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1、UltrasonicAcousticEmissionsfromLeafXylemofPottedWheatSubjecttoaSoilDroughtandRewateringCycleAvailableonlineatwww.sciencedirect.corn200^6c'u34i6355s……@……?My2006.,5(5):一.".avUltrasonicAcousticEmissionsfromLeafXylemofPottedWheatSubjecttoaSoilDroughtandRewateringCycle
2、儿AXiu—ling一,ZHANGLi—hua,MARui—kun,WANGZhen—lin,ZHANGQuan—guoandYAOYan—rong2lCollegeofAgronomy.ShandongAgriculturalUniversity.Taian271018.PR.China.InstituteofCerealandOilCrops,HebeiAcademyofAgriculturalandForestrySciences,Shqiazhuang050031,P.R.ChinaAbstractUltrason
3、icacousticemlsslons(AEs)fromleafxylemofbothwaterstressedandwellwateredpottedwinterwheat(TriticumaestivumL.)plantsduringdroughtandrewateringcyclewereinvestigatedwitha'PCI一2BasedAESystem'(PhysicalAcousticsCorp.NewJersey,USA)forestimationofleafxylemcavitationandembol
4、ism.VeryfewAEsoccurredinxylemofwheatleavesinwell—wateredplant,andalsoinplantsubjecttomildandmoderatesoilwaterstressconditionsoverthefirst4dofthedroughtcycle.GreatamountsofAEshaveoccurredsinced5ofthedroughtcycleasplantshowedobviousleafcurling,indicatingsignificantc
5、avitationinleafxylemonplantexposedtoseveresoilwaterdeficit.Atthispoint,relativesoilwatercontent(RSWC)andleafxylempressure(1)droppedto24.0—26.5%and一1.92MPa,respectively,withreductionsinleafstomatalconductance(gs),leaftranspiration(Tr)andleafCO2assimilationrate(A)of
6、asmuchas69.8,60.7and46.5%,respectively.Theeffectofsoilwaterdeficitwasintheorderg.>Tr>A>AE.Waveformphysicalpropertyparameterssuchasamplitude,counts,risetime,duration,absoluteenergyandsignalstrengthwereanalyzed.Theseparametersvariedwithinverybroadranges,wit
7、hfrequencydistributionofmostparametersbeingwellfittedbytheexponentialfunctionY=Y.一Aexp(一x/t).TheproportionofstrongerAEsignalsroseassoildehydrated.WhileAEsoccurrenceinwaterstressedplantremainedhigherthaninwell—wateredcontrolatthefollowingdayafterrewatering,waveform
8、signalstrengthandrelatedphysicalpropertyparametersdroppedimmediatelytothatofcontro1.DifferenceinAEsoccurrencecharacterizationbetweenfield—grownandpotted
