Source-sink interactions in flowering and fruiting southern highbush blueberry

143 Pages·1997·4.6 MB·English

by  Maust, Brian E.

SOURCE-SINKINTERACTIONSINFLOWERINGANDFRUITING
SOUTHERNHIGHBUSHBLUEBERRY
-
By
BRIANE.MAUST
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
1997
ACKNOWLEDGEMENTS
SincereappreciationisextendedtoDr.JeffreyG.Williamson,chairman
ofthesupervisorycommittee, forhis counsel and directionthroughoutthe
researchprojectanddissertationpreparation. Appreciationisextendedto Dr.
Rebecca Darnell,cochairofthesupervisorycommittee, forhersupportand
advice and forthe use of her lab. Appreciation is also extended to other
members ofthesupervisorycommittee: Drs. Paul Lyrene, Karen Koch, and
KimberlynWilliams,fortheirencouragement,practicaladvice,andinsights.
I wanttoexpress myappreciationtoSteve Hissforhis helpwithso
manypracticalthingsandhiswillingnesstoshareexperiences. Ialsoenjoyed
thetimespentwiththemanygraduatestudentsinthedepartmentoverthe
years.
Aparticularandspecialappreciationisgiventomywife,Marcia,forher
support and understanding and to Katrina, Karla, and Joel, for their
encouragementduringthisprocess.
ii
TABLEOFCONTENTS
ACKNOWLEDGEMENTS
ii
ABSTRACT v
CHAPTERS
1 INTRODUCTION 1
2 REVIEWOFTHELITERATURE 4
BlueberryGrowthandDevelopment 5
CarbohydrateAvailability 6
CarbohydrateReserves 6
CarbohydrateProduction 10
CarbohydrateUseandSinkCompetition 22
CarbohydrateAllocationtoFruit 24
LeafArea:FruitRatio 25
TheEffectofFruitingonVegetativeBiomassAllocation . . 26
Respiration 29
Summary 32
3 FLOWERBUDDENSITYAFFECTSVEGETATIVEAND
REPRODUCTIVEDEVELOPMENTINFIELD-GROWNSOUTHERN
HIGHBUSHBLUEBERRYPLANTS 34
Introduction 34
MaterialsandMethods 36
ResultsandDiscussion 40
4 FLOWERBUDDENSITYINFLUENCESVEGETATIVEAND
REPRODUCTIVEDEVELOPMENTINCONTAINER-GROWN
SOUTHERNHIGHBUSHBLUEBERRYPLANTS 53
Introduction 53
iii
MaterialsandMethods 57
1995Experiment 57
1996Experiment 60
StatisticalAnalysis 63
ResultsandDiscussion 64
VegetativeDevelopmentandBiomassAllocation 65
Carbohydrates 69
LeafandWhole-CanopyNCER 71
ReproductiveDevelopment 73
5 CARBOHYDRATERESERVELEVELSANDFLOWERBUDDENSITY
INFLUENCEVEGETATIVEANDREPRODUCTIVEDEVELOPMENT
INSOUTHERNHIGHBUSHBLUEBERRYPLANTS 91
Introduction 91
MaterialsandMethods 93
PlantMeasurements 94
CarbohydrateAnalysis 95
NetC02ExchangeRateMeasurements 96
StatisticalAnalysis 97
Results 97
Carbohydrates 98
PlantDevelopment 99
ReproductiveDevelopment 100
Discussion 101
6 SUMMARYANDCONCLUSIONS 115
LITERATURECITED 119
BIOGRAPHICALSKETCH 135
iv
AbstractofDissertationPresentedtotheGraduateSchool
oftheUniversityofFloridainPartialFulfillmentofthe
RequirementsfortheDegreeofDoctorofPhilosophy
SOURCE-SINKINTERACTIONSINFLOWERINGANDFRUITING
SOUTHERNHIGHBUSHBLUEBERRY
By
BrianE.Maust
August1997
Chair:Dr.JeffreyG.Williamson
Cochair:Dr.RebeccaL.Darnell
MajorDepartment:HorticulturalSciences
Experimentswereconductedtotestthehypothesisthatflowerbuddensity
(FBD) (flowerbud-cm"1canelength)affectsvegetativebudbreakandsubsequent
reproductive and vegetative development in two southern highbush blueberry
(Vaccinium corymbosum L.) cultivars, 'Misty' and 'Sharpblue'. The effect of
carbohydrate reserve concentrations on vegetative budbreak and subsequent
reproductiveandvegetativedevelopmentwasalsoexamined.
Thenumberofvegetativebudsthatbrokedormancyandgrewdecreased
asFBDincreasedonindividualcanesoffield-grownplantsoronentireplantsof
container-grown'Misty'and'Sharpblue'plants. Leafareaandleafarea:fruitratios
decreased as FBD increased. Although net C02 exchange rates (NCER) for
individual leaves increased asFBDincreased in 'Sharpblue' atthetime offruit
ripening,whole-canopyNCERatfruitripeningdecreasedasFBDincreasedinboth
'Misty'and'Sharpblue'. Fruitfreshweightincreasedandthefruitdevelopment
periodwasshortenedasthe leafarea:fruitandwhole-canopyNCER:fruitratios
increased.
Rantsplacedinagreenhousewithenriched(ENR)C02concentrations(=700
//mol-mol*1)for38daysduringDecemberandJanuuaryhadelevatedrootstarch
concentrationscomparedtoplantsplacedinanambient(AMB) C02greenhouse
(3360//mol-mol"1). ENRplantshad increasedvegetative budbreakcomparedto
AMBplantsin'Sharpblue'butnotin'Misty'. However,leafareaandwhole-canopy
NCERweregreaterinENRcomparedtoAMBplantsinbothcultivars. FruitFW
washigherinENRplantscomparedtoAMBplantsonlyin'Sharpblue'.
Rootandcanestarchconcentrationsatbloom,28daysafterbloom(DAB),
andatfruitharvestdecreasedasFBDincreasedinAMBplants,butinENRplants,
rootandcanestarchconcentrationsdecreasedasFBDincreasedonlyatbloomand
onlyin'Misty'. Rootandcanestarchconcentrationsdecreasedbetweendormancy
and28DABinAMBandENR'Misty'and'Sharpblue'plants,but,exceptforroot
starchin'Misty',rootandcanestarchincreasedatfruitharvest. Rootandcane
dryweightsweresimilarasFBDincreasedinAMBandENR'Misty'and'Sharpblue'
plants.
Large,earlyripeningfruitcommandsthebestpricesforproducers. These
studiesdemonstratedthat by reducing FBDor increasing carbohydrate reserve
concentrations,producerscouldpotentiallyincreasefruitsizeandadvanceripening.
vi
CHAPTER1
INTRODUCTION
Floralbudbreakandfruitsetinmanysouthernhighbushblueberry
(SHB) [VacciniumcorymbosumL.)cultivarsbeginpriortovegetative
budbreak. Fieldobservationsindicatethatheavyflowerandfruitloadsmay
delayandreducevegetativebudbreakandshootgrowthinsomeSHB
cultivars. Thisissupportedbytheobservationthatpartialremovalofflower
budsbyshoottippruningwillincreasevegetativebudbreak. Thissuggests
thatinitialflowerandfruitloadcaninfluencethetimingandextentof
vegetativebudbreakandshootgrowthinSHB.
Flowerandfruitloadaffecttheextentofvegetativegrowthinother
fruitcrops. Reducedgrowthordeathofrootsoccursduringperiodsof
rapidfruitgrowthorhighfruitloadandleadstodeclineinsomeplants
(Avery, 1969;Cannell, 1985;Chamont, 1993;Head, 1969;Maggs, 1963).
Intomato(LycopersiconesculentumL.)(Hurdetal., 1979;Murneek, 1926)
andapple[Ma/usdomesticaBorkh.)(Schechteretal., 1992),newleaf
productionislowerandfinalleafsizesmalleronfruitingplantscomparedto
nonfruitingplants. Fruitingplantsoftenhaveloweroverallleafareathan
nonfruitingplants(Averyetal., 1979;Head, 1969; Kappel, 1991;Maggs,
1963;Schafferetal., 1986c;Schechteretal., 1994). Althoughhighflower
1
2
andfruitloadshavebeenobservedtodecreasevegetativegrowthinSHB,
theextentofthisreductionandthesubsequenteffectonreproductive
growthareunknown.
Thereductioninshootgrowthassociatedwithhighflowerandfruit
loadsmayhaveasignificanteffectonleafarea:fruitratiosandreproductive
growth. Theeffectofleafarea:fruitratiosonfruitsize,quality,andrateof
developmenthasbeenstudiedinnumerousfruitcrops,andthinningis
practicedforsometreefruitstoincreaseleafarea:fruitratiosandfruitsize.
Inrabbiteyeblueberry[Vaccinium asheiReade),aleaf:fruitratioofone
largeleaf(*20cm2)perfruitwasneededforoptimumfruitproduction
(PattenandNeuendorff, 1989). However,thereisnoinformationonthe
effectsofleafarea:fruitratiosonfruitdevelopmentinSHB.
FlowerandfruitloadmayalsoaffectthenetC02exchangerates
(NCER)oftheleaves. HighfruitloadscanleadtoincreasesinNCERonan
individualleafbasis. However,NCERoffruitingplantscomparedto
nonfruitingplantsmaynotbegreateronawhole-canopybasisdueto
differencesinoverallleafarea. Whole-canopyNCERandcarbohydrate
productionmaybemoreimportantthanindividualleafNCERand
carbohydrateproductionindeterminingfinalfruitsizeandmaturityinSHB,
butthathasnotyetbeenresearched.
Thereductioninvegetativegrowthassociatedwithhighflowerand
fruitloadsmayberelatedtoinsufficientcarbohydrateavailability. Thelevel
ofcarbohydratereservesandtheabilitytomobilizereservesmaybecritical
indeterminingthetimingandextentofvegetativebudbreak,whichinturn
wouldinfluencesubsequentreproductiveandvegetativedevelopment.
Differencesinflowerbudnumbermayleadtosignificantdifferencesin
reservecarbohydratelevels. Additionally,somecarbohydratereservesmay
notbeeasilymobilizeddependinguponlocationofthereserves. Theuseof
carbohydratereservesandthesubsequentneedfortheirreplenishmentare
apparent,butthelevelsofcarbohydratereserves,theiraccessibility,and
theirroleinvegetativebudbreakhavenotbeenstudiedinSHB.
Thehypothesistobetestedinthisresearchisthatflowerandfruit
loadaffectthetimeandextentofvegetativebudbreakandcanopy
development. Thisinturnwasexpectedtoaffectreproductivedevelopment
insouthernhighbushblueberrycultivars. Thespecificobjectivesareto
determine1)theeffectsofflowerbudandfruitdensityonvegetative
budbreakanddevelopment,leafandwhole-canopynetC02exchangerates,
carbohydratereservelevels,fruitsize,andfruitripeningperiodand2)the
effectsofdifferentcarbohydratereservelevelsonvegetativebudbreakand
development,whole-canopynetC02exchangerates,fruitsize,andfruit
ripeningperiod.
CHAPTER2
REVIEWOFTHELITERATURE
ThecultivatedblueberryisamemberofthefamilyEriacaceae,the
subfamilyVaccinioideae,thegenus Vaccinium,andthesubgenus
Cyanococcus(Camp, 1945). SectionCyanococcusisindigenoustoNorth
AmericaandseveralspeciesarenativetoFlorida. Althoughblueberriesare
currentlycultivatedworldwide,NorthAmericastillproducesthemajorityof
theblueberriesconsumed. Florida,withitsearlygrowingseasonandearly
ripeningcultivars,hasbeenabletocapitalizeonthehighpricesavailablein
AprilandMay,butmanyproductionproblemsexist.
GrowingconditionsforblueberryproductioninFloridaandthe
southeasternU.S.differfromthoseinthetraditionalnorthernblueberry
growingareas. Floridahasmilderwinters,alongergrowingseason,and
higheraveragetemperatures. Thishasledtothedevelopmentofdifferent
cultivarsofblueberriesforproductionunderFloridaconditions. The
southernhighbushblueberry(SHB)cultivars,tetraploidinterspecifichybrids
ofVacciniumcorymbosumand V.darrowi,areapromisingclassthat
includes'Sharpblue', 'Misty, 'Flordablue', 'Avonblue', 'Gulfcoast', 'Reveille',
'Bladen', 'Cooper', 'O'Neal', 'Marimba', 'BlueRidge',and 'CapeFear'. In
4