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1、EffectofLocalSoilHydraulicConducƟvityDropUsingaThree-DimensionalRootWaterUptakeModelTomSchröder,*MathieuJavaux,JanVanderborght,BerndKörfgen,andHarryVereeckençÄã®ÊÄ:FThecouplingofsoilandrootwaterfluxesattheplantscaleisaparƟcularlychallengingtask.Numericalthree-dimen-ÊÊ
2、ãRsionalplant-scalemodelsexistthatconsiderthesesoil–rootinteracƟons.TheinfluenceofthehydraulicconducƟvityã®ÊÄdropatthemicroscopicscaleandespeciallytheeffectonrootwateruptakeisnotyetassessedinsuchmodels.InthisSÄstudy,ananalyƟcalapproachdescribingthehydraulicconducƟvity
3、dropfromthebulksoiltothesoil–rootinterfaceforathree-dimensionalplant-scalemodelwasderivedandvalidatedbynumericalmeans.Withthesetools,quanƟficaƟonÖ®½ÊÊãÝSRofthelocalhydraulicconducƟvitydropwithƟmewaspossible.Furthermore,theeffectofthehydraulicconducƟvitydropontheƟmeocc
4、urrenceofplantstresswasevaluated.Rootwateruptakewasassessed,withandwithoutconsid-eringthehydraulicconducƟvitydroparoundsinglerootsinathree-dimensionalplant-scalemodelintermsoftotalwateruptakeattherootcollarunderdifferentsoilandrootproperƟes.Itwasshownthatthetotalroot
5、wateruptakewasstronglyaffected,especiallyundercondiƟonswheretheradialroothydraulicconducƟvity,whichregulatesrootwateruptake,waslargerthanthesoilhydraulicconducƟvity,whichregulateswaterflowinthesoil.ThesefindingswerebackedupbynumericalvalidaƟonofthemodelusingmeshrefineme
6、nt.IncorporaƟonofthehydraulicconducƟvitydroparoundindividualrootsinathree-dimensionalplant-scalemodelcansolveproblemswithgreateraccuracyforlargergridresoluƟons,andwithsmallercomputaƟonalƟmes,thannotconsideringthehydraulicconducƟvitydrop.ÄÙÝãĮĦã«uptakeofwaterbyroot
7、sisandwaterscarcityonlocalrootwateruptakearenotdirectlyUimportantforavarietyofenvironmentalandagriculturalconsideredbutmustbedescribedusingempiricalrelationsthatpurposes,suchasyieldpredictionunderwaterscarcitycondi-describelocalwateruptakecompensationmechanisms(Jarv
8、is,tions,irrigationmanagement,andassessmentofpollutantfate1989).Thechoiceofthecompensationfunctionsmayhaveincroppedsoils.Thefirsttypeofmode
