园艺英语：Grafting2完整版

WHYUSEROOTSTOCKS?1)Propagation2)ControlofTreeCroppingandFruitSize/Quality3)Resistance/TolerancetoSoil-BornePestsandDiseases4)Resistance/TolerancetoAbioticStressConditionsWHYUSEROOTSTOCKS?Propagation:Traditionally,rootstockswereusedprimarilyasamethodforpropagatingselectedscioncultivars.Treefruitspeciesdonotdeveloptrue-to-typewhenpropagatedfromseedandpropagationofselectedscioncultivarsispossibleonlybyvegetativemethods.Propagationofmostcultivarsoftemperatetreefruitsisverydifficultusingtraditionalstooling/layeringorcuttingmethods,althoughsomecultivarsofmorellotartcherryandplum

havealwaysprovedanexceptiontothisrule.usedtechniquesofbuddingand/orgraftingformillenniaandthesimplestandmostreliablemethodforvegetativepropagationoffruittreeshasreliedoncombiningarootstockwiththescioncultivarviabudding/grafting.Horticulturisthaveusedtechniquesofbuddingand/orgraftingformillenniaandthesimplestandmostreliablemethodforvegetativepropagationoffruittreeshasreliedoncombiningarootstockwiththescioncultivarviabudding/grafting.ControlofTreeVigor:Inafewspeciesoftemperatefruits,rootstocksprovidetheprincipalmethodofcontrollingtheexcessiveinherentvigorofthescioncultivar.Thevigorofapple,pear,plumand,morerecently,sweetcherrytreescanbecontrolledveryeffectivelybychoiceofanappropriaterootstock.Thisoptionhasbeenavailableforapplesandpearsforseveralcenturies,butcommerciallyviabledwarfingandsemi-dwarfingrootstocksforstonefruitspecieshavebeenintroducedonlyoverthelast80yearsorso.ControlofTreeCroppingandFruitSize/QualityProducersofapplesandpearshaverecognizedforalongtimethatbychoiceofsuitablerootstocktheirtreescanbeinducedtocropearlierintheirlives(exhibitimprovedprecocity)andcropmoreabundantlyandconsistently.

Morerecentlyithasbeenshownthatcertainrootstockscanalsoinfluencefruitsizeandquality.Forinstance,theapplerootstockM.9induceslargerfruitsizethanmanyotherrootstocksandthiseffectcannotbeexplainedintermsofreducedcroploads.Resistance/TolerancetoSoil-BornePestsandDiseasesSoil-bornepestsanddiseasesare,inmanyareasofproduction,amajorconstraintonfruitandnutproduction.Rootstockshavebeenselectedthatprovideresistanceortolerancetothemostdamagingofthesepestsanddiseasesandareessential,oftenprovidingtheonlymeansbywhichthefruitcropscanbeproducedintheseareas.Soil-bornediseases(suchasPhytophthorasp.)arethemostdamagingalthoughpestssuchasthewoollyappleaphid(Eriosomalanigerum)areequallyimportantinsomeproductionregions.Currentlythereislittleunderstandingconcerningwhysomerootstocksshowimprovedresistance/tolerancetothesedamagingorganisms.Resistance/TolerancetoAbioticStressConditionsRootstocksarealsousedtoadaptscioncultivarstosoilsorclimaticconditionsthatareotherwisenotfullysuitedtotheircultivation.Areasofproductionthatexperiencesustainedperiodsofverylow(sub-zero)wintertemperaturesneedrootstocksthataretoleranttowintercold.Similarly,climaticareasorsoilssubjecttotransientdroughtconditionsrequirerootstockscapableofcompetingwithweedsand/orgrassesforreducedwaterreservesand/orinducingefficientwaterusebythescioncultivar.Whatarethealternative