污水处理英文文献

IrrigSci(2006)24:129–135DOI10.1007/s00271-005-0016-6

IRRIGATIONOFFRUITTREESANDVINES

AmosNaorÆYoniGalÆMotiPeres

Theinherentvariabilityofwaterstressindicatorsinapple,nectarineandpearorchards,andthevalidityofaleaf-selectionprocedureforwaterpotentialmeasurements

Publishedonline:14October2005ÓSpringer-Verlag2005

AbstractThefollowingtwotopicswereexamined:(1)Thevariabilityinthemeasurementofleafwaterpo-tential(LWP),stemwaterpotential(SWP),maximumdailytrunkshrinkage(MDS),andsoilwatertension(SWT)inapple,nectarineandpearorchards;and(2)Thevalidityofaleaf-selectionprocedureforSWPmeasurementsincommercialappleorchards.27treeswereselectedinanappleorchard,27inanectarineorchard,and30inapearorchard.Thetreeswereclosetoeachother.Themeasurementscomprisedof:middaySWPinapple,nectarineandpear;middayLWPinapple;MDSinappleandnectarine;andSWTinpear.Themeanandstandarderrors(SEs)ofeachwaterstatusindicatorineachspecieswerecalculatedforanincreasingsamplesize.Thesamplesizesre-quiredforstableaverageswere:SWP–4,5,and8treesforapple,nectarineandpear,respectively;MDS–17and16treesforappleandnectarine,respectively;SWT–21forpeartrees.TherelativeSEs(i.e.percentofpopulationmean)were2.4,6.1and10.1%inSWP/LWP,MDSandSWT,respectively.Possibleexplana-tionsforthedi eringvariabilityofthevariouswaterstatusindicatorsarediscussed.Theresultsshowthatsmallersamplesweresu cienttorepresentSWPandLWPproperlythanwhatwasrequiredforMDSandSWT.9commercialappleplotswereselectedandabout25randomlyselectedleaveswereusedformiddaySWPmeasurementsineachplot(i.e.experi-mentalsets).About5leavesoncloselyadjacent‘‘representative’’treeswereselectedineachofthecommercialplots(http://www.77cn.com.cnmercialsets)andmidday

CommunicatedbyE.Fereres

A.Naor(&)

GolanResearchInstitute,P.O.Box97,12900Kazrin,IsraelE-mail:amosnaor@research.haifa.ac.ilTel.:+792-4-6962402Fax:+792-4-6961930

Y.GalÆM.Peres

MinistryofAgricultureandRuralDevelopment,MotiPress-ExtensionService,10200KiryatShmona,Israel

SWPwasmeasured.Theaveragedi erenceinSWPbetweentheexperimentalandthecommercialsetswas–0.127MPa.Thechoiceofcloselyadjacenttreesin-creasedthedeviationfromtheexperimentalsets.Theuseofareasonablesamplesize(n=7)mayenablemiddaySWPtobemeasuredwithin±0.15MPainmostcommercialorchards.

Introduction

Theamountoffreshwateravailableforirrigationworldwideisdecreasing,especiallyinthesemi-aridzoneswheredrinkingwaterresourcesarelimited.Therefore,thereisaconstantneedtoimprovethee ciencyofwateruseandaccurateirrigationscheduling,bymeansofwaterstressindicators,isoneofthetoolsthatcanhelpgrowerstoachievethisgoal.

Therearenumeroussoilandplantwaterstatusindicatorsincommercialuse(Goldhammeretal.1999a;Howell1996;Pheneetal.1990).Soilwaterstatussensorsarethemostpopularwaterstressindicatorsforirriga-tionscheduling(Howell1996;Pheneetal.1990),includinginperennialtrees.Plantwaterstatusindicatorshavebeenmainlyusedinresearchonenvironmentalphysiologyandirrigation,buttheirpracticalapplicationforirrigationschedulinghasbeenlimited.Predawnandmiddayleafwaterpotentialshavebeentheplantwaterstatusparametersmostcommonlyproposedforirriga-tionschedulinginorchards,andresearch ndingsduringthepastdecadesuggestthatmiddaystemwaterpoten-tialisasigni cantandreliableplantwaterstatusindi-catorforschedulingtheirrigationofmanydeciduoustrees(Naor,1999;Shackeletal.1997),includingalmond(GurusingheandShackel1995),apple(Naoretal.1995,1997),nectarine(Naoretal.1999,2001),pear(Marsaletal.2002;Naoretal.2000;Ramosetal.1994),andprune(Lampinenetal.1995;McCutchaanandShackel1992;Shackeletal.2000).Diurnalstemdiametercon-tractionhadbeenproposedinthepast(Klepper1968;

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Klepperetal.1971)asanindicatorofplantwaterstatus,andtheuseofmeasurementsofdiurnalchangesinstemdiameterforirrigationschedulinghasattractedrenewedattentionbecauseofimprovementsinLVDTrobustness(Cohenetal.2001;Goldhameretal.1999a,b;Huguetetal.1992).

Thenumberofmeasurementsrequiredfortheproperrepresentationofwaterstatuswillbea ectedbythesensitivityofthewaterstressindicatortochangesinmoistureavailabilityandbythevariabilityofthemeasurement.Forexample,themaximumdailytrunkshrinkage(MDS)hasbeenfoundtobemoreresponsivetomoistureavailabilitythanstemwaterpotential(SWP)(Cohenetal.2001;Goldhameretal.1999a,b;NaorandCohen2003;IntriglioloandCastel2004),buttheMDSwasmorevariable.Asaresult,di erencesbetweenmeasurementsofSWPweremorefrequentlysigni cantthanthosebetweenMDSmea-surements(NaorandCohen2003;IntriglioloandCastel2004);indicatingthataconsiderationofthesensitivityandthevariabilitytogetherwilldeterminetherequiredsamplesize.Non-uniformirrigationapplicationandspatialvariabilityofsoilhydraulicproperties(e.g.,RussoandBresler1982;WarrickandNielsen1980)maynecessitateanincreaseinthesam-plesizefortheproperrepresentationoforchardwaterstatus.Moststudiesonthee ectofspatialvariabilityonthesamplesizerequiredforproperrepresentationofwaterstatuswereconductedin eldcrops,whichhavelowervariabilitythanperennialorchardsbecauseoftheminimalsoiltillageinthelatter.

MiddaySWPiswidelyusedforschedulingtheirri-gationofdeciduousorchardsintheGolanHeightsandUpperGalilee,Israel.Thegrowersselectabout ve‘‘representative’’treesineachcommercialplot,thesetreesarealwaysselectedincloseproximitytoonean-other,toenablethetechniciantotakeasmanymea-surementsaspossibleperday.Thereare,however,uncertainitiesabouthowrepresentativeasthelocationthetreeswereselected.

Theobjectivesofthepresentstudywere:(1)totestthevariabilityinthemeasurementofleafwaterpo-tential(LWP)andSWP,maximumdailytrunkshrinkage,andsoilwatertensioninuniformapple,nectarineandpearplots;(2)toevaluatethevariabilityofmiddaySWPincommercialappleorchards;and(3)toevaluatethevalidityoftheleaf-selectionprocedureforSWPmeasurementsincommercialappleorchardsinIsrael.

Materialsandmethods

TheexperimentswereconductedinthenorthernpartofIsrael,http://www.77cn.com.cnmercialapple,nectarineandpearorchardswereusedforthestudy,andirrigationandotheragronomicp …… 此处隐藏：21411字，全部文档内容请下载后查看。喜欢就下载吧 ……