Guidelines for fertilizer use in vineyards based on nutrient content of grapevine parts

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ContentslistsavailableatScienceDirect

Scientia

Horticulturae

j o u r n a l ho me p a g e :w w w . e l s e v i e r . c o m / l o c a t e / s c i h o r t i

Guidelines

for

fertilizer

use

in

vineyards

based

on

nutrient

content

of

grapevine

parts

Margarida

Arrobas

∗

,

Isabel

Q. Ferreira,

Sara

Freitas,

João

Verdial,

M. Ângelo

Rodrigues

MountainResearchCentre(CIMO),PolytechnicInstituteofBraganc¸a,Ap1172,5301-855Braganc¸a,Portugal

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received23January2014

Receivedinrevisedform14April2014 Accepted16April2014

Availableonline4May2014 Keywords:

Vitisvinifera

Tissuenutrientconcentration Tissuenutrientcontent Fertilizerrecommendation

a

b

s

t

r

a

c

t

Plantanalysisplaysamajorroleinfertilizerrecommendationsforperennialtreecropsandvines.Plant

analysis,however,doesnotquantifytherateofnutrientstoapply.Theapproachdevelopedinthiswork

takesintoaccountthecontentofthenutrientsingrapevinepartsandtheirdynamicwithintheplant

toassistintheestimationoftheamountoffertilizertoapply.Groupsofthreevineswerecutatground

levelonfourdifferentdatesfromSeptember14thtoNovember28th.Ontheﬁrstsamplingdatethe

vineswereseparatedintotrunk,cordons,canes,leavesandclustersfordeterminationofdrymatter

contentandelementalcomposition.Onthefollowingdatesthevineswereseparatedintotheplantparts

thatwerestillpresent,sincetheclusterswereonlypresentontheﬁrstsamplingdateandtheleaves

ontheﬁrsttwo.Toassessthemobilityofnutrientswithintheplant,samplesofphloemvesselsand

sawdustoftheentiretrunkweretakenaswellassamplesofchloroticandgreenleaves.Nitrogen(N),

potassium(K),phosphorus(P)andboron(B)showedmobilitywithintheplantwhereascalcium(Ca)

andmagnesium(Mg)didnot.TheremovalofnutrientsinclustersiscriticalforestimatingNandK

fertilizerrates.Clustersremoved19.9kgNha−1_and_28.7_kg_K_ha−1_._In_the_case_of_N,_it_is_also_important

toassessthesystem’sabilitytorecyclethenutrientcontainedintheleavesandcaneswhichamounted

to49.4kgNha−1.Phosphorus,calciumandmagnesiumapplicationsmightnotjustifybeingtakeninto

accountintheannualfertilizationplan.Thus,theestablishmentofthefertilizationprogrammeshould

beanutrient-speciﬁcexercisewhichtakesintoaccountallsourcesofinformation,includingtargetyield

andnutrientcontentinclusters,thevineyardmanagementstrategiesinﬂuencingnutrientuseefﬁciency

fromfallenleavesandpruningsandsoiltestingandplantanalysis.

1. Introduction

Adequate nutrition is essential for the growth and yield of grapevinesasforanycrop.Nitrogenisthemajornutrient affect-inggrapevinevigourandmustquality(Brunettoetal.,2007;Akin et al., 2012; Pérez-Álvarez et al., 2013).The addition of K can increasesgrapeyield, astheresultof increasedclusternumber andweight(AmiriandFallahi,2007).Astrongcorrelationbetween Kgrapevinenutritionalstatusandmustattributeshasalsobeen observed.ExcessKlevelsingrapeberriescanresultinahighjuice pH,withadetrimentalimpactonwinequality(Mpelasokaetal., 2003;Fogac¸aetal.,2007;AssimakopoulouandTsougrianis,2012; Cuéllaretal.,2013).

∗ Correspondingauthor.Tel.:+351273303255;fax:+351273425675. E-mailaddress:marrobas@ipb.pt(M.Arrobas).

Invines,asinothercrops,anyexcessoffertilizerusemustbe avoided.Thepriceoffertilizershasincreased,particularlythose containingNandP.ThepriceofNhasbeendirectlyinfluencedby theincreasethepriceofcrudeoil,andthepriceofPhasreflected thepriceinstabilityassociatedthefinitesupplyofphosphaterocks fromwhichPfertilizersareobtained(Smil,2001;Gilbert,2009). It shouldalsobestressedtheenvironmentalimpactpotentially associatedtotheexcessiveuseoffertilisers,particularlyofthose containingN(Powlson,1993).

Soilanalysishasbeenroutinelyusedtoassesssoilconditions forplantgrowthandtheneedforsupplementalfertilizers(Havlin etal.,2005).Chemicalsoilanalysisindicatesthepotential avail-abilityofsomenutrientsthatrootsmaytakeupunderconditions favourableforplantgrowth(Römheld,2012).Soilanalysiscanalso beinformativeconcerningpossibletoxicitiesofsaltandboron.Soil pHcanalsobeusefulinpredictingmineralnutritionalproblems. Inspiteoftheimportanceofsoilanalysisinthefertilizer recom-mendationprogrammesforannualcrops,ithaslostfavouroverthe http://dx.doi.org/10.1016/j.scienta.2014.04.016

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Table1

SelectedsoilpropertiesinSeptember2012inthe0–20cmsoillayer.

Soilproperties Sand(%) 62.7 Silt(%) 19.5 Clay(%) 17.8 OrganicC(Walkley–Black)(gkg−1₎ _1.4 pH(Soil:water,1:2.5) 6.7 Exchangeablebasesa K(Cmolckg−1) 1.16 Na(Cmolckg−1) 0.15 Ca(Cmolckg−1) 7.51 Mg(Cmolckg−1) 4.79

Exchangeableacidity(Cmolckg−1) 0.23

Cationexchangecapacity(Cmolckg−1) 13.85

ExtractableP(mgkg−1₎b ₆₆

ExtractableK(mgkg−1₎b ₁₉₆

ExtractableB(mgkg−1₎c _1.1

a_Ammonium_acetate,_pH_7.

b _Extracted_by_ammonium_lactate_plus_acetic_acid,_buffered_at_pH_3.7. c _Boiling_water_and_azomethine-H_procedures.

yearsforperennialdeep-rootedcrops,suchasfruittreesandvines, becauseofthedifficultyindefiningwithsufficientaccuracythe rootzonesfromwhichdeep-rootingplantstakeupmostoftheir nutrients(Winkleretal.,1974;Römheld,2012).

Plantanalysisisoftenthemostreliablemethodofassessingcrop nutritionalstatus,currentlybeingthebasisofthefertilizer recom-mendationprogrammesfortreecropsandvines.Severalstudies havebeendoneinordertoestablishthemostappropriatetissue foranalysis.Leafbladeandpetiolehavebeenthemajor compet-ingones(Brunettoetal.,2007;AssimakopoulovandTsougrianis, 2012;Benitoetal.,2013).Althoughthepreferenceforpetioleshas beenincreasing,leafbladeanalysiscontinuestobeused.Several differentsamplingdateshavealsobeenused.Thesamplingdate isofmajorimportance,sincetissuenutrientconcentrationsvary greatlyduringthegrowingseason(Römheld,2012).Invines,the mostpopularsamplingdatesareﬂoweringandveraison(Winkler etal.,1974;Porroetal.,1995;Mullinsetal.,2007;Benitoetal., 2013).Otherresearchersconsidertheissueevenmorecomplex. AccordingtoPorroetal.(1995),thechoiceofthesamplingtime shouldbemadeaccordingtothediagnosticpurpose.Benitoetal. (2013)proposedtheuseofdifferenttissuesanddifferent samp-lingdatesdependingonthenutrienttobeanalyzed.Inspiteof theeffortthathasbeenmadeinthestandardizationoftheprocess ofsampling,studieshaveshownthatnutrientconcentrationsin planttissuesfrequentlyfalloutsidetherangescurrentlyconsidered normaloradequateinpublishedstandards(Winkleretal.,1974; Davenportetal.,2012).Thegreatvariabilityinplantanalysisresults hasledtotheestablishmentofstandardsforlocalgrowing condi-tions(Porroetal.,2001;Davenportetal.,2012;García-Escudero etal.,2013),importantcommercialcultivars(Fallahietal.,2005; García-Escuderoetal.,2013),orevenrootstock-scioncombinations (LehoczkyandKocsis,1998).However,themajorlimitationofplant analysistechnologyisitsinabilitytoprovidequantiﬁedratesof nutrientstobeapplied.

Theresultsofplantanalysisareusuallyinterpretedby com-paring actual data with previous established critical values or sufﬁciencyranges(MillsandJones,1996).Inordertoimprovethe accuracyofthediagnosisofthenutritionalstatusofcrops,other formsofinterpretationhavebeendeveloped.DRIS(Diagnosisand RecommendationIntegratedSystem)hasprobablybeenthemost popular.DRISusesratiosofnutrients,whichreducesthesensitivity oftissueanalysistoplantage(Römheld,2012).Martínetal.(2013)

establishedpreliminaryDRISnormsforleafbladeandpetiolesof TempranillocultivargraftedonRichter-110,atbothﬂoweringand veraison,inLaRioga,Spain.InspiteofDRIShavingbeen devel-opedbyBeauﬁlsin1973,andnormsforseveralcropshavingbeen

established (Summer, 1997; Beverly et al., 1984; Goh and Malakouti,1992)mostlaboratorieshavenotyetadoptedit.The majorproblemis theregionalsensitivity ofthenorms(Mackay etal.,1987).Theoutputisalsonoteasytomanage.DRISorders theelementnutrientsaccordingtotheirdegreeofdeﬁciency,but itdoesnotprovideinformationonthefertilizerratestoapply.

Insummary,therehasbeenabundantworkusingplantanalysis asameansofmonitoringplantnutritionalstatus.However,the effortinthequantiﬁcationoftheratesofnutrientstoapplytothe cropshasbeenmarkedlyless.Theapproachheredevelopedtriesto deﬁnethemagnitudeoffertilizerratestoapply,byestimatingthe nutrientsremovedinclustersatharvestandtakingintoaccount thecapabilityofthesystemtorecyclethenutrientscontainedin thefallenleavesandprunings.

2. Materialsandmethods

2.1. Experimentalsite

TheexperimenttookplaceintheStaApolóniafarminBragança (41.797288–6.766033)North-easternPortugal.Theregion bene-fitsfroma MediterraneanclimatewithsomeAtlanticinfluence. Meanannualtemperatureandannualprecipitationare12.3◦Cand 7583mm,respectively.ThevineyardisplantedinaeutricCambisol loamytextured.Selectedsoilpropertiesrecordedatthebeginning oftheexperimentarepresentedinTable1.

Thegrapevinesusedinthisstudywererandomlyselectedfrom anon-irrigatedvineyardofcv.ViosinhoBlancgraftedon Richter-110.Thecv.Viosinhohadmediumvigour,theclustersandberries aresmallandthepelliculeisyellowishgreen.ItisgrowninDouro ValleyinPortwineproductionandinotherregionstoproducetable wine.Thevineyard plantationdatesfrom1997.Thevineswere spacedat2.5mbetweenrowsand1.4mwithinrows(∼2860vines perhectare).ThevineyardhasbeenprunedasGuyotdouble,with anaveragecroploadof24budspervine.Theshootsweresupported bythreehorizontalwiresplacedat60,90and120cmheightfrom thesoil.Thefarmermanagedthewinterweedsbyanapplicationof aglyphosatebasedherbicidebyMarch.Theweedsemerginginthe springhaveusuallybeencontrolledbyMayusingacultivator.The fertilizationmadebythefarmerusuallyincludestheapplicationof acompoundNPKfertilizeratanapproximaterateof20kg(N,P2O5,

andK2O)ha−1localizedinanarrowstripof1mwidealongtherow.

Tocontrolfungusdiseases,namelypowderymildew(Erisiphe neca-tor)and/ordownymildew(Plasmoparaviticola),thefarmersprayed fungicides,differingintheactiveingredientandinthenumberof applicationsfromoneyeartoanother,accordingtotheregional advisorysystemforvineprotection.

2.2. Experimentalsetupandlaboratoryanalysis

Atveraison,threesamplesofleafpetiolesweretakenfromthe leavesoppositetotheclustersintheplotwherethestudywilltake placetoassessthevinenutritionalstatusatthestandardizeddate ofsampling.Atthattime,twelvegrapevinesofsimilarvigourwere markedforfurtherexperimentaluse.Thepre-selectedvineswere thereaftercutatthegroundlevelingroups ofthreedistributed overfourdifferentdatesfromharvestuntiltheleaveshave com-pletelyfallen(September14th,October16th,November2nd,and November28th).

Onallofthefoursamplingdates,theperennialstructureofthe vineswasdividedintotrunkandcordons.Samplesofsawdustwere recordedfromtheentiresectionoftrunkandcordons,after remov-ingthedeadbark,byusingahandsaw.Thesawdustwasthereafter driedat70◦Ctobeanalyzedforelementalcomposition.Alsofrom thetrunkandthecordons,samplesofthephloemvesselswere

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obtained.Thedeadbarkwasﬁrstlyremovedandthereafter thin-nerbladesoflessthan1mmofphloemtissuewereseparatedfrom thewoodymaterial(xylem)witha sharpknife.Thesamplesof phloemvesselswerealsooven-driedat70◦Candground. Addi-tionally,intactportionsoftrunkandcordonswereoven-driedat constantweightallowingestimatingthedrymatterpercentagein thoseplantparts.

Onthetwoﬁrstsamplingdatesthecanesweredividedinto threeparts(basal,middleandtop)andtheleaveswereseparated fromthewood.Thereafter,leavesandwoodofthethreepartswere weighedfresh.Asubsampleofeachpartwasalsoweighedfresh beingthereafteroven-dried at70◦C todeterminethedry mat-tercontentoftheplanttissues.Thesubsampleswerethereafter ground.Onthethirdandfourthsamplingdatesonlythecaneswere preparedaccordingasabove.Fewleaveswerepresentonthevines atthethirdsamplingdateandnoneatallatthefourthsampling date.

Theclusterswereweighedontheﬁrstdateofsampling.The clustersofeachindividualvinewerecutandweighedfresh.The rachiswasseparatedfromtheberriesandtheseedsremovedfrom theberries. Allthese three components of theclusters(rachis, seeds,pulppluspellicule)wereweighedfresh.Rachisandseeds wereoven-driedat70◦C,weigheddryandgroundandanalyzed forelementalconcentration.Thepulp(pluspellicule)wasanalyzed forfresh.Theremainingmaterialwasthereafterdriedatthesame temperaturetoallowestimationofitsdrymattercontent.

OnOctober16th,threesamplesof50chloroticandgreenleaves (blade+petiole)werecollectedfromvinessurroundingthosethat weremarkedtobeuprooted.Thechloroticandthegreenleaves werecollectedfromasimilarpositioninthecanopyfromthebasal partofthecanes.

Allthetissuesamplesabovementionedwereanalyzedfor car-bon,nitrogen,phosphorus,potassium,calcium,magnesium,boron, copper,zinc,ironandmanganeseconcentrations.Tissueanalyses wereperformedbyWalkley–Black(C),Kjeldahl(N),colorimetry (BandP),ﬂameemissionspectrometry(K)andatomicabsorption spectrophotometry(Ca,Mg,Cu,Zn,FeandMn)methods(Walinga etal.,1989).

2.3. Statisticalanalysis

For each sampling date three vines (three replicates) were uprooted.Threereplicateswerealsotakenwhenleafpetioleswere collectedatveraisontoassesstheinitialvinenutritionalstatusand whenchloroticandgreenleavesweresampledonOctober16th. Thestandarddeviationwasthestatisticusedtoshowhowmuch variationfromtheaverageexists.

Table2

Nutrientconcentrationinleafpetioles(mean±SD)takenfromtheoppositeleaves totheclustersatveraison.

Macronutrients(gkg−1) Micronutrients(mgkg−1) Nitrogen 7.9±0.9 Boron 19.3±1.1 Phosphorus 4.0±0.4 Iron 69.4±7.5 Potassium 10.9±0.6 Manganese 45.7±6.1 Calcium 25.7±2.8 Copper 30.6±4.3 Magnesium 8.7±0.6 Zinc 32.8±5.1 3. Results

Calcium wasthemostconcentrated nutrientin leafpetioles takenatveraison(25.7gkg−1).Phosphoruswasthe macronutri-entleastabundantinleafpetioleswithanaverageconcentration of4.0gkg−1(Table2).

Atharvesttheleavesarethemostconcentratedtissuesofthe vineinN,particularlytheyoungerleavesofthetopofthecanes. Leaf N concentrations were 16.9, 18.3and 19.6gkg−1, respec-tively inbasal, middle and topleavesof thecanes(Table3).A moderatelyhighNconcentrationwasalsopresentin theseeds (14.8gkg−1).Thewoodyparts(trunk,cordonsandcanes),hadN concentrationslowerthan4gkg−1.PulpalsoshowedlowN con-centrations(4.5gkg−1)incomparisontotheothertissuesofthe vine.Phosphorus appearedinhighconcentrationsintheleaves, inparticular inthoseofthebasal partof thecanes(2.0gkg−1). Seeds(1.9gkg−1)and rachis (1.8gkg−1) arealso tissues show-ingahighconcentrationofP.RachisshowedaparticularlyhighK concentration(28.6gkg−1).Inthepulp,Kconcentrationis moder-atelyhigh(8.3gkg−1),whereasintheseedsitwasparticularlylow (2.4gkg−1).LeavesshowedKconcentrationsvaryingfrom7.6to 10.2gkg−1.Inthewoodyparts,Kconcentrationdecreasedfromthe leasttothegreaterligniﬁedtissues,varyingfrom7.3to3.0gkg−1, respectively in theapex of thecane and in thetrunk.Calcium andmagnesiumconcentrationsinvinetissuesfollowedasimilar trend.Calciumwaspresentinahighconcentrationintheleaves,in particularinthoseatthebaseofthecane(30.8gkg−1).Grape clus-tershadlowCaconcentrations,particularlythepulp(1.8gkg−1). Calcium concentrations in the woody parts varied from 5.0 to 7.3gkg−1.Magnesiumconcentrationinbasalleaveswas6.4gkg−1 andinthepulp0.6gkg−1.Boronappearedinhighconcentrationsin theleaves,inparticularintheyoungerones(19.5mgkg−1). How-ever,Bconcentrationsinthecaneswerealsoappreciable,varying from16.6to19.1mgkg−1.Ingrapeclusters,Bconcentrationdid notsigniﬁcantlyvaryamongthedifferenttissues,with10.2,11.7 and12.3mgkg−1,respectivelyinpulp,seedsandrachis.Thetrunk Table3

Tissuenutrientconcentrations(mean±SD)inthedifferentplantpartsofagrapevinesampledatharvestonSeptember14th.

C N P K Ca Mg B(mgkg−1₎ (gkg−1) Plantpart Trunk 562.8±8.3 2.7±0.2 0.5±0.1 3.0±0.4 6.2±1.7 1.6±0.1 5.6±2.0 Cordons 563.0±4.8 3.6±0.5 0.6±0.2 3.3±0.1 7.3±1.7 1.9±0.3 8.4±0.2 Cane Basal 569.8±3.1 3.3±0.2 0.7±0.0 4.1±0.7 5.0±0.7 1.7±0.2 16.8±1.2 Middle 567.5±1.9 3.3±0.2 0.7±0.0 4.7±2.0 5.9±0.7 2.2±0.4 16.6±0.2 Top 560.7±4.7 4.0±0.4 0.8±0.2 7.3±1.5 6.5±0.8 2.9±1.0 19.1±1.2 Leaves Basal 501.6±3.4 16.9±1.0 2.0±0.3 7.6±0.7 30.8±2.0 6.4±2.4 17.7±2.2 Middle 513.3±3.2 18.3±0.7 1.7±0.3 9.0±1.0 22.9±2.3 4.7±1.6 18.7±2.3 Top 519.0±7.3 19.6±0.9 1.6±0.2 10.2±2.4 23.6±2.5 5.0±1.4 19.5±2.5 Grape Pulp 543.7±9.9 4.5±0.3 0.8±0.0 8.3±0.8 1.8±0.2 0.6±0.1 10.2±6.2 Seed 571.7±2.4 14.8±0.4 1.9±0.4 2.4±0.3 5.5±0.5 1.4±0.1 11.7±0.8 Rachis 521.4±8.4 9.1±1.4 1.8±0.5 28.6±5.5 5.9±0.5 1.4±0.4 12.3±1.8

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Table4

Drymatter(DM)andtissuenutrientcontent(mean±SD)ofthedifferentplantpartsofavinesampledatharvesttimeonSeptember14th.

Plantpart DM(Mgha−1) N P K Ca Mg B(gha−1) (kgha−1₎ Trunks 5.1±0.8 14.3±3.6 2.8±0.9 15.5±2.8 33.4±13.1 8.4±0.9 30.5±13.3 Canes 2.3±0.7 7.7±2.2 1.6±0.5 10.8±0.7 12.9±4.6 4.8±0.8 38.6±11.2 Leaves 2.2±0.4 41.7±8.6 3.8±1.2 20.3±1.2 55.9±15.7 11.4±2.9 41.7±4.7 Clusters 3.5±0.6 19.9±3.7 3.2±0.8 28.7±2.1 8.2±1.2 2.5±0.4 36.1±17.7 Total 13.0±2.4 83.5±18.0 11.4±3.3 75.3±4.1 100.4±33.5 27.0±4.3 146.8±29.2

showedthelowestBconcentration(5.6mgkg−1)amongstallthe tissuesofthevine.

Theabovegroundpartofthevinesaccountedfor13.1Mgha−1 dry matter (DM) at harvest (Table 4). The woody parts, trunk/cordonsandcanes,accountedfor7.4Mgha−1,theleavesfor 2.2Mgha−1andclustersfor3.5Mgha−1.Thefreshweightof clus-terswas14292kgha−1.ThetotalamountsofN,P,K,Ca,MgandB thatwerefoundintheabovegroundpartofthevineswere, respec-tively,83.6,11.4,75.3,100.4,27.1kgha−1and146.9gha−1.Halfof Nintheplantwaspresentintheleaves(41.7kgha−1).Theclusters alsocontaineda signiﬁcantamountofN(19.9kgha−1), whereas thewoodypartscontainedonly14.3kgha−1(trunkandcordons) and 7.7kgha−1 (canes). Phosphorus appeared more evenly dis-tributedinall tissuesthan N,although leaves(3.8kgha−1)and clusters(3.2kgha−1)containedthehighest amounts.Potassium waspresentinsigniﬁcantamountsinalltheabovegroundparts ofthevine.The clusters,however,containedthemajorportion (28.7kgKha−1)followedby theleaves(20.3kgKha−1).Calcium wasthenutrientmostabundantintheabovegroundpartofthe vine. The leaves accountedfor more than 50% of the nutrient. TheclusterswereamodestpoolofCa(8.2kgha−1),whereasthe woodyplantpartscontainedrelativelyhighamountsofthe nutri-ent(46.3kgha−1).ThedistributionofMginthevineswassimilarto thatofcalcium.Inatotalof27.1kgMgha−1,theleavesaccounted for 11.4kgha−1, the trunk/cordons plus canes for 13.2kgha−1 andtheclustersfor2.5kgha−1.Boronalsoappearedevenly dis-tributedbetweentheabovegroundpartsofthevine.Leaves,canes,

clustersandtrunk/cordonscontainedrespectively41.7,36.1,38.6 and30.5gha−1.

Inonlytwoofthefoursamplingdates(September14thand October16th),vinesstillhadleaves.LeafNconcentrationgreatly decreasedinthemonth,betweenthetwosamplingdates.The pat-ternwassimilar amongthe leavesofthe differentlocationsof thecane.Inthemiddlepartofthecane,forinstance,leafN con-centrationdecreasedfrom18.3gkg−1 to13.3gkg−1(Fig.1).Leaf Pconcentrations variedover time in a similarmannerasN. In themiddlepartofthecane,leafPconcentrationdecreasedfrom 1.7gkg−1to1.2gkg−1betweenSeptember14thandOctober16th. LeafKconcentrationvariedlittlefromSeptember14thtoOctober 16th.Meanvalueswereverycloseto10gkg−1.LeafCa concentra-tionsgreatlydifferedamongthedifferentpartsofthecaneinthe samplingofSeptember14th.Thehighervalueswerefoundinthe basalleaves(30.8gkg−1).OnOctober16th,allthethreegroupsof leavespresentedsimilarCaconcentrations,rangingfrom24.2to 26.2gkg−1.LeafMgconcentrationpresentedasimilarvariationto thatobservedtoCa.InSeptemberthevaluesrangedfrom4.7to 6.4gkg−1andinOctoberfrom4.8to5.7gkg−1.LeafB concentra-tiondecreasedfromSeptembertoOctoberinallgroupsofleaves, aswasobservedforNandP.ThevaluesinSeptemberrangedfrom 17.7to19.5gkg−1andinOctoberfrom17.1to17.6gkg−1.

12

14

16

18

20

22 Leaf B conc. (g kg

-1

)

Basal

Middle

Top

Sep, 14 Oct, 16

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Table5

Nutrientconcentrationsinchloroticandgreenleaves(mean±SD)collectedfromadjacentvinestothatwerecutandinsimilarpositioninthecanopyonthesamplingdate ofOctober16th.

Leaves N P K Ca Mg B(mgkg−1)

(gkg−1)

Green 11.9±1.3 1.5±0.2 10.3±0.9 26.2±2.6 5.7±1.8 18.1±1.0 Chlorotic 6.2±0.4 1.4±0.4 6.9±1.4 31.2±3.6 6.7±1.5 20.1±1.3

lowKconcentrationscomparedwithgreenleaves.RegardingleafP concentrations,therewasfoundtobeaslightdecreaseastheleaves weregettingchlorotic;forCa,MgandBaslightincreasewasfound. CaneNconcentrationsincreasedovertimefromripeninguntil late November (Fig. 2). Regarding P, it seems that there was a decrease innutrient concentrations betweenthe samplingof SeptemberandOctober,andstabilizationoraslightincreaseasthe seasonprogressedtotheautumn.TheconcentrationofKincanes followedanoppositepatterntoP.Initially,fromSeptember14thto October16th,Kconcentrationsincreasedandthereafterdecreased untillateNovember.Calcium,magnesiumandboronshowedlittle variationincanesfromharvestuntiltheendofNovember.

Wood(trunkandcordons)Nconcentrationsslightlyincreased fromSeptember14thtoOctober16th,remainingthereafterfairly constant(Fig.3).Nitrogenconcentrationsin thephloemvessels were higher than those observed in the xylem. It seems that therewasanincreaseinNconcentrationsfromSeptember14th toNovember2nd,andthereafterapronounceddecrease,whenall theleaveshadfallen.Phosphorusconcentrationsinthewooddid notsignificantlyvaryovertime.However,inthephloemvessels thetrendwassimilartothatincanes,firstshowingadecreaseand thereafteranincrease.Potassiumconcentrationsinphloemvessels andwoodpresentedasimilartrend,firstexperiencinganincrease and,onthelastsamplingdates,adecrease.Calciumand magne-siumconcentrationsinphloemvesselswerehigherthanthosein wood.Boronconcentrationsincreasedfromthefirsttothefourth samplingdatesinthewoodypartandalsointhephloemvessels. TheincreaseinBconcentrationsinthewoodypartwasprobably duealsotothepresenceofphloemtissuesinthewoodysample

whichincludedtissuefromtheentiretrunkexcludingthedead bark.

4. Discussion

Ingrapevines,ithasbeenusualtoﬁndtissuenutrient concen-trationsoutsidethepublishedstandardrangeseveninvineyards withapparentnormalgrowth.However,thepetiolenutrient con-centrationsatveraisonherereportedwerenotgreatlydissimilar tothosefoundintheliterature(MillsandJones,1996;Fallahietal., 2005;Davenportetal.,2012;García-Escuderoetal.,2013),which suggestedthatthenutritionalstatusofthevineyardusedinthis studyiswithintheadequaterangeforthenutrientsconsidered.

LeaveswerethetissuesofthehighestNconcentrationsinthe vines.Thesamewastruefortheothernutrients,Kconcentrations inrachisbeingtheonlyexception.Nitrogenformspartofseveral cellconstituents,suchasproteins,nucleicacidsandchlorophyll, whichjustiﬁesitsrelativeabundanceintheleaves(Hawkesford etal.,2012).Inthiswork,nutrientconcentrationwasdeterminedin thewholeleaf(blade+petiole)fromsub-samplesincludingallthe leavesofacanesection.Asfarasweknow,therearenopublished dataanalyzingsamplesofwholevineleavestakenatharvest.Even so,recordedleafnutrientconcentrationsareofthesameorderof magnitudeasthosefoundintheliteratureforbladesoftheleaves opposite totheclusterand takenat veraison(Davenport etal., 2012;García-Escuderoetal.,2013).Previousstudieshaveshown thatgrapesarethemajorsinkforKafterberrygrowthcommences (Mpelasokaetal.,2003;Ponietal.,2003;Mullinsetal.,2007). How-ever,clusterscontainedthehighest(rachis)andthelowest(seeds)

0

1

2

3

4

5

6 C

ane

N

c

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(g

k

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Sep,

Oct, Nov,

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16

02

28

0.0

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14 16 02 28

Fig.3.Nutrientconcentrationsinthesawdustoftrunkandcordons(wood)andintheouterlayerofthetrunk,mainlycomposedbyphloemvessels(phloem),forfour samplingdatesfromripening,September14thtolateNovember28th.

Kconcentratedtissuesofthevine.Thepulppresentedamoderately highKconcentration.Themostplausibleexplanationforthehigh Kconcentrationintherachisistheroleofthenutrientinthe trans-portationofphotosynthatesfromleaftoberry(Mpelasokaetal., 2003;Fogac¸aetal.,2007;Hawkesfordetal.,2012).Nutrient con-centrationsinwoodyplantpartsgenerallyincreasedfromtrunk tocordonsandcanes,whichmeanthattheoldertissuesareless concentratedinessentialnutrientsthantheyoungerones.

Theclusterscontained19.9kgNha−1,representing1.4kgNper tonne of freshfruit. On average, N removed per tonne of fruit wasofsimilarmagnitudetothevaluesreportedbyMullinsetal. (2007).However,theseareverylowvalues(∼10%)ifcompared toamountsofNusuallyremovedbyannualcrops,suchasmaize andpotato,whichcanamounttomorethan200kgNha−1(Kirda etal.,2005;Badretal.,2012).Theamountsoftheothernutrients removedingrapewere3.2,28.7,8.2and2.5kgha−1and36.1gha−1, respectivelyforP,K,Ca,MgandB.Thenutrientsremovedinthe grapeareanintegrallosstothesoil–plantsystem.About50%ofN (41.7kgha−1)intheabovegroundpartofthevinewasintheleaves atharvesttime.Nitrogenintheleavescanberemobilizedtothe perennialpartsandreusedinthenextseason(White,2012). Nitro-gencanalsobelostthroughvolatilizationdirectlyfromcanopy totheatmosphere, inparticularattheend ofthegrowing sea-son(WetselaarandFarquhar,1980;EichertandFernández,2012). Nitrogenstill presentinthefallenleavescansuffer mineraliza-tioninthesoilandbetakenupbytherootsorlostthroughNH3

volatilization,leachingordenitriﬁcation.Nitrogenpresentincanes (7.7kgha−1)canfollowthesameroutesifpruningsareleftonthe ground.IfpruningsareremovedtheirNislostfromthesoil–plant system.Potassiumplaysasigniﬁcantroleinplantmetabolismbut itdoesnotintegrateorganicstructures(Hawkesfordetal.,2012). Potassiumpresentinleaves(20.3kgha−1)canberemobilizedto theperennialstructureduringsenescence,duetoitshighmobility (Mpelasokaetal.,2003;Hawkesfordetal.,2012).Otherportioncan beleacheddirectlyfromthelivingleaves(EichertandFernández, 2012)or releasedtothesoil duringthemineralization ofdead

leaves.Potassiuminthecanescanalsoreturnornottothesoil dependingonthedestinationoftheprunings.Phosphorus,calcium, magnesiumandboronpresentintheleavesandcanesamounted to5.4,68.8and16.2kgha−1and80.3gha−1.Thesenutrientswill returntothesoilsolutioninthecourseofthemineralizationofcrop residues.

Tofollowthedynamicofthenutrientsinthegrapevine, tis-suesfromdifferentplantparts, collectedat differenttimeafter grapeharvest,wereanalyzed.Thetimeof samplingwasshown toaffectleafconcentrationsofallmineralelements.Nitrogen con-centrationinvineleavesusuallydecreasesasthegrowingseason progress(Porro etal.,1995;Peuke, 2009), likelyduetodilution effectsorremobilizationtofruitsandseeds.Afterharvest,plant growthisreducedornil,andremobilizationstofruitsends.The decreaseinleafNconcentrationobservedfromSeptember14thto October16thmaybeattributedtoNremobilizationtothe peren-nialstructuresortogaseousNlossestotheatmosphere.Thelower Nconcentrationfoundinchloroticleavesincomparisontogreen leaves,wouldbetheresultofthesamephenomena.Theincrease inNconcentrationincanesandtrunkandcordonsobservedfrom September14thtoNovember2ndsupportsthethesisthatatleast partoftheNpresentinleaveswasremobilizedtoperennial struc-tures.Itiswell-knownthatremobilizationofnutrientsfromthe leavesto woody parts is a typicalfeature of perennial species beforeleafdrop(White,2012).Trunkandcordonsshoweda sud-dendecreaseinNconcentrationfromNovember2ndtoNovember 28th, which maymean that N remobilization continuedtothe roots.Previousstudieshaveshownthatingrapevine,Nreserves arelocatedpredominantlyintherootsandarecomprisedofamino acids(mostlyarginine)andproteins(Zapataetal.,2004) Phospho-rusisamobileelementwhichcanbereadilytranslocatedwithin aplant(Mullisetal.,2007;White,2012).Invineleaves, P usu-allydecreasesoverthegrowingseason(Benitoetal.,2013).The resultsofthetemporaldynamicofPinleavesshowedadecreasein leafPconcentrationfromSeptember14thtoOctober16thandalso betweengreenleavesandchloroticleaves.Thewoodyplantparts,

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canesand trunk,showed minimumP concentrationin October 16th.TheseresultsseemtoindicatepossibleremobilizationofP torootsoccurredearlierintheautumnincomparisontothe remo-bilizationofN.

Potassiumischaracterizedbyhighmobilityinplantsatalllevels, withinindividualcellsorinlong-distancetransportviathexylem andphloem(Mpelasokaetal.,2003;White,2012).Potassium con-centrationintheleavesdidnotchangegreatlybetweenSeptember 14thandOctober26th.However,chloroticleavesshowed signif-icantlylowerKlevelsthangreenones.Potassiumconcentration incanesandtrunkincreasedfromSeptember14thtoOctober16th anddecreasedfromNovember2ndtoNovember28th.Inthetrunk, KconcentrationincreasedfromSeptember14thtoNovember2nd anddeceasedthereafter.Thissequenceofrecordsseemsto indi-catealaterremobilizationofKfromleavestothewoodypartsin comparisontoN.Aconcurrentorcomplementaryexplanationfor thelowKconcentrationfoundinchoroticleavesisleachingfrom thecanopy.

Therewasnogreatevidencethatsigniﬁcantremobilizationof CaandMghadoccurredfromtheleavestothewoodyplantparts. ChloroticleaveshadhigherCaandMgconcentrationsthangreen ones.Inthewoodyparts,thedynamicofCaandMgconcentrations wasalsonotrelevant.Theresultslikelyreﬂectthelowmobilityin thephloemofbothnutrients(White,2012).

ThereductioninleafBconcentrationoccurringfromSeptember 14thtoOctober16thwasnotconﬁrmedbyareductioninB con-centrationinchloroticleavesincomparisontogreenleaves.The analysis of theB in the woodyparts showedan increase in B concentrationfromSeptember14thtoNovember28th.The mobil-ityof Bin planttissuesisgenerally consideredasintermediate (White,2012).However,itseemsthatBmobilitygreatlydepends onplant species and cultivars (Brownand Shelp, 1997). Peuke (2009)reportedchangesinboronleavessimilartothatobservedto Nduringthegrowingseason.OurresultsseemtoconﬁrmB mobil-ityingrapevineinspiteofalackofBconcentrationmeasuredin chloroticleaves.

In a tentative estimation of the nutrient balance in a vine-yard,nutrient removal from thesystem and nutrient recycling within thesystem shouldbe taken into account. The vineyard lost1.4kgNha−1 pertonneoffreshfruit,representingatotalof ∼20kgNha−1 forthis study.Starting from∼42kgNha−1 inthe leavesatharvest, approximately50%disappearedduring senes-cence,whichmaymeanthatitwasremobilizedtotheperennial structuresand/orlostthroughvolatilizationfromthecanopy.The otherhalfpart(∼21kgNha−1)waspresentinthefallenleaves.The fateofthisNisverydifficulttopredict:itcanbelostby ammo-niavolatilizationiftheleavesundergomineralizationatthesoil surfaceandsoilpHishighor,onceinthesoil,itcanbelostby leachingordenitrification.Thegroundmanagementofthe vine-yardmayalsobeofgreat importance.Covercrops,forinstance, cancompetewiththegrapevinefortheinorganicN inthesoil (Celette et al.,2009; Celetteand Gary, 2013)reducing the effi-ciencyofNrecycling.Nitrogen in thecanes (∼8kgNha−1)may haveasimilardestinationtothatreferredtoforleavesthat min-eralizeinthesoilorarelostifthepruningsareremovedfromthe vineyard.

Thevineyardlost28.7kgKha−1intheclusters.Thisamount rep-resents∼2.0kgKha−1yr−1pertonneoffreshfruit.Ifpruningsare removed,thevineyardmayloseanother∼11kgKha−1.Potassium containedintheleaveswillreturntothesoil,whetheritisleached outfromsenescingleavesorreleasedduringthemineralization processinsoil.Potassiumdoesnotundergogaseouslossesandthe riskofKleachingfromthesoilismuchlessthanthatofN.Thus, thecomponentofrecyclingiseasiertoestablishforKthanforN.To establishanaccurateKfertilizationprogramme,itisalsonecessary toknowtheKavailabilityinthesoilandtheKnutritionalstatusof

thevineyard,sinceanyexcessinKapplicationshouldbeavoided duetothenegativeimpactinwinequality.

TheamountsofP,CaandMgremovedfromthesystemin clus-tersaresmall,andthenutrientscontainedin theleavescanbe recycledinthesoil.Therecommendationsystemshouldinvolve monitoringsoilfertilityandplantnutritionalstatusofvinesinorder todecideifanyabnormalsituationshouldbecorrected.Aregular additionofP,CaandMgshouldnotbeneeded.

TheamountofBinvolvedinplantmetabolismis verysmall. However,thereisalongexperienceofobservingsymptomsofB deﬁciencyinperennialcrops,suchasvine,almondandolive,inthis regionandinseveralotherpartsoftheworld.Therecommendation systemshouldconsistofmonitoringvineBnutritionalstatus.Since Bisamobileelementinthesoil,theapplicationshouldbeannual afteritisprovedthatthesoildoesnotsupplyenoughBforvine metabolism.

5. Conclusions

The establishment of a suitable fertilization programme for vineyardsmust considerdifferentstrategies for each individual nutrient.InthecaseofN,itisofparticularimportancetotakeinto accounttheamountofnutrientremovedinthefruitasiscurrently donebymostsoiltestingandplantanalysislaboratories.Thisstudy showedthatisalsoimportanttotakeintoaccounttheprobableloss ofNcontainedinleavesandcanesatharvest,whichmayrepresent alossgreaterthanthatfromfruits,dependingonhowNisrecycled withintheagrosystem.ForK,itisnotonlyimportanttoconsider theamountofnutrientremovedinfruit,butalsotheamountof Knaturallyavailableinthesoil,sincesoilscansupply consider-ableamountsofK.Potassiuminleavesisentirelyrecycledsince thenutrientdoesnotintegrateinorganicstructures,which facili-tatesitsleachingfromleavestothesoil,andalsobecauseitdoes notformvolatilecompounds.Phosphorus,calciumandmagnesium maynotjustifyyearlyapplications,butprobablyonlycorrections inspeciﬁcsituations,relatingtopHorlowPavailabilityinthesoil, sincenutrientremovalsaresmall.TheamountofBinvolvedinplant metabolism,andremovedinfruits,isverysmall.However,Bshould beappliedregularly,sinceitisamobileelementinthesoil,butonly afterithasbeendiagnosedbyplantanalysisthatthesoildoesnot supplyenoughofthiselementforplantmetabolism.

Thus, to establish an accurate fertilization programme, the decision-makingprocessshouldhaveinformationontargetyield andvineyardmanagementstrategiesinfluencingtheefficiencyof useofnutrientspresentinleavesandcanes.Datafromsoiltesting andplantanalysiscontinuestobeofparamountimportance.By integratingallsourcesofdataitwillbepossibletoprescribe fertil-izerratestoensureanadequatenutritionalstatusofvines,without potentiallydetrimentaleffectsonwinequalityorenvironmental damage.Inpractice,forarationaluseoffertilizers,nutrient-specific fertilizationplansareneeded.

Acknowledgment

SupportedbytheMountainCentre(CIMO),PolytechnicInstitute ofBraganc¸a,Portugal(PEst-OE/AGR/UI0690/2011StrategicProject –UI690–2011-2012).

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