农学类专业英语电子版 34页

ACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT1FUNDAMENTALMETHODSINLIFESCIENCEHowisitthatscientistsprobesoskillfullyintothemonumentoflifeanddiscoversomuchaboutitsfoundations?Whatisitabouttheirmannerofthinkingthatyieldssuchpreciseresults?Thescientificmethodisaformalizedwayofansweringquestionsaboutcausationinthenaturalworld.Inprinciple,thescientificmethodhasthreemainsteps(althoughinpracticescientistsworkinmanydifferentways).Thefirststepistocollectobservations,phenomenawhichcanbedetectedbythesenses(vision,hearing,smell,taste,andtouch).Observationscanbealsomadeindirectly,throughuseofspecialequipment(suchasamicroscope)thatextendedtherangeofperception.Withpractice,wecanbecomeskilledatmakingsystematicobservations.Thismeansfocusingoneormoresensesonaparticularobjectoreventintheenvironment,andscreeningoutthe“backgroundnoise”ofinformationthatprobablyhasnobearingonourfocus.Second,thescientistthinksofhypothesis,ideasaboutthecauseofwhathasbeenobserved.Thethirdstepisexperimentation,performingtestsdesignedtoshowthatoneormoreofthehypothesisismoreorlesslikelytobeincorrect.Hypothesizingmeansputtingtogetheratentativeexplanationtoaccountforanobservation.Noscientistcanputforwardanideaanddemandthatitbebelievedastrue,noquestionsasked.Inscience,therearenoabsolutetruths.Thereareonlyhighprobabilitiesthatanideaiscorrectinthecontextofobservationsandtestsmadesofar.Insteadofabsolutes,thereissuspendedjudgment.Thismeansahypothesisistentativelysaidtobevalidifitisconsistentwithobservationsathand.Youwon’t(orshouldn’t)hearascientistsay,“thereisnootherexplanation!”Morelikelyyouwillhear,“Basedonpresentknowledge,thisexplanationisourbestjudgmentatthemoment.”Oftentheweightofevidenceissoconvincingthatthehypothesisbecomesacceptedasatheory:acoherentsetofideasthatformageneralframeofreferenceforfurtherstudies.Inscience,theword“theory”isnotusedlightly.Itisbestowedonlyonhypothesisthatcanberelieduponwithaveryhighdegreeofconfidence.Testingthehypothesisthroughexperimentsisattheheartofscientificinquiry.Experimentsmustbedesignedsothattheirresultsareasunambiguousashumaningenuitycanmakethem.Forthisreason,experimentshavetoincludecontroltreatmentsaswellasexperimentaltreatments.Thetwodifferonlybythefactors(s)inwhichyouareinterested.1\nACONCISETEXTBOOKOFAGRICULTURALENGLISHCollectingandorganizingtestresultsisanecessaryprocessinbiologicalexperiments.Datatablesorgraphsareusedtoorganizeanddisplayinformationforanalysis.Graphsareespeciallyusefulinillustratingtrendsofpatterns.Dataanalysisislessmechanicalandmoreconceptualthancollectingandorganizingtheinformation.Often,statisticaltestsareusedtodetermineifdifferencesbetweenexperimentaldataandcontroldataaresignificantorarelikelydueonlytochance.Ifitcanbearguedthatthedifferencesareduetochanceonly,thenitcanalsobearguedthattheindependentvariablehadnoeffect.Generalizingfromtestresultsrequirescarefulandobjectiveanalysisofthedatagathered.Usually,thehypothesisundertestisacceptedorrejectedonthebasisofconclusionsdrawn.Astatementiswrittenaboutwhatnewinsights(ifany)havebeengainedintotheoriginalproblem.Apparenttrendsarenotedwhenthesamedataappearintestresultsgatheredoveraperiodoftime.Often,furtherquestionsandhypothesisareposedinanattempttoguideadditionalstudiesoftheproblem.Newwordsandexpressionsprobev.探索convincinga.令人信服的monumentn.殿堂，纪念馆coherenta.相干的，连贯的formalizev.使……成为正式的bestow(on)v.赠与，授予causationn.起因，原因attheheartof在……核心observationn.观察（结果inquiryn.探索，探究，询问microscopen.显微镜unambiguousa.清楚的，明确的perceptionn.感知能力，感觉ingenuityn.智慧，机灵systematica.系统的illustratev.说明screenout排除mechanicala.无思想的，呆板的havenobearingon与……无关conceptuala.概念的，观念的experimentationn.实验，试验independentvariable自变量，处理因子moreorless差不多，大致insight(into)n.领悟，深刻的了解hypothesizev.提出假说posev.提出（问题），引起puttogether组织suspendv.使悬而未决tentativea.暂时的，试探性的judgmentn.判断，评价2\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT2ACCOMPLISHMENTSINPLANTBREEDINGPlantbreedershavedevotedconsiderableattentiontobreedingforyield.Theseprogramsusuallyhaveemphasizedselectionforhigheryieldsbasedonyieldtestingresults.Itisalsotrue,however,thatplantbreedershavefordecadessoughttoimproveyieldbymanipulatingwhatareoftentermedphysiologicalcomponentsofyield.Inthissectionwegivetwoexamplesofimprovementsincropplantsresultingfromselectionofdesirableplanttypes.Theseexamplesdeservespecialattentionbecausetheyinvolvewheatandrice,whichrankfirstandsecondintheworldinprovidingfoodforthehumanpopulation.Inthesecrops,breedershaveselectednewgenecombinationsandnewplanttypesthatarehighlyproductiveunderawiderangeofgrowingconditions,especiallywhenfertilityishigh.RiceBreedingThedevelopmentofshort-staturericevarietiesattheInternationalRiceResearchInstitute(IRRI)inthePhilippinesbeganinthe1960sfollowingobservationsthatshort-strawedvarietiesyieldedmorethanthetaller,leafierindicavarietieswhengivennitrogenfertilizer.Anumberofcharacterswereassociatedwithgenerallyhigheryieldsandthenitrogenresponse.Theresponsiveselectionswereshortandhadmanytillersandgoodresistancetolodging.Theirleaveswereshort,thick,relativelynarrow,erect,darkgreen,andremainedfunctionaluntilshortlybeforeharvest.Subsequentgeneticstudiesrevealedthatasinglegenecontrolledmanyoftheleafcharactersaswellasheightandtillering.Twoadditionalcharacters,earlymaturityandhighfloretfertility,thoughnotcontrolledbytheabovementionedgene,wereincorporatedintothegeneticpackagethatcontributedtohighyieldundernitrogenfertilization.InbreedingfornewplanttypesatIRRI,awell-adaptedtropicalindicavarietieswerecrossedwithintroducedvarietiesofeitherjaponicaorindicatypes,whichservedassourcesofthedesirablenewtraits.Observationofpopulationsresultingfromthesecrossesindicatedthatthedesirable,short,lessleafyplantswerenotcompetitiveandhencewerebeingeliminatedfromthebreedingpopulations.Theshort,lessleafyplantscompeteverypoorlyinthemixturewithtallplants,butinpurestandstheshortplantsyieldmorethanthetall.Consequently,amassselectionprocedureisusedtoincreasetheproportionofdesirableshortplantsinthebreedingpopulations.The3\nACONCISETEXTBOOKOFAGRICULTURALENGLISHpopulationsareplantedsparselysothatthetall,leafyplantscanbeeliminatedfromthepopulation.Seedharvestedfromtheremainingplantsisusedforthenextgeneration.Selectionagainstthetallleafyplantsiscontinuedforseveralgenerationsuntilalltheremainingplantsareshort.Thentheseedfromindividualplantsisincreasedandconventionalyieldtestingisinitiated.Manyoftheshortplantswiththecombinationofusefulcharacteristicsdescribedabovehavebeenhighlyproductive.Oneplant,IR-8,gainedworldwiderecognitionbecauseofitsveryhighyields,especiallyinresponsetonitrogenfertilization.SemidwarfWheatIn1935awheatselectionofhybridorigin,‘Norin10’,wasreleasedforuseinJapan.Norin10was1/2to2/3astallascommonwheatvarietiesandhadmoreheads.IntheUSA,Norin10wasnotusefulasavariety,butasaparentincrossesitprovidedgenesthatstartedarevolutioninwheatbreeding.Onebreeder,O.A.Vogel,aUSDAplantbreederatPullman,Washington,crossesNorin10withordinarywheatssuchas‘Brevor’,FromthesecrossescamethefirsthighlyproductivesemidwarfwheatsintheUSA.Thefirstnewsemidwarf,‘Gaines’,andacloselyrelatedsemidwarf,‘Nugaines’,soonachievedgreatpopularity,andotherwheatbreedersbegantoconcentrateonsemidwarfwheat.N.E.Borlaug,winnerofaNobelPeacePrizeinpartforhisresearchonwheat,madeextensiveuseoftheWashingtonwheatsandtheNorin10genes.By1986semidwarfwheatswerebeinggrownsuccessfullyintheUSAandinmorethan20foreigncountries.Asmanyasadozencharacterspotentiallycontributedirectlytohighyieldinshort-staturerice.However,lessisknownaboutthephysiologicalbasisforhighproductivityinthesemidwarfwheats.Semidwarfwheatsaremoreresistanttolodgingthantheirtallercounterparts,butlodgingresistanceisnottheentirereasonfortheyielddifferencebecausesemidwarfvarietiesareoftensuperiortotallvarietieswhenlodgingdoesnotoccur.Manyofthesemidwarfwheatshavemoreheadsperunitareathantallerwheatsandahigherratioofgraintostraw(highereconomictobiologicalyield).Theleavesofmanyproductivesemidwarfwheatsaregenerallysimilartothedroopy,wide,andlongleavesoftallerwheats.Consequently,theproductivesemidwarfwheatsandshort-staturericesdiffergreatlyinleafcharacteristics.Whateverthebasisforthehigheryieldsinthenewriceandwheatvarietiestheirsuperioritysuggeststhatcropscanbemademoreproductivebymodifyingtheirgeneralform.4\nACONCISETEXTBOOKOFAGRICULTURALENGLISHNewwordsandexpressionsaccomplishmentn.成就，成绩tropicala.热带的devote…to贡献，奉献crossv.,n.杂交decaden.十年introducev.引进manipulatev.调节，操纵japonican.粳physiologicala.生理（学）的traitn.(相对)性状componentn.构成因子competev.竞争desirablea.有利的，理想的mixturen.混合（物）planttype株型purestand单一群体populationn.人口，群体massselection混合选择fertilityn.肥力，育性sparselyadv.稀short-stature矮秆generationn.世代strawn.麦秆，稻草semidwarfa.半矮秆的indican.籼hybridn.杂种nitrogenn.氮headsn.穗charactern.性状varietyn.品种beassociatedwith与…联系起来parentn.亲本responsen.响应，反应breedern.育种家responsivea.有响应的ordinarya.普通的，一般的selectionn.选系concentrate集中（精力）于tillern.,v.分蘖droopya.披（弯曲或下垂）floretn.小花modifyv.修改，改良incorporatev.掺合formn.形态well-adapteda.适应性好的5\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT3CROPPRODUCTIONProductionoffoodisaproblemofmajorconcernintheworldtoday.Theworld’sfoodsupply,grosslyinadequateinmanycountriestoday,willneedtobeincreasedgreatlyintheyearsaheadifthebasicnutritionalrequirementsofanexplosiveworldpopulationaretobesatisfied.Otherwise,thespecterofhunger,malnutrition,andfamine,alreadyarealitywithtwo-thirdsoftheworld’speople,willcontinuetospreadandgrow,andthenutritionalgapbetweenthedevelopedandtheunderdevelopedcountrieswillcontinuetowiden.Fieldcropsprovidetheprincipalsourceoftheworld’sfoodsupply.Over50%ofthehumanfoodconsumedcomesdirectlyfromsevencerealgrains;over40%comesfromriceandwheat.Otherfoodsofvegetableoriginincludetherootcrops,oilseeds,vegetables,fruits,andnuts.Forageandgraincropsutilizedaslivestockfeedmaybeconsumedindirectlyasmeat,milk,oreggs.Fieldcrops,inadditiontotheirproductionforhumanfoodandlivestockfeed,areutilizedforfiber,fuel,plastics,stimulants,andmanyothercommercialuses.Forthesepurposeswegrowcropslikecotton,jute,fiberflax,tobacco,soybeans,linseedflax,andcorn.Thepotentialforutilizingplantsassourcesofenergyhasbeenlittleexploited.Whenthishappenstheproductionoffoodmaybeplacedfurtherinjeopardy.Toincreasecropproduction,fourimportantinputsneedmajorattention:water,fertilizer,pestcontrol,andcropvariety.Thefirstthree-water,fertilizer,andpestcontrol-relatetoculturalpracticesthatprovideamoredesirableenvironmentinwhichtogrowthecrop.Thefourth-thecropvariety-relatestotheinherentabilityoftheplanttoproducewithintheenvironmentprovided.Inotherwords,moreproductiveplantsandgreaterfoodproductionmayresultbothbyimprovingtheenvironmentforcropgrowthandbyimprovingtheheredityofthecrop.Improvingtheheredityofacrop,statedmostsimply,isaccomplishedbybreedingbettervarieties.Hereditaryimprovementsincropvarietiesaremadeinvariousways.Theimprovedvarietymaybemorevigorousinitsgrowth,thusproducingahigheryieldthroughthemoreefficientuseofthesunlight,carbondioxide,water,andplantnutrientsavailabletoit.Itsstructuremaybealteredsothatitwillstanduntilharvestwithlesslossfromlodgingorshattering.Plantsmaybeselectedwithmoretolerancetostress,sothatasatisfactoryyieldwillbeharvestedwhenenvironmentalconditionsoverwhichthegrowerhasnocontrolareunfavorable.Toaccomplishthisobjectivethebreederstrivesforearlymaturity,6\nACONCISETEXTBOOKOFAGRICULTURALENGLISHincreasedwinterhardiness,orresistancetoheat,drought,disease,andinsectdamage.Culturalpracticestoincreaseyield-fertilization,irrigation,applicationofchemicalsforpestcontrol-mustberepeatedwitheachnewcroppingseason.Hereditaryimprovementsaremoreorlesspermanent;byplantingimprovedvarieties,thebenefitsmaybereapedoverandover.Maximumcropproductioncannotbeachievedeitherbyuseofsuperiorculturalpracticesorbyplantingimprovedvarietiesalone.Withoutgoodproductionpracticesthehighyieldpotentialofasuperiorvarietywouldbylargelywasted.Neitherwillmaximumbenefitsberealizedfromgoodproductionpracticesunlessapotentiallyhighyieldingvarietyisgrown.Newwordsandexpressionsinadequatea.不足的vigorousa.茂盛的explosivea.爆炸性的carbondioxide二氧化碳spectern.幽灵,妖怪,缭绕心头的恐惧（或忧虑等）lodgingn.倒伏malnutritionn.营养不良shatteringn.裂荚（果）faminen.饥荒stressn.胁迫consumev.消耗，消费satisfactorya.令人满意的stimulantn.兴奋剂unfavorablea.不利的nutn.坚果strivefor为实现…而努力juten.黄麻maturityn.熟期，熟性flaxn.亚麻winterhardiness越冬性linseedn.亚麻籽resistancen.抗性injeopardy处于受损失的危险境地culturalpractice栽培措施inherenta.内在的，遗传的permanenta.永久的productivea.高产的reapv.获得heredityn.遗传maximuma.最大的hereditarya.遗传的superiora.优越的7\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT4WHATSHOULDAMODERNPLANTBREEDERLEARN?Botany.Plantbreedersshouldbeaccomplishedbotanistsinordertounderstandthetaxonomy,anatomy,morphology,andreproductionoftheplantswithwhichtheywork..GeneticsandCytogenetics.Theplantbreederneedsathoroughunderstandingofthemechanismofheredityinplantssincemodernplantbreedingmethodsarebasedonaknowledgeofgeneticprinciplesandchromosomebehavior.Thisknowledgeisbeingextendedtothemolecularlevelwithadvancesinbiochemicalgenetics.PlantPhysiology.Varietyadaptationisdeterminedbytheresponseofplantstotheirenvironment,whichincludestheeffectsofheat,cold,drought,andsoilnutrientresponse.Theplantbreederstrivestomakeinherentmodificationsofphysiologicalprocessesthatwillenabletheplanttofunctionmoreefficiently.PlantPathology.Plantdiseasereducescropyields.Hostresistanceisanimportantmeansofcombatingmanyplantdiseases.Evaluationoftheresponseoftheplantgenotypetoinfectionbythepathogenisanessentialpartofbreedingforhostplantresistance.Entomology.Biologicalcontrolofinsectpopulationsbybreedingforinsectresistanceisanimportantwayofreducinginsectdamageincropplants.PlantBiochemistry.Inherentimprovementsinthenutritivevalueofacropvarietyaregivenattentionbytheplantbreeder.Suitabilityforindustrialutilizationoftendeterminesthemarketdemandforaparticularvarietyofacrop.Thisincludessuchcharacteristicsasthemillingandbakingqualitiesofawheatvariety,thecookingandeatingqualitiesofaricevariety,thefiberqualitiesofacottonvariety.Biochemicalgeneticsiscontributingtowardabetterunderstandingofthestructureandfunctionofthegene.Statistics.Theplantbreedercomparestheperformanceofmanygeneticallydifferentstrains.Soundfieldplottechniquesandsuitablemethodsforstatisticalanalysesofdataarenecessarytoobtainreliableresultsandtointerprettheresultscorrectly.Theapplicationofstatisticalprocedureshasprovidedforabetterunderstandingoftheinheritanceofquantitativecharacteristicsandforpredictingthepossiblegeneticadvancethatmaybeobtainedwithparticularsystemsofmating.Agronomy.Inadditiontoallofthese,thebreederoffieldcropsshouldbeasoundagronomist.Plantbreedersshouldknowcropsandtheirproduction.8\nACONCISETEXTBOOKOFAGRICULTURALENGLISHTheyshouldunderstandwhatthefarmerwantsandneedsinthewayofnewvarieties.Onlythenwilltheybeabletoevaluatecriticallythebreedingmaterialsavailabletothem,plananefficientbreedingprogram,anddirecttheirbreedingeffortstowardtheagronomicallyimportantobjectives.Thesesciencesarethetoolswithwhichtheplantbreederworks.Theplantgermplasmsavailabletothebreederaretherawmaterials.Thebreederusesknowledgeofthesesciencestofashionfromtherawmaterialsnewandimprovedvarietiesofcropplants,justasanengineerusesknowledgeofmathematics,physics,andchemistryintheconstructionofanewbridge,oramodernskyscraper.Itisapparentthatplantbreederscannotbespecialistsinallofthesefieldsofplantscience.Inthepracticeofplantbreedingtheyarenotworkingexclusivelyinanyofthem.Theworkofplantbreedersistoapplythewholeoftheirknowledgeofthesesciencesandtheirexperiencetowardthedevelopmentofsuperiorvarieties.Iftheyshouldneedadditionalinformationabouttheinheritanceofaplantcharacterwithwhichtheyareworking,oraboutatechniqueformeasuringtheresistanceofplantstosomeenvironmentalcondition,theymayconductexperimentstostudythosespecificproblems.Suchspecializedresearchisanadjuncttotheirplantbreedingactivitiesandtheinformationgainedmayhelpthemintheguidanceanddirectionoftheirbreedingresearch.Oftentimesabreedermaycombinetheoreticalexperimentationinoneormoreofthesefieldswithbreedingstudies.Thisbroadensunderstandingoftheseareasofknowledgeandtheirrelationtothebreeder’sparticularbreedingproblemsandisadesirableactivitytocarryoutinconjunctionwithabreedingprogram.Sincetheimprovementofanimportantfieldcroplikecorn,wheat,cottonusuallyinvolvesworkinseveralofthesefieldsofplantscience,themostrapidadvanceismadewhenateamofspecialistsingenetics,plantphysiology,plantpathology,entomology,andbiochemistryworkcooperativelywiththeplantbreeder.Thespectacularaccomplishmentsinplantbreedingareusuallytheresultofsuchteamwork.Specialknowledgeandexpertisemaythenbecoordinatedanddirectedtowardthedevelopmentofsuperioragronomicvarieties.Newwordsandexpressionsaccomplisheda.熟练的millv.研磨botanistn.植物学家bakev.烘烤9\nACONCISETEXTBOOKOFAGRICULTURALENGLISHreproductionn.繁殖qualityn.品质thorougha.彻底的，全面的performancen.表现genetica.遗传的strainn.品系chromosomen.染色体sounda.正确的，合理的，有能力的，可靠的moleculara.分子的fieldplot田间试验biochemicala.生物化学的statisticala.统计的adaptationn.适应性，适应inheritancen.遗传hostn.寄主quantitativea.数量的combatv.对抗，对付geneticadvance遗传进展evaluationn.评价，鉴定matev.交配genotypen.基因型systemofmating繁殖系统pathogenn.病原agronomistn.农艺学家controln.防治agronomicala.农艺的suitabilityn.适合（性）adjunct(to)n.附属品，附加物germplasmn.种质inconjunctionwith与…一道fashionv.做成，制造cooperativea.协作的，合作的skyscrapern.摩天大楼spectaculara.出色的，辉煌的，精彩的specialistn.专家exclusivea.排他的10\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT5SELECTIONANDBREEDINGMETHODSWheninitiatingabreedingprogramforaphysiologicaltrait,theobjectiveistocombinethephysiologicaltraitwithotherdesiredtraitsthathaveaccumulatedineliteselectionsorcommercialvarieties.Consequently,thebreedercommonlymakescontrolledcrossesinvolvingtwoormoreparentalvarieties.Threeselectionmethodscommonlyusedtomanipulateplantpopulationsinbreedingprogramsarereviewedbrieflyinthefollowingsections.MassselectionMassselectionreferstoaprocedureinwhichindividualplantsareselectedinheterogeneouspopulations.Theoriginalpopulationsmaybeobtainedthroughartificialhybridizationinvolvingtwoormoreparentalvarieties.Alternatively,theymaybeobtainedbymixingseedofdifferentsourcesandallowinginterplantpollinationtooccurnaturally.Seedfromselectedplantsineachgenerationorcycleofselectioniscompositedtoformanewheterogeneouspopulationandisusedtogrowthenextgeneration.Selectionmaybeforeasilyobservedcharacters,suchashigherorleafangle,orforcharactersthatrequireharvestandseedanalysis,suchasproteinoroilcontent.Thepopulationisexpectedtobeimprovedwitheachgenerationofselection.Theimprovedpopulationmaybeutilizeddirectlyasanewvariety,orplantspossessingdesiredcharacteristicsmaybeselectedandtheirseedincreasedtobecomeanewvariety.Athirdalternativeistoutilizetheimprovedpopulationasasourceofinbredlinesinahybridbreedingprogram.Thelikelihoodofsuccessusingmassselectiondependsonmanyfactors,includingwhetherthecropiscross-orself-fertilized.Inself-fertilizedcrops,littleintercrossingoccurstotheplantsbecomehomozygousatarapidrateandnewgenecombinationsareunlikelyafterafewgenerations.Incontrast,crossingnaturallyoccursbetweenplantsofcross-fertilizedcrops;thusheterozygosityismaintained,andnewgenecombinationsareformedeachgeneration.However,effectivenessofselectionisreducedbyone-halfincross-fertilizedascomparedtoself-fertilizedspeciesbecauseseedsborneoncross-fertilizedplantsandusedtoadvancetothenextgenerationreceiveone-halfoftheirgeneticcomplementfromarandom(unselected)maleparent.Anotherveryimportantfactorindeterminingthesuccessofmassselectionistheheritabilityofthecharacterunderselection.Traitssuchasyield11\nACONCISETEXTBOOKOFAGRICULTURALENGLISHhavelowheritabilityandarenotwellsuitedtomassselectionofindividualplants.However,massselectioncanbeeffectiveforhighlyheritabletraits.Forexample,itshouldbepossibletoeffectivelychangeleafarea,leafangle,orshapeandsizeofinflorescencebymassselection.PedigreeSelectionInpedigreeselectionbothfamiliesandplantswithinfamiliesareevaluated.Seedforthenextgenerationcomesfromindividualplants,andindividualplantprogeniesarekeptseparatethroughouttheseveralgenerationsofselection.ThenamepedigreeisappliedsinceitisusuallypossibletotracethelineageofaplantorlineinanadvancedgenerationbacktotheF2orF1plantfromwhichitwasderived.Pedigreeselectionisusedextensivelyinbreedingself-fertilizingcropsandindevelopinginbredlinesforuseasparentsofhybridvarieties.Plantmaterial(populations)forpedigreeselectionoftenisobtainedbycrossingparentalvarietiesthatpossessbetweenthemthetraitsandgenesdesiredinanewvariety.Wheneachparentishomozygous,theF1progenyplantsaregeneticallysimilar,andselectionisnoteffectiveinthisF1generation.IntheF2generationeachplantisgeneticallydifferent,anddesirableplantsareselected.EffectivenessofselectionintheF2generationdependsonmanyfactors,includingtheamountofgeneticvariationforthecharacterbeingselectedandtheinfluenceofenvironmentonthecharacter.AsageneralruleselectionintheF2generationisnotdonefortraitsoflowheritabilityorfortraitswhosemeasurementistime-consumingorexpensive.ThepatternofselectionfollowedissimilarintheF3,F4andF5generations.Inthesegenerations,thebestfamiliesarechosenfirst,andthenindividualplantswithintheelitefamiliesareselected.Seedfromtheselectedplantsisusedtogrowthefamiliesofthenextgeneration.Selectiononthefamilybasis,whichisfrequentlyveryeffective,isanimportantadvantageofpedigreeselectioncomparedtosomeotherselectionmethods.Eachgenerationaffordsarepeatedopportunityforfamilyselection.Pedigreeselectionismoreexpensivethanmassselectionbutthegainfromselectionmaymorethanoffsettheincreasedcosts.Also,plantbreedershavefoundwaystomechanizeplantingandharvestingsothatcostscanbekeptlow.FollowingtheF5generation,itiscustomarytobeginreplicatedtestingforyieldandotherlowlyheritabletraitssuchasmillingandbakingqualityinwheat.Yieldevaluationnormallyrequires3to4yearsbeginningwithpreliminarytrailsatoneortwolocations.12\nACONCISETEXTBOOKOFAGRICULTURALENGLISHBackcrossMethodThebackcrossmethodofbreedingdiffersinobjectiveandprocedurefromthemassandpedigreeselectionmethods.Theobjectiveinmostbackcrossprogramsistoimproveanexistingvarietyorinbredlinebyaddingadesirablecharacternotpossessedbythevariety.Theprocedureentailstransferringtheusefulcharacterfromadonorlinetothedesirablevarietyorinbredline.Thetransferisaccomplishedbymakingacrossbetweenthedesirablevariety,calledtherecurrentparent,andthedonorline.Repeatedcrosses(backcrosses)totherecurrentparentaremadewithprogenyselectedforthedesiredcharacterfromthedonor.Theproportionofthegenescomingfromthedonorvarietyisreducedbyone-halfwitheachbackcrosstotherecurrentnparent;afterncrossesandbackcrossestheproportionis(1/2).Thus,withsixbackcrossesaftertheoriginalcross,theproportionofgermplasmfromthe7donorparenttheoreticallyis(1/2)=1/128.Exceptforthegenetransferred,donorgenesarerapidlyreplacedbygenesoftherecurrentparent.Themostextensiveuseofbackcrossinghasbeentotransfersinglegenesfordiseaseresistanceintostandardvarieties.Theseprogramshaveshownthatitisgenerallypossibletotransferacharacterfromonelinetoanotherwhenonegenecontrolsthecharacterbeingtransferred.Backcrossingislesssuitableforcharacterscontrolledbymorethanoneortwogenes.Anotherimportantconsiderationinbackcrossbreedingistheextenttowhichallofthegenesfromtherecurrentparentarerecoveredafterrepeatedbackcrosses.Failuretorecoverallofthegenesoftherecurrentparentisseriouswhenundesirablegenesarecloselylinkedtothedonorgene.Theformulagivenabovedoesnotapplyforgeneslinkedtothegenebeingtransferred.Backcrossingmaybeofspecialinterestinbreedingforphysiologicaltraitscontrolledbyoneortwogenesfoundinotherwiseinferiorgeneticbackgrounds.Whenthisisthecase,thebackcrossingprocedurewouldbehelpfulinincorporatingthedesiredtraitintoagoodgeneticbackground.Newwordsandexpressionsinitiatev.启动complementn.需要的数额programn.程序，计划geneticcomplement遗传组成（分）accumulatev.积累maleparent父本eliten.精英，顶尖individuala.,n.个体（的）commerciala.商业的，商用的heritablea.可遗传的13\nACONCISETEXTBOOKOFAGRICULTURALENGLISHselectv.选择inflorescencen.花序heterogeneousa.异质的，不同源的pedigreen.系谱，家谱hybridizationn.杂交familyn.家（系），科interplanta.植物间的progenyn.后代pollinationn.授粉separatea.隔离的，分开的cyclen.轮，周期，循环traceback追溯compositev.混合，合成lineagen.血统，世系proteinn.蛋白质linen.系，家系contentn.含量derive(from)v.衍生，产生increasev.增加，繁殖hybridvarietyn.杂种品种hybridbreeding杂种选育patternn.模式，方式fertilizev.受精，施肥offsetv.补偿，抵消cross-fertilized自由授粉mechanizev.使…机械化self-fertilized自花授粉customarya.习惯上的，依照惯例的intercrossv.互交replicatev.重复，复制homozygousa.纯合的preliminarya.初步的combinationn.组合trialn.试验heterozygosityn.杂合（性）locationn.地点，位置bearv.结（实）backcrossn.,v.回交advancev.提升，进步originala.最早的，原始的entailv.涉及theoreticallyad.理论上transferv.转移standardvariety标准品种donorn.供体，提供者recoverv.回复，恢复recurrenta.周期性的，经常发生的linkv.连接，结合recurrentparent轮回亲本closelylinked紧密连锁proportionn.比例，部分geneticbackground遗传背景14\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT6MANASANEXPLOITEROFNATUREForperhaps3,000,000yearsormore,manlivedinreasonablebalancewiththeorganismsabouthim.Parasites,disease,andthedifficultsearchforfoodkeptman’snumberslowandhewasonequalfootingwithotheranimalswithinthenaturalsystem.Althoughheutilizedtheplantsandanimalsthatsurroundedhim,theextentofhisdepredationswaslimitedandreversiblesincehisnumberswerefew.Morethan10,000yearsagohowever,manlearnedtoselectandcultivateplants,aprogressivestepthathelpedfreehimfromthelaborofbaresubsistenceandallowedhimtoengageincreativeendeavorsandtocongregateineverlargergroupsformutualbenefits.Hisheightenedcapacityforreasoning,hismemory,andhisingenuityledhimtoimprovestillfurtherhiswell-being.Itwasthenthattheconsequencesofman’sactivitiesbegantoextendbeyondthebordersofhislimitedfieldsandtowns.HemayhaveextinguishedsuchPleistoceneanimalsasthewoollymammoth.Hisuseoffireontheprairiesappearstohavemaintainedgrasslandswhereotherwisetreesmighthavegrown.Thesmokefromthesefiresandfromextensiveslash-and-burnagriculturefilledtheskieswithhazelongbeforephotochemicalsmogeverstunghiseyes.Byhisingenuityandinventivenesshelearnedtoreleaseenergybyburningcoalandoil,tomanufacturemachinesthatwouldgreatlyamplifythelaborsofhishands,toworkmetalsandtoforgenewalloys,whileatthesametimeselecting,andcultivatingbettercropsandimprovinghisdomesticatedstockofanimals.Thesevariousskillsandpracticeseventuallyencouragedtheworld-wideproliferationofman.Mandiscoveredthebenefitsofminingthegreatoredeposits,pumpingthereservoirsofoil,diggingtherichcoalbedsfromcarboniferousstrata,plowingandplantingtheprairies,cuttingtheforests,andgenerallyhelpinghimselftotheabundantandapparentlylimitlessresourcesoftheworld.Intheprocesshebecamesedentaryratherthannomadic,heimprovedhishealth,extendedhislifespan,reducedhisworkingtime,addedleisurehours,livedmorecomfortably,increasedtheabundanceofhisfoodsupply,andincreasedinnumbersexponentially(10to100to1,000).Hecouldhunt,fish,harvest,andexploitwithoutconcernfortheconsequencestotheenvironment.Thensuddenly,verysuddenly,withinthemostrecentdecadesofman’stimeonEarth,hebegantorealizethatresourceswerelimitedandhastilyinstigatedsomeattemptstoconservetheenvironment.Still,hisbehaviourgenerallybeliedanyconvictionthatheshouldliveinaprudentsociety.Man’spopulation15\nACONCISETEXTBOOKOFAGRICULTURALENGLISHstilldoublesinnumberevery35years;hisdemandfordomesticproductsdoublesevery14years,andhisconsumptionofenergydoubles,intheUnitedStates,every8.5yearsandworldwideataslower,yetrapidlyincreasing,rate.Manmanufacturesexoticproductsthataregenerallynondegradable(i.e.,theydonotdecay)butarecarriedbythesedimentationcycletoaccumulateinthebottomsoflakes,rivers,andoceansorarepiledinrefuseheapsorarestrewnaboutthelandscape.Consideringthattheseproductsconsumeresourcesthatarenonrenewable,man’sfailuretorecyclethesematerialsmaybeseenasanactofirresponsibilitytowardtheneedsoffuturegenerations.Thecarelessandgreedyconsumptionofresourcesbyanygroupofpeoplecannotbejustifiedinthecontextoftheultimatewell-beingofmankind.WhenthefirstmenlandedontheMooninJuly1969andreportedduringthevoyagetheirviewsoftheplanetEarth,seenasalonely,isolated,utterlyself-dependentsatelliteoftheSunsuspendedinspace,theordinarycitizenbegantorealizehowlimitedandfinitehisspaceandresourcesreallywere.Thebiospherewasseenindeedasaverythinshell,protectedfromSumandspacebyaveilofairandsupportedbyafragileanddisturbedrockycrust.Coupledwiththisnewappreciationwastherealizationthattheworld’spopulationwasexpandingatanalarmingarte,aratethat,ifcontinuedforanothercentury,almostcertainlywouldmeanmassstarvation,pandemicoutbreaksofdisease,andgeneraldegradationofsociety.Itnolongerwasself-evidentthatmancouldmanagesuchacomplexsociety,keepitingoodhealth,andmaintainahighstandardoflivingindefinitely.Newwordsandexpressionsexploitv.开发，利用photochemicala.光化学的prasiten.寄生虫smogn.烟雾footingn.地位，基础，平衡stingv.刺伤，冒犯depredationn.（由攻击等造成的）破坏amplifyv.放大，增强cultivatev.栽培workv.定形，打造progressivea.前进的，进步的forgev.锻造barea.基本的，仅够的alloyn.合金subsistencen.生计，生存domesticatev.驯化、驯养endeavorn.尽力，努力stockn.原种，家畜，砧木congregatev.聚集proliferationn.（迅速的）繁殖mutuala.相互的oredeposit矿藏16\nACONCISETEXTBOOKOFAGRICULTURALENGLISHheightenv.加强，提高reservoirn.水库well-beingn.（健康、幸福等的）状况carboniferousa.产煤的，石炭纪的borern.钻孔器strata(pl.)n.层extinguishv.使…不复存在carboniferousstrata石炭纪Pleistocenea.更新世的sedentarya.久坐的woollya.毛的nomadica.游牧的，流浪的mammothn.猛犸exponentiala.指数的woollymammoth毛象exponentiallyad.slash-and-burn刀耕火种hastya.过于匆忙的，急急忙忙的hazen.薄雾instigatev.使…开始，怂恿exotica.吸引人的，漂亮的，引进的domestica.家务的，家用的，国产的degradablea.可降解的uttera.完全的，绝对的nondegradablea.不可降解的utterlyad.sedimentationn.沉积，沉淀suspendv.悬浮pilev.堆积finitea.有限的refusen.废物，垃圾biospheren.生物圈heapn.堆veiln.遮掩，罩strewv.撒crustn.硬的表面renewablea.可再生的appreciationn.评价，欣赏nonrenewablea.不可再生的pandemica.（全国或全世界）流行的recyclev.再生outbreakn.爆发，突然发生carelessa.粗心的self-evidenta.不言而喻的，明显的justifyv.证明是，正当的，有理的indefinitea.无限期的17\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT7BOTANICALCLASSIFICATIONSincethereisalargenumberoffiledcropplants,alogicalorderinarrangingvariousspeciesisessential.Whilegeneralplantmorphologyisnecessarytodescribeaspecies,thereproductivestructures(flowers)giveamorevalidandmuchmoreconstantreflectionofthebroadrelationshipsamongplants.Sincethebasicflowerstructureofaplantspeciesisrelativelyconstantandmuchlesssubjecttoenvironmentalvariation,itformsthebasisforthegeneralclassificationoffloweringplants,whichincludeourfieldcropplants.Whiletaxonomists,paleobotanists,andgeneticistscontinuetointeracttoproduceamorepreciseclassification,youshouldrecognizethattheLinnaeusconceptofclassifyingplantshasremainedrelativelyintactsincetheth18century.ItissafetopredictthattheSwedishphysician,CarlvonLinne(1708-1778),betterknownasLinnaeus,willcontinuetobecreditedforaworkablesystemofplantclassificationbasedonstructuraldifferencesandsimilaritiesinthemorphologyofreproductiveparts,theorgansleastlikelytobechangedbyenvironment.Linnaeusandhisassociatesarealsocreditedwiththedevelopmentofthebinomialsystemofnomentclature,whichdesignatesvariousorganismsbygenusandspecies.Insystematictaxonomy,closelyalliedspeciesareplacedtogetherinataxonomicunitcalledthegenus.Forexample,thegenusnameforallwheats,whetherhardredwinter,softredwinter,durum,hardredspringorwhite,isTriticum.However,thespeciesnamesaestivumandturgidumdistinguishbetweenspeciesofthegenusTriticum.Thespeciesisaunitcomprisedofsimilarorganismscapableofreproducingthemselves.Threeoffourcharacteristicsareusuallytheminimumnumberacceptablefordistinguishingaspecies.Suchdistinctionsmaybebehavioral,morphological,physiological,orecological.Durumwheats,whichdifferinchromosomenumberfromthecommon(aestivum)wheats,areusedformanufactureofmacroniandspaghetti.Commonwheatsareusedforcereal,bread,andpastry.AsearlyastheMiddleAgesscientistsrecognizedthataninternational,universal,scholarlylanguagewasneededsothattheycouldspeakofvariousorganismsinthesamemannerandstillbesurethattheyweretalkingaboutthesamebeing.DuringthiserathemostimportanttreatiseswerewritteninLatin.Today,Latinremainsastheacceptedlanguageforthescientificnamingofplantsandanimals.Itisadeadlanguage,andthereforeunchanging,which18\nACONCISETEXTBOOKOFAGRICULTURALENGLISHmakesitsuitableforinternationaluseinthescientificnomenclatureofplants.Thoughseeminglyabstracttothenewstudentoftaxonomy,scientificnameshavemeaning.Forexample,TrifoliumpratenseL.referstoredclover,andthewordTrifoliummeans“threeleaflets”whilethetermpratensemeans“ofmeadows”.Theletter“L.”citestheauthor,Linnaeus,whonamedredclover,Trifoliumpratense.Severaltaxabesidesthegenusandspeciesarequitenecessaryinpigeon-holingvariousplants.Whenstudyingthefollowingtable(omitted),notethemajortaxa(kingdom,division,class,order,family)andminortaxa(genus,species,andsometimessubspecies,race,andsubrace)ofthreecommoncropplants,namely,corn,soybean,andcotton.Themajortaxafromkingdomthroughclassarethesameforallcropplants.However,beginningwiththesubclass,majorchangesoccurasweclassifyvariouscropplants.Forexample,cornbelongstotheMonocotyledonaewhilebothsoybeanandcottonbelongtotheDicotyledonae.Forthecropscientist,itisrelativelyeasytoremembertheclassificationtaxaoffieldcropssincemostoftheseplantsaregrassesandlegumes.Ifyouknowthetaxaforthesetwofamilies,othermembersofthesefamiliesobviouslyfallintothesameclassificationschemeatleastuptotheplantfamilylevel.Newwordsandexpressionsbotanicala.植物学的distinctionn.区分，差别，标志classificationn.分类behaviorala.行为的fieldcrop大田作物ecologicala.生态学的logicala.合逻辑的durumwheat硬粒小麦ordern.序列，顺序，（分类学上的）目commonwheat普通小麦speciesn.种macronin.马可尼（空心面）reproductivea.繁殖的，生殖的spaghettin.细条实心面floweringplant显花植物cerealn.麦片，谷物，谷类植物taxonomistn.分类学家pastryn.糕点paleobotanistn.古植物学家beingn.存在，生物geneticistn.遗传学家eran.时代Linnaeus林奈(人名)Latinn.拉丁文physiciann.医生namev.命名betterknownasdeada.失效的，不起作用的creditv.归功于，相信clovern.三叶草19\nACONCISETEXTBOOKOFAGRICULTURALENGLISHpartn.零部件，器官，部分leafletn.小叶organn.器官termn.术语，期（限）associaten.同事，伙伴meadowsn.草地，牧场binomialn.二项式的taxa(pl)n.分类单位nomenclaturen.命名法pigeon-holev.分类，归档designatev.称呼，命名omitv.省略organismn.生物kingdomn.界，王国genusn.属divisionn.门，部分allyv.与…联姻（结盟）classn.纲，班，类型wheatn.麦类，小麦ordern.目minimuma.最小的familyn.科racen.宗，小种subspeciesn.亚种subracen.亚小种Monocotyledonaen.单子叶植物soybeann.大豆Dicotyledonaen.双子叶植物cottonn.棉花grassn.禾本科（植物）subclassn.亚纲legumen.豆科（植物）20\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT8GROWTHANALYSISOFCROPSCropgrowthinthefieldhasbeencharacterizedbyasystemofgrowthanalysisbasedmostlyondrymatteraccumulationrates.Sincecropyieldsarebasedonlandarea,themostmeaningfulanalysisofcropgrowthisonalandarearatherthananindividualplantbasis.Developmentofmethodstoanalyzecropgrowthhasprovidedabetterunderstandingofgrowthprocessesandyieldlimitations.CropgrowthrateThedrymatteraccumulationrateperunitoflandareaisreferredtoas-2-1cropgrowthrate(CGR),normallyexpressedasg(moflandarea)day.Cropgrowthrateismeasuredbyharvestingplantsatfrequentintervalsandcalculatingtheincreaseindryweightfromoneharvesttothenext.RootsareexcludedinmanystudiesofCGR.Foragiventimeinterval,CGR=(W2-W1)/SA(t2-t1)WhereW1andW2arecropdryweightatbeginningandendoftheinterval,t1andt2arethecorrespondingdays,andSAisthesoilareaoccupiedbytheplantsateachsampling.ThemostaccuratemeasureofCGRthroughoutagrowingseasonisobtainedbysamplingatfrequentintervals.Growthonasoilareabasisfollowsapatternidenticaltothegrowthpatternofindividualplantsandforthesamereasons.ThemaximumCGRoccurswhenplantsarelargeenoughordenseenoughtoexploitalltheenvironmentalfactorstothegreatestdegree.Infavorableenvironments,thismaximumCGRoccurswhenleafcoveriscompleteandmayrepresentthemaximumpotentialdrymatterproductionandsolarenergyconversionrateforagivenspecies.ValuesinthefollowingtablerepresentsomeofthemaximumCGRreportedforcropspecies.TableMaximumcropgrowthratesreportedforsomecropplants.+CropMaximumCGRCorn51Sorghum51Millet54Sugarcane42Rice27Soybean23Peanut28Alfalfa20Sugarbeet32+Thesevaluesarenotvalidforexactcomparisonsamongspecies,sinceclimaticconditionswerequitedifferentforthecropslisted.21\nACONCISETEXTBOOKOFAGRICULTURALENGLISHTropicalorwarm-seasongrasscropssuchascorn,sorghum,millet,andsugarcanehavehigherCGRthantheothercropspecies.Thereasonforthisdifference,atleastinpart,isthemoreefficientphotosynthesisofmosttropicalgrasseswiththeC4photosyntheticpathway.RiceisatropicalgrassbutlacksC4photosynthesis.DifferencesinspecieswithC3andC4photosynthesisarediscussedelsewhere.Growthrateislowearlyinthegrowthofthecropbecauseofincompletecoverandthelowpercentageofsunlightintercepted.ArapidincreaseinCGRoccursasthecropdevelops,theleafareaexpands,andlesslightpenetratesthroughthecroptothesoilsurface.ThemaximumCGRgenerallycoincideswiththeearlyfruitingstageanddecreasesastheplantmaturesbecauseofcessationofvegetativegrowth,lossofleaves,andsenescence.StudiesofCGRareimportantintheinterpretationofyielddifferencesamongcropvarietiesandculturalpractices.Sincecropyieldsmaybeaffectedbymanyfactorsduringthegrowingseason,analysisofgrowththroughoutthegrowthcyclemaybehelpfulinexplainingyielddifferences.RelativegrowthrateRelativegrowthrate(RGR)istheincreaseinplantweightperunitof-1-1weightalreadypresentandmaybeexpressedasg(gofdryweight)day.Atanygiveninstantduringgrowth,RGR=(1/w).(δw/δt)wherewistheplantdryweightandδw/δtisthechangeindryweightperunittime.Justasincomefromalargesavingsaccountisgreaterthanfromasmallone,potentialgrowthofalargeplantislikelytobegreaterthanthatofasmallplant.Relativegrowthratedecreaseswithplantage.Thisdecreaseisduetothefactthatanincreasingpartoftheplantisstructuralratherthanmetabolicallyactivetissueandassuchdoesnotcontributetogrowth.Thedecreaseisalsodueinparttoshadingandincreasedageoflowerleaves.NetassimilationrateSinceleafsurfacesinterceptsunlightandabsorbCO2inphotosynthesis,itisdesirableinsomecasestoexpressgrowthonthebasisofleafarea.Thedrymatteraccumulationrateperunitofleafareaistermednetassimilationrate(NAR).Atanyinstantduringcropgrowth,NAR=(1/A).δw/δtwhereAistheleafareaandδw/δtisthechangeinplantdryweightper-2-1unittime.TheNARisexpressedasg(mofleafarea)day.22\nACONCISETEXTBOOKOFAGRICULTURALENGLISHNetassimilationrateisameasureoftheaverageefficiencyofleavesonaplantorinacropstand.Itishighestwhenallleavesareexposedtofullsunlightandthereforehighestwhenplantsaresmallandleavesarefewenoughthatnoneareshadedbyothers.Asplantsgrow,moreandmoreleavesfullyorpartiallyshaded;thus,NARdecreasesduringthegrowingseason.ThedecreaseinNARwithplantagemayalsobepartiallyduetotheolderaverageleafageandresultinglowerphotosyntheticefficiency.Adisadvantageofusingleafareaasabasisforgrowthexpressionisthatonlytheaverageefficiencyinproducingdrymatterisknown.Olderleavesatthebottomoftheplantorcropstandmaybecontributingnothingtogrowth,whileyoung,upperleavesmayhaveanefficiencymuchgreaterthanindicatedbytheNAR.Aseconddisadvantageisthatleafpetioles(usuallynotincludedinleafarea)andstemsmaycarryonphotosynthesis,andinsomecropstheinflorescencemaycontributesubstantiallytofruitformation.Incerealssuchasbarleytheinflorescencemaycontributeupto50%ofthedryweightofthegrain.Newwordsandexpressionsgrowthn.生长，增长pathwayn.途径，通道mattern.物质interceptv.中途拦截accumulationn.积累penetratev.透过，穿透meaningfula.有意义的coincide(with)v.同时发生processn.过程fruitingn.结果limitationn.限制，无能cessationn.停止intervaln.（时间）间隔senescencen.衰老excludev.排除，不包括growthcycle生长周期correspondinga.相应的instantn.刹那，片刻，当时occupyv.占有savingaccount储蓄帐户samplingn.取样metabolicala.代谢的densea.密集metabolicallyad.solara.太阳的tissuen.组织solarenergy太阳能shadev.遮荫conversionn.转换neta.净的，纯的，最终的potentiala.潜在的，n.潜力assimilationn.同化（作用）warm-season温带standn.蔸，穴，枝丛sorghumn.高粱petiolen.叶柄milletn.粟stemn.茎sugarcanen.甘蔗barleyn.大麦photosynthesisn.光合作用grainn.籽粒photosynthetica.光合作用的23\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT9THECONCEPTOFDISEASEINPLANTSAplantishealthy,ornormal,whenitcancarryoutitsphysiologicalfunctionstothebestofitsgeneticpotential.Thesefunctionsincludenormalcelldivision,differentiation,anddevelopment;absorptionofwaterandmineralsfromthesoilandtranslocationofthesesubstancesthroughouttheplant;photosynthesisandtranslocationofthephotosyntheticproductstoareasofutilizationorstorage;metabolismofsynthesizedcompounds;reproduction;andstorageoffoodsuppliesforoverwinteringorreproduction.Wheneverplantsaredisturbedbypathogensorbycertainenvironmentalconditionsandoneormoreofthesefunctionsisinterferedwithbeyondacertaindeviationfromthenormal,thentheplantsbecomediseased.Theprimarycausesofdiseaseareeitherpathogeniclivingorganisms(pathogens)orfactorsinthephysicalenvironment.Thespecificmechanismsbywhichdiseasesareproducedvaryconsiderablywiththecausalagentandsometimeswiththeplant.Atfirsttheplantreactstothedisease-causingagentatthesiteofaffliction.Thereaction,ofachemicalnature,isinvisible.Soon,however,thereactionbecomesmorewidespread,andhistologicalchangestakeplacethatmanifestthemselvesmacroscopicallyandconstitutethesymptomsofthedisease.Affectedcellsandtissuesofdiseasedplantsareusuallyweakenedordestroyedbydisease-causingagents.Theabilityofsuchcellsandtissuestoperformtheirnormalphysiologicalfunctionsisreducedorcompletelyeliminated;asaresult,plantgrowthisreducedortheplantdies.Thekindsofcellsandtissuesthatbecameinfecteddeterminethetypeofphysiologicalfunctionthatwillbeaffectedfirst.Thus,infectionoftheroot(forexample,rootrots)interfereswithabsorptionofwaterandnutrientsfromthesoil;infectionofthexylemvessels(vascularwilts,certaincankers)interfereswithtranslocationofwaterandmineralstothecrownoftheplant;infectionofthefoliage(leafspots,blights,mosaics)interfereswithphotosynthesis;infectionofthecortex(corticalcanker,viralandmycoplasmalinfectionsofphloem)interfereswiththedownwardtranslocationofphotosyntheticproducts;flowerinfections(bacterialandfungalblights,viral,mycoplasmal,andfungalinfectionsofflowers)interferewithreproduction;andinfectionsoffruit(fruitrots)interferewithreproductionorstorageofreservefoodsforthenewplant.Incontrast,thereisanothergroupofdiseasesinwhichtheaffectedcells,insteadofbeingweakenedordestroyed,arestimulatedtodividemuchfaster24\nACONCISETEXTBOOKOFAGRICULTURALENGLISH(hyperplasia)ortoenlargeagreatdealmore(hypertrophy)thannormalcells.Suchhybperplasticorhypertrophiedcellsresultinthedevelopmentofusuallynonfunctioningabnormallylarge,orabnormallyproliferatingorgansorintheproductionofamorphousovergrowthsonnormal-lookingorgans.Over-stimulatedcellsandtissuesnotonlydivertmuchoftheavailablefoodstuffstothemselvesandawayfromthenormaltissues,butfrequently,bytheirexcessivegrowth,crushadjacentnormaltissuesandinterferewiththephysiologicalfunctionsoftheplant.Inplants,then,diseasecanbedefinedasthemalfunctioningofhostcellsandtissuesthatresultsfromtheircontinuousirritationbyapathogenicagentorenvironmentalfactorandleadstothedevelopmentofsymptoms.Diseaseisaconditioninvolvingabnormalchangesintheform,physiology,integrity,orbehavioroftheplant.Suchchangesmayresultinpartialimpairmentordeathoftheplantoritsparts.Pathogensmaycausediseaseinplantsby(1)weakeningthehostbycontinuallyabsorbingfoodfromthehostcellsfortheirownuse;(2)killingordisturbingthemetabolismofhostcellsthroughtoxins,enzymes,orgrowth-regulatingsubstancestheysecrete;(3)blockingthetransportationoffood,mineralnutrients,andwaterthroughtheconductivetissues;and(4)consumingthecontentsofthehostcellsuponcontact.Diseasescausedbyenvironmentalfactorsresultfromextremesintheconditionssupportinglife(temperature,moisture,light,andsoon)andinexcessiveordeficientamountsofchemicalsabsorbedorrequiredbyplants.Newwordsandexpressionsgeneticpotential遗传潜力nutrientn.营养成分celldivision细胞分裂xylemn.木质部differentiationn.分化vesseln.导管，脉管mineraln.矿物质vasculara.维管的translocationn.转运wiltn.萎蔫metabolismn.新陈代谢cankern.溃疡，癌肿synthesizev.合成crownn.根颈compoundn.化合物foliagen.叶overwinteringn.越冬spotn.斑点deviationn.偏离，偏差blightn.枯萎病pathogenica.致病的，病原的mosaicn.花叶病25\nACONCISETEXTBOOKOFAGRICULTURALENGLISHpathogenn.病原cortexn.皮层specifica.具体的，确切的，专一的corticala.皮层的，外层的causala.原因的，构成原因的virala.病毒的agentn.施动者，作用物，因子mycoplasmala.菌质的afflictionn.折磨，疼痛phloemn.韧皮部chemicala.化学的downwarda.向下的invisiblea.看不见bacteriala.细菌的histologicala.组织学的fungala.真菌的symptomn.症状stimulatev.促进，刺激infectv.侵染，感染，传染hyperplasian.增生，增殖infectingn.感染，侵染hypertrophyn.肥大，过渡生长（增大）rotn.腐烂，腐坏hyperplastica.增生的hypertrophieda.过渡增大的secretev.分泌amorphousa.无定形的，无分化结构的blockv.阻止，阻碍overgrowthn.生长过旺，过渡生长transportationn.运输divert(to)v.使…转向conductivea.能传导的，导电（热）的adjacenta.邻近的，附近的conductivetissue输导组织malfunctioningn.功能失调contentn.内含物，内容irritationa.刺激，不适contactn.接触integrityn.完整（性）extremen.极端impairmentn.削弱，损害excessivea.过量的toxinn.毒素deficienta.不足的，缺乏的enzymen.酶growth-regulatingsubstance生长调节物质26\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT10CONTROLOFPLANTDISEASESApartfrombeingintellectuallyinterestingandscientificallyjustified,thestudyofthesymptoms,causes,andmechanismsofplantdiseaseallowsthedevelopmentofmethodstocombatplantdiseasesand,thus,increasesthequantityandimprovesthequalityofplantproducts.Methodsofcontrolvaryconsiderablyfromonediseasetoanother,dependingonthekindofpathogen,thehost,andtheinteractionofthetwo.Incontrollingdiseases,plantsaregenerallytreatedaspopulationsratherthanasindividuals,althoughcertainhosts(especiallytrees,ornamentals,andsometimes,virus-infectedplants)maybetreatedindividually.Withtheexceptionoftrees,however,thedamageorlossofoneorafewplantsisusuallyconsideredinsignificant,andcontrolmeasuresaregenerallyaimedatsavingthepopulationsratherthanafewindividualplants.Consideringtheregularitywithwhichmostseriousdiseasesofcropplantsappearinanareayearafteryear,therapidspreadofmostplantdiseases,andthedifficultyofcuringadiseaseafterithasbeguntodevelop,itiseasytounderstandwhyalmostallcontrolmethodsareaimedatprotectionplantsfrombecomingdiseasedratherthanatcuringthemaftertheyhavebecomediseased.Asamatteroffact,fewinfectiousplantdiseasescanbesatisfactorilycontrolledinthefieldbytherapeuticmeans,althoughcertaindiseasescanbecuredunderexperimentalconditions.Thevariouscontrolmethodscanbeclassifiedasregulatory,cultural,biological,physical,andchemical,dependingonthenatureoftheagentsemployed.Regulatorycontrolmeasuresaimatexcludingapathogenfromahostorfromacertaingeographicarea.Mostculturalcontrolmethodsaimathelpingplantsavoidcontactwithapathogenandateradicatingorreducingtheamountofapathogeninaplant,afield,oranarea.Biologicalandsomeculturalcontrolmethodsaimatimprovingtheresistanceofthehostoratfavoringmicroorganismsantagonistictothepathogen.Finally,physicalandchemicalmethodsaimatprotectingtheplantsfrompathogeninoculumthatislikelytoarriveandatcuringaninfectionthatisalreadyinprogress.Epidemiologicalstudiescanhelpdeterminehoweffectivevariouscontrolsmightbeforaparticulardisease.Ingeneral,reducingorexcludingtheinitialinoculumismosteffectiveforthemanagementofmonocyclicpathogens.Controlssuchascroprotation,removalofalternatehosts,andsoilfumigationreducetheinitialinoculum.Becausepolycyclicpathogensincreasemany27\nACONCISETEXTBOOKOFAGRICULTURALENGLISHtimestheamountofinitialinoculumduringthegrowingseason,reducingtheinitialinoculummustusuallybeaccompaniedbyacontrol(suchaschemicalprotectionorhorizontalresistance)thatalsoreducestheinfectionrate.Manycontrols,forexampletotallyexcludingapathogenfromanarea,areusefulforbothmonocyclicandpolycyclicpathogens.Newwordsandexpressionsapartfrom除…之外eradicatev.根除，消灭intellectuala.智力的，思维的favorv.偏袒，使（某事物）顺利intellectuallyad.microorganismn.微生物scientifica.科学的antagonistica.对抗的，敌对的scientificallyad.inoculumn.接种物，种菌combatv.试图减少、减弱或消灭epidemiologicala.流行病学的quantityn.数量particulara.具体的，特殊的ornamentaln.观赏植物initiala.最初的，原始的savev.拯救monocyclica.单循环的，单周期的regularityn.规律性，规则性rotationn.轮作spreadn.传播，扩散alternatea.交替的curev.治愈，治好alternatehost交替寄主protectv.保护，防止fumigationn.熏蒸消毒infectiousa.感染的，传染的polycyclica.多循环的therapeutica.治病的，治病术的horizontala.水平的regulatorya.管理的horizontalresistance水平抗性28\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT11WHATISECOLOGY?Ecologyisconcernedwiththerelationshipsbetweenplantsandanimalsandtheenvironmentinwhichtheylive.Thissimpleexplanationisthekindofansweraschoolchildwouldofferifasked“whatisecology?”buttheexplanation,althoughapparentlyneatandsimple,doesnotspecifywhatismeantbyrelationshipsandwhatismeantbyenvironment.Thesetwowordsoccurthroughoutthisbookandweshallthereforebeginbyconsideringwhattheymean.Therearemanypossiblekindsofrelationshipsbetweenorganisms(plants,animals,andotherlivingthingslikeviruses)andthatpartofthenon-livingworldinwhichtheyoccur.Anextremelyimportantoneiswhoeatswhom,andanother,perhapsequallyimportant,iswhobreedswithwhom.Theconceptoftheenvironmentcoversjustabouteverythingassociatedwithorganisms,andincludesotherorganismsandnonlivingpartoftheworldinwhichlifeoccurs.Theweather,thephysicalandchemicalcompositionofthesoil,andseasonalchangesinthelengthofdaylight,areallpartsofanorganism’senvironment,andthewordthereforehasaboutthesamemeaningassurroundings.Noorganismexistswithoutanenvironment;organismsandtheenvironmentsinwhichtheyliveconstituteanextremelythinlayeronthesurfaceoftheearth,oftencalledthebiosphere,inwhichtheverycomplexityofecologicalrelationshipstendstofrustratescientificanalysis.Nevertheless,carefulconsiderationrevealssomeorderinthebiospherewhichcanbeunderstoodanddefined,althoughitmustbeadmittedthatwearestillalongwayfromformulatinggeneraltheoriesofthekindfamiliartostudentsofchemistry,physics,andmathematics.Theessentialfeatureoflivingorganismsasopposedtonon-livingobjectsisthattheyreproduceandreplicatethemselves.Organismsareassociatedwithlandorwithwater;manykindsspendthegreaterpartoftheirlifeintheair,butnoneexistsentirelyintheair.Themostfamiliarorganisms,treesandplants,andtheanimalsthatfeedonthem,areobviouslyassociatedwiththeground,buteveryoneknowsthatbothfreshandsaltwatersupportavarietyofplantandanimallife.TheGreeksusedthewordoikostodescribeahome,aplacetowhichyoucouldreturnandwhereyouunderstoodandwerefamiliarwiththelocalenvironment.Fromthiswordwehavederivedthetermsecologyand29\nACONCISETEXTBOOKOFAGRICULTURALENGLISHeconomicstodescribethesubjectsconcernedwithaspectsofhomelife.Ecologybeganasdescriptivenaturalhistorybutnowadaysscientistsstudyanddescribeecologicalphenomenainquantitativeterms,oftentosuchanextentthatscientificmagazinesdevotedtoecologypublisharticlesthatlookmorelikepagesfromtextbooksinmathematics.Muchthesameappliestothescientificstudyofeconomics.Buteconomicsandecologyaresubjectsinwhichintuitionalsoplaysanimportantrole,andalthoughbothsubjectshavereceivedrigorousmathematicaltreatmentitcouldbedoubtedifthishastoldusagreatdealthatwedidnotknowalready.Inrecentyearsecologyhasbecomeahouseholdword.Ithasbeguntoenterintodiscussionsabouteconomicdevelopment,industrialgrowth,andstandardsofliving,butthereisoftenconfusion.Manypeoplethinkecologyisanotherwordforpollutionortheconservationofrareanimals;othersseeitassomethingofapoliticalplotagainsteconomicgrowth.Onlynowhaveasubstantialnumberofpeoplebecomeconcernedabouttrendsinthegrowthofthehumanpopulationandtheconsumptionofnaturalresources,andwiththisconcernfearsforthefutureareincreasinglyexpressed.Whatexactlyhasgeneratedthisinterest,andwhyecology,untilrecentlyaratherobscuresubject,cometotheforefront?Inindustrialcountriesthemostimportantsingleeventhasbeentherealizationanddemonstrationthatpollutionresultingfromindustryandagricultureisharmfultopeopleandtothesurroundingsinwhichpeoplelive.Industrialpollutioncomesfromwasteproductsofthemanufacturingandserviceindustries,andtheseproductsaredifficult,oratleastexpensive,todisposeof,whileagriculturalpollutionresultsfromtheaccumulationoftoxicchemicalsderivedfrompesticidesandfertilizers.Butalthoughthepresentawarenessofecologymayhavebeenstimulatedbytheapparentdangersofpollution,thisisnotprimarilywhatecologyisabout.Itisamuchbiggerandmorecomplexsubjectthanthis,andtounderstandecologywemustmoveawayfromthisrestrictedthoughcommonviewpoint.Ecologyisnotevenprimarilyaboutman;indeeditcoversalllivingorganisms,andalthoughmostpeoplewillundoubtedlybeinterestedintheimplicationsofecologyforhumanlifeandwelfare,tounderstandthesubjectitisnecessarytoabandonanentirelyman-orientedapproachandtoconsiderinsteadtheinter-relationshipsofalllifeandtheenvironment.Hopefullythiswillleadtoabetterunderstandingandmorerespectsforplantandanimallifeandperhapshelptoexplainhowthepresentlackofbalancebetweenmanandtheenvironmenthascomeabout.30\nACONCISETEXTBOOKOFAGRICULTURALENGLISHEvidently,then,therearetwofacetstooursubject.Oneismainlybutnotentirelydisinterestedscientificinquiry,theothermorediffuseandconcernedwithpoliticalandeconomicproblemsofover-population,theconsumptionofresources,pollution,conservation,andtheplightofunder-developedcountries.Ecologyasascienceinvolvesdetailedandpainstakingmeasurementsofpopulationsizesofplantsandanimals,birthanddeathrates,thesupplyandutilizationofenergyandnutrientsintheenvironment,andrelatedsubjects.Itisreallyasophisticatedandacademicformofnaturalhistory.Theotherfacetismoreconcernedwithman’splaceinnatureandthreatstothequalityoflife.Thetwofacetsarecompatiblealthoughcuriouslyenoughpeopleactiveandvocalinonearerarelyactiveandvocalintheother.Mostscientificecologiststakenopublicstandonthewider,lessclearlydefinedissuesthatafflictmankind,butapartfromjournalistsandwriterstherearefewprofessionalpoliticalecologists.Newwordsandexpressionsecologyn.生态学beconcernedwith与…有关apparentlyad.显然dispose(of)n.去除，处理，解决neata.简洁的pesticiden.杀虫剂，农药specifyv.确切说明，评述fertilizern.化肥，肥料compositionn.组成restricteda.有限的，受约束的surroundingn.周围的物体，条件implicationn.合意，暗示，暗指的layern.层welfaren.幸福，福利frustratev.妨碍，阻挠abandonv.放弃considerationn.考虑，思索approachn.途径formulatev.确切地表达，形成comeabout发生opposev.反对，相反facetn.情况或问题的方面，刻面Greekn.希腊人disinteresteda.不偏不倚的，公正无私的descriptivea.描述的，描写的inquiryn.调查，询问nowadaysad.现今，时下diffusea.不集中的，扩散的，广泛的phenomena(pl.)n.现象plightn.困境，苦境devote(to)v.献身（于）under-developeda.经济不发达的intuitionn.直觉sophisticateda.复杂的，综合的rigorousa.严格的，精确的compatiblea.能共存的，亲和的，兼容的householdn.家庭vocala.直言的，用言语自由表达意见和感情的confusionn.混淆，混乱takea/one’sstandon表明态度，宣布conservationn.保护，保存definev.解释，阐明31\nACONCISETEXTBOOKOFAGRICULTURALENGLISHrarea.稀有的，罕见的afflictv.使人痛苦，折磨rarelyad.professionala.职业的，专业的plotn.阴谋，密谋ecologistn.生态学家consumptionn.消耗forefrontn.最前部，最重要之处obscurea.朦胧的，模糊的pollutionn.污染demonstrationn.证明，论证，示范32\nACONCISETEXTBOOKOFAGRICULTURALENGLISHUNIT12HOWANEWCULTIVARREACHESTHEFARMER?Atypicalprocedurebywhichanewcultivarofafieldcropdevelopedbyastateagriculturalexperimentstationreachesthefarmermaybedescribedasfollows:(1)Acultivarisreadyforreleaseanddistributionwhenithasbeenproventobedistinctlysuperiortoanddifferentfromexistingcommercialcultivarsinatleastoneormorecharacteristics,andatleastsatisfactoryinallotherimportantrespects.(2)Thedecisionforreleaseismadebythebreederinconsultationwithappointedboardsofreview,accordingtoproceduresestablishedbythestateagriculturalexperimentstationforreleaseofanewcultivar.Theplantbreedermakersalimitedincreaseofbreederseedofthenewcultivar,theamountvaryingfromafewtoafewhundredkilograms.Thebreederseedisthengenerallyturnedovertotheagencyresponsibleformakingthefoundationseedincrease.(3)Foundationseedisincreasedfrombreederseed.Theorganizationmakingthefoundationseedincreasevariesindifferentstates.Inmoststates,afoundationseedprogramhasbeendevelopedwithintheagriculturalexperimentstation.Insomestates,foundationseedisproducedbyprivatefoundationseedstocksorganizationscloselyassociatedwiththeagriculturalexperimentstation.(4)Atleastoneyearbeforedistributionbytheoriginatingstation,eachstateexperimentstationintheregionofadaptationofthenewcultivarisnormallyinformedofplantstoreleasethecultivar,andseedissuppliedtotheminquantitiestopermitfieldplottestingatoneormorelocations.(5)Thecultivarisnamedattheoriginatingstation,inconsultationwithrepresentativesofotherstateagriculturalexperimentstationswithintheregion,andtheUnitedStatesDepartmentofAgricultureinthecaseofcooperativestate-federalbreedingprograms.(6)Priortodistribution,eitherbreederorfoundationseedissharedwithintheregionwithotherstateagriculturalexperimentstations,whichmaywishtomakeasimultaneousincreaseanddistributionofthenewcultivar.Anadequatequantityoffoundationseedshouldbeavailabletosupplyimmediateneedsfortheproductionofregisteredandcertifiedseedbeforereleaseordistributionismade.(7)Foundationseedisthesourceofregisteredseed.Distributionof33\nACONCISETEXTBOOKOFAGRICULTURALENGLISHfoundationseed,plusapublicannouncement,constitutesaformalreleasebytheoriginatingstation.Initialdistributionoffoundationseedisusuallymadeonlytoexperiencedgrowerstoconservetheseedsupplyofanewcultivar,butlaterdistributionmaybemadetogrowersofregisteredorcertifiedseedwithoutrestrictioninsofarasthesupplyofseedpermits.(8)Registeredseedisthesourceofcertifiedseed,althoughcertifiedseedmaybeproduceddirectlyfromfoundationseedwhentheregisteredclassisomitted,certifiedseedissoldtofarmerswithoutrestriction.(9)New,improvedcropcultivarsmayberegisteredbytheCropScienceSocietyofAmerica.AdescriptionofeachcultivarregisteredbythesocietyispublishedinCropScienceandbecomestheofficialdescriptionofthecultivar.Newwordsandexpressionstypicala.典型的，有代表性的regionn.地区，区域developv.培育informv.通知，告知staten.州sharev.共有，分享，合用experimentstation试验站simultaneousa.同时的releasen.释放，发行，发表adequatea.足够的distributionn.分发，分送immediatea.紧接的，立即的commerciala.商业的，推广的registerv.注册，登记consolationn.协商，商讨registeredseed注册种子，原种appointv.委派，挑选certifyv.（书面）证明increasen.繁殖，增加certifiedseed合格种子breederseed育种家种子formala.正式的，正规的turnover移交insofaras在…范围内，到…的程度agencyn.机构，代理（处）CropScienceSocietyofAmerica美国作物学会foundationseed基础种子descriptionn.描述，叙述，形容organizationn.组织，机构，系统officiala.官方的，正式的programn.工作计划，活动安排stocksn.原种originatev.创造，发明34