Download - Transpiration of leaves with Cobra4 · Transpiration, Water and nutrients transport, Influence of wind, Temperature, Humidity and type of leaves Overview Principle The purpose of

Student'sSheet

Printed:15/05/201913:08:11|P4110360

Robert-Bosch-Breite10 Tel:+49551604-0 [email protected]

D-37079Göttingen Fax:+49551604-107 www.phywe.com

Difficulty

Easy

PreparationTime

10Minutes

ExecutionTime

40Minutes

RecommendedGroupSize

2Students

TranspirationofleaveswithCobra4(ItemNo.:P4110360)

CurricularRelevance

AdditionalRequirements:

Roseorsimilarplant(withthickleaves)

Plasticbag

Knife

AndroidtabletoriPad

PHYWEmeasureApp

ExperimentVariations:

withComputerwithUSBport,Windows

Keywords:

Transpiration,Waterandnutrientstransport,Influenceofwind,Temperature,Humidityandtypeofleaves

Overview

Principle

Thepurposeofplanttranspirationistotransportwaterandnutrientsfromtheplantrootstotheleaves.Inthisexperimentplant

transpirationisinvestigatedbymeansofpressuredecreasemeasurements.Pressuredecreaseisbroughtaboutbyvegetal

dischargefromtheleavesintotheenvironment.Itisthebasisofthecontinuouswatercurrentfromthesoil.Inthisexperiment

comparethetranspirationofleavesundervariousenvironmentalconditions.

AreaofExpertise:

Biology

EducationLevel:

University

Topic:

PlantPhysiology/

Botany

Subtopic:

WaterBalance

Experiment:

Transpirationof

leaveswithCobra4

Student'sSheet

Printed:15/05/201913:08:11|P4110360



Fig.1:Experimentset-up

Equipment

ExperimentwithCobra4Wireless/USB-LinkwithAndroidtabletoriPad

Student'sSheet

Printed:15/05/201913:08:11|P4110360



PositionNo. Material OrderNo. Quantity

1 Cobra4Wireless/USB-Linkincl.USBcable 12601-10 1

2 Cobra4Sensor-UnitPressure,7barabsolute 12647-00 1

3 HolderforCobra4withsupportrod 12680-00 1

4 Supportbase,variable 02001-00 1

5 Supportrod,stainlesssteel,500mm 02032-00 3

6 Bosshead 02043-00 2

7 Universalclamp 37715-00 1

8 Testtube,200x30mm,sidearm,PN29 36331-00 1

9 Rubbertubing,i.d.6mm 39282-00 1

10 Plasticine,10sticks 03935-03 1

11 Rubberstopper26/32,1hole1,5mm 39258-09 1

12 Beaker,low,BORO3.3,1000ml 46057-00 1

13 digitalmagneticstirrerwithheating,stainlesssteel,280°C,100-1500rpm FHO-

RSM10HS

1

14 Rubberbands,50pieces 03920-00 1

15 Hot/coldairblower,1800W 04030-93 1

16 USBchargerforCobra4Mobile-Link2andWireless/USB-Link 07932-99 1

Additional

material:

AndroidtabletoriPad

PHYWEmeasureApp


Plasticbag

Knife

Android iPad

ExperimentwithCobra4Wireless/USB-LinkandPC

https://play.google.com/store/apps/details?id=com.phywe.measure

https://itunes.apple.com/de/app/phywe-measure-hd/id938694493

Student'sSheet

Printed:15/05/201913:08:11|P4110360



PositionNo. Material OrderNo. Quantity

1 curricuLABmeasureLAB 14580-61 1

2 Cobra4Wireless/USB-Linkincl.USBcable 12601-10 1

3 Cobra4Sensor-UnitPressure,7barabsolute 12647-00 1

4 HolderforCobra4withsupportrod 12680-00 1

5 Supportbase,variable 02001-00 1

6 Supportrod,stainlesssteel,500mm 02032-00 3

7 Bosshead 02043-00 2

8 Universalclamp 37715-00 1

9 Testtube,200x30mm,sidearm,PN29 36331-00 1

10 Rubbertubing,i.d.6mm 39282-00 1

11 Plasticine,10sticks 03935-03 1

12 Rubberstopper26/32,1hole1,5mm 39258-09 1

13 Beaker,low,BORO3.3,1000ml 46057-00 1

14 digitalmagneticstirrerwithheating,stainlesssteel,280°C,100-1500rpm FHO-

RSM10HS

1

15 Rubberbands,50pieces 03920-00 1

16 Hot/coldairblower,1800W 04030-93 1

17 USBchargerforCobra4Mobile-Link2andWireless/USB-Link 07932-99 1

Additional

material:

ComputerwithUSBport,Windows


Plasticbag

Knife

Tasks

1. Comparethetranspirationofleavesundervariousenvironmentalconditionsandgeneratepressurecurves.

2. Discussthedifferencesbetweenthedifferentpressurecurves.

Student'sSheet

Printed:15/05/201913:08:11|P4110360



Set-upandprocedure

Set-up

SetuptheequipmentasinFig.1.

Useoneofthetwosupportrodswhichisattachedtothesupportbasetoholdthetesttube.

AttachtheCobra4Wireless/USB-LinktotheCobra4Sensor-UnitPressuretotheholderontheothersupportrodinsucha

waythattheairintakenozzleoftheSensor-UnitPressureispositionedapprox.2cmhigherthanthehoseconnectorofthe

testtube.

UseashortpieceofhosetoconnecttheairintakenozzleoftheSensor-UnitPressuretothehoseconnectorofthetest

tube.

Fillthetesttubewithwaterandfastentherubberstopperwithoutanyformationofairbubblesinthetesttube.

ConnecttheCobra4Wireless/USB-LinktothetabletinthewirelessWiFimodeafterswitchingiton.

Startthesoftware .TheCobra4measuringdevicewillbeautomaticallydetected.

Selectthemeasurementwindowofyourchoice.Itisbesttochoosethemeasurementwindowwiththe

measurementgraph.

Fig.2:SelectingtheSensor-UnitPressureinthemeasureAPP

Student'sSheet

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Procedure

Experiment1

Cutoffasmallleafyshootorasoil-plantjustabovethesoil.Peelfromthelowerpartoftheshootwithaknifeandcutthe

endoffataslant(45°).

Quicklypushtheshootthroughthestopperandsealthestopperwellwithplasticine.

Withoutdelay,removethehosefromtheairintakenozzleoftheSensor-UnitPressure,fitthestopperwithplantonthetest

tube(avoidingairbubbleformationinthetesttube)andfitthehosebackontheSensor-Unit.

Caution!Donotletanywaterpenetrateintothepressuresensorwhiledoingthis!

Startmeasurement(idealrunningtime:atleast100s,butlongerisbetter–measurementwasmadefor1000sinthe

examplegiven).

Taketheinitialandfinalpressuresfromthemeasuredvaluesandcalculatethedifference.

Experiment2a:(PreparationasforExperiment1)

Exposetheplanttoacoldflowofairfromthedryerduringmeasurement.

Experiment2b:

Setthedryertohotairandexposetheplanttothehotflowofairfromthedryerduringmeasurement.

Experiment3:

Bring½litreofwatertoboilingandcollectthesteamthatisgivenoffinaplasticbagforsomeseconds(Caution!Donot

allowtheplasticbagtotouchthehotbeaker!).

Puttheplasticbagovertheplant,closeitwithanelasticbandandstartmeasurement.

Student'sSheet

Printed:15/05/201913:08:11|P4110360



Resultandevaluation

Resultsandevaluation

Results

Experiment1:Withtheplantusedinthispartoftheexperimentandinstillair,thepressuredecreasedbyapprox.2.8kPa

overameasurementtimeof1000s(Fig.3).

Fig.3:Measurementresult(Experiment1)–Planttranspirationinstillair

Experiment2:Duringthesamelengthoftimeinacoldflowofair,thepressuredecreasedbyapprox.3.8kPa(Fig.4),ina

hotflowofairbyapprox.6.3kPa(Fig.5).

Fig.4:Measurementresult(Experiment2b)–Planttranspirationinaflowofcoldair

Student'sSheet

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Fig.5:Measurementresult(Experiment2b)–Planttranspirationinaflowofhotair

Experiment3:Notranspirationtookplaceinsteam(Fig.6).

Fig.6:Measurementresult(Experiment3)–Planttranspirationunderveryhighair

humidity

Evaluation

Plants"sweat"justaspeopledoandaretherebyphysiologicallyandmorphologicallysuitedtotheirspecificenvironment.They

transpireathightemperaturesandpasswatertotheenvironment.Transpirationservesforthetransportofwaterandnutrients.

Theunderpressurethatiscausedbytranspirationdrawswaterupfromtheroots,nutrientsaretransportedfromtherethrough

thestemtotheleaves.Innature,windplaysanimportantroleinthetranspirationofplants.Forexample,plantsthatgrowon

windyhillsidesaremorelignifiedandplantsthatgrowinthedesertsinktheirstomataintosmallleafhollowsthatare

additionallymattedandcoveredwithalayerofwax,sothatthetranspirationcausedbythehotdesertwindsiskeptaslowas

possible.Transpirationisgreatlylimitedwhenaplantisexposedtohighairhumidityasthesurroundingairisalreadysaturated

withwater.Plantsthatexistinareassubjectedtosuchhumidityhavestomatathatprotrudetoincreasetheirtranspiration.

Student'sSheetPrinted:15/05/201913:08:11|P4110360



Set-upandprocedure

Set-up

SetuptheequipmentasinFig.1.

Useoneofthetwosupportrodswhichisattachedtothesupportbasetoholdthetesttube.

AttachtheCobra4Wireless/USB-LinktotheCobra4Sensor-UnitPressuretotheholderontheothersupportrodinsuchawaythattheairintakenozzleoftheSensor-UnitPressureispositionedapprox.2cmhigherthanthehoseconnectorofthetesttube.

UseashortpieceofhosetoconnecttheairintakenozzleoftheSensor-UnitPressuretothehoseconnectorofthetesttube.

Fillthetesttubewithwaterandfastentherubberstopperwithoutanyformationofairbubblesinthetesttube.

SetupaconnectionoftheCobra4Wireless/USB-LinktothePCeitherwirelesslyorwiththeUSBcableandswitchiton.

Startthesoftware .TheCobra4measuringdevicewillbeautomaticallydetected.

Choosetheexperimentfromthestartscreenbyselecting`LoadExperiment`.Accordingly,choose“PHYWEexperiments”,searchfor“P4110360”,andselectdesiredfoldercontainingtheexperiment.Allnecessarypresettingwillbeloaded.

Procedure

Experiment1

Cutoffasmallleafyshootorasoil-plantjustabovethesoil.Peelfromthelowerpartoftheshootwithaknifeandcuttheendoffataslant(45°).

Quicklypushtheshootthroughthestopperandsealthestopperwellwithplasticine.

Withoutdelay,removethehosefromtheairintakenozzleoftheSensor-UnitPressure,fitthestopperwithplantonthetesttube(avoidingairbubbleformationinthetesttube)andfitthehosebackontheSensor-Unit.Caution!Donotletanywaterpenetrateintothepressuresensorwhiledoingthis!

Startmeasurement(idealrunningtime:atleast100s,butlongerisbetter–measurementwasmadefor1000sintheexamplegiven).

Taketheinitialandfinalpressuresfromthemeasuredvaluesandcalculatethedifference.

Experiment2a:(PreparationasforExperiment1)

Exposetheplanttoacoldflowofairfromthedryerduringmeasurement.

Experiment2b:

Setthedryertohotairandexposetheplanttothehotflowofairfromthedryerduringmeasurement.

Experiment3:

Bring½litreofwatertoboilingandcollectthesteamthatisgivenoffinaplasticbagforsomeseconds(Caution!Donotallowtheplasticbagtotouchthehotbeaker!).

Puttheplasticbagovertheplant,closeitwithanelasticbandandstartmeasurement.

Student'sSheet

Printed:15/05/201913:08:11|P4110360



Resultandevaluation

Resultsandevaluation

Results

Experiment1:Withtheplantusedinthispartoftheexperimentandinstillair,thepressuredecreasedbyapprox.28hPa

overameasurementtimeof1000s(Fig.3).

Fig.3:Measurementresult(Experiment1)–Planttranspiration

instillair

Experiment2:Duringthesamelengthoftimeinacoldflowofair,thepressuredecreasedbyapprox.38hPa(Fig.4),ina

hotflowofairbyapprox.63hPa(Fig.5).

Fig.4:Measurementresult(Experiment2b)–Plant

transpirationinaflowofcoldair

Fig.5:Measurementresult(Experiment2b)–Plant

transpirationinaflowofhotair

Student'sSheet

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Experiment3:Notranspirationtookplaceinsteam(pressuredifferenceapprox.2hPa,Fig.6).

Fig.6:Measurementresult(Experiment3)–Planttranspiration

underveryhighairhumidity

Evaluation

Plants"sweat"justaspeopledoandaretherebyphysiologicallyandmorphologicallysuitedtotheirspecificenvironment.They

transpireathightemperaturesandpasswatertotheenvironment.Transpirationservesforthetransportofwaterandnutrients.

Theunderpressurethatiscausedbytranspirationdrawswaterupfromtheroots,nutrientsaretransportedfromtherethrough

thestemtotheleaves.Innature,windplaysanimportantroleinthetranspirationofplants.Forexample,plantsthatgrowon

windyhillsidesaremorelignifiedandplantsthatgrowinthedesertsinktheirstomataintosmallleafhollowsthatare

additionallymattedandcoveredwithalayerofwax,sothatthetranspirationcausedbythehotdesertwindsiskeptaslowas

possible.Transpirationisgreatlylimitedwhenaplantisexposedtohighairhumidityasthesurroundingairisalreadysaturated

withwater.Plantsthatexistinareassubjectedtosuchhumidityhavestomatathatprotrudetoincreasetheirtranspiration.