文档介绍：该【17在干旱地区最大化水分生产率的一种非充分灌溉农业战略策略 】是由【小屁孩】上传分享，文档一共【10】页，该文档可以免费在线阅读，需要了解更多关于【17在干旱地区最大化水分生产率的一种非充分灌溉农业战略策略 】的内容，可以使用淘豆网的站内搜索功能，选择自己适合的文档，以下文字是截取该文章内的部分文字，如需要获得完整电子版，请下载此文档到您的设备，方便您编辑和打印。:..AgriculturalWaterManagement96(2009)1275–1284ContentslistsavailableatScienceDirectAgriculturalWaterManagementjournalhomepage:ate/agwatReviewDe?citirrigationasanon-farmstrategytomaximizecropwaterproductivityindryareasSamGeerts*,(UniversityofLeuven),DivisionofSoilandWaterManagement,Celestijnenlaan200E,B-3001Leuven,BelgiumARTICLEINFOABSTRACTArticlehistory:De?citirrigation(DI)-sensitivegrowthstages,thispracticeaimstoAccepted14April2009maximizewaterproductivityandtostabilize–ratherthanmaximize–?:,acertainminimumamountofseasonalWateruseef?,,?.........................................................................................................................................................................................................................................................................................................................................................................?citirrigation:deliberatelytoleratingdroughtstress.................................................................?citirrigation................................................................................................................................................................................................................................................................................?citirrigation..................................................................?citirrigation....................................................?citirrigationstrategies......................................................................................................................................................1280Acknowledgements..............................................................................................1280References.....................................................................................................(DebaekeandAboudrare,2004).Traditionally,agriculturalresearchhasfocusedprimarilyonmaximizingtotalTosustaintherapidlygrowingworldpopulation,,focushasshiftedtothelimitingfactorsproductionwillneedtoincrease(Howell,2001),yettheportionofinproductionsystems,notablytheavailabilityofeitherlandorfreshwatercurrentlyavailableforagriculture(72%),de?citirrigation(DI)hasbeenwidely(CaiandRosegrant,2003).Hence,sustainablemethodstoincreaseinvestigatedasavaluablestrategyfordryregions(English,1990;cropwaterproductivityaregainingimportanceinaridandsemi-Pereiraetal.,2002;FereresandSoriano,2007)*.:+3216329754;fax:+-mailaddresses:sam.******@,******@discusscropwaterproductivitymodelingasatoolforassessing().-3774/$–seefrontmatter?:.:..,(2009)1275–(ETrel:ratioofactualevapotranspiration,ETa,tocropETundernon-stressed,standardconditions,ETc).,differentsectionscanbedistin-guishedthatmayvaryinwidthorthatmayevenbeabsent:Cropwaterproductivity(WP)orwateruseef?ciency(WUE),asreviewedbyMolden(2003),isakeytermintheevaluationofDI-Sectiona:Ifinsuf?cientwaterisappliedduringthecropcycle,,resultinginlow-qualityyieldde?nedastheratioofthemassofmarketableyield(Ya)tothe(shriveledgrainsorfruitswithlowmarketvalue)oreventotalvolumeofwaterconsumedbythecrop(ETa):lossofyield(YazarandSezen,2006).Inthissection,WPisverylow,andcropyieldandWPcanonlybeincreasedifaWP?Ya(1)considerableamountofwaterisaddedandsectionbisreachedETa(Geertsetal.,2008b).-Sectionb:Onceaminimumamountofwater(A),rainfalland/orirrigation,yields(andthereforedistinguishingbetweenthesetwoprocessesin?eldexperiments,WP),ithasaconcaveshape:increasingwatersupplywill(ET)(al.,1998).-scarceregions,cropswithhighWPshouldbe-Sectionc:Withadditionalwaterapplication,theproductionpreferred,,enearlylinear,withasloperangingfromhigh-energyfruitandgraincrops((1979)pointoutthatthecontent)mayhavealowerabsoluteWPvalue(StedutoandrelationshipbetweenYrelandETrelremainslinearforETreluptoaAlbrizio,2005),theirnutritionalvalueishigher,(),althoughthislowerlimithasconsideredwhenassessingthesecropsforuseindrought-pronenotbeende?-Sectiond:Asobservedformanycrops,(thesumofrainfallandirrigation)orastheamountofwaterupperlimitofETrel,theproportionalyieldincreaseperunitETtranspired().,forcropssuchasalfalfa,sugarbeets(DoorenbosandKassam,1979),wheat(.,2002;Zhangetal.,2008;al.,2006)orcotton(Henggeleretal.,2002;Kanberetal.,2006;DeTar,2008),whileitThecropwaterproductionfunction(CWPfunction)expressesmaybealmostabsentforothercrops,suchasmaize(Kipkorirtherelationbetweenobtainedmarketableyield(Ya)andthetotaletal.,2002;Farre′andFaci,2006;Payeroetal.,2006).Intheamountofwaterevapotranspired(ETa)(Stewartetal.,1977;literature,binationsofHexemandHeady,1978;DoorenbosandKassam,1979;Taylorlinearfunctions(‘brokenstick’model).etal.,1983).Thehighestwateref?ciencylevelintheCWPfunctionWhenthecropwaterfunctionincludesexcessirrigationand/,theorrainfall,ithasamorepronouncedSshape(),creatinganCWPfunctionhasalogisticshape(Hanksetal.,1969;Hanks,additionalsection:1974).Itsaxesaremadedimensionlessbyplottingrelativeyield-Sectione:ApplyingmorewaterthanrequiredbyETcwillnot(Yrel:ratioofactual,Ya,tomaximumpossibleyieldundergivenincreaseyield,asthewaterislostthroughunproductivesoilonditions,Ym)versusrelativeevapotranspirationevaporationand/,yieldmightevendeclineasaresultofwaterloggingorleachingofnutrientsfromtherootzone(al.,2006;Cabelloetal.,2009).Inthissection,irrigationisthereforenotrequired,?rstderivingtheWPfunction(WPversusETa)andthensettingthe?,WPishighestatpointBiftheextrapolatedY-interceptispositiveandhighestatpointCoratahigherETaiftheextrapolatedY-(Eq.(2)),itislocatedatthepointwhereEq.(3)-d?aETatbtcETa1(2)deWPsection-dT2dET?acETa(3)aThedistinctionbetweendrought-tolerantand-(CWP)(a),(b),notstraightforwardanddependsontherangeofETawithinwhich(c),(d)and(e)?ned().(Ya)andpotentialyield(Ym)onditions,whileac,(ETa)andseasonalcropwaterrequirements(ETc).requirementsaremet(pointD).:..,(2009)1275–(CWP)functionsforarelativelydrought-tolerant(a)andadrought-sensitive(b)(ETrel<1)isevenlydistributedoverthereferstofullyirrigatedcropsfromwhichwateriswithheldduringcroppingcycle,,,determinedCWPfunctions(CWPsfunction).However,formany‘‘de?citirrigation’’isthereforeusedastheonlytermthroughoutcrops,droughttolerancevariesstronglybetweengrowthstagesthisreview.(,2008).Hence,theCWPfunctionsfortheseSincedroughttolerancevariesconsiderablybygenotypeandindividualgrowthstageswilldifferinshapefromtheCWPsbyphenologicalstage,DIrequirespreciseknowledgeofcropfunction,ountfortheeffectoftheresponsetodroughtstressforeachofthegrowthstages(KirdabiningvariousCWPfunctionsperetal.,1999).Inaddition,correctapplicationofDIrequiresaphenologicalstageisdif?cult,inpartbecausetherearedifferentthoroughassessmentoftheeconomicimpactoftheyieldcombinationmethods,particularlywithlinearCWPfunctionsreductioncausedbydroughtstress(English,1990;Englishand(sectionc)(Jensen,1968;HillerandClark,1971;Hanks,1974;Raja,1996;SepaskhahandAkbari,2005;Sepaskhahetal.,2006).Stewartetal.,1977;Varlevetal.,1996),andeachmethodhasInareaswherewateristhemostlimitingfactor,(CWPcmaybeeconomicallymorepro?tableforthefarmerthanfunction)couldbeconstructed,differentiatingdroughtstressmaximizingyields(English,1990).Forinstance,watersavedlevelsoverthephenologicalstages,thegeneralshapewouldbyDIcanbeusedtoirrigatemoreland(onthesamefarmorinremainsimilartothatoftheCWPsfunction,butincreasedscatterthewateruser’scommunity),which–giventhehighopportunitywouldmakeitmoredif?–pensatefortheeconomiclossduecontext,esavaluabletoyieldreduction(Kipkoriretal.,2001;Alietal.,2007).-richtowater-poorareasarepossible,asrecentlydemonstratedinCalifornia,?citirrigation:deliberatelytoleratingdroughtstressalfalfa(al.,2007).Astheseexamplessuggest,??-,-tolerantphenologicalstages,oftenthevege-,