除草劑毒理學(xué)

HerbicideToxicology202023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(chóng)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第1頁(yè)HerbicideToxicologyPartI:Introduction,definition

FactorsaffectingitsactivityAbsorptionandTranslocationHerbicideMetabolismPartII:ModeofAction2第2頁(yè)P(yáng)artIIntroductionAherbicideisapesticideusedtokillunwantedplants.Herbicidesarechemicalsthatinhibitorinterruptnormalplantgrowthanddevelopment.Weedicide

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

soil-appliedherbicidesundercoolconditionsthan

underwarmtemperaturesbecauseplantemergence

isdelayedandmetabolismisslowed.Ontheother

hand,extremelyhightemperaturessometimes

increasecropinjurysimplybyplacingtheplant

undermultiplestresses.16第16頁(yè)1.Factorsaffectingherbicideactivity3).SoilcharacteristicsSoilcharacteristicsaffectingherbicideactivityaretexture,organicmatter,andpH.17第17頁(yè)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(yè)1.Factorsaffectingherbicideactivity3).Soilcharacteristics：Soiltexture:Atthesametime,thechanceofcropinjuryisgreateroncoarse-texturedsoilslowinorganicmatterbecauseahigherproportionoftheappliedherbicideisavailableforplantuptake.Soil-appliedherbicideratesmayneedtobeadjustedaccordingtosoiltextureandorganicmattercontent.19第19頁(yè)1.Factorsaffectingherbicideactivity3).Soilcharacteristics：SoilpH:SoilpHinfluencestheavailabilityandpersistenceofcertainherbicidesinthesoil.SoilpHcanaltertheionicnatureoftheherbicidemolecule,whichinfluencesadsorption,solubility,andrateofherbicidebreakdown.20第20頁(yè)1.Factorsaffectingherbicideactivity3).Soilcharacteristics：SoilpH:Thetriazineherbicides(atrazine莠去津)andsomeofthesulfonylureaherbicides(Amber醚苯磺隆,)aremoreactiveandmorepersistentinhighpHsoils(>7.0)thaninlowpHsoils.21第21頁(yè)1.Factorsaffectingherbicideactivity4)EnvironmentalconditionsEnvironmentalconditionscanhaveatwo-foldeffectontheperformanceofpostemergenceherbicides.Higherhumidityandfavorabletemperaturesgenerallyresultingreaterherbicideabsorptionandactivityinplants.22第22頁(yè)1.FactorsaffectingherbicideactivityEnvironmentalsoinfluencesherbicideefficacy

byaffectingplantgrowth.Plantsaregenerally

mostsusceptibletopostemergenceherbicideswhen

activelygrowing.Extremeenvironmentalconditions

thatslowplantgrowthandthickenleafcuticlesoften

increaseplanttolerancetoaherbicide.23第23頁(yè)1.FactorsaffectingherbicideactivityCropinjuryfromaherbicide,however,canincreaseduringpoorgrowingconditionsbecauseofslowermetabolismanddetoxificationoftheherbicide.24第24頁(yè)1.FactorsaffectingherbicideactivityThus,ifcroptoleranceisbasedontheabilityofthecroptorapidlymetabolizetheherbicide,thepotentialforcropinjurymayincreaseandweedcontroldecreaseifaherbicideisappliedwhenplantsarenotactivelygrowing.25第25頁(yè)1.FactorsaffectingherbicideactivityForthisreason,mostherbicidelabelscautionagainstapplicationduringextremeenvironmentalconditions.26第26頁(yè)1.Factorsaffectingherbicideactivity5)PlantsAnnualplantsareusuallymoresusceptibletoherbicideswhentheyaresmallthanwhentheyaremature.Astheymature,plantsdevelopthickerwaxlayersonleafsurfaces,reducingherbicideabsorption.27第27頁(yè)1.Factorsaffectingherbicideactivity5)PlantsEstablishedperennialweedstendtobemoresusceptibletoherbicidesifappliedduringtheearlyfloweringstageofgrowthortoactivelygrowingplantsinthefall,probablybecauseapplicationatthesetimesresultsinthegreatesttranslocationoftheherbicidetotheroots.28第28頁(yè)2.Absorption,TranslocationA)Foliarabsorption:cuticlewax(lipophilic):no-polarCuticlecutin(角質(zhì),hydrophilic):polarPectin(膠質(zhì)):hydrophilic29第29頁(yè)Foliarabsorption30第30頁(yè)Foliarabsorption31第31頁(yè)a).FoliarabsorptionAbsorptionoffoliar-appliedherbicidesviathestomata(氣孔)canalsobeanimportantrouteofentry.32第32頁(yè)a).FoliarabsorptionSprayadjuvantsoradditivesoftenimprovesprayretentionandabsorptionbyplantfoliagebyreducingthesurfacetensionofthespraysolution,allowingthespraydroplettospreadmoreevenlyovertheleafsurface.33第33頁(yè)a).Foliarabsorption34第34頁(yè)a).FoliarabsorptionHerbicideabsorptionmaybefurtherenhancedbyinteractingwiththewaxycuticularlayerontheleafsurface.35第35頁(yè)a).FoliarabsorptionSprayadjuvantscanincreaseweedcontrol,butpotentiallycanreduceselectivitybyincreasingthesprayretentionandherbicideabsorptionbythecropmorethanbytheweed.Thus,sprayadjuvantsshouldbeusedonlyifrecommendedontheherbicidelabel.36第36頁(yè)b).TranslocationinplantsContactherbicidesarenottranslocated.Contactherbicidesgenerallyareineffectiveforlong-termperennialweedcontrol.Systemicherbicidescanbetranslocatedtootherpartsoftheplanteitherinthexylem(木質(zhì)部)orthephloem37第37頁(yè)b).TranslocationinplantsThexylemisnonlivingtissuethroughwhichwaterandnutrientsmovefromtherootstotheshootsandleavesofplants.Translocationinthexylemisonlyupwardandoutwardinplantsfromtherootstotheleavesandleafmargins.Phloemisaliving,conductingsysteminwhichmaterialscanmovebothupwardanddownward.38第38頁(yè)Translocation39第39頁(yè)b).TranslocationinplantsHerbicidescanbetranslocatedinthexylem,thephloem,orboth.Herbicidestranslocatedonlyinthexylemaremosteffectiveassoil-appliedorearlypostemergencetreatmentsbecausetranslocationisonlyupward.Atrazine(莠去津)isagoodexampleofaherbicidethatistranslocatedonlyinthexylem.40第40頁(yè)b).TranslocationinplantsPhloemtranslocatedherbicidesthatmovedownwardandsuppressrootandrhizome(根莖)growth,aswellastopgrowth,providethebestperennialweedcontrol.2,4-Disexampleofsystemicherbicidesthatwilltranslocateinthephloemandprovidegood,long-termcontrolofcertainperennialweeds.41第41頁(yè)3.HerbicideMetabolismMetabolismisoneofthemostimportantwaysaplantcanescapethetoxiceffectsofaherbicide.Herbicide-tolerantplantsoftenhavetheabilitytometabolizeorbreakdownthechemicaltononactivecompoundsbeforeitcanbuilduptotoxiclevelsatthesiteofaction.42第42頁(yè)3.HerbicideMetabolismSusceptibleplantsareunabletodetoxifyherbicides.Selectivityofmanyherbicidesisbasedondifferingratesofmetabolism.Metabolismcanbereducedincertainenvironmentalconditionssuchascoldweather.Reducedmetabolismofanherbicidecanbethecauseofcropinjury.43第43頁(yè)4.AlteredSiteofActionAnalteredsiteofactioncanresultindramaticresistancetoaherbicide.Analteredsiteofactionreferstogeneticallydifferentplantbiotypesthathaveastructurallyalteredsiteofactionthatpreventsherbicidebindingandactivity.44第44頁(yè)4.AlteredSiteofActionAtrazine(莠去津)isineffectiveonresistantbiotypebecauseaconformationalchangeinthechloroplastpreventsitfrombindingatthesiteofaction.45第45頁(yè)P(yáng)artII:HerbicideModeofActionHerbicidescanworkatvarioussitesinplants.Theygenerallyinterferewithaprocessessentialfornormalplantgrowthanddevelopment.Herbicidescanbeclassifiedbysiteofactionbasedonhowtheyworkandtheinjurysymptomstheycause.46第46頁(yè)P(yáng)artII:HerbicideModeofActionTobeeffective,herbicidesmust1)adequatelycontactplants;2)beabsorbedbyplants;3)movewithintheplantstothesiteofaction,withoutbeingdeactivated;4)reachtoxiclevelsatthesiteofaction.47第47頁(yè)P(yáng)otentialSitofActionPhotosynthesis(food)Respiration(energy)Aminoacids(proteins/growth)Lipids(cellmembranes)Pigments(energy/lightcapture)Mitosis(celldivision)48第48頁(yè)P(yáng)artII:HerbicideModeofAction1).PhotosynthesisInhibitors2).PigmentInhibition3).AminoAcidSynthesisInhibition4).LipidSynthesisInhibition5).CellMembraneDisruption6).GrowthRegulators7).SeedlingGrowthInhibitors49第49頁(yè)50第50頁(yè)1.PhotosynthesisInhibitorsPhotosyntheticinhibitorherbicidescontrolmanybroadleafandsomegrassweeds.Plantsarenotaffectedbytheherbicideuntilaftertheyemergeandbeginphotosynthesis.51第51頁(yè)1.PhotosynthesisInhibitorsPhotosynthesisinhibitorsshutdownthephotosynthetic(foodproducing)processinsusceptibleplantsbybindingtospecificsiteswithintheplant'schloroplasts.Inhibitionofphotosynthesiscouldresultinaslowstarvationoftheplant.52第52頁(yè)1.PhotosynthesisInhibitorsHowever,theplantexperiencesamorerapiddeaththatisbelievedtobeduetotheproductionofsecondarytoxicsubstances.Susceptibleplantstreatedwithaphotosyntheticinhibitordiefromabuildupofhighlyreactivemoleculesthatdestroycellmembranes.53第53頁(yè)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(yè)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第55頁(yè)1.PhotosynthesisInhibitorsTheselectiveactionoftriazine(三嗪類,如莠去津)herbicidesisprimarilydeterminedbydifferentialmetabolism.Plantspeciessuchascornandsorghumpossesstheglutathione-S-transferase(GST)enzymeandcanselectivelymetabolizetriazineherbicidesintonontoxicsubstances.56第56頁(yè)1.PhotosynthesisInhibitorsSymptomologyInterveinalorveinal(葉脈)yellowingfollowedbydeathofplanttissuefromleafmarginsinwardPostemergenceapplicationscauserapidburningofplanttissueCropstoleranttopostappliedPI’smayexhibitspottedleafyellowingorbronzing57第57頁(yè)1.PhotosynthesisInhibitorsSymptomBladex草凈津;百得斯

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