibitionLipidsynthesisinhibitorspreventtheformationoffattyacids,componentsessentialfortheproductionofplantlipids.Lipidsarevitaltotheintegrityofcellmembranesandtonewplantgrowth.Thelipidsynthesisinhibitorherbicidesinhibitasinglekeyenzymeinvolvedinfattyacidbiosynthesis.80除草劑毒理學(xué)4.LipidSynthesisInhibitionThelipidsynthesisinhibitorherbicidesinhibitmeristematicactivitybyinhibitingtheacetyl-CoAcarboxylase(ACCase,乙酰輔酶A羧化酶)enzymethatisinvolvedinthesynthesisoflipidsandfattyacids.Fenoxiapro-p-ethyl驃馬Easilytodevelopresistance81除草劑毒理學(xué)4.LipidSynthesisInhibition82除草劑毒理學(xué)4.SymptomologyInitialinjuryinmeristematicregionsoccurswherenewestleavesaredevelopingTheseregionswillturnchlorotic,whichisfollowedbynecrosisTheaffectedareawillbecome“rotted”andwilleasilyseparatefromrestofplantInjurywilldevelopslowly(7to14days)83除草劑毒理學(xué)4.Symptomology“rotted”meristem84除草劑毒理學(xué)5.CellMembraneDisruptionCellmembranedisruptersarepostemergencecontactherbicidesthatareactivatedbyexposuretosunlighttoformoxygencompoundssuchashydrogenperoxide.Theseoxygencompoundsdestroyplanttissuebyrupturingplantcellmembranes.Destructionofcellmembranesresultsinarapidbrowning(necrosis)ofplanttissue.85除草劑毒理學(xué)5.CellMembraneDisruptionThecellmembranedisruptorherbicidesdestroycellmembranes,causingcellcontentstoleakoutanddesiccationofplanttissue.Onabrightandsunnyday,herbicideinjurysymptomscanoccurin1to2hours.86除草劑毒理學(xué)5.CellMembraneDisruptionProtoporphyrinogenoxidase(原卟啉原氧化酶PPO)inhibitoraciflourfen雜草焚,fomesafen虎威,PhotosystemIelectrondiverters:paraquat百草枯87除草劑毒理學(xué)5.CellMembraneDisruptionThecellmembranedisruptersareprimarilynontranslocatedherbicidesthatarelightactivated.Paraquat(百草枯)anddiquat(敵草快)arerelativelynonselectivechemicalsusedtocontrolallexistingvegetationandaspreharvestdesiccants.Theseherbicidesquicklyformhighlyreactivecompoundsintheplantsthatrupturecellmembranes,causingthefluidstoleakout.88除草劑毒理學(xué)5.CellMembraneDisruptionThoroughspraycoverageisessentialforgoodpostemergenceweedcontrol.Becausetheyarenottranslocatedtotheroots,theseherbicidesareineffectiveforlong-termperennialweedcontrol.89除草劑毒理學(xué)5.SymptomologyRapidyellowingfollowedbydesiccationofaffectedplanttissueSymptomsgenerallyappearfirstonleaftips．Driftoroff-targetapplicationmayshowspeckledleafburn90除草劑毒理學(xué)5.SymptomologyBlazerInjuryonPeanutValorInjuryonPeanut91除草劑毒理學(xué)5.Symptomology92除草劑毒理學(xué)6.GrowthregulatorherbicidesTheseherbicidesmimicnaturalgrowthhormones,andthus,upsetthenaturalhormonebalanceinplants.Theyaffectseveralplantprocessessuchascelldivision,cellenlargement,proteinsynthesisandrespiration.93除草劑毒理學(xué)6.GrowthregulatorherbicidesThekillingactionofgrowth-regulatingchemicalsisnotcausedbyanysinglefactor,butratherbythedisruptionofseveralgrowthprocessesinsusceptibleplants.2,4-Disverysensitivetocottonplant94除草劑毒理學(xué)6.GrowthregulatorherbicidesSyntheticAuxins:2,4-D,MCPA(2甲4氯)AuxinTransportInhibitors:Diflufenzopyr(氟吡草腙)95除草劑毒理學(xué)6.SymptomologyBroadleafplantstemtwistingandcurlingLeavesonbroadleafplantsexhibitcupping,crinkling,strapping,ordrawstringeffectSymptomsongrassplantsincludeleafrolling,crinkling,bracerootfusionandmalformation.Also,flowersterilityandmissinggrainincrops.96除草劑毒理學(xué)6.SymptomologyMalformedbracerootsBlastedgrainheads97除草劑毒理學(xué)7.SeedlingGrowthInhibitorsSeedlinggrowthinhibitorsinterferewithnewplantgrowth,therebyreducingtheabilityofseedlingstodevelopnormallyinthesoil.Herbicidesinthesefamiliesmustbesoil-applied.Theseherbicidesareonlyeffectiveonseedlingofannualorperennialweeds.98除草劑毒理學(xué)7.SeedlingGrowthInhibitorsTheseherbicidesincludebothseedlingrootinhibitorsandshootinhibitors.(1)Therootinhibitorsinterruptcelldivision(mitosis)stoppingrootgrowthinseedlingplants.(2)Theshootinhibitorsdisruptproteinsynthesis,celldivision,cellenlargementandweakencellmembranes.(3)Themicrotubuleassemblyinhibitor.99除草劑毒理學(xué)7.SeedlingGrowthInhibitorsTheseedlingshootandrootinhibitors(acetamides,suchasalachlor甲草胺,acetochlor乙草胺,butachlor丁草胺)Acetamide(乙酰胺)herbicidesareusedpreemergenceorwithshallowsoilincorporationtocontrolannualgrassesandsomebroadleafweedsinavarietyofcrops.Theacetamidesdonotcontrolemergedplants.100除草劑毒理學(xué)7.SeedlingGrowthInhibitorsTheprimarysiteofabsorptionandactionoftheseherbicidesonbroadleafspeciesistheroots,whiletheprimarysiteofabsorptionandactionongrassspeciesistheemergingshoot.101除草劑毒理學(xué)7.SeedlingGrowthInhibitorsTheacetamidesarenotreadilytranslocatedintheplant,soherbicideplacementandavailabilityareimportant.Themechanismofactionoftheacetamideshasnotbeenwelldefined,butappeartointerferewithnormalcellulardevelopmentinseedlingplants.(抑制發(fā)芽種子α-淀粉酶及蛋白酶的活性)102除草劑毒理學(xué)7.SeedlingGrowthInhibitorsThemicrotubuleassemblyinhibitor:Dinitroaniline(二硝基苯胺):trifluralin(Treflan)氟樂(lè)靈Dinitroanilineherbicidesaregenerallyappliedpreplantincorporatedtocontrolannualgrassesandsomebroadleafweedsinmanycrops.Trifluralinneedtobeincorporatedtoavoidphotodecompositionandvolatilitylosses.103除草劑毒理學(xué)7.SeedlingGrowthInhibitorsThedinitroanilineherbicidesareabsorbedbybothrootsandshootsofemergingseedlings,butarenotreadilytranslocated.Theemergingshootistheprimarysiteofabsorptionandactionongrassspecies.104除草劑毒理學(xué)7.SeedlingGrowthInhibitorsTheseherbicides(dinitroaniline)aremitoticpoisonsthatinhibitcelldivision.Thus,themeristematicregions,suchasthegrowingpointsofstemsandroots,aremostaffected.Selectivitymaybebasedonmetabolism,aswellasherbicideplacementandtypeofemergenceofthegrassspecies.105除草劑毒理學(xué)7.SymptomologyofRootInhibitorsRootsonsusceptibleplantswillbestubbyandthick,especiallylateralrootsRootlimitationmaycausestuntingofplantsandphosphorusdeficiencysymptomsBroadleafplantsmayhaveswollenhypocotyls(胚軸)106除草劑毒理學(xué)7.SymptomologyofRootInhibitorsProwlInjuryonCorn107除草劑毒理學(xué)7SymptomologyofshootInhibitorsGrasscropsmayleafoutunderground,leavesmayexhibitimproperleafunfurling,andcrinklingAffectedcropsmayshowerraticstandandheightBroadleafplantsmayexhibitleafpuckeringoradrawstringeffect108除草劑毒理學(xué)7SymptomologyofshootInhibitorsDualInjuryonFieldCorn109除草劑毒理學(xué)PartIII:MajorHerbicideThispartissupplementarymaterials.110除草劑毒理學(xué)PartIII:MajorHerbicide2,4-Disacolorless,odorlesspowderusedasaherbicide.Therearemanyformsorderiv