简介：ＩｎｔｒｏｄｕｃｔｉｏｎＡｌｏｎｇｗｉｔｈｉｎｔｅｇｒａｔｅｄｒｅｇｉｏｎａｌｃｏｏｐｅｒａｔｉｏｎ，ｉｎｔｅｒｅｇｉｏｎａｌａｓｏｃｉａｔｉｏｎｈａｓｂｅｎｔｈｅｍａｉｎｐａｒｔｏｆｒｅｇｉｏｎａｌｅｃｏｎｏｍｉｃｄｅｖｅｌｏｐｍｅｎｔｉｎｓｏｍｅ...

简介：Propertiesofthesoilsurfacelayer,thetemporalpatternofthemicroclimatevariablesaswellascropconditionwerecombinedtoanalyzethecharacteristicsoftheevapotranspirationfromwinterwheatfieldsinasalinesoilarea.Inordertoaccomplishthisanalysis,evapotranspirationwasdividedintoevaporationfromthesoilandtranspirationfromwheat.Moreover,theeffectofsoilsalinityonevapotranspirationwasevaluatedthroughtherelationshipbetweenactualevapotranspirationandpotentialevapotranspiration(Ea/Eo)andthetotalsoilwaterpotential(ψ)wasdividedintotwocomponents:matricpotential(ψM)andosmoticpotential(ψo).Twositeswithdifferentsalinitylevelswerechosenforthisstudy,locatedinHebeiProvince,China.MeasurementswereconductedinApril-May1997andMay1998.TheBowenratiomethodwasusedtoestimatetheactualevapotranspiration(Ea),whereaspotentialevapotranspiration(Eo)wasestimatedusingPenman'sequation.Measurementsofsoilevaporation(Es)wereobtainedwithmicro-lysimeters,andtranspirationwascalculatedfromthedifferencebetweenEaandEs.Theresultsshowthattranspirationcomprisedonaveragealmost80%oftotalevapotranspiration.Evaporationfromthesoildifferedslightlybetweenyears,butthisvariationwasdominatedbytheleafareaindex(LAI),whichrangedfrom4to5duringthestudyperiodof1997and1998.Soilelectricconductivity(EC),whichisdirectlyrelatedtoosmoticpotential,rangedfrom1.9to3.5mScm-1in1997andwasnegligiblein1998.Ourresultsindicatethatlowerosmoticpotentialdecreasesthetotalsoilwaterpotential,thusaffectingplanttranspiration.Hence,itispossibletosaythatsoilsalinityactuallydecreasesevapotranspirationfromwinterwheatfields.