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