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thisguide Whythisguide?
Aboutthisguide ThisCucumberEcologicalGuideisdevelopedbytheFAOInter-CountryProgramme(ICP)forIPMinVegetablesinSouthandSoutheastAsia.ThisguideissummarizedfrommanydocumentsandreportsoncucumberinVietnamandothercountries.Theobjectiveofthisecologicalguideistoprovidegeneraltechnicalbackgroundinformationoncucumberproduction,supplementedwithfieldexperiencesfromtheNationalIPMProgrammes,FAO’sVegetableIPMProgramme,andfromanizationsactiveinfarmerparticipatoryIPMinVietnamandothercountries. Whowillusethisguide?
NationalIPMprogrammes,IPMtrainers,andothersinterestedinIPMtrainingandfarmerparticipatoryresearch. Sometechnicalissuesinthisecologicalguidearenewplicated,requiringcontributionsfrommanyrelatedsectors.Inaddition,thetimeforpreparingthisguidewaslimitedandthematerialmayhavesomemistakes.Wehopetogetfeedbackandcontributionsfromallreaders,IPMtrainersandfarmersinordertoimprovethematerial. Theguidecanbeusedasreference.ItisnotanofficialtrainingdocumentforIPMinvegetables. Forcontributions,pleasesendto: FAORegionalVegetableIPMProgrammeRoomA25,39MaliwanMansionPhraAthitRoadBangkok10200Tel:(662)6974274Fax:(662)6974422email:Johannes.Ketelaar@ Cucumberecologicalguide2008 ii ____________________________________________________________________________________________Why
thisguide TableofContents
I.GeneralIntroduction
1 1.TheCucurbitaceaeFamily
1 1.1.CharacteristicsofCucurbitaceaeFamily 1.2.CucurbitsmonlygrowninVietnam 1.3.Mainproblemsofcucurbits 1.4.Sourcesofinformation(referencesandexperts)
2.Thecucumbercropasafarmingenterprise
2 2.1.History 2.2.Importanceofcrop:foodandcashvalue 2.3.Economicpotentialofthecrop 2.4.Analysisofmainproblemsincucumbercultivation 2.5.Approachtosolvingmainproblems
3.Biologicalfacts
3 3.1.Botanicalcharacteristics:taxonomy,morphology 3.2.Growthstagesanddevelopment 3.3.Relationbetweenvegetativegrowthandpoddevelopment 3.4.Abioticfactors,growthanddevelopment II.CropManagement
6 1.Croprotation
6 1.1.Importanceinrelationtonutrientavailabilityinthesoil 1.2.Importanceinrelationtopestanddiseaseincidence 1.3.Rotationguidelines:crops,cycle,etc.
2.Intercropping
7 2.1.Advantagesanddisadvantagesinrelationtopestanddisease incidence,marketing,soilutilization,andconservation 2.2.Suitablecrops 2.3.Method:timing,spacing,etc.
3.Varietyselection
9 3.1.Demandandsupply:howtochooseavariety 3.2.Characteristicsmonlyavailablevarieties 3.3.CucumbermonlygrowninVietnam
4.Seedpreparation 10 4.1.Healthyseed 4.2.Selectioncriteria,method(infield,atharvestandbeforeplanting) 4.3.Storage 4.4.Seedtreatment
5.Landpreparation 12 5.1.Soiltype/characteristicsinrelationtosuitabilityforcucumber 5.2.Preparation Cucumberecologicalguide2008 iii ____________________________________________________________________________________________Why
thisguide 5.2.1.Characteristicsinrelationtosuitabilityforcucumber5.2.2.Method:cultivation,bedpreparation,etc
6.Cropestablishment 13 6.1.Directplanting 6.2.Usingseedling
7.Pollinationandfruitsetting 15
8.Fertilization 16 8.1.Nutrientneeds:amount,timinginrelationtogrowthstages,effect ofvariousnutrientsonfruitproduction 8.2.Organicfertilizer 8.3.anicfertilizer 8.4.Cucumberfertilizationguide
9.Watermanagement 20 9.1.Waterrequirementsatseedling,vegetative,andfruitingstages 9.2.Method:irrigation,drainage,etc. 10.Stakingandpruning 21 10.1.Importanceofstaking 10.2.Timingandmethod 10.3.Pruning 11.Weedmanagement 22 11.1.Weedsandimpactofweedsoncropdevelopment 11.2.Timing 11.3.Method 12.Majordiseasesofcucumber 24 12.1.Damping-off–Fusarium,Rhizoctonia,Pythium,and hthorasp 12.2.Bacterialwilt–Erwiniatracheiphilia 12.3.YellowFusariumwilt–Fusariumoxysporum 12.4.Downymildew–Pseudoperonosporacubensis 12.5.Powderymildew–Eryshiphecichoraciarum 12.6.Targetleafspot–Corynesporacassiicola 12.7.Angularleafspot–Pseudomonassyringaepv.lachrymans 12.8.virus 12.9.Gummystemblight–Didymellabryoniae 12.10.Cucumbermosaicvirus 12.11.Physiologicaldisorders 13.Majorinsectpestsofcucumber 56 13.1.Leafminer–Liriomyzasp. 13.2.Aphids-Aphisgossyppii 13.3.Stripedcucumberbeetle–Diabroticasp. 13.4.Spidermites–Tetranychussp. 13.5.Whitefly–Bemisiatabaci Cucumberecologicalguide2008 iv ____________________________________________________________________________________________Why
thisguide 13.6.Thrips–Thripssp. 14.Harvesting 77 References 78 Plates: CommonPestsandDiseasesofCucumber 79 Cucumberecologicalguide2008 v ____________________________________________________________________________________________Why
thisguide IGeneralIntroduction
1.TheCucurbitaceaeFamily CropsbelongingtotheCucurbitaceaefamilymonlycalledcucurbits.Cucurbitsareabiggroupofvegetablesthatincludecucumber,bittergourd,squash,bottlegourd,ridgegourdandsnakegourd.Cucumbermonlyusedforsaladsandpickleswhilesquashandmostofthegourdsareforcooking.Watermelonandmuskmelonaretakenasdessertwhilewaxgourdispreparedasjamandbiscuits. Intheworldthereare120generaand1000speciesdistributedintropicalandsubtropicalareas.CucurbitsaretropicalinoriginandgrownmostlyinAfrica,tropicalAmerica,andAsia,mainlySoutheastAsia.SomegeneraarefoundinSouthandEastAsiawhilesomearealsodistributedintemperateareas.InVietnam,thereare23generaand53speciesofcucurbits. Cucurbitsareperennialcropsandmultiplybyseedsalthoughfewareclones. 1.1.CharacteristicsofCucurbitaceaefamily Cucurbitsmonbotanicalcharacteristicsasfollows: Roots:Therootsystemisextensiveandlargelysuperficial.Thetaprootislongandadventitiousrootsdevelopupto60cm.Therootsystemofdroughttolerantvarietiescangrow170-180cmdeep. Stem:Stemsare3-8angledbranches.Vinesextendupto9-10m.Thenodesproducerootswhentheyreachthesoilundersaturatedhumidity. Leaves:Leavesaresimpleandmosthave3-5lobeswithdifferentshapes.Somearedeeplylobed,e.g.,watermelon. Flowers:Flowersaresolitaryorinclusters,mostbeinggynoecious.Somearehermaphroditus,dioecious,andromonoecious. Fruits:Fruitsaresolidandulent. Seeds:Cucurbitshavemanyseedsofdifferentshapesandcolors,e.g.,watermelonexceptchayotewithonlyoneseedperfruit. 1.2.CucurbitaceaemonlygrowninVietnam CucurbitcropsgrowninVietnamareclassifiedasfollows:
1.Cucumis:cucumber,muskmelon2.Citrullus:watermelon3.Cucurbita:pumpkin,squash4.Lagenaria:bottlegourd5.Momordica:bittergourd6.Luffa:loofah7.Trichosanthes:snakegourd8.Benincasa:waxgourd Cucumberecologicalguide2008
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thisguide 9.innia:ivygourd10.Sechium:chayote 1.3.Mainproblemsofcucurbits AsothercropsintheCucurbitaceaefamily,cucumberhasmanyfieldproblemssuchasinsectpestsanddiseases,deterioratedvarietiesandreducedfruitquality. Pollination:Cucumberiscross-pollinatedbyinsects.Theratioofmaleandfemaleflowersandnumberofbeesorotherpollen-feedinginsectsareimportantfactorsaffectingtheyield.Theconstantreductioninpopulationsofpollen-feedinginsectsduetopesticidemisuseesaproblemforpollination. 1.4.Sourceofinformation Seelistofreferences
2.Thecucumbercropasafarmingenterprise 2.1.History MostcucurbitspecieshaveanAfricanorigin.However,cucumberisbelievedtohaveoriginatedfromthefoothillsoftheHimalayaswherethecloselyrelatedwildspeciesC.hardwickiiRoylestillexists.InIndia,thecucumberwasalreadybeingcultivated3000yearsago,anditwasknowninancientEgypt,GreeceandtheRomanEmpire.Inthe6thcentury,itwascultivatedinChinaandwasprobablythesourceofthefirstcucurbittoreachMalaysia.Nowitiscultivatedworldwide. 2.2.Importanceofcrop:foodandcashvalue Cucumberisgrownforitsimmaturefruitsthatareusedassaladvegetableandforpickles.Theslicingcucumberarepeeled,slicedandservedwithvinegarordressingorasaningredientofsalads.Cucumberandothercucurbitfruitsaregenerallyfat-freeandlowinsodium.However,processedcucumbers(pickles)canhavehighsodiumcontents. Cucumberisthehighestexport-processedproductwithincreasingproductivityannually. 2.3.Economicpotentialofthecrop Comparedwithothervegetables,cucumberupiesfourthplaceinimportanceintheworld,followingtomato,colecropsandonion.In1987,worldacreageofcucumberwasestimatedatabout850,000hawithatotalproductionof12.5milliontons.AbouthalfofthisproductionwasfromAsia,withChinaleadingat240,000haand3.7milliontonsin.ThetotalproductionforSoutheastAsiawas:Indonesia-40,000haand291,000t(1988);thePhilippines-1000haand6000t(1987);Thailand-12000haand143000t(1988). Picklingcucumber(gherkins)isnotpopularinSoutheastAsia.Westerncountries.prefertoimportsmall-sizegherkinsduetohighlaborcostsforharvestingfromIndonesiaandVietnam.ordingtostatisticsfromtheVietnamFruitandVegetableCooperationinVietnam,picklingcucumberfromnorthernexport-foodfactoriesexportedtoEuropeanmarketswas1117,2184and2309tonsin1992,1993and1995,respectively.Iningyears,marketsforthisproductwillnotonlybestable,butalsowillbedevelopedintermsoftypesandvolume.Goodproductionandnewtechniquesforvarieties, Cucumberecologicalguide2008
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thisguide cultivationandprocessingtechnologywillhelpbringabouthigherefficiencyandbetterqualityofproducts. 2.4.Analysisofmainproblemsincucumbercultivation Therearemanydifficultiesassociatedwithcucumbercultivationsuchasinsectpestsanddiseases,varietiesandmarkets. -Pestsanddiseases:Pestsanddiseasesoncucumberarenotasmanyasinsolanaceousorcruciferouscrops.Usually,problemswithpestsanddiseasesarelinkedtocroptimingandyield. -Varieties:Cucumbervarietiesdeterioraterapidlybecausetheyarepollinatedbyinsects.Varietiesaffecttherequirementsofprocessingfactoriesregardingfruitsizeandquality.Thislimitstheexpansionofconsumptionmarketsaswellasexpansionofcucumbercultivationareas. 2.5.ApproachtosolvingmainproblemsApplyingpropercultivationbinedwithIPMwillreducedamagebyinsectpestsanddiseasesoncucumber.Majordiseasesofcucumber,suchasangularleafspot,powderymildew,downymildew,andsoil-bornediseases,suchasbacterialwilt,canbepreventedbycultivationandotherculturalpractices.Growingresistantvarietiescaneffectivelyreduceinsectpestsanddiseases. SeedrehabilitationorusingF1varietiestogrowwillensurequalityandyieldofcucumber.Insomecases,F1varietiesgivehigheryieldthanpurevarieties.
3.Biologicalfacts 3.1.Botanicalcharacteristics:taxonomy,morphology Cucumberisanannualcropandaclimbingherb.Infavorableconditions,itsgrowthdevelopmentdurationcanlast12-13months. Root:Thecucumberrootsystemdevelopsweakly.Rootlengthcanbe10-25cminsandyloamsoil.Therootsystemmakesup1.5%ofthetotalbiomass.Secondaryrootsdistributeonthesurfacecoveringanareaofabout60-90cmwide.Varietiesthatarelongmaturinghavestrongerrootsystemsandpartsabovetheground.F1varieties,however,havelongerrootsthanparentvarietiesatanystageofcropgrowthanddevelopment.Therefore,thedevelopmentoftherootsystemsattheearlystagesiscloselyrelatedtoyield. Leaves:Leavesarealternate,simple,inoutlinetriangular-ovate.Leaf-bladesare3-7lobedanddeeplycordateatbase,acuteatapex.Lobesaretriangular,acuteatapexanddentate. Stem:Thestemsofthecucumberproducevines;are4-5angledandsparinglybranched.Thelengthofthemainstemmaybe2-3m. Flower:Flowersareaxillaryandunisexualandasionallyhermaphrodite.However,duetotheprocessofevolutionandhumaninterventions,newflowertypesuramongcucumbersuchas: •gynoecious •hermaphroditus Cucumberecologicalguide2008
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thisguide •gynoandromonoecious •gynomonoecious •andromonoecious Amongthesetypes,thegynoeciousandhermaphroditusflowersplayasignificantroleinbreedingandinproducingF1seeds. Theyellowflowershave4-5calyxes.Maleflowersaresingleorborneinclusters,smallerthanfemaleflowersthathave4-5calyxes.Femaleflowersaresolitaryonshortthickpedicelsof3-5mmlong.Flowershave3-4ovules. Fruit:Fruitschangecolorfrompalegreenwhenyoungtowhite,yelloworbrownwhenripeneddependingonthecoloroffruitspines.Fruitswithwhitespinesaregreenandneverturnyellow.Theyarewhitish-greenwhenripened.Fruitswithblackorbrownspinesareyelloworbrownincolorwhenripened. Seed:Seedsarelightyellowandtheweightof1000seedsisabout20-30g.Thereareabout150-500seedsperfruit. 3.2.Growthstagesanddevelopment pletesalifecycle,fromseedtoseed,inoneseason.Cucumbersareusuallygrownforafewmonths,althoughtheycanbecroppedfor12monthsorlongerwhengrowingconditions(water,fertilization,etc.)areoptimalandplantsarenotexhaustedbydiseasesorinsectpests. Cucumberrequires50-70hotdaystogiveaharvest.Earlymaturingvarietieshavegrowthdevelopmentdurationof50days,monvarieties-60daysandlatematuringvarieties-70days.Thegeneralgrowthstagesforcucumberare: •Seed.•Seedlingstage-usuallytheperiodfromemergingseedtotransplantingtothe mainfield.•Vegetativestage-fromtransplantinguntilthefirstflowerbudsdevelop.•Floweringstage-plantwithflowerbudsandopenflowers.•Fruitingstage-plantwithsmalltofull-sizedfruits.•Harvestingstage-periodwhenplantyieldsmaturefruits. Thesegrowthstagesareoverlappingintime: harvestingstage seedlingstage flowering&fruitingstage vegetativestage 20-35DAT 35-45DAT Timesowing 0-20DAS 20-35DAS DAS=DaysaftersowingDAT=Daysaftertransplanting Cucumberecologicalguide2008
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thisguide 3.3.Relationbetweenvegetativegrowthandpoddevelopment Vegetativegrowthiscloselyrelatedtoflowering,fruitformationanddevelopmentstages.Ifcucumbercropsaregrowninpoorsoil,especiallywhenthereislackofnitrogen,theywilldevelopslowlyandfruitswillbesmallandbitter.Fruitformationisalsocloselyrelatedtosoilnutrients.Cucumbergrownonloamy-lighttexturedorsandyloamsoil,giveshigherqualityfruitsthanonotherkindsofsoil. 3.4.Abioticfactorsandgrowthdevelopment Effectsoftemperature Cucumberrequiresawarmclimate.Seedscangerminateat12-13ºC,however;theoptimumtemperatureforcucumbergrowthdevelopmentis25-30º
C.Highertemperatureswillthecropdevelopmentandunderlongdurationtemperaturesof35-40ºC,theplantwilldie.Attemperaturesbelow15ºC,theplantwillloosebalancebetweenassimilationandcatabolism. Temperaturedirectlyaffectstimeofflowering.Atoptimumtemperature,theplantproducesfemaleflowers26daysaftergermination.Thelowertemperature,theslowertheplantproducesflowers.Degree-daysfromgerminationuntilthefirstharvestoflocalvarietiesis900ºCanduntiltheendofseasonare1650º
C. Effectsoflight Cucumberfavorslightsofshortdaylength.Thesuitabledaylengthfortheplanttogrowanddevelopis10-12hours/day.Anabundanceoflighttendstoincreasephotosynthesis,productivity,increaseyield,fruitquality,andreducetimeforthefruittomature.Thesuitablelightintensityforcucumberiswithin15,000–17,000lux. Effectsofhumidity Thecucumberfruitis95%water,thustheplanthasahighrequirementofhumidity.Ontheotherhand,duetolargefoliageandhighdrainagecoefficient,cucumberneedsthehighestamountofwateramongcucurbitcrops.Theoptimumsoilhumidityforcucumberis85-95%andairhumidityat90-95%.Ithaslowabilitytotoleratedrought.Waterdeficiencyresultstoweakdevelopmentoftheplantandtheumulationofcucurbitacinswhichcausesbittertasteoffruits.Cucumberfloweringandfruitdevelopmentstagesneedthehighestamountofwater. Effectsofsoilandnutrients Cucumberhasstricterrequirementsofsoilthanothercucurbitsduetoitsweakrootsystem.Thesuitablesoilissandyloam,loamy-lighttexturedsoil,withpHlevelof5.56.5. Astudyofcucumberproductivityusingmineralfertilizersshowedthatcucumberneedsmorepotassium,followedbynitrogenandphosphorus.Cucumbercannotbegiventoomuchfertilizer,butquicklyrespondstonutrientdeficiency. Cucumberecologicalguide2008
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thisguide II.CropManagement
1.Croprotation 1.1.ImportanceinrelationtonutrientavailabilityinsoilCroprotationreducesfertilitydegradationandnutrientdeficiency.Whenthesamecropisplantedinthesamefieldeveryseason,therewillbeacontinuousconsumptionofthesamenutrientsfromthesoil.Addingchemicalfertilizerswillsupplyonlypartofthenutrientsthatareconsumed,mostlyN,PandK.Addingchemicalfertilizerscontainingthedeficientnutrientswillnotsolvetheproblem.Itisnecessarytointroducecroprotationandanicmattertothesoil.Rotationwithgreenmanurecropssuchaslegumesincreasesnitrogensupplytothecrops. 1.2.Importanceinrelationtopestanddiseaseincidence Someofmonseriouspestsanddiseaseswhichliveinthesoilattackarangeofplantswithinthesamebotanicalfamily-butnoothers.Ifthekindsofplanttheyattackarecontinuallygrowninthesamearea,thepestsanddiseasescanbuilduptoinfectiouslevel.Onceasoil-bornediseasehasenteredafielditisverydifficulttogetridoff.Ifthereisabreakofseveralseasonsorevenseveralyearsinwhichothercrops(ofdifferentfamily)aregrown,theirpopulationwillbereducedandwilleventuallybesuppressed.Thisisthemainreasonforrotatingcrops. Rotationismosteffectiveagainstdiseasesthatattackonlyonecrop.However,controllingmanydiseasesthatinfectseveralcropsofthesameplantfamilyrequiresrotationwithanentirelydifferentfamily.Unfortunately,somepathogens,suchasthosecausingwiltsandrootrots,attackmanyfamiliesandrotationisunlikelytoreducedisease. Inaddition,somefungiproduceresistant,long-livedreproductivestructuresaswellastheimmediatelyinfectiousforms.Forexample,theblacksclerotiaproducedbythefungus,Sclerotiniacansurviveforyears.Pythiumandhthoracanalsoproducelong-livedrestingspores.Suchsporeshelpthesefungitosurviveforalongtimewithoutahost.Survivalofpathogenswithoutahostplantdependsonfactorsliketheenvironment,temperature,groundwater,etc.Someindicationson“survivalrates”perdiseasearementionedinthesectionsonindividualdiseases.Thefollowingarefewexamples: Diseases Earlyblight(Alternariasolani)Mosaicvirus(TMV)Southernblight(Sclerotiniasclerotiorum)Wilting(FusariumandVerticillium) Diseasecanstayaliveinthesoilwithoutsolanaceousplantfor:atleast1year2years7yearsManyyears(almostindeterminate) 1.3.Rotationguidelines:cropsandcycles CucumberisavegetablecropbelongingtotheCucurbitaceaefamilyandisattackedbypestsofothercucurbitssuchaswatermelon,waxgourd,pumpkin,bottlegourd,luffa,bittergourdsandsquash.Theseproblemsarelimitedwhencucumberisrotatedwith Cucumberecologicalguide2008
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thisguide non-cucurbitcropssuchaswaterplantsincludingriceandjute.moncroprotationformulapracticedinNorthernVietnamisthefollowing: Formula Growingarea Croprotationformula
1 VegetableWhiteradish–Kohlrabi–Cucumber(waxgourd)–Green intensive mustard farmingSep-Dec Oct-Dec.Dec-Jun Jul–Aug
2 VegetableTomato-Kohlrabi-Cucumber(waxgourd)–Whiteradish intensivefarming Aug-DecDec-Feb.Dec-Jun Jul–Aug
3 VegetableTomato/Cucumber–Corn–Summerleafyvegetable intensivefarming Aug.-Dec. Jan-MayJun–Aug.
4 VegetableFrenchbean-Tomato/Cucumber–Greenmustard/white intensive radish farming Oct-Feb Feb-May Jul–Oct
5 Semi- Cucumber–Earlyriceautumnseason–Frenchbean/Short- vegetable durationbrassicas intensivefarming Feb–May Jun–Oct Oct–Jan (Source:MaiThÞPh-¬ngAnh,CurriculumforVeg.MSc,1996)
2.Intercropping 2.1.Advantagesanddisadvantagesinrelationtopestanddiseaseincidence,marketing,soilutilizationandconservation Intercroppingisthesimultaneouscultivationoftwoormorecropsinonefield.Itcanalsobecalledmixedcroppingorpolyculture.Whenplantsofdifferentfamiliesareplantedtogetheritismoredifficultforinsectpestsanddiseasestospreadfromoneplanttothenext.Insectshavemoredifficultyinfindinghostplantswhentheyarecamouflagedbetweenotherplants.Fungalsporesmaylandonnon-hostplantswheretheyarelost.Naturalenemiesofinsectpestsgetachancetohideintheothercrops.Whentheintercropistallerthanthecucumberplantstheycanforma“barrier”thusreducingspreadofinsectpestsanddiseases. Certainintercroppedplantsexcretechemicalsorodorswhichrepelinsectpestsofotherplants.Examplesareonionandgarlic.Thestrongsmellrepelssomeinsects,andtheyflyawayandwillnotattackotherplantsgrowingbetweentheonionorgarlicplants. Cucumberecologicalguide2008
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thisguide Intercroppedsolanaceouscropswithonionorgarlicreducedlevelsofwhitefliesandaphidsontomatoes(Tumwine,1999). Otherplantsmayhavenematicidalactivity,killingnematodesinthesoil.Anexampleissesame:rootextractscausedmortalityofnematodesinlaboratorytests(Karshe,1993).Another“famous”nematode-killeristheflowerTagetessp.whichcaneffectivelycontrolnematodesontomato(Tumwine,1999).ordingtoAVRDC(1994),intercroppingtomatowithcowpeacouldbeusedinIPMinthetropicstocontrolbacterialwilt. Intercropscouldalsoreducetheriskofcropfailurebyprovidinganalternativecropandadditionaletoafarmer.However,whentheintercropistallerthanmaincrop(e.g.sunflowerorhum)itmaycauseyieldreductionduepetitionforlight,spaceandnutrients(Tumwine,1999).Seeboxbelow. Otherdisadvantagesincludemoredifficultharvestingoperationsduetodifferentripeningtimesofthecrops,andtheplanningofcroprotationscheduleisplicated.Intercroppingisusuallyabitmorelaborintensive. Effectsofintercroppingontomatolateblightdisease:astudyfromUganda ExperimentswereconductedinUgandatoidentifycropswhichcouldbegrownwithtomatoandwhichreducedlateblightdisease(hthorainfestans).Tallandshortcropswereintercroppedwithtomatoandsanitation(removalofinfectedleaves,shootsandflowers)werepracticed.Someconclusionsfromthesestudieswere: •Lateblightincidenceinintercroppedplotswaslowerthanincontrolplot(alsoduetosanitationpractices). •Soybeanandsesamepatibleforintercroppingwithtomatoesat60cmbetweenrowspacing. •Tallplantssuchashumandsunflowerhaveasuppressiveeffectontomatogrowthandproductivitywhenintercropped,presumablybecauseofshading. •Sanitationalonehadanegativeeffectontomatogrowthandproduction.•Rowspacingbetweenintercropsiscrucialtominimizesideeffectssuchas shadingpetitionfornutrients.(Tumwine,1999) 2.2.SuitablecropsIntercroppingshouldensuresomerequirements,suchasnotaffectingorreducingtheyieldofthemaincrop,harvestingtimeshouldnotbetoodifferentfromthemaincrop,anditmustbringabouthigherbenefitsthanthemono-croppingsystem. Somecropscanbeintercroppedduetotheirdifferentgrowthdevelopmenttimesanddifferentmorphologicalcharacteristics.Forexample,inVietnam,farmersoftenintercropspringonion,greenmustard,kohlrabi,radish,Chinesecabbagebetweenrowsofcucurbits. Cucumberecologicalguide2008
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thisguide 2.3.Method:timingandspacingSomeintercroppingpracticesthathavebeenappliedinVietnaminclude:-Cucumbergrowntogetherwithradish,greenmustard,andChinesecabbage.Radishshouldbesownatthetimeoftransplantingcucumber.Itisessentialtotakegoodcareofthecucumbertoavoidpoordevelopmentresultinginlowyields.VarietiesofgreenmustardandChinesecabbageusedforintercroppingshouldbeofshortduration(40-45days),grownbetweentworowsofcucumber.(Source:IPMtrainersinHanoi,April/2000).
3.Varietyselection 3.1.Demandandsupply:howtochooseavariety?
Theselectioncriteriaforavarietytogrowwillvarydependingonthepurposeforitsconsumption(asfreshfruitsorforprocessing).Varietiesforfruitprocessingaredividedintothefollowinggroups:smallfruitgroup;mediumfruitgroupandbigfruitgroup. 3.2.Characteristicsmonlyavailablevarieties Smallfruitgroup:-verysmallcucumberfruits(babycucumber)havelengthofbelow11cmanddiameterof2.5-3.5cm.Productsforprocessingare2-3dayoldfruits.Thisgrouphasshortgrowthduration(65-80days)withanaverageweightof150-220fruits/kg.Mostvarietiesinthisgrouparegynoecious,suchastheF1Marinda,F1Dunja,F1Levina(Dutch)andAmericanvarieties.OnlyMarindavarietyhasabunchof3-5fruitsoneachleafaxilandalthoughyieldisnothigh(3-8tons/ha)itsmarketvalueisstillhigh.Therefore,growingthisvarietyisstillpreferred.Inadditiontofreshconsumption,thisfruitgroupisusedforprocessing.Onemajorproductiondifficultyforthisgroupisthatthevarietiesaresusceptibletodisease,mainlydownymildewcausingmoderatetoseveredamage. Mediumfruitgroup:-includesmostlocalvarietiesandF1hybridvarieties.Fruitsare13-20cmlongand3.5-4.5cmindiameter.Thegrowthdurationofvarietiesinthemediumfruitgroupis75-85daysandyieldisabout22-25tons/ha.Somevarietiesinthisgroupcanbeslicedtoputinglassbottles. Bigfruitgroup:-includesF1hybridvarietiesfromTaiwan,AmericaandJapan.Taiwanvarietiesare25-30cmlong,4.5-5cmindiameter,cylinder-shapedfruit,lightgreenincolorandhavewhitespines.Japanesevarietiesarelonger,about30-45cmlong,about4-5cmindiameter,fruitsaresmoothorwrinkledwithwhitespinesandaredarkgreenincolor.Varietiesinthisgrouphaverelativelyhighyieldatanaverageof30-45tons/haandsometimes50tons/haifcultivationisgood. 3.3.CommonlygrowncucumbervarietiesinVietnam TherearemanyhybridandimportedcucumbervarietieswhicharegrownnowinVietnambutthemonlygrownonesarethoseinthesmallandbigfruitgroups. Smallfruitgroup -HybridvarietyPC1byFoodCropsResearchInstitute.Thisvarietyhasagrowthdurationof35-40days,developswellwithhighyieldofabout35-40tons/ha.Thefruitsaresmall,about9x3.2cmandweigh100-110g/fruitwiththickpulp(1.2cm).This Cucumberecologicalguide2008
9 ____________________________________________________________________________________________Why
thisguide varietyissuitableforexport.Fruitscanbestoredforalongtime,lengtheningthetimeforlocalconsumption.Immaturefruitscanbeharvestedforprocessingasbabycucumber.Fruitsrarelyturnyellowafterharvest.Freshfruitsarecrispyandhavegoodsmell.Plantsaretoleranttomajordiseasessuchaspowderymildew,downymildew,bacterialwiltandvirusdiseases.VarietyPC1canbegrowninbothSpring-SummerseasonandAutumn-Winterseasonandcangivehighyield. Bigfruitgroup -HybridSaoXanh1byFoodCropsResearchInstitute.Thisvarietyhasagrowthdurationof85-90daysandharvestingtimelastsfor40-45days.Plantsofthisvarietydevelopwellandcharacterizedwiththickstemanddarkgreenleaves.Fruitsarebig,about23cmlongandabout3.5-4.0cmindiameter.Averagefruitweightis200g/fruit,withthickpulp(1.3cm).Fruitsrarelyturnyellowafterharvest.Freshfruitsarecrispyandhavegoodsmellandgoodquality.Consumerslikethevarietyverymuch.Ithashighyieldatanaverageof35-40tons/ha.Plantsarerelativelytoleranttomajordiseasessuchaspowderymildew,downymildew,bacterialwiltandvirusdiseases.ThevarietycanbegrowninbothSpring-SummerseasonandAutumn-Winterseason. -F1Müxanh:providedbyEast-Westpany.Plantdevelopswellwithalotofbranches.Itissuitabletogrowduringrainyseason.Itcanresistsdownymildew.Harvestingstartsabout35-37daysafterplanting.Averageyieldis3-4kg/plant.Fruitsarestraight,greenincolor,15-17cmlong,withwhitespines,goodquality,sweet,crispyandcanbestored10daysafterharvest. -F1MütrangfromEast-WestSeedCompany.Plantsofthisvarietydevelopwellwithalotofbranches.Itissuitabletogrowindifferentseasonsandshowsresistancetodiseases.Itproducesalotoffruitswithayieldofabout3-4kg/plant.Fruitscanbeharvestedat15differenttimes.Theplantgivesthefirstharvestabout35-37daysaftersowing.Fruitsarestraight,palegreenincolor,15-17cmlong,withwhitespinesandcanbestoredtendaysafterharvestwithoutturningyellow. -F1124fromEast-WestSeedCompany.Thevarietygiveshighyieldofabout48tons/ha. -F1702fromEast-WestSeedCompany.Itcanbeplantedbothintherainyanddryseason.Fruitsarestraight,about20cmlongandgreenincolor.Theaverageyieldis5.4-9.5tons/1000m2.
4.Seedpreparation 4.1.Healthyseed Likesomeothercrops,cucumberispropagatedbyseed;thereforeseedsplayaveryimportantroleindeterminingfruityield.Farmersusuallyhavesomecriteriaforselectingseedssuchasseedpurityandgerminationpercentage. Forcucurbitseeds,therequirementforseedpurityis99%withapercentageofmixtureat0.05%andnoweedseeds.Seedsshouldbelightyellow,withweightof1000seeds(P<1000seeds)rangingfrom20–30andwiththenumberofseeds/fruitat150-500. Thegerminationpercentageofcucumberseedsis70%.Onesimplemethodthatcanbeusedtocheckgerminationabilityofcucumberseedsistoputabout100-500seeds Cucumberecologicalguide2008 10 ____________________________________________________________________________________________Why
thisguide onwettissue(orcotton)lyingonasmalldish.Theseedsarethencoveredbyclothorfilterpaper.Thenumberofgerminatedseedsiscountedafter24hoursandseedgerminationisobservedforthreedays. 4.2.Selectioncriteriaandmethod(infield,atharvestandbeforeplanting) Togetcucumberseedsforpropagation,fieldsofdifferentcucumbervarietiesshouldbeatleast2kmawayfromeachother.Normally,only3or4fruits/plantcanbeharvestedforgettingseeds.Oftenfruitsinthemiddlesectionofplantarecollected.Afterthefirstharvest,fruitsinthemiddlesectionoftheplantarekeptandfemaleflowerswhichopenlaterareremovedinordertohavemorenutrientsforseedfruits. Seedfruitsarepickedat25-30dayold,andthentheyarekeptfor4-5daysforphysiologicalmaturation.Togettheseeds,thefruitsareopenedverticallyandasmallspooncanbeusedtocollecttheseeds,putinaplasticbasinfor24hours,thenwashedandexposedtosunlight3-4times. SeedsfromF1varietiesshouldnotbekeptforthenextseason. 4.3.Storage Likeothervegetableseeds,cucumberseedseasilylosetheirgerminationabilityiftheyarestoredundernormalconditions.Inordertokeepseedsforthenextseason,twomethodseithertheclosestorageorcoldstoragemethodsmaybeapplied. -Closestorage:Driedseedsareplacedinbottles,jars,potswithsomelimeunderneathtoavoidcondensation.Containersshouldbeclosedcarefullywithlids.Seedscanbestoredfor3-4yearsusingthismethod. -Coldstorage:Driedseedsareplacedinpaperorplasticbagsthenputincoldroomwithtemperaturesof-4°
C.Seedscanbestoredfor15-20yearsusingthismethod. 4.4.SeedtreatmentSeedtreatmentisaimedtodisinfecttheseedsorprotectthemagainstpeststhatmayposehazardsduringgerminationandsubsequentstagesofplantgrowth.Inaddition,sometreatmentmethodscanstimulateseedstogerminatequickly.Theseedtreatmentmaybephysicalorchemical. Physicaltreatment-mayconsistofsoakingseedsinwarmwaterorapplyingdryheat.Thedurationofthetreatmentdependsontheseedstructureandthethicknessofitsskin.Cucumberseedsaresoakedinwaterat50ºCfor120minutesduetothickskin.Heattreatment,however,isnotnormallyagoodpracticebecauseittendstoreducegermination.Theviabilityofheat-treatedseedsalsodecreaseswithcontinuedstorageaftertreatment.Therefore,alternativemethodsmustbeexploredbeforeusingheattreatment. Chemicaltreatment-usuallyconsistsofafungicide,insecticide,oramixtureofboth.ThemonfungicidesusedforseedtreatmentareThiram(Tetramethylthiuramdisulfide)andCaptan(N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide).Botharebroadspectruminactionandhavelowmammaliantoxicity.Somesystemicfungicides,suchasRidomil(metalaxyl)provideprotectionagainstfungaldiseasesuptomaturityoftheplant. Cucumberecologicalguide2008 11 ____________________________________________________________________________________________Why
thisguide
5.Landpreparation 5.1.Soiltype/characteristicsinrelationtosuitabilityforcucumber Comparedtoothercucurbits,cucumberplanthasastricterrequirementofsoiltypeasitsrootsystemdevelopsandabsorbsnutrientspoorly.ResearchesshowthatsandyloamorsandysoilsaresuitableforgrowingcucumberbecauseitabsorbsheatfasterthanothersoilsinSpringseasonanditssmallparticlestructurehelpspreventseedlingsfromcollapseduetorainandwind. Thecucumberrootsystemisshallow(only25-30cmdeepfromground)resultinginpoorabilitytotoleratedrought,floodingandmakingthecropsusceptibletopestsanddiseases.Therefore,thesoilforcucumberplantingshouldbepreparedcarefully.Thebestwayistokeepploughedsoilfor5-7days,thensprinklecrushedlimetosterilizeandkillsoil-bornediseases.Raisedbedsarepreparedbeforeplanting. Cucumberrequiresloamylight-texturedsoil,suchasloamysoilorsandyloamsoilwithpHlevelof5.5-6.5. 5.2.Preparation 5.2.1..CharacteristicsofgoodsoilinrelationtosoilcultivationmethodsSoilproductivityisdefinedasthecapacityofthesoiltoproduceaspecificcrop(orsequenceofcrops)underaspecificmanagementsystemwhichincludesplantingdate,fertilization,irrigationschedule,tillage,andpestcontrol. Soilproductivityisverycloselyrelatedtothedepthsoil.Inmanycases,thethinnersoilis,thelowerisitsabilitytosupplywaterandnutrients.Inaddition,soilproductivitydependslargelyuponthekindofsoilsandlocalenvironmentalconditions.soil20-40cmdeepissuitableforgrowingvegetablesandlong-rootcrops. 5.2.2.Methodofsoilcultivationandbedpreparation Landpreparationaffectssoilnutrientconservation.Invegetablegrowingareas,landpreparationisoftendonemanuallyorwiththehelpofdraftanimalssuchasbuffaloes,cowsandhorses.Theresultissubstandardlandpreparationparticularlyinheavysoilswhicharemorelabor-intensive.Theusualproblemwithmanuallandpreparationisinadequatedepth.Thestepsinlandpreparationarethefollowing: a)Clearing/mowing:Thisisanoptimalstepnecessaryonlyinopeningnewareasforgrowingvegetablesandinpreparingthefieldafteraprolongedmismanagedfallow(rest)period.Underthiscondition,thefarmmaybetooweedytobeplowed.Beforeplowing,then,itmaybenecessarytoclearthefieldofobstructionsandtallweeds. b)Plowing:Likeothervegetablecrops,thesoilforgrowingcucumbershouldnotbetoofine.Ifitistoofine,itwillcovervoidspaceforair.Soilstructureaffectsrootdistribution,adventitiousrootsandrootquality.Studieshaveshownthat80%ofcucumberrootsdevelopandaredistributedinalayerof20mm.Topsoilonbedsshouldbe1-3cmor5cmhigh.Intheprocessofraisingbeds,however,trytosoilfinerthantheunderneathlayer.Thisisabasictechnicalrequirementofraisingbedsforvegetables. Cucumberecologicalguide2008 12 ____________________________________________________________________________________________Why
thisguide c)Raisingbeds:Thelengthofbedsdependsontheterrainbutshouldnotbemorethan100m.Ifthebedistoolong,itisnotconvenientforfieldcare,watering,andfertilization.Thewidthofthebedisnormally120cm,dependingoneachcucumbervariety.Bedheightshouldnotbemorethan25-30cm. Theshapeofraisedbedswillvarydependingontheseason.BecauseoftherainsinSummerseason,itisadvisabletopreparehighandnarrowraisedbedsforgrowingthecropandtodigtrenchesbetweenthebedsfordrainage.InthedryWinterseasonraisedbedscanbeflat,largeoralittlebitdeepinthecentertokeepwaterandfertilizer.
6.Cropestablishment 6.1.DirectplantingVegetablescanbeclassifiedintothreecategories,dependingontheplantingpractice:cropsthataretransplanted,cropsthatareusuallydirect-seeded,andcropsthatshouldbedirect-seeded.Cucumbersaretransplantedorusuallydirect-seeded. Direct-seedingpreventscropsfrombeinginjuredandhelpsthemtodevelopquickly.Sometubercrops,suchascarrotandradisheasilydevelopforkedrootduetorootdamageatseedlingstage.Therefore,theyshouldbedirect-seeded.Likeothercucurbits,cucumberrootsareeasilyaffected.However,whendirect-seedingcannotbedoneitisadvisabletogrowseedlingsinbananaleafpotstoavoidrootsfrombeingdamagedduringtransplanting. Thecucumbercropdevelopsquicklyinthefieldevenwhenconditionsarenotideal.Directseedingcanincreasethenumberofseasons.Seedscanbesowninthefieldevenbeforethepreviouscropisharvested.Thisallowsplantingoftheseedlingsimmediatelyafterharvestingthepreviouscrop,reducingtheperiodwhenthefieldisunproductive. Direct-seedingalwaysrequiresthreetofourtimesmoreamountofseedthantransplanting.Whenthecostoftheseedishigh,asinhybridseed,transplantingmaybemendedinsteadofdirect-seeding. Indirect-seeding,itisdifficulttocontrolthedepthofseeding,resultinginpooremergence.Ifseedsareplacedtoodeeply,itisdifficultforseedstogerminateorittakesalongertimefortheiremergence.Inmanycases,whensoilisnotpreparedwell,largesoilclumpsalsomakeitdifficultforseedstoemerge.Thereforedirectseedingrequiresfinesoilparticles.However,ifseedsareplacedtooshallow,theyedryandhot,difficulttogerminateandeasytobeeatenbybirdsandinsectpests. Timeofsowing Thegrowthdurationofcucumberisveryshort.Ittakesonly35-45daysfromsowinguntilfloweringstage,and45-55daysuntilharvest.Timeofsowingisdeterminedbytheseason.Cucumberrequireswarmclimateanditsseedcangerminateattemperaturesof12-13º
C.Thus,sowingtimeshouldbedeterminedbasedonclimateandtemperature. Incoldareas,seedsshouldnotbesowninWinterseasonwhentemperatureisunder10º
C.Underthatcondition,itwillbedifficultforseedstogerminateortheymayeven Cucumberecologicalguide2008 13 ____________________________________________________________________________________________Why
thisguide die.Ifseedscangerminate,itwilltakealongtimeandtheplantswilldeveloppoorly.Incoldareas,seedsareoftensowninthegreenhousethreeweeksbeforethereisnomorefrostortwoweeksafterthereisfrostinthefield.Intropicalareas,sowingtimeshouldbeconsideredcarefullysoasnottoaffectfloweringandpodformation.Floweringandpollinationwilliftemperatureisover35º
C.Iftemperatureis35ºCforseveraldays,plantsmaydie. ExampleoftimeofsowingintheNorthofVietnam:InWinter-Springseason,farmerssowcucumberseedsduringdayswhenthetemperatureis10°
C.Forthefirstfivedaysaftersowing,noneofseedsgerminateatall.Inthefollowingdays,someseedsgerminatealthoughatalowpercentage.Whenthetemperatureincreasestoabout15°C,seedsstarttogerminatealthoughnotuniformlyandittakesalongtime.Somefarmerssowseedslaterwhendaysarewarmerandthepercentageofgerminationishigherwithshortergerminationtime.Iftemperatureishighandthereismuchrainduringfloweringstage,flowerscannotbepollinatedresultinginlowpercentageoffruitformationandreducedyield.Therefore,thebesttimeforsowingshouldbedeterminedcarefullyespeciallyintheWinter-Springseason,otherwiseyieldswillbeaffected. (Source:DocumentofT¹ThuCóc,NguyÔnThÞPh-¬ngAnh) Insomeareas,thesowingtimeinSpringseasonisabout20–30Marchor15April–15May.IntheSummerseason,itisabout1–15Julyor1–20August. InnorthernVietnam,cucumbersowingtimefollows: •Winterseason:sowingseedsattheendofSeptemberorbeginningofOctober;harvestfrom15Novemberto15December. •Springseason:sowingseedsfrom10Februaryto15March.•Summerseason:sowingseedsattheendofAprilorbeginningofMay;harvest from15Juneto30July. Method Cucumbersareseededdirectlyintoholesinthefield.Holesarepreparedafterraisingbeds.Holesarespaced40-50cmapartinrowsspaced60cmapart.Transplantingdensityisabout33,000holes/ha.Seedsareplaceddirectlyinholesat2-3seedsperhole.Plantsarethinnedlatertokeeponly1-2plants/hole.ForF1seeds,plantonlyoneseedperhole.Cucumberseedshavethickskin,thustheyshouldbesoakedinwarmwaterbeforesowinginWinterseason.Sowseedsonthebedsatadepthof1-1.5cmandcoverwithhumusorricehuskbeforewatering. Cucumberecologicalguide2008 14 ____________________________________________________________________________________________Why
thisguide Precisionsowing:inspirationfromJessore,Bangladesh:AfarmerfromJessoreusesawoodenframewithsmallpinswhichheplacesonthesoilofthenurserybedsasaguideforsowingeggplantseeds.Thepinsmakesmallholesinthesoilatequalintervalstoindicatethepointsforsowingseeds.Hethensows2to3seedsineachhole.Withthismethodofprecisionsowing,thisfarmerisabletogetagoodnurseryusingonlyasmallamountofseed.Goodidea,especiallyforexpensivehybridseed!
☺(m.FarmerYousuf,Jessore,Bangladesh,1998) 6.2.Usingseedling Inmanycases,duetothelonggrowthdurationofthepreviouscroporunfavorableconditionsfordirect-seeding,transplantingcanbedonebymakingbananaleafpotsforseedlings.Inadditiontoaddressingcroptiming,theuseofbananaleafpotspreventsrootdamageorminimizesmechanicalwoundsonrootsofseedlingsduringtransplantingthataffectsplantgrowthanddevelopment. Potscanbemadeoutofbananaleaves,polyethelenebags,jarsorothermaterials.Thepotsareusuallyfilledwithcleansoilandpost.Varioussoilmixescanbeused,forexamplesub-soilpost.Oneortwoseedsaresownineachpot.Thepotsarewateredregularlyandprotectedfromfullsunorrain,ifnecessary. Pottingseedlingsversusflatfieldbeds,experiencesfromAsia:InatomatostudyinHaiPhongprovince,Vietnam,seedlingsfortheIPMtreatmentswereraisedinbananaleafpotsfilledwithcleansoilpost,whereasfarmerstraditionallyraisedtheminflatfieldseedbeds.Farmersfoundthattherewaslessdampingoffinseedlings,andlessseedwasneeded,whenplantswereraisedincleanconditionsinpotsratherthanintraditionalseedbeds.☺(source:Dr.J.Vos,2000) Cucumbertransplantsareusuallyabout4–6weeksoldandhave4or5trueleaveswhensetintothefield.Transplantsusuallyhavestraight,thickstemsanddisease-freeleaves.Potsorpolyethelenebagsareusuallyremovedattransplanting.Eachholeshouldhave1or2transplants.Thesoilshouldberaiseduphightoensureasturdyplantthatwillnotfalloverwhenitreachesitfullsize.Theplantisirrigatedaftertransplanting.
7.Pollinationandfruitsetting Mostcucumbers,whethermonoeciousorgynoecious,requireinsectstotransferpollenbetweenflowersofthesameordifferentplant.Fruitabortioncanreach100%inflowersbaggedtoexcludeinsectvisitors(Stanghellinietal.,1997),butself-pollinationratesof Cucumberecologicalguide2008 15 ____________________________________________________________________________________________Why
thisguide 30-36%havebeendocumentedintheabsenceofinsects(Jenkins,1942;Gingraset.al.,1999)andasmallrateofparthenocarpyisknowntoexist(Gustafson,1939;Gingraset.al.,1999).Nevertheless,insectpollinationisthenorm. Allofthemajorvarietiesareinterfertile.Eachstigmashouldreceiveseveralhundredgrainsofpollenforbestfruitsetandquality(Seatonetal.,1936).Pollengrainsdonotnecessarilyneedtobespreadevenlyonallthreelobesofthestigmatoformagoodfruit,butitdoestakemultiplebeevisitstooptimizefruit-set.Theminimumnumberofrequiredbeevisitsperflowerisprobablyvariety-dependentandhasbeenrecordedas8-12(Connor,1969;Stephen,1970;Lord,1985),18(Stanghellinietal.,1997)andsix(Gingrasetal.,1999). About30%oftheflowersingynoeciousplantingsshouldbemaleinordertooptimizepollinationandeconomicreturn(ConnorandMartin,1971).Thismeansthatgynoeciousvarietiesrequireasupplementalsourceofmaleflowers.Thisisdoneisbymercialseedwitharound10%monoeciousseed. Cucumberproducedfromearlyflowersonyoungplantsoftenhavefewerseedsandinferiorparedtofruitproducedpetitiononmorematurevines(ConnorandMartin,1970).Inunpublishedstudies,theseauthorsfoundthatoldervinesproducelargerfemaleflowerswithmoreovules.Thus,fruitqualitymaybeimprovedifpollinationcouldbedelayeduntilvinesaremoremature.ConnorandMartintestedthisideawithselectedmonoecious,gynoeciousandgynoecioushybridvarieties.Delayingpollination(withcagestoexcludeorincludebees)forupto11daysafterthefirstappearanceoffemaleflowersincreasedthenumberoffruitperplantandthedollarvalueperacre.Theincreasewaslikelyduetostrongervineandrootgrowthinmorematureplants. Itisdifficulttorealizethebenefitsofdelayedpollinationunderfieldconditions.Theonlywaytodelaypollinationinmonoeciousvarietiesistodelayimportationofhoneybeehives,butonecannotpracticallykeepwildbeesfromvisitingtheplants.Withgynoeciousvarieties,onecaninterplantmale-bearingmonoeciouspollenizervarietiesafewdaysafterplantingthegynoeciousvariety.Assuch,maleflowerseavailabletobeesonlyaftergynoeciousplantshavereachedasuitablelevelofmaturity.ConnorandMartin(1969a,b)mendedalternatinga12m-widestripofgynoeciousvarietywithanarrowstripofmonoeciouspollenizervarietiesafewdaysafterthegynoeciousvariety.Thestripofmonoeciouspollenizershouldprobablybenowiderthan1m(Free,1993).Delayedpollinationingynoeciousvarietiesisplicatedbythefactthatevengynoeciousplantsproduceafewmaleflowers. CucumbersaregrowninEuropethatsetfruitparthenocarpicallywithoutpollination.Pollinationisundesirableinthiscontextbecauseitresultsinmisshapen,devaluedfruit.Growersexcludepollinatorswithmodifiedglasshousesandgovernment-enforcedrestrictionsonbeekeeping(Free,1993)
8.Fertiliza
thisguide Whythisguide?
Aboutthisguide ThisCucumberEcologicalGuideisdevelopedbytheFAOInter-CountryProgramme(ICP)forIPMinVegetablesinSouthandSoutheastAsia.ThisguideissummarizedfrommanydocumentsandreportsoncucumberinVietnamandothercountries.Theobjectiveofthisecologicalguideistoprovidegeneraltechnicalbackgroundinformationoncucumberproduction,supplementedwithfieldexperiencesfromtheNationalIPMProgrammes,FAO’sVegetableIPMProgramme,andfromanizationsactiveinfarmerparticipatoryIPMinVietnamandothercountries. Whowillusethisguide?
NationalIPMprogrammes,IPMtrainers,andothersinterestedinIPMtrainingandfarmerparticipatoryresearch. Sometechnicalissuesinthisecologicalguidearenewplicated,requiringcontributionsfrommanyrelatedsectors.Inaddition,thetimeforpreparingthisguidewaslimitedandthematerialmayhavesomemistakes.Wehopetogetfeedbackandcontributionsfromallreaders,IPMtrainersandfarmersinordertoimprovethematerial. Theguidecanbeusedasreference.ItisnotanofficialtrainingdocumentforIPMinvegetables. Forcontributions,pleasesendto: FAORegionalVegetableIPMProgrammeRoomA25,39MaliwanMansionPhraAthitRoadBangkok10200Tel:(662)6974274Fax:(662)6974422email:Johannes.Ketelaar@ Cucumberecologicalguide2008 ii ____________________________________________________________________________________________Why
thisguide TableofContents
I.GeneralIntroduction
1 1.TheCucurbitaceaeFamily
1 1.1.CharacteristicsofCucurbitaceaeFamily 1.2.CucurbitsmonlygrowninVietnam 1.3.Mainproblemsofcucurbits 1.4.Sourcesofinformation(referencesandexperts)
2.Thecucumbercropasafarmingenterprise
2 2.1.History 2.2.Importanceofcrop:foodandcashvalue 2.3.Economicpotentialofthecrop 2.4.Analysisofmainproblemsincucumbercultivation 2.5.Approachtosolvingmainproblems
3.Biologicalfacts
3 3.1.Botanicalcharacteristics:taxonomy,morphology 3.2.Growthstagesanddevelopment 3.3.Relationbetweenvegetativegrowthandpoddevelopment 3.4.Abioticfactors,growthanddevelopment II.CropManagement
6 1.Croprotation
6 1.1.Importanceinrelationtonutrientavailabilityinthesoil 1.2.Importanceinrelationtopestanddiseaseincidence 1.3.Rotationguidelines:crops,cycle,etc.
2.Intercropping
7 2.1.Advantagesanddisadvantagesinrelationtopestanddisease incidence,marketing,soilutilization,andconservation 2.2.Suitablecrops 2.3.Method:timing,spacing,etc.
3.Varietyselection
9 3.1.Demandandsupply:howtochooseavariety 3.2.Characteristicsmonlyavailablevarieties 3.3.CucumbermonlygrowninVietnam
4.Seedpreparation 10 4.1.Healthyseed 4.2.Selectioncriteria,method(infield,atharvestandbeforeplanting) 4.3.Storage 4.4.Seedtreatment
5.Landpreparation 12 5.1.Soiltype/characteristicsinrelationtosuitabilityforcucumber 5.2.Preparation Cucumberecologicalguide2008 iii ____________________________________________________________________________________________Why
thisguide 5.2.1.Characteristicsinrelationtosuitabilityforcucumber5.2.2.Method:cultivation,bedpreparation,etc
6.Cropestablishment 13 6.1.Directplanting 6.2.Usingseedling
7.Pollinationandfruitsetting 15
8.Fertilization 16 8.1.Nutrientneeds:amount,timinginrelationtogrowthstages,effect ofvariousnutrientsonfruitproduction 8.2.Organicfertilizer 8.3.anicfertilizer 8.4.Cucumberfertilizationguide
9.Watermanagement 20 9.1.Waterrequirementsatseedling,vegetative,andfruitingstages 9.2.Method:irrigation,drainage,etc. 10.Stakingandpruning 21 10.1.Importanceofstaking 10.2.Timingandmethod 10.3.Pruning 11.Weedmanagement 22 11.1.Weedsandimpactofweedsoncropdevelopment 11.2.Timing 11.3.Method 12.Majordiseasesofcucumber 24 12.1.Damping-off–Fusarium,Rhizoctonia,Pythium,and hthorasp 12.2.Bacterialwilt–Erwiniatracheiphilia 12.3.YellowFusariumwilt–Fusariumoxysporum 12.4.Downymildew–Pseudoperonosporacubensis 12.5.Powderymildew–Eryshiphecichoraciarum 12.6.Targetleafspot–Corynesporacassiicola 12.7.Angularleafspot–Pseudomonassyringaepv.lachrymans 12.8.virus 12.9.Gummystemblight–Didymellabryoniae 12.10.Cucumbermosaicvirus 12.11.Physiologicaldisorders 13.Majorinsectpestsofcucumber 56 13.1.Leafminer–Liriomyzasp. 13.2.Aphids-Aphisgossyppii 13.3.Stripedcucumberbeetle–Diabroticasp. 13.4.Spidermites–Tetranychussp. 13.5.Whitefly–Bemisiatabaci Cucumberecologicalguide2008 iv ____________________________________________________________________________________________Why
thisguide 13.6.Thrips–Thripssp. 14.Harvesting 77 References 78 Plates: CommonPestsandDiseasesofCucumber 79 Cucumberecologicalguide2008 v ____________________________________________________________________________________________Why
thisguide IGeneralIntroduction
1.TheCucurbitaceaeFamily CropsbelongingtotheCucurbitaceaefamilymonlycalledcucurbits.Cucurbitsareabiggroupofvegetablesthatincludecucumber,bittergourd,squash,bottlegourd,ridgegourdandsnakegourd.Cucumbermonlyusedforsaladsandpickleswhilesquashandmostofthegourdsareforcooking.Watermelonandmuskmelonaretakenasdessertwhilewaxgourdispreparedasjamandbiscuits. Intheworldthereare120generaand1000speciesdistributedintropicalandsubtropicalareas.CucurbitsaretropicalinoriginandgrownmostlyinAfrica,tropicalAmerica,andAsia,mainlySoutheastAsia.SomegeneraarefoundinSouthandEastAsiawhilesomearealsodistributedintemperateareas.InVietnam,thereare23generaand53speciesofcucurbits. Cucurbitsareperennialcropsandmultiplybyseedsalthoughfewareclones. 1.1.CharacteristicsofCucurbitaceaefamily Cucurbitsmonbotanicalcharacteristicsasfollows: Roots:Therootsystemisextensiveandlargelysuperficial.Thetaprootislongandadventitiousrootsdevelopupto60cm.Therootsystemofdroughttolerantvarietiescangrow170-180cmdeep. Stem:Stemsare3-8angledbranches.Vinesextendupto9-10m.Thenodesproducerootswhentheyreachthesoilundersaturatedhumidity. Leaves:Leavesaresimpleandmosthave3-5lobeswithdifferentshapes.Somearedeeplylobed,e.g.,watermelon. Flowers:Flowersaresolitaryorinclusters,mostbeinggynoecious.Somearehermaphroditus,dioecious,andromonoecious. Fruits:Fruitsaresolidandulent. Seeds:Cucurbitshavemanyseedsofdifferentshapesandcolors,e.g.,watermelonexceptchayotewithonlyoneseedperfruit. 1.2.CucurbitaceaemonlygrowninVietnam CucurbitcropsgrowninVietnamareclassifiedasfollows:
1.Cucumis:cucumber,muskmelon2.Citrullus:watermelon3.Cucurbita:pumpkin,squash4.Lagenaria:bottlegourd5.Momordica:bittergourd6.Luffa:loofah7.Trichosanthes:snakegourd8.Benincasa:waxgourd Cucumberecologicalguide2008
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thisguide 9.innia:ivygourd10.Sechium:chayote 1.3.Mainproblemsofcucurbits AsothercropsintheCucurbitaceaefamily,cucumberhasmanyfieldproblemssuchasinsectpestsanddiseases,deterioratedvarietiesandreducedfruitquality. Pollination:Cucumberiscross-pollinatedbyinsects.Theratioofmaleandfemaleflowersandnumberofbeesorotherpollen-feedinginsectsareimportantfactorsaffectingtheyield.Theconstantreductioninpopulationsofpollen-feedinginsectsduetopesticidemisuseesaproblemforpollination. 1.4.Sourceofinformation Seelistofreferences
2.Thecucumbercropasafarmingenterprise 2.1.History MostcucurbitspecieshaveanAfricanorigin.However,cucumberisbelievedtohaveoriginatedfromthefoothillsoftheHimalayaswherethecloselyrelatedwildspeciesC.hardwickiiRoylestillexists.InIndia,thecucumberwasalreadybeingcultivated3000yearsago,anditwasknowninancientEgypt,GreeceandtheRomanEmpire.Inthe6thcentury,itwascultivatedinChinaandwasprobablythesourceofthefirstcucurbittoreachMalaysia.Nowitiscultivatedworldwide. 2.2.Importanceofcrop:foodandcashvalue Cucumberisgrownforitsimmaturefruitsthatareusedassaladvegetableandforpickles.Theslicingcucumberarepeeled,slicedandservedwithvinegarordressingorasaningredientofsalads.Cucumberandothercucurbitfruitsaregenerallyfat-freeandlowinsodium.However,processedcucumbers(pickles)canhavehighsodiumcontents. Cucumberisthehighestexport-processedproductwithincreasingproductivityannually. 2.3.Economicpotentialofthecrop Comparedwithothervegetables,cucumberupiesfourthplaceinimportanceintheworld,followingtomato,colecropsandonion.In1987,worldacreageofcucumberwasestimatedatabout850,000hawithatotalproductionof12.5milliontons.AbouthalfofthisproductionwasfromAsia,withChinaleadingat240,000haand3.7milliontonsin.ThetotalproductionforSoutheastAsiawas:Indonesia-40,000haand291,000t(1988);thePhilippines-1000haand6000t(1987);Thailand-12000haand143000t(1988). Picklingcucumber(gherkins)isnotpopularinSoutheastAsia.Westerncountries.prefertoimportsmall-sizegherkinsduetohighlaborcostsforharvestingfromIndonesiaandVietnam.ordingtostatisticsfromtheVietnamFruitandVegetableCooperationinVietnam,picklingcucumberfromnorthernexport-foodfactoriesexportedtoEuropeanmarketswas1117,2184and2309tonsin1992,1993and1995,respectively.Iningyears,marketsforthisproductwillnotonlybestable,butalsowillbedevelopedintermsoftypesandvolume.Goodproductionandnewtechniquesforvarieties, Cucumberecologicalguide2008
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thisguide cultivationandprocessingtechnologywillhelpbringabouthigherefficiencyandbetterqualityofproducts. 2.4.Analysisofmainproblemsincucumbercultivation Therearemanydifficultiesassociatedwithcucumbercultivationsuchasinsectpestsanddiseases,varietiesandmarkets. -Pestsanddiseases:Pestsanddiseasesoncucumberarenotasmanyasinsolanaceousorcruciferouscrops.Usually,problemswithpestsanddiseasesarelinkedtocroptimingandyield. -Varieties:Cucumbervarietiesdeterioraterapidlybecausetheyarepollinatedbyinsects.Varietiesaffecttherequirementsofprocessingfactoriesregardingfruitsizeandquality.Thislimitstheexpansionofconsumptionmarketsaswellasexpansionofcucumbercultivationareas. 2.5.ApproachtosolvingmainproblemsApplyingpropercultivationbinedwithIPMwillreducedamagebyinsectpestsanddiseasesoncucumber.Majordiseasesofcucumber,suchasangularleafspot,powderymildew,downymildew,andsoil-bornediseases,suchasbacterialwilt,canbepreventedbycultivationandotherculturalpractices.Growingresistantvarietiescaneffectivelyreduceinsectpestsanddiseases. SeedrehabilitationorusingF1varietiestogrowwillensurequalityandyieldofcucumber.Insomecases,F1varietiesgivehigheryieldthanpurevarieties.
3.Biologicalfacts 3.1.Botanicalcharacteristics:taxonomy,morphology Cucumberisanannualcropandaclimbingherb.Infavorableconditions,itsgrowthdevelopmentdurationcanlast12-13months. Root:Thecucumberrootsystemdevelopsweakly.Rootlengthcanbe10-25cminsandyloamsoil.Therootsystemmakesup1.5%ofthetotalbiomass.Secondaryrootsdistributeonthesurfacecoveringanareaofabout60-90cmwide.Varietiesthatarelongmaturinghavestrongerrootsystemsandpartsabovetheground.F1varieties,however,havelongerrootsthanparentvarietiesatanystageofcropgrowthanddevelopment.Therefore,thedevelopmentoftherootsystemsattheearlystagesiscloselyrelatedtoyield. Leaves:Leavesarealternate,simple,inoutlinetriangular-ovate.Leaf-bladesare3-7lobedanddeeplycordateatbase,acuteatapex.Lobesaretriangular,acuteatapexanddentate. Stem:Thestemsofthecucumberproducevines;are4-5angledandsparinglybranched.Thelengthofthemainstemmaybe2-3m. Flower:Flowersareaxillaryandunisexualandasionallyhermaphrodite.However,duetotheprocessofevolutionandhumaninterventions,newflowertypesuramongcucumbersuchas: •gynoecious •hermaphroditus Cucumberecologicalguide2008
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thisguide •gynoandromonoecious •gynomonoecious •andromonoecious Amongthesetypes,thegynoeciousandhermaphroditusflowersplayasignificantroleinbreedingandinproducingF1seeds. Theyellowflowershave4-5calyxes.Maleflowersaresingleorborneinclusters,smallerthanfemaleflowersthathave4-5calyxes.Femaleflowersaresolitaryonshortthickpedicelsof3-5mmlong.Flowershave3-4ovules. Fruit:Fruitschangecolorfrompalegreenwhenyoungtowhite,yelloworbrownwhenripeneddependingonthecoloroffruitspines.Fruitswithwhitespinesaregreenandneverturnyellow.Theyarewhitish-greenwhenripened.Fruitswithblackorbrownspinesareyelloworbrownincolorwhenripened. Seed:Seedsarelightyellowandtheweightof1000seedsisabout20-30g.Thereareabout150-500seedsperfruit. 3.2.Growthstagesanddevelopment pletesalifecycle,fromseedtoseed,inoneseason.Cucumbersareusuallygrownforafewmonths,althoughtheycanbecroppedfor12monthsorlongerwhengrowingconditions(water,fertilization,etc.)areoptimalandplantsarenotexhaustedbydiseasesorinsectpests. Cucumberrequires50-70hotdaystogiveaharvest.Earlymaturingvarietieshavegrowthdevelopmentdurationof50days,monvarieties-60daysandlatematuringvarieties-70days.Thegeneralgrowthstagesforcucumberare: •Seed.•Seedlingstage-usuallytheperiodfromemergingseedtotransplantingtothe mainfield.•Vegetativestage-fromtransplantinguntilthefirstflowerbudsdevelop.•Floweringstage-plantwithflowerbudsandopenflowers.•Fruitingstage-plantwithsmalltofull-sizedfruits.•Harvestingstage-periodwhenplantyieldsmaturefruits. Thesegrowthstagesareoverlappingintime: harvestingstage seedlingstage flowering&fruitingstage vegetativestage 20-35DAT 35-45DAT Timesowing 0-20DAS 20-35DAS DAS=DaysaftersowingDAT=Daysaftertransplanting Cucumberecologicalguide2008
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thisguide 3.3.Relationbetweenvegetativegrowthandpoddevelopment Vegetativegrowthiscloselyrelatedtoflowering,fruitformationanddevelopmentstages.Ifcucumbercropsaregrowninpoorsoil,especiallywhenthereislackofnitrogen,theywilldevelopslowlyandfruitswillbesmallandbitter.Fruitformationisalsocloselyrelatedtosoilnutrients.Cucumbergrownonloamy-lighttexturedorsandyloamsoil,giveshigherqualityfruitsthanonotherkindsofsoil. 3.4.Abioticfactorsandgrowthdevelopment Effectsoftemperature Cucumberrequiresawarmclimate.Seedscangerminateat12-13ºC,however;theoptimumtemperatureforcucumbergrowthdevelopmentis25-30º
C.Highertemperatureswillthecropdevelopmentandunderlongdurationtemperaturesof35-40ºC,theplantwilldie.Attemperaturesbelow15ºC,theplantwillloosebalancebetweenassimilationandcatabolism. Temperaturedirectlyaffectstimeofflowering.Atoptimumtemperature,theplantproducesfemaleflowers26daysaftergermination.Thelowertemperature,theslowertheplantproducesflowers.Degree-daysfromgerminationuntilthefirstharvestoflocalvarietiesis900ºCanduntiltheendofseasonare1650º
C. Effectsoflight Cucumberfavorslightsofshortdaylength.Thesuitabledaylengthfortheplanttogrowanddevelopis10-12hours/day.Anabundanceoflighttendstoincreasephotosynthesis,productivity,increaseyield,fruitquality,andreducetimeforthefruittomature.Thesuitablelightintensityforcucumberiswithin15,000–17,000lux. Effectsofhumidity Thecucumberfruitis95%water,thustheplanthasahighrequirementofhumidity.Ontheotherhand,duetolargefoliageandhighdrainagecoefficient,cucumberneedsthehighestamountofwateramongcucurbitcrops.Theoptimumsoilhumidityforcucumberis85-95%andairhumidityat90-95%.Ithaslowabilitytotoleratedrought.Waterdeficiencyresultstoweakdevelopmentoftheplantandtheumulationofcucurbitacinswhichcausesbittertasteoffruits.Cucumberfloweringandfruitdevelopmentstagesneedthehighestamountofwater. Effectsofsoilandnutrients Cucumberhasstricterrequirementsofsoilthanothercucurbitsduetoitsweakrootsystem.Thesuitablesoilissandyloam,loamy-lighttexturedsoil,withpHlevelof5.56.5. Astudyofcucumberproductivityusingmineralfertilizersshowedthatcucumberneedsmorepotassium,followedbynitrogenandphosphorus.Cucumbercannotbegiventoomuchfertilizer,butquicklyrespondstonutrientdeficiency. Cucumberecologicalguide2008
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thisguide II.CropManagement
1.Croprotation 1.1.ImportanceinrelationtonutrientavailabilityinsoilCroprotationreducesfertilitydegradationandnutrientdeficiency.Whenthesamecropisplantedinthesamefieldeveryseason,therewillbeacontinuousconsumptionofthesamenutrientsfromthesoil.Addingchemicalfertilizerswillsupplyonlypartofthenutrientsthatareconsumed,mostlyN,PandK.Addingchemicalfertilizerscontainingthedeficientnutrientswillnotsolvetheproblem.Itisnecessarytointroducecroprotationandanicmattertothesoil.Rotationwithgreenmanurecropssuchaslegumesincreasesnitrogensupplytothecrops. 1.2.Importanceinrelationtopestanddiseaseincidence Someofmonseriouspestsanddiseaseswhichliveinthesoilattackarangeofplantswithinthesamebotanicalfamily-butnoothers.Ifthekindsofplanttheyattackarecontinuallygrowninthesamearea,thepestsanddiseasescanbuilduptoinfectiouslevel.Onceasoil-bornediseasehasenteredafielditisverydifficulttogetridoff.Ifthereisabreakofseveralseasonsorevenseveralyearsinwhichothercrops(ofdifferentfamily)aregrown,theirpopulationwillbereducedandwilleventuallybesuppressed.Thisisthemainreasonforrotatingcrops. Rotationismosteffectiveagainstdiseasesthatattackonlyonecrop.However,controllingmanydiseasesthatinfectseveralcropsofthesameplantfamilyrequiresrotationwithanentirelydifferentfamily.Unfortunately,somepathogens,suchasthosecausingwiltsandrootrots,attackmanyfamiliesandrotationisunlikelytoreducedisease. Inaddition,somefungiproduceresistant,long-livedreproductivestructuresaswellastheimmediatelyinfectiousforms.Forexample,theblacksclerotiaproducedbythefungus,Sclerotiniacansurviveforyears.Pythiumandhthoracanalsoproducelong-livedrestingspores.Suchsporeshelpthesefungitosurviveforalongtimewithoutahost.Survivalofpathogenswithoutahostplantdependsonfactorsliketheenvironment,temperature,groundwater,etc.Someindicationson“survivalrates”perdiseasearementionedinthesectionsonindividualdiseases.Thefollowingarefewexamples: Diseases Earlyblight(Alternariasolani)Mosaicvirus(TMV)Southernblight(Sclerotiniasclerotiorum)Wilting(FusariumandVerticillium) Diseasecanstayaliveinthesoilwithoutsolanaceousplantfor:atleast1year2years7yearsManyyears(almostindeterminate) 1.3.Rotationguidelines:cropsandcycles CucumberisavegetablecropbelongingtotheCucurbitaceaefamilyandisattackedbypestsofothercucurbitssuchaswatermelon,waxgourd,pumpkin,bottlegourd,luffa,bittergourdsandsquash.Theseproblemsarelimitedwhencucumberisrotatedwith Cucumberecologicalguide2008
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thisguide non-cucurbitcropssuchaswaterplantsincludingriceandjute.moncroprotationformulapracticedinNorthernVietnamisthefollowing: Formula Growingarea Croprotationformula
1 VegetableWhiteradish–Kohlrabi–Cucumber(waxgourd)–Green intensive mustard farmingSep-Dec Oct-Dec.Dec-Jun Jul–Aug
2 VegetableTomato-Kohlrabi-Cucumber(waxgourd)–Whiteradish intensivefarming Aug-DecDec-Feb.Dec-Jun Jul–Aug
3 VegetableTomato/Cucumber–Corn–Summerleafyvegetable intensivefarming Aug.-Dec. Jan-MayJun–Aug.
4 VegetableFrenchbean-Tomato/Cucumber–Greenmustard/white intensive radish farming Oct-Feb Feb-May Jul–Oct
5 Semi- Cucumber–Earlyriceautumnseason–Frenchbean/Short- vegetable durationbrassicas intensivefarming Feb–May Jun–Oct Oct–Jan (Source:MaiThÞPh-¬ngAnh,CurriculumforVeg.MSc,1996)
2.Intercropping 2.1.Advantagesanddisadvantagesinrelationtopestanddiseaseincidence,marketing,soilutilizationandconservation Intercroppingisthesimultaneouscultivationoftwoormorecropsinonefield.Itcanalsobecalledmixedcroppingorpolyculture.Whenplantsofdifferentfamiliesareplantedtogetheritismoredifficultforinsectpestsanddiseasestospreadfromoneplanttothenext.Insectshavemoredifficultyinfindinghostplantswhentheyarecamouflagedbetweenotherplants.Fungalsporesmaylandonnon-hostplantswheretheyarelost.Naturalenemiesofinsectpestsgetachancetohideintheothercrops.Whentheintercropistallerthanthecucumberplantstheycanforma“barrier”thusreducingspreadofinsectpestsanddiseases. Certainintercroppedplantsexcretechemicalsorodorswhichrepelinsectpestsofotherplants.Examplesareonionandgarlic.Thestrongsmellrepelssomeinsects,andtheyflyawayandwillnotattackotherplantsgrowingbetweentheonionorgarlicplants. Cucumberecologicalguide2008
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thisguide Intercroppedsolanaceouscropswithonionorgarlicreducedlevelsofwhitefliesandaphidsontomatoes(Tumwine,1999). Otherplantsmayhavenematicidalactivity,killingnematodesinthesoil.Anexampleissesame:rootextractscausedmortalityofnematodesinlaboratorytests(Karshe,1993).Another“famous”nematode-killeristheflowerTagetessp.whichcaneffectivelycontrolnematodesontomato(Tumwine,1999).ordingtoAVRDC(1994),intercroppingtomatowithcowpeacouldbeusedinIPMinthetropicstocontrolbacterialwilt. Intercropscouldalsoreducetheriskofcropfailurebyprovidinganalternativecropandadditionaletoafarmer.However,whentheintercropistallerthanmaincrop(e.g.sunflowerorhum)itmaycauseyieldreductionduepetitionforlight,spaceandnutrients(Tumwine,1999).Seeboxbelow. Otherdisadvantagesincludemoredifficultharvestingoperationsduetodifferentripeningtimesofthecrops,andtheplanningofcroprotationscheduleisplicated.Intercroppingisusuallyabitmorelaborintensive. Effectsofintercroppingontomatolateblightdisease:astudyfromUganda ExperimentswereconductedinUgandatoidentifycropswhichcouldbegrownwithtomatoandwhichreducedlateblightdisease(hthorainfestans).Tallandshortcropswereintercroppedwithtomatoandsanitation(removalofinfectedleaves,shootsandflowers)werepracticed.Someconclusionsfromthesestudieswere: •Lateblightincidenceinintercroppedplotswaslowerthanincontrolplot(alsoduetosanitationpractices). •Soybeanandsesamepatibleforintercroppingwithtomatoesat60cmbetweenrowspacing. •Tallplantssuchashumandsunflowerhaveasuppressiveeffectontomatogrowthandproductivitywhenintercropped,presumablybecauseofshading. •Sanitationalonehadanegativeeffectontomatogrowthandproduction.•Rowspacingbetweenintercropsiscrucialtominimizesideeffectssuchas shadingpetitionfornutrients.(Tumwine,1999) 2.2.SuitablecropsIntercroppingshouldensuresomerequirements,suchasnotaffectingorreducingtheyieldofthemaincrop,harvestingtimeshouldnotbetoodifferentfromthemaincrop,anditmustbringabouthigherbenefitsthanthemono-croppingsystem. Somecropscanbeintercroppedduetotheirdifferentgrowthdevelopmenttimesanddifferentmorphologicalcharacteristics.Forexample,inVietnam,farmersoftenintercropspringonion,greenmustard,kohlrabi,radish,Chinesecabbagebetweenrowsofcucurbits. Cucumberecologicalguide2008
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thisguide 2.3.Method:timingandspacingSomeintercroppingpracticesthathavebeenappliedinVietnaminclude:-Cucumbergrowntogetherwithradish,greenmustard,andChinesecabbage.Radishshouldbesownatthetimeoftransplantingcucumber.Itisessentialtotakegoodcareofthecucumbertoavoidpoordevelopmentresultinginlowyields.VarietiesofgreenmustardandChinesecabbageusedforintercroppingshouldbeofshortduration(40-45days),grownbetweentworowsofcucumber.(Source:IPMtrainersinHanoi,April/2000).
3.Varietyselection 3.1.Demandandsupply:howtochooseavariety?
Theselectioncriteriaforavarietytogrowwillvarydependingonthepurposeforitsconsumption(asfreshfruitsorforprocessing).Varietiesforfruitprocessingaredividedintothefollowinggroups:smallfruitgroup;mediumfruitgroupandbigfruitgroup. 3.2.Characteristicsmonlyavailablevarieties Smallfruitgroup:-verysmallcucumberfruits(babycucumber)havelengthofbelow11cmanddiameterof2.5-3.5cm.Productsforprocessingare2-3dayoldfruits.Thisgrouphasshortgrowthduration(65-80days)withanaverageweightof150-220fruits/kg.Mostvarietiesinthisgrouparegynoecious,suchastheF1Marinda,F1Dunja,F1Levina(Dutch)andAmericanvarieties.OnlyMarindavarietyhasabunchof3-5fruitsoneachleafaxilandalthoughyieldisnothigh(3-8tons/ha)itsmarketvalueisstillhigh.Therefore,growingthisvarietyisstillpreferred.Inadditiontofreshconsumption,thisfruitgroupisusedforprocessing.Onemajorproductiondifficultyforthisgroupisthatthevarietiesaresusceptibletodisease,mainlydownymildewcausingmoderatetoseveredamage. Mediumfruitgroup:-includesmostlocalvarietiesandF1hybridvarieties.Fruitsare13-20cmlongand3.5-4.5cmindiameter.Thegrowthdurationofvarietiesinthemediumfruitgroupis75-85daysandyieldisabout22-25tons/ha.Somevarietiesinthisgroupcanbeslicedtoputinglassbottles. Bigfruitgroup:-includesF1hybridvarietiesfromTaiwan,AmericaandJapan.Taiwanvarietiesare25-30cmlong,4.5-5cmindiameter,cylinder-shapedfruit,lightgreenincolorandhavewhitespines.Japanesevarietiesarelonger,about30-45cmlong,about4-5cmindiameter,fruitsaresmoothorwrinkledwithwhitespinesandaredarkgreenincolor.Varietiesinthisgrouphaverelativelyhighyieldatanaverageof30-45tons/haandsometimes50tons/haifcultivationisgood. 3.3.CommonlygrowncucumbervarietiesinVietnam TherearemanyhybridandimportedcucumbervarietieswhicharegrownnowinVietnambutthemonlygrownonesarethoseinthesmallandbigfruitgroups. Smallfruitgroup -HybridvarietyPC1byFoodCropsResearchInstitute.Thisvarietyhasagrowthdurationof35-40days,developswellwithhighyieldofabout35-40tons/ha.Thefruitsaresmall,about9x3.2cmandweigh100-110g/fruitwiththickpulp(1.2cm).This Cucumberecologicalguide2008
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thisguide varietyissuitableforexport.Fruitscanbestoredforalongtime,lengtheningthetimeforlocalconsumption.Immaturefruitscanbeharvestedforprocessingasbabycucumber.Fruitsrarelyturnyellowafterharvest.Freshfruitsarecrispyandhavegoodsmell.Plantsaretoleranttomajordiseasessuchaspowderymildew,downymildew,bacterialwiltandvirusdiseases.VarietyPC1canbegrowninbothSpring-SummerseasonandAutumn-Winterseasonandcangivehighyield. Bigfruitgroup -HybridSaoXanh1byFoodCropsResearchInstitute.Thisvarietyhasagrowthdurationof85-90daysandharvestingtimelastsfor40-45days.Plantsofthisvarietydevelopwellandcharacterizedwiththickstemanddarkgreenleaves.Fruitsarebig,about23cmlongandabout3.5-4.0cmindiameter.Averagefruitweightis200g/fruit,withthickpulp(1.3cm).Fruitsrarelyturnyellowafterharvest.Freshfruitsarecrispyandhavegoodsmellandgoodquality.Consumerslikethevarietyverymuch.Ithashighyieldatanaverageof35-40tons/ha.Plantsarerelativelytoleranttomajordiseasessuchaspowderymildew,downymildew,bacterialwiltandvirusdiseases.ThevarietycanbegrowninbothSpring-SummerseasonandAutumn-Winterseason. -F1Müxanh:providedbyEast-Westpany.Plantdevelopswellwithalotofbranches.Itissuitabletogrowduringrainyseason.Itcanresistsdownymildew.Harvestingstartsabout35-37daysafterplanting.Averageyieldis3-4kg/plant.Fruitsarestraight,greenincolor,15-17cmlong,withwhitespines,goodquality,sweet,crispyandcanbestored10daysafterharvest. -F1MütrangfromEast-WestSeedCompany.Plantsofthisvarietydevelopwellwithalotofbranches.Itissuitabletogrowindifferentseasonsandshowsresistancetodiseases.Itproducesalotoffruitswithayieldofabout3-4kg/plant.Fruitscanbeharvestedat15differenttimes.Theplantgivesthefirstharvestabout35-37daysaftersowing.Fruitsarestraight,palegreenincolor,15-17cmlong,withwhitespinesandcanbestoredtendaysafterharvestwithoutturningyellow. -F1124fromEast-WestSeedCompany.Thevarietygiveshighyieldofabout48tons/ha. -F1702fromEast-WestSeedCompany.Itcanbeplantedbothintherainyanddryseason.Fruitsarestraight,about20cmlongandgreenincolor.Theaverageyieldis5.4-9.5tons/1000m2.
4.Seedpreparation 4.1.Healthyseed Likesomeothercrops,cucumberispropagatedbyseed;thereforeseedsplayaveryimportantroleindeterminingfruityield.Farmersusuallyhavesomecriteriaforselectingseedssuchasseedpurityandgerminationpercentage. Forcucurbitseeds,therequirementforseedpurityis99%withapercentageofmixtureat0.05%andnoweedseeds.Seedsshouldbelightyellow,withweightof1000seeds(P<1000seeds)rangingfrom20–30andwiththenumberofseeds/fruitat150-500. Thegerminationpercentageofcucumberseedsis70%.Onesimplemethodthatcanbeusedtocheckgerminationabilityofcucumberseedsistoputabout100-500seeds Cucumberecologicalguide2008 10 ____________________________________________________________________________________________Why
thisguide onwettissue(orcotton)lyingonasmalldish.Theseedsarethencoveredbyclothorfilterpaper.Thenumberofgerminatedseedsiscountedafter24hoursandseedgerminationisobservedforthreedays. 4.2.Selectioncriteriaandmethod(infield,atharvestandbeforeplanting) Togetcucumberseedsforpropagation,fieldsofdifferentcucumbervarietiesshouldbeatleast2kmawayfromeachother.Normally,only3or4fruits/plantcanbeharvestedforgettingseeds.Oftenfruitsinthemiddlesectionofplantarecollected.Afterthefirstharvest,fruitsinthemiddlesectionoftheplantarekeptandfemaleflowerswhichopenlaterareremovedinordertohavemorenutrientsforseedfruits. Seedfruitsarepickedat25-30dayold,andthentheyarekeptfor4-5daysforphysiologicalmaturation.Togettheseeds,thefruitsareopenedverticallyandasmallspooncanbeusedtocollecttheseeds,putinaplasticbasinfor24hours,thenwashedandexposedtosunlight3-4times. SeedsfromF1varietiesshouldnotbekeptforthenextseason. 4.3.Storage Likeothervegetableseeds,cucumberseedseasilylosetheirgerminationabilityiftheyarestoredundernormalconditions.Inordertokeepseedsforthenextseason,twomethodseithertheclosestorageorcoldstoragemethodsmaybeapplied. -Closestorage:Driedseedsareplacedinbottles,jars,potswithsomelimeunderneathtoavoidcondensation.Containersshouldbeclosedcarefullywithlids.Seedscanbestoredfor3-4yearsusingthismethod. -Coldstorage:Driedseedsareplacedinpaperorplasticbagsthenputincoldroomwithtemperaturesof-4°
C.Seedscanbestoredfor15-20yearsusingthismethod. 4.4.SeedtreatmentSeedtreatmentisaimedtodisinfecttheseedsorprotectthemagainstpeststhatmayposehazardsduringgerminationandsubsequentstagesofplantgrowth.Inaddition,sometreatmentmethodscanstimulateseedstogerminatequickly.Theseedtreatmentmaybephysicalorchemical. Physicaltreatment-mayconsistofsoakingseedsinwarmwaterorapplyingdryheat.Thedurationofthetreatmentdependsontheseedstructureandthethicknessofitsskin.Cucumberseedsaresoakedinwaterat50ºCfor120minutesduetothickskin.Heattreatment,however,isnotnormallyagoodpracticebecauseittendstoreducegermination.Theviabilityofheat-treatedseedsalsodecreaseswithcontinuedstorageaftertreatment.Therefore,alternativemethodsmustbeexploredbeforeusingheattreatment. Chemicaltreatment-usuallyconsistsofafungicide,insecticide,oramixtureofboth.ThemonfungicidesusedforseedtreatmentareThiram(Tetramethylthiuramdisulfide)andCaptan(N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide).Botharebroadspectruminactionandhavelowmammaliantoxicity.Somesystemicfungicides,suchasRidomil(metalaxyl)provideprotectionagainstfungaldiseasesuptomaturityoftheplant. Cucumberecologicalguide2008 11 ____________________________________________________________________________________________Why
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5.Landpreparation 5.1.Soiltype/characteristicsinrelationtosuitabilityforcucumber Comparedtoothercucurbits,cucumberplanthasastricterrequirementofsoiltypeasitsrootsystemdevelopsandabsorbsnutrientspoorly.ResearchesshowthatsandyloamorsandysoilsaresuitableforgrowingcucumberbecauseitabsorbsheatfasterthanothersoilsinSpringseasonanditssmallparticlestructurehelpspreventseedlingsfromcollapseduetorainandwind. Thecucumberrootsystemisshallow(only25-30cmdeepfromground)resultinginpoorabilitytotoleratedrought,floodingandmakingthecropsusceptibletopestsanddiseases.Therefore,thesoilforcucumberplantingshouldbepreparedcarefully.Thebestwayistokeepploughedsoilfor5-7days,thensprinklecrushedlimetosterilizeandkillsoil-bornediseases.Raisedbedsarepreparedbeforeplanting. Cucumberrequiresloamylight-texturedsoil,suchasloamysoilorsandyloamsoilwithpHlevelof5.5-6.5. 5.2.Preparation 5.2.1..CharacteristicsofgoodsoilinrelationtosoilcultivationmethodsSoilproductivityisdefinedasthecapacityofthesoiltoproduceaspecificcrop(orsequenceofcrops)underaspecificmanagementsystemwhichincludesplantingdate,fertilization,irrigationschedule,tillage,andpestcontrol. Soilproductivityisverycloselyrelatedtothedepthsoil.Inmanycases,thethinnersoilis,thelowerisitsabilitytosupplywaterandnutrients.Inaddition,soilproductivitydependslargelyuponthekindofsoilsandlocalenvironmentalconditions.soil20-40cmdeepissuitableforgrowingvegetablesandlong-rootcrops. 5.2.2.Methodofsoilcultivationandbedpreparation Landpreparationaffectssoilnutrientconservation.Invegetablegrowingareas,landpreparationisoftendonemanuallyorwiththehelpofdraftanimalssuchasbuffaloes,cowsandhorses.Theresultissubstandardlandpreparationparticularlyinheavysoilswhicharemorelabor-intensive.Theusualproblemwithmanuallandpreparationisinadequatedepth.Thestepsinlandpreparationarethefollowing: a)Clearing/mowing:Thisisanoptimalstepnecessaryonlyinopeningnewareasforgrowingvegetablesandinpreparingthefieldafteraprolongedmismanagedfallow(rest)period.Underthiscondition,thefarmmaybetooweedytobeplowed.Beforeplowing,then,itmaybenecessarytoclearthefieldofobstructionsandtallweeds. b)Plowing:Likeothervegetablecrops,thesoilforgrowingcucumbershouldnotbetoofine.Ifitistoofine,itwillcovervoidspaceforair.Soilstructureaffectsrootdistribution,adventitiousrootsandrootquality.Studieshaveshownthat80%ofcucumberrootsdevelopandaredistributedinalayerof20mm.Topsoilonbedsshouldbe1-3cmor5cmhigh.Intheprocessofraisingbeds,however,trytosoilfinerthantheunderneathlayer.Thisisabasictechnicalrequirementofraisingbedsforvegetables. Cucumberecologicalguide2008 12 ____________________________________________________________________________________________Why
thisguide c)Raisingbeds:Thelengthofbedsdependsontheterrainbutshouldnotbemorethan100m.Ifthebedistoolong,itisnotconvenientforfieldcare,watering,andfertilization.Thewidthofthebedisnormally120cm,dependingoneachcucumbervariety.Bedheightshouldnotbemorethan25-30cm. Theshapeofraisedbedswillvarydependingontheseason.BecauseoftherainsinSummerseason,itisadvisabletopreparehighandnarrowraisedbedsforgrowingthecropandtodigtrenchesbetweenthebedsfordrainage.InthedryWinterseasonraisedbedscanbeflat,largeoralittlebitdeepinthecentertokeepwaterandfertilizer.
6.Cropestablishment 6.1.DirectplantingVegetablescanbeclassifiedintothreecategories,dependingontheplantingpractice:cropsthataretransplanted,cropsthatareusuallydirect-seeded,andcropsthatshouldbedirect-seeded.Cucumbersaretransplantedorusuallydirect-seeded. Direct-seedingpreventscropsfrombeinginjuredandhelpsthemtodevelopquickly.Sometubercrops,suchascarrotandradisheasilydevelopforkedrootduetorootdamageatseedlingstage.Therefore,theyshouldbedirect-seeded.Likeothercucurbits,cucumberrootsareeasilyaffected.However,whendirect-seedingcannotbedoneitisadvisabletogrowseedlingsinbananaleafpotstoavoidrootsfrombeingdamagedduringtransplanting. Thecucumbercropdevelopsquicklyinthefieldevenwhenconditionsarenotideal.Directseedingcanincreasethenumberofseasons.Seedscanbesowninthefieldevenbeforethepreviouscropisharvested.Thisallowsplantingoftheseedlingsimmediatelyafterharvestingthepreviouscrop,reducingtheperiodwhenthefieldisunproductive. Direct-seedingalwaysrequiresthreetofourtimesmoreamountofseedthantransplanting.Whenthecostoftheseedishigh,asinhybridseed,transplantingmaybemendedinsteadofdirect-seeding. Indirect-seeding,itisdifficulttocontrolthedepthofseeding,resultinginpooremergence.Ifseedsareplacedtoodeeply,itisdifficultforseedstogerminateorittakesalongertimefortheiremergence.Inmanycases,whensoilisnotpreparedwell,largesoilclumpsalsomakeitdifficultforseedstoemerge.Thereforedirectseedingrequiresfinesoilparticles.However,ifseedsareplacedtooshallow,theyedryandhot,difficulttogerminateandeasytobeeatenbybirdsandinsectpests. Timeofsowing Thegrowthdurationofcucumberisveryshort.Ittakesonly35-45daysfromsowinguntilfloweringstage,and45-55daysuntilharvest.Timeofsowingisdeterminedbytheseason.Cucumberrequireswarmclimateanditsseedcangerminateattemperaturesof12-13º
C.Thus,sowingtimeshouldbedeterminedbasedonclimateandtemperature. Incoldareas,seedsshouldnotbesowninWinterseasonwhentemperatureisunder10º
C.Underthatcondition,itwillbedifficultforseedstogerminateortheymayeven Cucumberecologicalguide2008 13 ____________________________________________________________________________________________Why
thisguide die.Ifseedscangerminate,itwilltakealongtimeandtheplantswilldeveloppoorly.Incoldareas,seedsareoftensowninthegreenhousethreeweeksbeforethereisnomorefrostortwoweeksafterthereisfrostinthefield.Intropicalareas,sowingtimeshouldbeconsideredcarefullysoasnottoaffectfloweringandpodformation.Floweringandpollinationwilliftemperatureisover35º
C.Iftemperatureis35ºCforseveraldays,plantsmaydie. ExampleoftimeofsowingintheNorthofVietnam:InWinter-Springseason,farmerssowcucumberseedsduringdayswhenthetemperatureis10°
C.Forthefirstfivedaysaftersowing,noneofseedsgerminateatall.Inthefollowingdays,someseedsgerminatealthoughatalowpercentage.Whenthetemperatureincreasestoabout15°C,seedsstarttogerminatealthoughnotuniformlyandittakesalongtime.Somefarmerssowseedslaterwhendaysarewarmerandthepercentageofgerminationishigherwithshortergerminationtime.Iftemperatureishighandthereismuchrainduringfloweringstage,flowerscannotbepollinatedresultinginlowpercentageoffruitformationandreducedyield.Therefore,thebesttimeforsowingshouldbedeterminedcarefullyespeciallyintheWinter-Springseason,otherwiseyieldswillbeaffected. (Source:DocumentofT¹ThuCóc,NguyÔnThÞPh-¬ngAnh) Insomeareas,thesowingtimeinSpringseasonisabout20–30Marchor15April–15May.IntheSummerseason,itisabout1–15Julyor1–20August. InnorthernVietnam,cucumbersowingtimefollows: •Winterseason:sowingseedsattheendofSeptemberorbeginningofOctober;harvestfrom15Novemberto15December. •Springseason:sowingseedsfrom10Februaryto15March.•Summerseason:sowingseedsattheendofAprilorbeginningofMay;harvest from15Juneto30July. Method Cucumbersareseededdirectlyintoholesinthefield.Holesarepreparedafterraisingbeds.Holesarespaced40-50cmapartinrowsspaced60cmapart.Transplantingdensityisabout33,000holes/ha.Seedsareplaceddirectlyinholesat2-3seedsperhole.Plantsarethinnedlatertokeeponly1-2plants/hole.ForF1seeds,plantonlyoneseedperhole.Cucumberseedshavethickskin,thustheyshouldbesoakedinwarmwaterbeforesowinginWinterseason.Sowseedsonthebedsatadepthof1-1.5cmandcoverwithhumusorricehuskbeforewatering. Cucumberecologicalguide2008 14 ____________________________________________________________________________________________Why
thisguide Precisionsowing:inspirationfromJessore,Bangladesh:AfarmerfromJessoreusesawoodenframewithsmallpinswhichheplacesonthesoilofthenurserybedsasaguideforsowingeggplantseeds.Thepinsmakesmallholesinthesoilatequalintervalstoindicatethepointsforsowingseeds.Hethensows2to3seedsineachhole.Withthismethodofprecisionsowing,thisfarmerisabletogetagoodnurseryusingonlyasmallamountofseed.Goodidea,especiallyforexpensivehybridseed!
☺(m.FarmerYousuf,Jessore,Bangladesh,1998) 6.2.Usingseedling Inmanycases,duetothelonggrowthdurationofthepreviouscroporunfavorableconditionsfordirect-seeding,transplantingcanbedonebymakingbananaleafpotsforseedlings.Inadditiontoaddressingcroptiming,theuseofbananaleafpotspreventsrootdamageorminimizesmechanicalwoundsonrootsofseedlingsduringtransplantingthataffectsplantgrowthanddevelopment. Potscanbemadeoutofbananaleaves,polyethelenebags,jarsorothermaterials.Thepotsareusuallyfilledwithcleansoilandpost.Varioussoilmixescanbeused,forexamplesub-soilpost.Oneortwoseedsaresownineachpot.Thepotsarewateredregularlyandprotectedfromfullsunorrain,ifnecessary. Pottingseedlingsversusflatfieldbeds,experiencesfromAsia:InatomatostudyinHaiPhongprovince,Vietnam,seedlingsfortheIPMtreatmentswereraisedinbananaleafpotsfilledwithcleansoilpost,whereasfarmerstraditionallyraisedtheminflatfieldseedbeds.Farmersfoundthattherewaslessdampingoffinseedlings,andlessseedwasneeded,whenplantswereraisedincleanconditionsinpotsratherthanintraditionalseedbeds.☺(source:Dr.J.Vos,2000) Cucumbertransplantsareusuallyabout4–6weeksoldandhave4or5trueleaveswhensetintothefield.Transplantsusuallyhavestraight,thickstemsanddisease-freeleaves.Potsorpolyethelenebagsareusuallyremovedattransplanting.Eachholeshouldhave1or2transplants.Thesoilshouldberaiseduphightoensureasturdyplantthatwillnotfalloverwhenitreachesitfullsize.Theplantisirrigatedaftertransplanting.
7.Pollinationandfruitsetting Mostcucumbers,whethermonoeciousorgynoecious,requireinsectstotransferpollenbetweenflowersofthesameordifferentplant.Fruitabortioncanreach100%inflowersbaggedtoexcludeinsectvisitors(Stanghellinietal.,1997),butself-pollinationratesof Cucumberecologicalguide2008 15 ____________________________________________________________________________________________Why
thisguide 30-36%havebeendocumentedintheabsenceofinsects(Jenkins,1942;Gingraset.al.,1999)andasmallrateofparthenocarpyisknowntoexist(Gustafson,1939;Gingraset.al.,1999).Nevertheless,insectpollinationisthenorm. Allofthemajorvarietiesareinterfertile.Eachstigmashouldreceiveseveralhundredgrainsofpollenforbestfruitsetandquality(Seatonetal.,1936).Pollengrainsdonotnecessarilyneedtobespreadevenlyonallthreelobesofthestigmatoformagoodfruit,butitdoestakemultiplebeevisitstooptimizefruit-set.Theminimumnumberofrequiredbeevisitsperflowerisprobablyvariety-dependentandhasbeenrecordedas8-12(Connor,1969;Stephen,1970;Lord,1985),18(Stanghellinietal.,1997)andsix(Gingrasetal.,1999). About30%oftheflowersingynoeciousplantingsshouldbemaleinordertooptimizepollinationandeconomicreturn(ConnorandMartin,1971).Thismeansthatgynoeciousvarietiesrequireasupplementalsourceofmaleflowers.Thisisdoneisbymercialseedwitharound10%monoeciousseed. Cucumberproducedfromearlyflowersonyoungplantsoftenhavefewerseedsandinferiorparedtofruitproducedpetitiononmorematurevines(ConnorandMartin,1970).Inunpublishedstudies,theseauthorsfoundthatoldervinesproducelargerfemaleflowerswithmoreovules.Thus,fruitqualitymaybeimprovedifpollinationcouldbedelayeduntilvinesaremoremature.ConnorandMartintestedthisideawithselectedmonoecious,gynoeciousandgynoecioushybridvarieties.Delayingpollination(withcagestoexcludeorincludebees)forupto11daysafterthefirstappearanceoffemaleflowersincreasedthenumberoffruitperplantandthedollarvalueperacre.Theincreasewaslikelyduetostrongervineandrootgrowthinmorematureplants. Itisdifficulttorealizethebenefitsofdelayedpollinationunderfieldconditions.Theonlywaytodelaypollinationinmonoeciousvarietiesistodelayimportationofhoneybeehives,butonecannotpracticallykeepwildbeesfromvisitingtheplants.Withgynoeciousvarieties,onecaninterplantmale-bearingmonoeciouspollenizervarietiesafewdaysafterplantingthegynoeciousvariety.Assuch,maleflowerseavailabletobeesonlyaftergynoeciousplantshavereachedasuitablelevelofmaturity.ConnorandMartin(1969a,b)mendedalternatinga12m-widestripofgynoeciousvarietywithanarrowstripofmonoeciouspollenizervarietiesafewdaysafterthegynoeciousvariety.Thestripofmonoeciouspollenizershouldprobablybenowiderthan1m(Free,1993).Delayedpollinationingynoeciousvarietiesisplicatedbythefactthatevengynoeciousplantsproduceafewmaleflowers. CucumbersaregrowninEuropethatsetfruitparthenocarpicallywithoutpollination.Pollinationisundesirableinthiscontextbecauseitresultsinmisshapen,devaluedfruit.Growersexcludepollinatorswithmodifiedglasshousesandgovernment-enforcedrestrictionsonbeekeeping(Free,1993)
8.Fertiliza
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