除草劑毒理學(xué)

HerbicideToxicology202023年，生產(chǎn)農(nóng)藥234.2萬噸（折100%），同比增長18.8%。其中殺蟲劑84.5萬噸，占31.9%；殺菌劑19萬噸，占7.1%；除草劑108.9萬噸，占45%。

1第1頁HerbicideToxicologyPartI:Introduction,definition

FactorsaffectingitsactivityAbsorptionandTranslocationHerbicideMetabolismPartII:ModeofAction2第2頁PartIIntroductionAherbicideisapesticideusedtokillunwantedplants.Herbicidesarechemicalsthatinhibitorinterruptnormalplantgrowthanddevelopment.Weedicide

3第3頁PartIIntroductionHerbicidescanprovidecost-effectiveweedcontrolwhileminimizinglabor.Understandinghowherbicidesworkprovidesinsightintohowtousethechemicalsandhelpsdiagnoseperformanceproblemsandrelatedinjurysymptoms.4第4頁PartIIntroductionWeedsareproductofhumansociety.Primitiveman,thegathererandhunter,wasnotconsciousofweedsinthemodernsense.Contemporarymanhascreatedtheconceptofweedasaplantinaplacewhereitisnotwanted.5第5頁HerbicideSelectivitySelectivity:Thepotentialforaherbicidetokillcertainplantswithoutinjuringothersiscalledselectivity.SelectiveherbicideNon-selectiveherbicideContactherbicideSystemicherbicide6第6頁HerbicideSelectivityHerbicidesthatkillorsuppressthegrowthofmostplantspeciesarerelativelynonselective.Glyphosateandparaquathistoricallyhavebeenconsiderednonselectiveherbicides.7第7頁HerbicideSelectivityHowever,glyphosateisahighlyselectiveherbicidewhenusedinconjunctionwithcropsthathavebeengeneticallyengineeredwithresistancetoglyphosate8第8頁HerbicideSelectivityMostherbicidesusedincropproductionareselective.Herbicideselectivityisrelativeanddependsonseveralfactors,includingplantbiology,environment,herbicideapplicationrate,applicationtiming,andapplicationtechnique.9第9頁HerbicideSelectivityHerbicideselectivitymaybebasedonherbicideplacement,differentialsprayretention,absorption,translocation,metabolism,oraninsensitivesiteofaction.10第10頁1.FactorsaffectingherbicideactivityFactorsinfluencingherbicideactivityincludeapplicationrate,applicationtechnique,plantmaturity,andenvironmentalconditions.Inaddition,soilcharacteristicscanaffectsoil-activeherbicides.11第11頁1.FactorsaffectingherbicideactivityMoistureandtemperatureareenvironmentalfactorsthatinfluenceactivityofsoil-appliedherbicides.12第12頁1.Factorsaffectingherbicideactivity1).SoilmoistureSoilmoistureisimportantbecauseitinfluencesherbicideadsorptiontosoils.Therefore,theherbicideisunavailableforplantuptake.Adsorptionoccurswhenherbicidemoleculesadheretosoilparticlesandorganicmatter.Whileadsorbed,herbicidemoleculesareunavailableforabsorptionbyplants.13第13頁1.FactorsaffectingherbicideactivityWatermoleculescompetewithherbicidemoleculesforadsorptionsitesonsoilparticlesandorganicmatter.Therefore,herbicideadsorptionishighestunderdrysoilconditions,andlowestinmoistsoils.Consequently,weedcontrolisgenerallybestwithmoistsoilconditionsbecausemoreherbicideisavailableforplantuptakeinthesoilsolutionorgaseousphase.14第14頁1.Factorsaffectingherbicideactivity2).TemperatureTemperatureaffectstheactivityofsoil-appliedherbicidesprimarilybecauseofitsinfluenceontherateofseedgermination,emergence,andgrowth.15第15頁1.Factorsaffectingherbicideactivity2).TemperatureSeedlingplantstendtobemoresusceptibleto

soil-appliedherbicidesundercoolconditionsthan

underwarmtemperaturesbecauseplantemergence

isdelayedandmetabolismisslowed.Ontheother

hand,extremelyhightemperaturessometimes

increasecropinjurysimplybyplacingtheplant

undermultiplestresses.16第16頁1.Factorsaffectingherbicideactivity3).SoilcharacteristicsSoilcharacteristicsaffectingherbicideactivityaretexture,organicmatter,andpH.17第17頁1.Factorsaffectingherbicideactivity3).Soilcharacteristics：Soiltexture:Herbicide

adsorptionisgreaterinfine-texturedsoilshighin

organicmatter

thanincoarse-texturedsoilslowin

organicmatter.Thus,alowerproportionof

herbicide

isavailableinthefine-texturedsoils,soahigher

herbicideapplicationrateisrequiredtoprovidethe

samelevelofweedcontrolasinacoarse-textured

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

byaffectingplantgrowth.Plantsaregenerally

mostsusceptibletopostemergenceherbicideswhen

activelygrowing.Extremeenvironmentalconditions

thatslowplantgrowthandthickenleafcuticlesoften

increaseplanttolerancetoaherbicide.23第23頁1.FactorsaffectingherbicideactivityCropinjuryfromaherbicide,however,canincreaseduringpoorgrowingconditionsbecauseofslowermetabolismanddetoxificationoftheherbicide.24第24頁1.FactorsaffectingherbicideactivityThus,ifcroptoleranceisbasedontheabilityofthecroptorapidlymetabolizetheherbicide,thepotentialforcropinjurymayincreaseandweedcontroldecreaseifaherbicideisappliedwhenplantsarenotactivelygrowing.25第25頁1.FactorsaffectingherbicideactivityForthisreason,mostherbicidelabelscautionagainstapplicationduringextremeenvironmentalconditions.26第26頁1.Factorsaffectingherbicideactivity5)PlantsAnnualplantsareusuallymoresusceptibletoherbicideswhentheyaresmallthanwhentheyaremature.Astheymature,plantsdevelopthickerwaxlayersonleafsurfaces,reducingherbicideabsorption.27第27頁1.Factorsaffectingherbicideactivity5)PlantsEstablishedperennialweedstendtobemoresusceptibletoherbicidesifappliedduringtheearlyfloweringstageofgrowthortoactivelygrowingplantsinthefall,probablybecauseapplicationatthesetimesresultsinthegreatesttranslocationoftheherbicidetotheroots.28第28頁2.Absorption,TranslocationA)Foliarabsorption:cuticlewax(lipophilic):no-polarCuticlecutin(角質(zhì),hydrophilic):polarPectin(膠質(zhì)):hydrophilic29第29頁Foliarabsorption30第30頁Foliarabsorption31第31頁a).FoliarabsorptionAbsorptionoffoliar-appliedherbicidesviathestomata(氣孔)canalsobeanimportantrouteofentry.32第32頁a).FoliarabsorptionSprayadjuvantsoradditivesoftenimprovesprayretentionandabsorptionbyplantfoliagebyreducingthesurfacetensionofthespraysolution,allowingthespraydroplettospreadmoreevenlyovertheleafsurface.33第33頁a).Foliarabsorption34第34頁a).FoliarabsorptionHerbicideabsorptionmaybefurtherenhancedbyinteractingwiththewaxycuticularlayerontheleafsurface.35第35頁a).FoliarabsorptionSprayadjuvantscanincreaseweedcontrol,butpotentiallycanreduceselectivitybyincreasingthesprayretentionandherbicideabsorptionbythecropmorethanbytheweed.Thus,sprayadjuvantsshouldbeusedonlyifrecommendedontheherbicidelabel.36第36頁b).TranslocationinplantsContactherbicidesarenottranslocated.Contactherbicidesgenerallyareineffectiveforlong-termperennialweedcontrol.Systemicherbicidescanbetranslocatedtootherpartsoftheplanteitherinthexylem(木質(zhì)部)orthephloem37第37頁b).TranslocationinplantsThexylemisnonlivingtissuethroughwhichwaterandnutrientsmovefromtherootstotheshootsandleavesofplants.Translocationinthexylemisonlyupwardandoutwardinplantsfromtherootstotheleavesandleafmargins.Phloemisaliving,conductingsysteminwhichmaterialscanmovebothupwardanddownward.38第38頁Translocation39第39頁b).TranslocationinplantsHerbicidescanbetranslocatedinthexylem,thephloem,orboth.Herbicidestranslocatedonlyinthexylemaremosteffectiveassoil-appliedorearlypostemergencetreatmentsbecausetranslocationisonlyupward.Atrazine(莠去津)isagoodexampleofaherbicidethatistranslocatedonlyinthexylem.40第40頁b).TranslocationinplantsPhloemtranslocatedherbicidesthatmovedownwardandsuppressrootandrhizome(根莖)growth,aswellastopgrowth,providethebestperennialweedcontrol.2,4-Disexampleofsystemicherbicidesthatwilltranslocateinthephloemandprovidegood,long-termcontrolofcertainperennialweeds.41第41頁3.HerbicideMetabolismMetabolismisoneofthemostimportantwaysaplantcanescapethetoxiceffectsofaherbicide.Herbicide-tolerantplantsoftenhavetheabilitytometabolizeorbreakdownthechemicaltononactivecompoundsbeforeitcanbuilduptotoxiclevelsatthesiteofaction.42第42頁3.HerbicideMetabolismSusceptibleplantsareunabletodetoxifyherbicides.Selectivityofmanyherbicidesisbasedondifferingratesofmetabolism.Metabolismcanbereducedincertainenvironmentalconditionssuchascoldweather.Reducedmetabolismofanherbicidecanbethecauseofcropinjury.43第43頁4.AlteredSiteofActionAnalteredsiteofactioncanresultindramaticresistancetoaherbicide.Analteredsiteofactionreferstogeneticallydifferentplantbiotypesthathaveastructurallyalteredsiteofactionthatpreventsherbicidebindingandactivity.44第44頁4.AlteredSiteofActionAtrazine(莠去津)isineffectiveonresistantbiotypebecauseaconformationalchangeinthechloroplastpreventsitfrombindingatthesiteofaction.45第45頁PartII:HerbicideModeofActionHerbicidescanworkatvarioussitesinplants.Theygenerallyinterferewithaprocessessentialfornormalplantgrowthanddevelopment.Herbicidescanbeclassifiedbysiteofactionbasedonhowtheyworkandtheinjurysymptomstheycause.46第46頁PartII:HerbicideModeofActionTobeeffective,herbicidesmust1)adequatelycontactplants;2)beabsorbedbyplants;3)movewithintheplantstothesiteofaction,withoutbeingdeactivated;4)reachtoxiclevelsatthesiteofaction.47第47頁PotentialSitofActionPhotosynthesis(food)Respiration(energy)Aminoacids(proteins/growth)Lipids(cellmembranes)Pigments(energy/lightcapture)Mitosis(celldivision)48第48頁PartII:HerbicideModeofAction1).PhotosynthesisInhibitors2).PigmentInhibition3).AminoAcidSynthesisInhibition4).LipidSynthesisInhibition5).CellMembraneDisruption6).GrowthRegulators7).SeedlingGrowthInhibitors49第49頁50第50頁1.PhotosynthesisInhibitorsPhotosyntheticinhibitorherbicidescontrolmanybroadleafandsomegrassweeds.Plantsarenotaffectedbytheherbicideuntilaftertheyemergeandbeginphotosynthesis.51第51頁1.PhotosynthesisInhibitorsPhotosynthesisinhibitorsshutdownthephotosynthetic(foodproducing)processinsusceptibleplantsbybindingtospecificsiteswithintheplant'schloroplasts.Inhibitionofphotosynthesiscouldresultinaslowstarvationoftheplant.52第52頁1.PhotosynthesisInhibitorsHowever,theplantexperiencesamorerapiddeaththatisbelievedtobeduetotheproductionofsecondarytoxicsubstances.Susceptibleplantstreatedwithaphotosyntheticinhibitordiefromabuildupofhighlyreactivemoleculesthatdestroycellmembranes.53第53頁1.PhotosynthesisInhibitorsa、阻斷電子由QA到QB旳傳遞：取代脲類，三氮苯類b、克制光合磷酸化：苯氟磺胺c、截獲電子到NADP+旳傳遞：百草枯。54第54頁1.PhotosynthesisInhibitorsPhotosystemII,siteATriazine:atrazine莠去津

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

PhotosystemII,siteCbromoxynil溴苯腈,Bentazon苯達松55第55頁1.PhotosynthesisInhibitorsTheselectiveactionoftriazine(三嗪類,如莠去津)herbicidesisprimarilydeterminedbydifferentialmetabolism.Plantspeciessuchascornandsorghumpossesstheglutathione-S-transferase(GST)enzymeandcanselectivelymetabolizetriazineherbicidesintonontoxicsubstances.56第56頁1.PhotosynthesisInhibitorsSymptomologyInterveinalorveinal(葉脈)yellowingfollowedbydeathofplanttissuefromleafmarginsinwardPostemergenceapplicationscauserapidburningofplanttissueCropstoleranttopostappliedPI’smayexhibitspottedleafyellowingorbronzing57第57頁1.PhotosynthesisInhibitorsSymptomBladex草凈津;百得斯

Cotoran58第58頁1.Symptom59第59頁2.PigmentInhibitionThepigmentinhibitorherbicidesinterferewiththeproductionandprotectionofphotosyntheticpigments.Ultimately,chlorophyllproductionisinhibited,andplantfoliageturnswhite.Carotenoid類胡羅卜素60第60頁2.PigmentInhibitionPigmentinhibitorspreventplantsfromformingphotosyntheticpigments.Asaresult,theaffectedplantpartsbecomewhitetotranslucent.ThenewlydevelopedfoliageofmanyplantspeciesissosensitivetoCommand(廣滅靈)thatverysmallamountscanwhitennewplantgrowth.61第61頁2.PigmentInhibitionTheseherbicidescausethegreenpigments(chlorophyll)inplantstobedestroyed.Withoutchlorophyll,plantscannotphotosynthesizeandwilldie.Theseherbicidesareprimarilyxylemtranslocated,sotheyaremosteffectiveaspreemergencetreatments.62第62頁Chlorophylsynthesisinhibition63第63頁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第64頁2.PigmentInhibitionPigmentinhibitorscausewhitefoliage(“albinogrowth”)insusceptibleplantsNewgrowthwillnotcontainthenormalgreenpigmentationnecessaryforphotosynthesisAlbino（白化）growthmaybeobservedwithinveinsandbetweenveins(primarilywithCommand)65第65頁2.PigmentInhibitionCommandZorial66第66頁3.AminoAcidSynthesisInhibitionTheseherbicidesinhibitaminoacidsynthesiswhichisnecessaryfortheformationofplantproteins.67第67頁3.AminoAcidSynthesisInhibitionTheaminoacidsynthesisinhibitorsincludethefollowingherbicidefamilies:sulfonylureas(磺酰脲類),imidazolinones(咪唑啉酮類),sulfonamide(磺胺類),andaminoacidderivatives.Aminoacidsynthesisinhibitorsactonaspecificenzymetopreventtheproductionofspecificaminoacids,keybuildingblocksfornormalplantgrowthanddevelopment.68第68頁3.AminoAcidSynthesisInhibition69第69頁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第70頁3.AminoAcidSynthesisInhibitionAminoacidsareessentialbuildingblocksinproteinsandarerequiredforproductionofnewcells.ALSherbicidesarereadilyabsorbedbybothrootsandfoliageandtranslocatedinboththexylemandphloemtothesiteofactionatthegrowingpoints.Selectivityisbasedondifferentialmetabolismandsiteexclusion.71第71頁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第72頁3.AminoAcidSynthesisInhibitionGlyphosate(草甘膦,EPSP克制劑)isarelativelynonselectivepostemergenceherbicidethatisinactiveinthesoilbecauseofadsorption.GlyphosateresistantcropswithanalternativeEPSPenzymehavebeendevelopedthroughgeneticengineering.73第73頁3.AminoAcidSynthesisInhibition(3)Liberty(草銨磷,glufosinate)isabroad-spectrumpostemergenceherbicidethathasnosoilactivity.Libertyinhibitstheactivityoftheglutaminesynthetaseenzymethatisnecessaryfortheplanttoconvertammoniaintoothernitrogencompounds.74第74頁3.AminoAcidSynthesisInhibitionConsequently,ammoniaaccumulatesandglutaminelevelsdecrease.Plantdamageprobablyoccursduetothecombinedeffectsofammoniatoxicityanddeficiencyofaminoacidsrequiredforothermetabolicprocesses.Libertyhaslimitedtranslocation,sothoroughspraycoverageofsmallweedsgenerallyprovidesthebestperformance.75第75頁3.SymptomologyInjurysymptomsongrassincludestunting,purplecoloration,andinhibitedrootsystemswith“bottle-brush”appearanceBroadleafplantsymptomincludesformationofredorpurpleleafveins,yellowingofnewleaftissueandblackeningofterminalgrowthInitialyellowingfollowedbydeathofaffectedtissue76第76頁3.SymptomologyCadre“yellowflash”77第77頁3.Symptomology78第78頁4.LipidSynthesisInhibitionTheseherbicidesactbydisruptinglipidbiosynthesisingrassplants.Plantcellsandcellularorganellesallcontainlipidmembranes.Therefore,theseherbicidesaffectcellmembraneintegrityinthemeristematic(分生組織旳)areas.79第79頁4.LipidSynthesisInhibitionLipidsynthesisinhibitorspreventtheformationoffattyacids,componentsessentialfortheproductionofplantlipids.Lipidsarevitaltotheintegrityofcellmembranesandtonewplantgrowth.Thelipidsynthesisinhibitorherbicidesinhibitasinglekeyenzymeinvolvedinfattyacidbiosynthesis.80第80頁4.LipidSynthesisInhibitionThelipidsynthesisinhibitorherbicidesinhibitmeristematicactivitybyinhibitingtheacetyl-CoAcarboxylase(ACCase,乙酰輔酶A羧化酶)enzymethatisinvolvedinthesynthesisoflipidsandfattyacids.Fenoxiapro-p-ethyl驃馬Easilytodevelopresistance81第81頁4.LipidSynthesisInhibition82第82頁4.SymptomologyInitialinjuryinmeristematicregionsoccurswherenewestleavesaredevelopingTheseregionswillturnchlorotic,whichisfollowedbynecrosisTheaffectedareawillbecome“rotted”andwilleasilyseparatefromrestofplantInjurywilldevelopslowly(7to14days)83第83頁4.Symptomology“rotted”meristem84第84頁5.CellMembraneDisruptionCellmembranedisruptersarepostemergencecontactherbicidesthatareactivatedbyexposuretosunlighttoformoxygencompoundssuchashydrogenperoxide.Theseoxygencompoundsdestroyplanttissuebyrupturingplantcellmembranes.Destructionofcellmembranesresultsinarapidbrowning(necrosis)ofplanttissue.85第85頁5.CellMembraneDisruptionThecellmembranedisruptorherbicidesdestroycellmembranes,causingcellcontentstoleakoutanddesiccationofplanttissue.Onabrightandsunnyday,herbicideinjurysymptomscanoccurin1to2hours.86第86頁5.CellMembraneDisruptionProtoporphyrinogenoxidase(原卟啉原氧化酶PPO)inhibitoraciflourfen雜草焚,fomesafen虎威,PhotosystemIelectrondiverters:paraquat百草枯87第87頁5.CellMembraneDisruptionThecellmembranedisruptersareprimarilynontranslocatedherbicidesthatarelightactivated.Paraquat(百草枯)anddiquat(敵草快)arerelativelynonselectivechemicalsusedtocontrolallexistingvegetationandaspreharvestdesiccants.Theseherbicidesquicklyformhighlyreactivecompoundsintheplantsthatrupturecellmembranes,causingthefluidstoleakout.88第88頁5.CellMembraneDisruptionThoroughspraycoverageisessentialforgoodpostemergenceweedcontrol.Becausetheyarenottranslocatedtotheroots,theseherbicidesareineffectiveforlong-termperennialweedcontrol.89第89頁5.SymptomologyRapidyellowingfollowedbydesiccationofaffectedplanttissueSymptomsgenerallyappearfirstonleaftips．Driftoroff-targetapplicationmayshowspeckledleafburn90第90頁5.SymptomologyBlazerInjuryonPeanutValorInjuryonPeanut91第91頁5.Symptomology92第92頁6.GrowthregulatorherbicidesTheseherbicidesmimicnaturalgrowthhormones,andthus,upsetthenaturalhormonebalanceinplants.Theyaffectseveralplantprocessessuchascelldivision,cellenlargement,proteinsynthesisandrespiration.93第93頁6.GrowthregulatorherbicidesThekillingactionofgrowth-regulatingchemicalsisnotcausedbyanysinglefactor,butratherbythedisruptionofseveralgrowthprocessesinsusceptibleplants.2,4-Disverysensitivetocottonplant94第94頁6.GrowthregulatorherbicidesSyntheticAuxins:2,4-D,MCPA(2甲4氯)AuxinTransportInhibitors:Diflufenzopyr(氟吡草腙)95第95頁6.SymptomologyBroadleafplantstemtwistingandcurlingLeavesonbroadleafplantsexhibitcupping,crinkling,strapping,ordrawstringeffectSymptomsongrassplantsincludeleafrolling,crinkling,bracerootfusionandmalformation.Also,flowersterilityandmissinggrainincrops.96第96頁6.SymptomologyMalformedbracerootsBlastedgrainheads97第97頁7.SeedlingGrowthInhibitorsSeedlinggrowthinhibitorsinterferewithnewplantgrowth,therebyreducingtheabilityofseedlingstodevelopnormallyinthesoil.Herbicidesinthesefamiliesmustbesoil-applied.Theseherbicidesareonlyeffectiveonseedlingofannualorperennialweeds.98第98頁7.SeedlingGrowthInhibitorsTheseherbicidesincludebothseedlingrootinhibitorsandshootinhibitors.(1)Therootinhibitorsinterruptcelldivision(mitosis)stoppingrootgrowthinseedlingplants.(2)Theshootinhibitorsdisruptproteinsynthesis,celldivision,cellenlargementandweakencellmembranes.(3)Themicrotubuleassemblyinhibitor.99第99頁7.SeedlingGrowthInhibitorsTheseedlingshootandrootinhibitors(acetamides,suchasalachlor甲草胺,acetochlor乙草胺,butachlor丁草胺)Acetamide(乙酰胺)herbicidesareusedpreemergenceorwithshallowsoilincorporationtocontrolannualgrassesandsomebroadleafweedsinavarietyofcrops.Theacetamidesdonotcontrolemergedplants.100第100頁7.SeedlingGrowthInhibitorsTheprimarysiteofabsorptionandactionoftheseherbicidesonbroadleafspeciesistheroots,whiletheprimarysiteofabsorptionandactionongrassspeciesistheemergingshoot.101第101頁7.SeedlingGrowthInhibitorsTheacetamidesarenotreadilytranslocatedintheplant,soherbicideplacementandavailabilityareimportant.Themechanismofactionoftheacetamideshasnotbeenwelldefined,butappeartointerferewithnormalcellulardevelopmentinseedlingplants.(克制發(fā)芽種子α-淀粉酶及蛋白酶旳活性)102第102頁7.SeedlingGrowthInhibitorsThemicrotubuleassemblyinhibitor:Dinitroaniline(二硝基苯胺):trifluralin(Treflan)氟樂靈Dinitroanilineherbicidesaregenerallyappliedpreplantincorporatedtocontrolannualgrassesandsomebroadleafweedsinmanycrops.Trifluralinneedtobeincorporatedtoavoidphotodecompositionandvolatilitylosses.103第103頁7.SeedlingGrowthInhibitorsThedinitroanilineherbicidesareabsorbedbybothrootsandshootsofemergingseedlings,butarenotreadilytranslocated.Theemergingshootistheprimarysiteofabsorptionandactionongrassspecies.104第104頁7.SeedlingGrowthInhibitorsTheseherbicides(dinitroaniline)aremitoticpoisonsthatinhibitcelldivision.Thus,themeristematicregions,suchasthegrowingpointsofstemsandroots,aremostaffected.Selectivitymaybebasedonmetabolism,aswellasherbicideplacementandtypeofemergenceofthegrassspecies.105第105頁7.SymptomologyofRootInhibitorsRootsonsusceptibleplantswillbestubbyandthick,especiallylateralrootsRootlimitationmaycausestuntingofplantsandphosphorusdeficiencysymptomsBroadleafplantsmayhaveswollenhypocotyls(胚軸)106第106頁7.SymptomologyofRootInhibitorsProwlInjuryonCorn107第107頁7SymptomologyofshootInhibitorsGrasscropsmayleafoutunderground,leavesmayexhibitimproperleafunfurling,andcrinklingAffectedcropsmayshowerraticstandandheightBroadleafplantsmayexhibitleafpuckeringoradrawstringeffect108第108頁7SymptomologyofshootInhibitorsDualInjuryonFieldCorn109第109頁PartIII:MajorHerbicideThispartissupplementarymaterials.110第110頁PartIII:MajorHerbicide2,4-Disacolorless,odorlesspowderusedasaherbicide.Therearemanyformsorderivativesof