Irrigation with drainage solutions improves the growth and nutrients uptake in Juncus acutus

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ContentslistsavailableatScienceDirect

Ecological

Engineering

j ou rn a l h o m epa g e :w w w . e l s e v i e r . c o m / l o c a t e / e c o l e n g

Irrigation

with

drainage

solutions

improves

the

growth

and

nutrients

uptake

in

Juncus

acutus

Pedro

García-Caparrós

a

_,

_Alfonso

_Llanderal

a

_,

_Ahmed

_El-Tarawy

b

_,

_Pedro

_José

_Correia

c

_,

Maribela

Pestana

c

_,

_María

_Teresa

_Lao

a,∗

a_Higher_Engineering_School,_Department_of_Agronomy_of_the_University_of_Almeria,_Agrifood_Campus_of_{International}_Excellence_CeiA3,_Ctra._Sacramento

s/n,LaCa˜nadadeSanUrbano,04120,Almería,Spain

b_Department_of_Agriculture,_Kafrelsheikh_University,_Egypt

c_Universidade_do_Algarve,_MeditBio,_FCT,_Edifício_8,_Campus_de_Gambelas,_8005-139_Faro,_Portugal

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received29January2016

Receivedinrevisedform17June2016

Accepted20June2016

Availableonline2July2016

Keywords: Biomass

Electricalconductivity

Leachate Macrophyte

Nutrientuseefﬁciency

Ornamentalcascadecropsystem

a

b

s

t

r

a

c

t

ThepotentialcontaminationofsurfaceandgroundwaterbythenurseriesintheMediterraneanarea obli-gatestheuseofnovelsystemssuchasthecascadecroppingsystem.Theaimofthisworkwastoevaluate theeffectsofdrainagewaterderivedfromanornamental(RuscusaculeatusL.andMaytenus senegalen-sis(Lam.)Exell.)cascadecropsystemonthegrowthandpollutingelementsuptake(NandP)against astandardnutrientsolutioninJuncusacutusL.plants.Theexperimentconsistedofthreetreatments:a standardnutrientsolution(T0J;EC=150mSm−1),1:2diluteddrainagewater(T1J;EC=245mSm−1)and

therawdrainagewater(T2J;EC=310mSm−1).Biomass,plantandsubstrateparametersandtotalNand

Puptakebyplantsweredeterminedatthebeginningandattheendoftheexperiment.Thisexperiment showedthattheirrigationwithdilutedandrawdrainagewater(T1JandT2J)withlowerconcentrations

ofNandPcomparedtothecontroltreatment(T0J)supposedanincreaseofbiomassandconsequently

theincreaseofNandPuptake,wheretheplantsirrigatedwithhigherEC(rawdrainagewater)showed thehighestbiomassandtotalNandPuptake.

1. Introduction

Nowadays, the continuous growth of the ornamental plant industryovertheworldandinthesouthernofSpainhasbrought aboutmountingconcernoverthenutrients(NandP)leachedfrom thecontainersanditspotentialcontaminationofthesurfaceand groundwater(Lao,2005).Thedrainagesarenormallyrichin nutri-ents,buttheyarenotbalanced;moreover,thelevelsofNa+_and

Cl−arehighforthesensitivecultures(Carrionetal.,2005).The nitrateisleached frommostofthemineralsoilsand container

Abbreviations: AG,aboveground;BG,belowground;DW,dry weight;EEA,

europeanenvironmentalagency;Tf,ﬁnalplants;FW,freshweight;HPLC,high

per-formanceliquidcromatography;Ti,initialplants;IFDM,integratedfarmdrainage

management;LSD,leastsigniﬁcantdifference;PAR,photosyntheticallyactive

radi-ation;RH,relativehumidity;SBC,serialbiologicalconcentration;ANOVA,standard

analysisofvariance.

∗ Correspondingauthor.

E-mailaddresses:pedrogar123@hotmail.com(P.García-Caparrós),

alfonsollanderal@hotmail.com(A.Llanderal),tarawy101@yahoo.com

(A.El-Tarawy),pcorreia@ualg.pt(P.J.Correia),fpestana@ualg.pt(M.Pestana),

mtlao@ual.es(M.T.Lao).

media(Handreckand Black,1984)and althoughthephosphate isconsideredratherimmobilewithinmanysoils,itismuchmore readilyleachedfromthecontainermediacomposedofpinebarkor spaghnumpeatmoss(YeagerandBarrett,1984).Bothnutrientsare ofparticularconcernbecauseoftheircapacitytoleadto eutrophi-cationinwaterways(Kimetal.,2003;Tayloretal.,2005).Therefore, takingintoaccountexistinglegislationsuchastheNitrates Direc-tive (91/676/EEC) and the Drinking Water Directive (98/83/EC) whichsetamaximumallowableconcentrationfornitrate(NO3−)of

50mgL−1andEuropeanEnvironmentalAgency(EEA)(2005)which establishedarangeofphosphorus(P)of25–50␮gL−1inwater,it wouldbeadvisabletoreducetheenvironmentalpollutionthrough systemscompatiblewiththeenvironment.

The Integrated Farm Drainage Management(IFDM) systems employsequentialreuseofwaterwiththebiomassproductionto helpcontrolsalinegroundwater,thereductionofthewastewater andchemicalsandimprovingthesustainabilityofaridland irri-gatedagriculture(Blunketal.,2005).Oneexampleofthesesystems canbeaSerialBiologicalConcentration(SBC)oracascadecropping systemwherethedrainagewatercollectedfrombeneathonecrop isusedtoirrigatethenextmoresalttolerantcropintheseries try-ingtoreducealmostentirelythedrainagevolumefromthelast http://dx.doi.org/10.1016/j.ecoleng.2016.06.090

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Juncaceae (Balslev, 1996) widely distributed in salt marshes or poorly-drainedsoils(El-Shamyetal.,2012)andcanbefoundin theSpanishcoastalmarshcommunitiesandinseveralestuariesof theIberianPeninsula(SainzandRuiz,2006).Moreoverthisspecie hasawideecologicalrange,toleratingthesoilswithhighlevels ofsulphatesand chlorides(Fernández-Carvajal,1982). Cylindri-calleavesand stems(culms) witha sharppointontopemerge fromtherhizomeinbundlesandcanreach1minheight.During latespring/summer,theﬂoweringpaniclesoccursub-terminallyon stems.Theseeds(nuts)areprotectedwithintheinﬂorescenceand maystayontheplantfor6ormoremonthsbeforebeingdispersed bythewind(GreenwoodandMacFarlane,2009).

Althoughmuchhasbeenpublishedabouttheuseof macro-phytestoremove N andP in municipal, industrial,agricultural wastewatersand stormwaterrunoff (Vymazal,2007), verylittle isknownabouttheiruseasanornamentalcascadecropsystem undergreenhouseconditions.Therefore,inthepresentresearch, apotexperimentwithJ.acutusundergreenhouseconditionswas establishedinordertodeterminethepotentialtoremovenitrogen andphosphorusindilutedorrawdrainagefromanornamental cas-cadecroppingsystemincludingRuscusaculeatusL.andMaytenus senegalensis(Lam.)Excell.

2. Materialandmethods

2.1. Sitespeciﬁcationsandplantmaterial

Theexperiment wasconducted attheUniversity of Almería (36◦49N,2◦24W).

RootedcuttingofJ.acutusL.wereacquiredintrayswithplugsof 0.2Lfromacommercialnursery.Eachplantwastransplantedinto 1.5Lpolyethylenepotsfilledwithamixtureofsphagnum peat-mossand Perlite 80:20(v/v)and subjectedtonutrientsolution treatmentsfor8weeks(averagetimetoproducesaleablenursery cropsinpotsof1.5Lfollowingtheadvicesgivenbylocalgrowers). Thepotswereplacedonplastictraystocollectthedrainagesand coveredwithgalvanizedwiretoimpedethatthepotswerein con-tactwiththedrainages.Onthismeshofwireblack/white,smooth plasticsheetingwasplaced toavoid theevaporation; theblack sideofthefilmcouldavoidthemouldfungusandalgaegrowth andthewhitesidereflectsthesunandreducesthecondensation andheatbuild-up.Duringtheexperiment,plantsweregrownin agreenhouseof150m2_._The_{microclimatic}_conditions_inside_the

greenhousefortheexperimentalperiod,monitoredcontinuously withHOBOSHUTTLEsensors(modelH08-004-02,OnsetComputer Crop.,Bourne,MA)showedadailyaveragetemperatureof17.1◦C, relativehumidity(RH)of65.6%andphotosyntheticallyactive radi-ation(PAR)of71.6␮molm−2s−1.

2.2. Experimentaldesignandtreatments

Theexperiment consistedofthreetreatmentsusingdifferent

nutrientsolutions:T0J(150mSm−1;astandardnutrientsolutionor

control)reportedbyJiménezandCaballero(1990)foranadequate

growthofornamentalplantsunderMediterraneanconditionsand wasderivedfromtapwaterandH3PO4,HNO3andKNO3supplies),

T1J(245mSm−1;1:2diluteddrainagewater)andT2J(310mSm−1;

rawdrainagewater).Thenutrientsolutionsusedtoirrigatethe plantseverydaywerepreparedweekly.ThedrainagewaterofR. aculeatusirrigatedwiththestandardnutrientsolution(thesame asT0J)wascollectedweekly.Then,thisdrainagewaterwasusedto

elaborateweeklytwodifferentnutrientsolutions:T1M(1:2diluted

drainagewaterwithtapwater withthefollowing composition: 64,122.50,80.00,33.60and59.80mgL−1ofS,Cl,Ca,MgandNa; respectively,andECof90mSm−1)andT2M(rawdrainagewater)

toirrigatedailyeachtreatmentofM.senegalensis(Lam.)Excell.; respectively.Finally,theleachatescollectedweeklyfromthe irri-gationofM.senegalensis(T1MandT2M)wereusedtoirrigatedaily

eachtreatmentofJ.acutus;respectively(T1JandT2J)(Fig.1).The

experimentaldesignconsistedofthreetreatments(T0J,T1JandT2J),

fourblocksandfourplants(oneplantperpot)perblockgivinga totalof48plantswithaplantingdensityof10plantsm−2. 2.3. Nutrientsolutionsdeterminations

Foursamplesofnutrientsolutionpertreatmentwererandomly collectedweekly.

Each sample was composed by aliquots of 25mL, ﬁltered through0.45-␮mmembraneﬁltersandfrozenuntilnutrient anal-yses wereconducted.Fromeach sample,electrical conductivity and pHvalues weredeterminedby conductivitymeter andpH meter(modelsMilwaukeeC66andpH52(MilwaukeeInstruments, USA),respectively);andtheconcentrationsofnutrientswere deter-minedbyHPLC(HighPerformanceLiquidChromatography;model Metrohm883Basic ICPlus,anionsion exchangecolumnmodel Metrosep A SUPP 4, cations ion exchange column model Met-rosepC4100,ICconductivitydetectorrange(0–15000␮Scm-1), MetrohmAG,Switzerland)asdescribedbyCsákyand Martínez-Grau (1998). The chemical composition of each treatment was presentedinTable1.TheincreaseofpHin1:2dilutedandraw drainagewater(T1JandT2J)comparedtothecontroltreatmentcan

becanberelatedwiththeeffectofsubstrateinleachatepH increas-ingtheirvalueasreportedMerhautetal.,2006.Inaddition,the1:2 dilutedandrawdrainagewater(T1JandT2J)showedlowerN(1.8

and1.5-times)andP(3.7and2.2-times)concentrationscompared tothecontroltreatment(T0J),buthigherNa(8.5and9.8-times)and

Cl(5.6and6.5-times)concentrationsandconsequentlyhigherEC comparedtothecontroltreatment(T0J).

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Fig.1. Schematiclayoutoftheornamentalcascadecroppingsystem.

whereNSisthenutrientsolutionsuppliedineachtreatment,DisthedrainagecollectedineachtreatmentandTWisthetapwater.

2.4. Plantparametersandbiomass

Priortotheinitiationofthetreatmentsandattheendofthe experiment(8weeks),fourJuncusplantspertreatmentwere ran-domlyharvestedandthesubstrategentlywashedfromtheroots. Theplantsweredividedintobelowground(BG)andaboveground (AG)biomassandtherespectivefreshweights(FW)measured:the surfaceoftherootswasdriedwithblottingpaperpriorto weigh-ing.Belowgroundandabovegroundbiomasswerethenoven-dried at60◦Cuntilastableweightwasreachedinordertoprovidethe respectivedryweights(DW).Thetotalbiomasswascalculatedas thesumofBGandAG.Thefreshanddryweightswereexpressedin gm−2becauseweremultipliedbytheplantingdensity.Thewater contentinAG,BGandtotalplantwascalculatedasindicatedby Mateos-Naranjoetal.(2014)(FW-DW/FW)(−).

2.5. Substrateparameters

Priortotheinitiationofthetreatmentsandattheendofthe experiment (8weeks),four samplesofsubstrate per treatment wererandomlytaken,oven-driedfor48hat40◦Candthenpassed througha2-mmsieveandsubjectedtowatersuspensions(1:10). The substrate electrical conductivity (ECe)and pH were

deter-minedinthewatersuspensionbyconductivitymeterandpHmeter (modelsMilwaukeeC66andpH52(MilwaukeeInstruments,USA), respectively).Thenitrogenandphosphorusconcentrationswere determinedinsubstratewatersuspensionsbyHPLCasdescribed byCsákyandMartínez-Grau(1998).

2.6. Nutrientsuptakebyplants

Theoven-driedsamplestakenprior tothestartofthe treat-mentsandat theend oftheexperiment weregroundin amill anddividedintwosubsamples.Theanalysisofsolubleionicform (NO3−)inbelowandabovegroundbiomasswasdeterminedinone

subsamplefollowingwaterextractionbyHPLC(HighPerformance LiquidCromatography;modelMetrohm883BasicICPlus,anions ionexchangecolumnmodelMetrosepASUPP4,ICconductivity detectorrange(0–15000␮Scm−1),MetrohmAG,Switzerland)as describedbyCsákyandMartínez-Grau(1998).Theother subsam-plewasdigestedwithsulphuricacid(H2SO4,96%)inthepresence

ofhydrogenperoxide(H2O2,30%(w/v)andP-free)at300◦Cand

usedforthedetermination oforganicN.TheorganicN concen-trationwasquantiﬁedcolorimetrically(modelShimadzuUV-1201, Shimadzu,Japan)at630nm(Krom,1980)andthetotalP

concen-trationwasquantiﬁedcolorimetricallybythemolybdo-vanadate methodat430nm(Hogueetal.,1970).ThetotalNconcentration wascalculatedasthesumoftheorganicNandNO3−

concentra-tion.Thenutrientuptake(NU)inplantspriortothestartofthe treatmentsandattheendoftheexperimentwascalculatedbythe followingequation:

NU=(DWBG∗CBG+DWAG∗CAG)∗D (1)

Where:

DW: dry weight (g) of belowground (_BG) or aboveground biomass(_AG)

C:nutrientconcentration(mgnutrientg−1DW)inbelowground (_BG)orabovegroundbiomass(_AG)

D:Plantingdensity(numberofplantsm−2)

2.7. Relationsbetweentheplantparametersandthenutrientuse efﬁciency

Attheendofthetrial,therelationshipsbetweenthegrowth andnutrientparametersofJuncusplantsandtheECofnutrient solutions weretestedbyregression analysisandthebestﬁtted modelswereselectedbasedonthedeterminationcoefﬁcient(R2_).

Thenutrientsuseefﬁcienciesforeachtreatmentwerecalculated asthedifferencebetweenplantdryweight(ing)peramountof nutrientsupplied(ing)duringtheexperimentalperiod.

2.8. Statisticalanalysis

Theexperimentwasanalysedasacompletelyrandomizedblock design, and the values obtained for each plant and each vari-ablewereconsideredasindependentreplicates.TheAnalysesof Variance(ANOVA)andtheleastsigniﬁcantdifference(LSD)tests (P<0.05)wereusedtoassessthedifferencesbetweentreatments. AllstatisticalanalyseswereperformedusingStatgraphicsPlus Soft-ware(version5.1.).

3. Results

3.1. Plantparametersandbiomass

Throughouttheexperiment,therewerenomortalitiesofJuncus plantsortissuedamageattributedtothetestedtreatments.The irrigationwithdifferentnutrientsolutionsincreasedsigniﬁcantly theplantheight,numberofculmsandthefreshanddryweight ofbelowground,abovegroundandtotalplantinﬁnalplants(Tf)

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± ± ± ± Total 0.67±0.05ns 0.68±0.03ns 0.68±0.03ns 0.69±0.04ns

Table3

EffectsofthetreatmentsonpH,electricalconductivity(ECe),andNandP

con-centrationsofthesubstrateattheendoftheexperiment(Tf).T0J –standard

nutrientsolution,T1J–1:2diluteddrainagewater,andT2J–rawdrainagewater.

Theinitialvalueswerealsopresented(Ti).Inarow,treatmentswiththesame let-tersarenotsigniﬁcantlydifferentatP<0.05(ANOVAandLSDtest).Dataarethe means±standarddeviationoffoursubstratesamplespertreatment.

Ti Tf T0J T1J T2J ECe(mSm−1)130±10c 126±12c 209±18b 362±29a pH(H2O) 7.0±0.36b 6.8±0.22b 7.9±0.13a 8.0±0.08a N(mgKg−1₎ _1014.2_±_96.20_a_805.2_±_56.80_b_491.0_±_64.12_c_501.3_±_87.60_c P(mgKg−1₎ _90.80_±_6.35_a _74.94_±_6.29_b _51.93_±_7.06_c _46.40_±_6.96_c

comparedtotheinitialplants(Ti).Additionally,theirrigationwith

diluted(T1J)andrawdrainagewater(T2J)increasedsigniﬁcantly

theplantheight(1.1and1.2-times,respectively),thenumberof

culms(1.8and2.5-times,respectively)andthefreshanddryweight

oftotal plant(1.9and 2.6-times,respectively) comparedtothe

controltreatment(T0J).Nevertheless,therootlengthshowedthe

highestvalueinplantsirrigatedwiththecontroltreatment(T0J)

andthewater contentremainedwithoutsigniﬁcantdifferences

undertheirrigationwiththedifferentnutrientsolutions(Table2).

3.2. Substrateparameters

Attheendoftheexperiment,thepHvalueofthesubstrate sig-niﬁcantlyincreasedindilutedandrawdrainagewatertreatments (T1JandT2J)comparedtothecontroltreatment(T2J)butwithout

statisticaldifferencesbetweenthem.Ascanbeexpected,theECe

ofthesubstrateirrigatedwithrawdrainagewater(T2J)showed

thehighest valuemainlyduetotheaccumulationofNaand Cl (datanotpresented).TheconcentrationofNandPinthesubstrate decreasedsigniﬁcantlyinallthetreatmentsattheendofthe exper-imentshowingthelowestvaluesindilutedandrawdrainagewater (T1JandT2J)(Table3).

3.3. Nutrientuptake

Theirrigationwithdifferentnutrientssolutionsincreased sig-niﬁcantlythetotalNandPuptakeinbelowground,aboveground andtotalbiomassinplantsattheendoftheexperiment(T0J,T1J

andT2J)comparedtotheinitialplants(Ti).Moreover,theirrigation

withdiluted(T1J)andrawdrainagewater(T2J)increased

signif-icantlytheTNandTPuptakeinbelowground,abovegroundand totalbiomasscompared tothecontroltreatment(T0J),showing

Table4

Nutrientuseefﬁciencyofplantsirrigatedwithdifferenttreatmentsattheendof

theexperiment.T0J–standardnutrientsolution,T1J–1:2diluteddrainagewater,

andT2J–rawdrainagewater.Treatmentswiththesamelettersarenot

signiﬁ-cantlydifferentatP<0.05(ANOVAandLSDtest).ns:notsigniﬁcant.Dataarethe

means±standarddeviationoffourplantspertreatment.

Nutrientuse efﬁciency T0J T1J T2J NUE 10.70±1.07c 99.81±9.19b 123.15±12.32a PUE 37.80±3.22c 890.84±86.54b 1164.48±91.82a ClUE 6.6±0.61a 4.65±0.41b 3.11±0.31c SUE 12.88±1.31b 35.69±3.56a 40.73±4.10a CaUE 10.30±1.04ns 9.44±0.91ns 11.06±1.01ns MgUE 24.45±2.39b 36.24±3.02a 40.26±4.02a KUE 6.96±0.71b 22.53±2.52a 25.15±2.62a NaUE 13.90±1.25a 8.96±0.81b 6.37±0.61c

theplantsirrigatedwithrawdrainagewaterthehighestTNand

TPuptake(Fig.2AandB).

3.4. Correlationmodelsbetweengrowth-nutrientparameters andEC

The different parameters observed in J. acutus plants were relatedtotheECofthenutrientsolutionattheendofthetrial.The bestﬁttedmodels(thosewiththelargestR2_value)_were

polynomi-alsmodels.Alltheparametersstudiedshowedahighcorrelation withtheincreasingofECinnutrientsolution.The plantheight andnumberofculmsreachedamaximumvalueto310mSm−1, whereastherootlengthshowedthelowestvalueatthisEC(Fig.3A). Intermsofbiomass,thetotalFWandDWshowedahighraisewith increasingEC(Fig.3B)andthetotalNandPuptakewereenhanced whenECwasgraduallyraised(Fig.3CandD).

Ascanbeexpected,theNUEandPUEratiosincreased signif-icantlyin plantsirrigated withdilutedand raw drainagewater (T1JandT2J)comparedtothecontroltreatment(T0J),whereasthe

ClUEandNaUEratiosshowedanoppositetrendwithNUEandPUE ratiosdecliningsigniﬁcantlyin dilutedand raw drainagewater treatments(T1JandT2J)comparedtothecontroltreatment(T0J).

Ontheotherhand,theSUE,MgUEandKUEratiosincreasedwith drainagewatertreatments(diluted(T1J)andraw(T2J))compared

tothecontroltreatment(T0J)butwithoutstatisticaldifferences

betweenthem,and theCaUEratioremainedwithoutstatistical differencesunder theirrigationwithdifferentnutrientsolution treatments(Table4).

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Fig.2. Totalnitrogen(TN)(A)andtotalphosphorus(TP)uptake(B)(expressedingm−2₎_in_belowground_(BG),_aboveground_(AG)_and_total_biomass_(BG₊_AG)_at_the_initial

(Ti)andattheendoftheexperiment(Tf):T0J–standardnutrientsolution,T1J–1:2diluteddrainagewater,andT2J–rawdrainagewater.Treatmentswiththesameletters

arenotsigniﬁcantlydifferentatP<0.05(ANOVAandLSDtest).Dataarethemeans±standarddeviationoffourplantspertreatment.

4. Discussion

Theresearchonbiologicalresourcesusedastoolsformanaging thenurserypollutioncanbeoneofthefundamentalguidelines for thedesign and developmentof effective methodologies for theenvironmentalphytoremediation.Hence,thelocationofnative species with a high capacity for the nitrogen and phosphorus uptakeandforthegrowthintheleachatescanbeofparamount importancefortheremediationofthedrainagepollutionfromthe containergrownplants(Broschat,1995).

Ourexperimentalresultsdemonstratethattheincreaseofplant heightandnumberofculmsandconsequentlytheincreaseoffresh anddryweightofbelowground,abovegroundandtotalbiomassin plantsirrigatedwithdiluted(T1J)andrawdrainagewater

treat-ments(T2J)comparedtothecontroltreatment(T0J).Thisincrease

canberelated withtheslight increaseof ECin each treatment duetotheaccumulationofNa+ _and_Cl−_in_the_nutrient_solution

bythereuseofdrainageintheornamentalcascadecropping sys-tem, where the plants irrigated withraw drainage water (T2J)

showedthehighestvalueforalltheparameterspreviously com-mented.The increaseof theplantheightand numberof culms relatedwiththeECincreaseinthenutrientsolutionagreesvery wellwithTwilleyandBarko(1990)whoreportedanincreaseof plantheightinothermacrophytesplantsasMyriophyllumspicatum andPotamogetonperfoliatusirrigatedwithincreasingsalinity lev-elsnearto1875mSm−1.Neverthelessotherresearchersreported areductionoftheplantheightandnumberofculmsunder increas-ingsalinityinspecieswithinJuncaceaesuchasJ.acutusgrownat 1560mSm−1 (Greenwoodand MacFarlane,2009)and J.kraussii grownat10000mSm−1(Lymberyetal.,2006).

In our experiment, there was no clear trend between the rootlengthandirrigationwithdifferentnutrientsolutions.Plants irrigated with a standard nutrient solution (T0J) (lowest level

ofsalinity)showedthehighest rootlength,althoughtheirroot biomasswaslowerthantheothertreatments.Thisincreaseofroot lengthcanberelatedwithanormalstrategyshowedinhalophytes tomaintaintherootandrhizomesurvivalthroughdivertingthe energyfromabovegroundtobelowgroundunderlowerlevelsof salinity(Craine,2005).DifferentresultswerereportedbyRozema andBlom(1977)whonotedthattherootlengthofJ.gerardiiplants increasedaftersixweeksinplantsirrigatedwith1:2diluted

sea-watercomparedtothecontroltreatment(irrigationwithdistilled water).

Thefreshanddryweightincreaseduetotheslightincreasing ofECobtainedinourexperimentinJ.acutusplantsdifferedfrom theresultsreportedinotherexperimentswithspecieswithin Jun-caceaesuchasJ.acutusandJ.kraussii(GreenwoodandMacFarlane, 2009)andJ.acutusandJ.maritimus(Boscaiuetal.,2012)wherethe belowground,abovegroundandtotalbiomassinplantsdecreased withincreasingEC.

Theirrigationwithdifferentnutrientsolutionshad noeffect onthewatercontentinJ.acutusplants.Severalstudiesshoweda reductioninthewatercontentinJ.roemarianusirrigatedwith arti-ﬁcialseawater(4700mSm−1)(Touchetteetal.,2009),whileothers researchersreportedtheincrease of watercontentas a feature frequentlyperformedinmanyhalophytes(Crawford,1989), rep-resentingaveryefﬁcientwayofmitigationoftheadverseosmotic andtoxiceffectsofionsthroughthedilution.

Ascanbeexpected,theincreaseofbiomassinJ.acutusplants ledtoincreasethetotalNandPuptakeshowingacloser relation-ship(R2₌_0.89_and_0.93,_{respectively),}_therefore_the_highest_values

oftotalNandPuptakewerefoundinplantsirrigatedwiththeraw drainagewater(T2J),althoughthenitrateandphosphate

concen-trationswerelowerthaninthecontroltreatment(T0J).Although

theseresultscanbeunexpected,agreeingverywellwiththe find-ingsreportedbyShaverandMelillo(1984)whodemonstratedfor wetlandplantspeciesthat theefficiencyofNandPuptakeand theefficiencyoftheiruse(biomassproducedperunitofNandP acquired)tendstoincreaseasavailablenutrientsinputsdecrease. Attheend ofthetrial,theNstandingstocksvaluesin total biomassobtainedinourexperimentrangedfrom3to9gNm−2 beinglowerthanthevaluesreportedinotherexperimentswith macrophytessuchasPhragmitesaustralis(20–27gNm−2)( Maltais-Landryetal.,2009)andTyphalatifolia(29–51gNm−2)(Maddison etal.,2009).ConcerningtotheabovegroundNstandingstock val-ues, therangesreportedbyotherresearcherswerehigherthan therangeobtainedinourexperiment(2–6gNm−2).Tanner(1996) noted N standingstocks values in other macrophytes, suchas PhragmitesaustralisandGlyceriaof32and95gNm−2;respectively. Ennabilietal.(1998)reportedabovegroundNstandingstocks val-uesof11gNm−2 inJ.acutusgrowninwetlandsofMoroccoand Vymazal(2007)inareviewaboutnutrientsremovalsof

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macro-Fig.3.Relationshipbetweenthegrowthparameters(A),biomassparameters(B),totalnitrogenuptake–TN(C),totalphosphorusuptake–TP(D)andelectricalconductivity

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phytesinvarioustypesofconstructedwetlandsreportedrangesof 0.6–72gNm−2 (Johnston,1991),22–88gNm−2 (Vymazal,1995), 2–64gNm−2 (Vymazaletal.,1999)or2–29gNm−2 (Mitschand Gosselink, 2000). Similarly, to the previous results, the range of belowground N standing stocks values in our experiment (1–3gNm−2) was lower compared to the ranges reported by other researchers in other macrophytes suchas Typhalatifolia (12–19gNm−2)(Maddisonetal.,2009)andCalamograstis angusti-folia(12–28gNm−2)(SunandLiu,2007).

ThePuptake islowerthantheN uptakecapacity of macro-phytes(Vymazal,2007)beinginaccordancewithourresults,sothe abovegroundPstandingstockvalueswere4.5-timeslowerthan theaboveground Nstandingstockvaluesin thetreatmentwith thehighesttotalNandPuptake(rawdrainagewater(T2J)).The

Pstandingstocksvaluesintotalbiomassobtainedinour exper-imentrangedfrom1.0to2.8gPm−2 andwereinside fromthe rangesproposedbyotherresearchersinothermacrophytessuchas Phragmitesaustralis(2.0–2.6gPm−2)(HaberlandPerﬂer,1990)and Phalarisarundinacea (0.5–1.5gPm−2)(Vymazal,1999)grownin horizontalsub-surfaceﬂowbeds.ConcerningtotheabovegroundP standingstockvalues,therangenotedinourexperiment(0.6–1.4g Pm−2)agreesverywellwiththevaluereportedbyEnnabilietal. (1998)inJ.acutus(0.6gPm−2)andJ.maritimus(0.6gPm−2),but waslowercomparedtotherangesofabovegroundPstandingstock valuesreportedbyVymazal(2007)inareviewaboutPremovalof macrophytesinconstructedwetlands:0.1–6.8gPm−2(Johnston, 1991),0.1–11gPm−2(Vymazal,1995),0.01–19gPm−2(Vymazal etal.,1999)or3–15gPm−2(BrixandSchierup,1989).The below-groundPstandingstockrangeinourexperiment(0.6–1.4gPm−2) waslowercomparedtotherangereportedbyKaoetal.(2003)in othermacrophytessuchasJ.effusus(0.1–2.0gPm−2)andPhalaris arundinacea(0.1–1.2gPm−2).

Thechemicalanalysisofthesubstrateattheendofthetrial indicatedthattheNandPdepletioninthesubstrateofplants irri-gatedwithdilutedandrawdrainagewater(T1JandT2J)couldbe

relatedwiththehigheruptakeofNandPinthosetreatmentsas itwasexplainedabovetherebyincreasingtheNUEandPUEaswe reportedinourresults.

Accordingwithourresults,theirrigationwithdilutedandraw drainagewater(T1JandT2J)withlowerconcentrationsofNand

Pcomparedtothecontroltreatment(T0J)supposedanincreaseof

biomassandconsequentlytheincreaseofNandPuptake,wherethe plantsirrigatedwithhigherEC(rawdrainagewater)showedthe highestbiomassandtotalNandPuptakeandthusthehigh salin-itytolerantmacrophytesaregoodcandidatesinphytoremediation, becauseNaandClwereaccumulatedinthenutrientsolution.

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