TIMINGANDINTENSITYOFFLOWERINGOFSWEETORANGE[Citrussinensis (L.)Osbeck]ASAFUNCTIONOFLOCALWEATHERFACTORSANDCROP UNDERCENTRALFLORIDACONDITIONS JUANIGNACIOVALIENTEBANUET ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT OFTHEREQUIREMENTSFORTHEDEGREEOF DOCTOROFPHILOSOPHY UNIVERSITYOFFLORIDA 2001 Copyright2001 by JuanIgnacioValienteBanuet IwouldliketodedicatethisworktomymotherGuadalupeBanuet ACKNOWLEDGMENTS Iwould liketoexpress my sincere gratitude andappreciation toDr. L. Gene Albrigoforbeingmymentor;andforhisfriendship,guidance,andsupportthroughout mystudies,whichwereessentialinachievingthegoalsofthisresearch. IalsothankDr. JamesJ.Ferguson,andDr.HowardW.Beckfortheirrolesaschairmanandcochairman ofmysupervisorycommittee,respectively. Finally,IthankDr.FredS.Davies,andDr. FedroS.Zazuetafortheirscientificguidanceandencouragement. TheFloridaCitrusProductionResearchMarketingOrdergeneratedthefunding forthisresearch,andtheFloridaCitrusProductionResearchAdvisoryCouncilapproved thegrantoftheDecisionInformationSystemsforCitrusproject(DISCproject). Ithank eachandeveryoneoftheDISCprojectmembersfortheirtrustandtheopportunityto workforthem while supporting mydoctoral research. In particularI wouldliketo expressmygratitudetothefoundersandcooperatorsoftheDISCprojectMr.PeteSpyke, andMr.NormTodd. Ialsothankthe"DeficitIrrigationofTurf'project,theNational CouncilofScienceandTechnology(Mexico),andtheFlorida-MexicoInstitutefortheir supportduringpartofmygraduatestudies. IthanknumerouspeopleattheHorticultural SciencesDepartment, attheIFAS InformationTechnologiesOffice,andattheCitrus ResearchandEducationCenter(CREC),LakeAlfred,Florida,whoprovidedmewith helpandtechnicalassistance. InparticularIwouldliketoexpressmygratitudetoMr. NanLin,andMr.AndyKingfortheirhelpinprogramming. iv Iamalsothankfultothecitrusgrowersthatcooperatedwiththisresearch. Ithank Mr.Tunnowhoallowedtheuseofhisgroveandprovidedplantmaterialsforoneofthe fieldsites. IalsothanktheCRECforthesecondfieldsiteandplantmaterials. Atthepersonallevel,Ithankallofmyfriendswhomadelifealoteasierduring theseyearsofwork. Inparticular,IwouldliketothankMarthaCastanedaforherlove andsupportduringtheseyearsofhardwork. FortheirfriendshipandsupportIthank Diego, Erica, and Carmen Rojas, Victoria and Carmen Saiz de Omenaca, Carlos Arechiga, Marlene Rosales, Elena Lapiana, Mireia Lorenzo, Virginia Rada, Maritza Ojeda,ArturoBocardo,HusseinSanchez,JuanCarlosRodriguez,andOlgaMontenegro amongothers. Finally, I would like to send my gratitude to my family, in particularto my mother,mysistersGuadalupeandLaura,aswellasmybrothersJose,Eduardo,Alfonso, Guillermo,andLeopoldo. Allofthemandtheirfamiliesprovidedmewiththeinner strengthandnecessarysupporttowithstandthedifficulttimesthatcomewithaprojectof thisnature. V TABLEOFCONTENTS Eige ACKNOWLEDGMENTS iv LISTOFTABLES x LISTOFFIGURES xiv ABSTRACT J^iv 1. INTRODUCTION 1 OverviewofCitrusFlowering 1 FlowerBudInduction 2 FlowerBudDifferentiation 3 FlowerOpening 3 FactorsAffectingFloweringinCitrus 4 ExogenousFactors 5 Ambienttemperature 5 Soiltemperature 6 Waterrelations 6 EndogenousFactors 7 Plantmaterial 7 Plantage 7 Carbohydrates 8 Hormonesandgrowthregulators 9 Plantnutrition 12 Budandshootage 14 Cropload 15 InVitroFlowering 16 PhenologyStudiesofCitrusFlowering 17 ModelingofAgriculturalSystems 17 ExpertSystemsandDecisionSupportSystems 18 ModelingPhenologicalProcesses 19 ModelingCitrusFlowering 20 vi EFFECTOFLOWTEMPERATURESTRESSLEVELS,CROPLOAD,AND BUDAGEONTHEFLORALINDUCTIONOFSWEETORANGETREES [Citrussinensis(L.)Osbeck]INCENTRALFLORIDA 23 FlowerBudInduction 24 MonitoringFlowerBudInduction 25 EffectofAmbientTemperatures 26 EffectofCropLoad 27 EffectofBudAge 28 MaterialsandMethods 29 PlantMaterials 29 ExperimentalDesign 30 DataCollection 31 Analysis1. PhenologicalResponseof'Valencia'and'Hamlin'TreesasAffected bySeasonandCrop 33 Effectofseasonandcroploadonbudsproutingparameters 33 Effectofseasonandcroploadonfloweringphenology 34 Floraldistributionbyshootage(summervs.spring) 34 Analysis2. EffectofDifferentInductionLevelsonthePhenologicalResponseof 'Valencia'and'Hamlin'Trees 34 Effectsofdifferentinductionandcroploadtreatmentsonphenological parameters 34 Effectsofdifferentinductionlevelsonfloraldistributionbybudpositionalong theshoot 35 Analysis3. EffectofWeatherDataonPhenologicalResponseof'Valencia'and 'Hamlin'Trees 35 Inductionasafunctionofweather 35 Weatherdata 36 Phenologicalresponse 36 Results 36 AnalysisI. PhenologicalResponseof'Valencia'and'Hamlin'TreesasAffected bySeasonandCrop 36 Effectofseasonandcroploadonbudsprouting 36 Effectofseasonandcroploadonfloweringphenology 37 Floraldistributionbyshootage(summervs.spring) 38 Analysis2. EffectofDifferentInductionLevelsonthePhenologicalResponseof 'Valencia'and'Hamlin'Trees 39 Effectsofdifferentinductionlevelsandcroploadonphenologicalparameters..39 Effectsofdifferentinductionlevelsonfloraldistributionbybudpositionalong theshoot 40 Analysis3. EffectofWeatherDataonthePhenologicalResponseof'Valencia' and'Hamlin'Trees 41 Vegetativebudspershoot 41 Floweringbudspershoot 41 Flowersperfloweringbud 41 Flowerspershoot 42 Discussion 42 vii Analysis1. EvaluationofPhenologicalResponse(BudSproutingandFlowering Parameters)of'Valencia'and'Hamlin'TreesasAffectedbySeasonandCrop Load 42 Budsproutingparameters 42 Effectofseasonandcroploadonfloweringphenology 43 Floraldistributionbyshootage(summervs.spring) 44 Analysis2. EffectofDifferentInductionLevelsonthePhenologicalResponseof 'Valencia'and'Hamlin'Trees 45 Effectsofdifferentinductionlevelsandcroploadonphenologicalparameters..45 Effectsofdifferentinductionlevelsonthefloraldistributionbybudposition alongtheshoot 47 Analysis3. EffectofWeatheronthePhenologicalResponseof'Valencia'and 'Hamlin'Trees 47 Vegetativebudspershoot 47 Floweringbudspershoot 48 Flowersperfloweringbud 49 Flowerspershoot 50 Conclusions 50 3. MODELINGFLOWERINGDATEOFSWEETORANGE[Citrussinensis(L.) Osbeck]TREESINCENTRALFLORIDABASEDONHISTORICAL WEATHERRECORDS 82 MaterialsandMethods 83 Analysis1.FloweringDateasaFunctionofAverageMonthlyTemperatures 85 Analysis2.FloweringDateasaFunctionofHoursAccumulativeWithinMonthly TemperatureRanges 86 Analysis3.DaystoFullBloomasaFunctionofStratifiedDegree-DayAnalysis afterFulfillmentofInductionStimuliandInitiationofDifferentiation 86 Analysis4.DaystoFullBloomasaFunctionofPhenologicalParametersAfter FulfillmentofInductionStimuliandInitiationofDifferentiation 87 Determiningdifferentiationtimeafterfulfillmentofinductionstimuliand initiationofdifferentiation 88 Determiningdateofinitiationofdifferentiationbasedonthereporteddatefor peakanthesis 88 Results 89 Analysis1.FloweringDateasaFunctionofAverageMonthlyTemperatures 89 Analysis2.FloweringDateasaFunctionofHoursAccumulatedWithinMonthly TemperatureRanges 89 Analysis3.DaystoFullBloomasaFunctionofStratifiedDegree-dayAnalysis afterFulfillmentofInductionStimuliandInitiationofDifferentiation 90 Analysis4.DaystoFullBloomasaFunctionofPhenologicalParametersafter FulfillmentofInductionStimuliandInitiationofDifferentiation 91 Determiningdifferentiationtimeafterfulfillmentofinductionstimuliand initiationofdifferentiation 91 Determiningdateofinitiationofdifferentiationbasedonthereporteddatefor peakanthesis 92 viii Discussion.. 92 Conclusions 97 4. IPRNETDEIGCRTAITOINO,NACNHDAPMTAENRA.GDEEMCEISNITONOFSTUPHPEOFRLTOSWYESRTIENMGFPORROCTEHSESOF SWEETORANGETREES[Citrussinensis(L.)Osbeck]UNDERFLORIDA CONDITIONS 110 MaterialsandMethods 112 OverallFrameworkoftheDISC-DSS 112 InductionMonitoringExpertSystem 112 TransitionfromInductiontoDifferentiationModels 114 ModelsforFloralOrganDifferentiation-TimetoBloomModels 115 Results 116 OverallFrameworkoftheDISC-DSS 116 InductionMonitoringExpertSystem 117 TransitionfromInductiontoDifferentiationModels 121 ModelsforFloralOrganDifferentiation-TimetoBloomModels 121 DiscussionandConclusions 123 APPENDIXA. DEVELOPMENTOFFLOWERINGBUDSINEXCISEDSTEMS OFSWEETORANGE[Citrussinensis,(L).Osbeck] 133 MaterialsandMethods 136 Experiment1. PreliminaryStudies 136 Experiment2. ForcingTechniquefortheDevelopmentofFlowersinPreviously InducedBuds 136 Collectionofplantmaterials 137 Shootpreparation 137 Shootforcing 137 Results 138 Experiment1. PreliminaryStudies 138 Experiment2. ForcingTechniquefortheDevelopmentofFlowersinPreviously InducedBuds 138 Discussion 138 Conclusions 140 LISTOFREFERENCES 143 BIOGRAPHICALSKETCH 149 ix LISTOFTABLES Table Page 2-1Descriptionofinductionandcroploadtreatments(6reps.)ofsweetorangetreesfor ValenciaandHamlinduringthe1998-1999and1999-2000seasons 53 2-2.Comparisonofbudsproutingparametersof'Hamlin'sweetorangetreesfromthe 1999tothe2000seasons(rows),andwithandwithoutcropload(columns)....54 2-3.Comparisonofbudsproutingparametersof'Valencia'sweetorangetreesfromthe 1999tothe2000seasons(rows),andwithandwithoutcropload(columns)....55 2-4.Comparisonoffloweringparametersof'Hamlin'sweetorangetreesfromthe1999 tothe2000seasons(rows),andwithandwithoutcropload(columns) 56 2-5.Comparisonoffloweringparametersof'Valencia'sweetorangetreesfromthe1999 tothe2000seasons(rows),andwithandwithoutcropload(columns) 57 2-6.Cumulativepercentagesoffloraldistributionbybudpositionalongtheshootof differentageshoots(summerandspring)for'Hamlin'and'Valencia'trees combiningthe1999and2000seasons 59 2-7.Summaryofanalysesofvarianceofbudsproutingparameters(totalsprouting, vegetative,andreproductivebudspershoot)for'Hamlin'and'Valencia'trees duringthe1999and2000seasons 60 2-8.Summaryofsproutingparameters(vegetativeandreproductivebudspershoot)for 'Hamlin'treesduringthe1999season 61 2-9.Summaryofsproutingparameters(vegetativeandreproductivebudspershoot)for 'Hamlin'treesduringthe2000season 62 2-10.Summaryofsproutingparameters(vegetativeandreproductivebudspershoot)for 'Valencia'treesduringthe1999season 63 2-11.Summaryof'Duncan'analysesofsproutingparameters(vegetativeand reproductivebudspershoot)for'Valencia'treesduringthe2000season 64 X