water Article Tomato Productivity and Quality in Aquaponics: Comparison of Three Hydroponic Methods ZalaSchmautz1,*,FionnaLoeu2,FrankLiebisch2,AndreasGraber1,AlexMathis1, TjašaGriesslerBulc3andRankaJunge1,* 1 InstituteofNaturalResourceSciences,ZurichUniversityofAppliedSciences,Grüental,8820Wädenswil, Switzerland;fish@urbanfarmers.com(A.G.);alex.mathis@zhaw.ch(A.M.) 2 InstituteofAgriculturalSciences,ETHZurich,Universitätsstrasse2,8092Zurich,Switzerland; fi.loeu@gmail.com(F.L.);frank.liebisch@usys.ethz.ch(F.L.) 3 FacultyofHealthSciences,UniversityofLjubljana,Zdravstvenapot5,1000Ljubljana,Slovenia; tjasa.bulc@zf.uni-lj.si * Correspondence:zala.schmautz@zhaw.ch(Z.S.);ranka.junge@zhaw.ch(R.J.); Tel.:+41-589-345-928(Z.S.);+41-589-345-922(R.J.) AcademicEditor:M.HaïssamJijakli Received:14September2016;Accepted:9November2016;Published:16November2016 Abstract: Aquaponics (AP) is a food production system that combines hydroponic (HP) crop productionwithrecirculatingaquaculture. Differenttypesofhydroponicsystemshavebeenused forgrowingcropsinaquaponics. However,veryfewstudieshavecomparedtheirsuitabilityand efficiencyinanaquaponiccontext. Thestudypresentedherecomparestomatoyield,morphological (external)andbiochemical(internal)fruitquality,andoveralltomatoplantvitalityfromthreedifferent HPsystems(nutrientfilmtechnique,dripirrigationsystem,andfloatingraftculture)andexamines thedistributionofnutrientsindifferentpartsofthetomatoplant. ThreereplicateAPsystemswere set up, each incorporating the three different HP systems coupled with a separate recirculating aquacultureunitgrowingNiletilapia. Theresultsshowedthatthechoiceofthecultivationsystem hadlittleinfluenceonmostoftheabove-mentionedproperties. Tomatofruitmineralcontentwas foundtobeinsimilarrangeforN,P,K,Ca,Mg,Fe,andZnasreportedintheliterature. Yieldand fruit quality were similar in all three systems. However, the drip irrigation system did perform slightlybetter. Theslightlyhigheroxygenradicalabsorbancecapacity(ORAC)ofthefruitsgrownin APincomparisontocommerciallyproducedandsupermarketderivedtomatoesmightindicatea potentialforproducingfruitswithhigherhealthvalueforhumans. Keywords: aquaponics;hydroponics;dripirrigation;floatingraftculture;nutrientfilmtechnique; tomato;tilapia 1. Introduction Duetotheincreasingdemandforfoodandtheneedtosavefreshwater,foodproductionefficiency must be increased. Currently, more than 70% of the world’s freshwater resources are used for agriculturalpurposes[1], increasingtheneedforimprovedwateruseefficiencyandtherecycling of water in semi- or closed production systems. Food provision has a significant impact on the environment through greenhouse gas emissions, depletion of phosphorus, use of land and water resources,andreleaseofchemicalproducts[2]. Ontheotherhand,todaymorethan54%oftheworld’s populationlivesinurbanareas. Itisexpectedthattheurbanizationtrendwillincreaseto66%ofthe globalpopulationby2050[3]. Urbanagriculturecanproducefoodlocally,usesresourcesveryefficientlyandhasaminimum negativeimpactontheenvironment[4]. Foodproducersnotonlyfacethechallengeofsupplying Water2016,8,533;doi:10.3390/w8110533 www.mdpi.com/journal/water Water2016,8,533 2of21 staplefoodstomeetcaloricdemand,butalsothechallengeofproducingawidevarietyofhighquality foodswithgoodnutritionalproperties. Therefore,itisimportanttofindsustainablefoodproduction systemswhichcanalsobemaintainedwithinsettlementsorcities. Aquaponics (AP) is one of the most promising sustainable systems for food production that combineshydroponicsystems(HP)withrecirculatingaquaculturesystems(RAS).Ithasthepotential to play a major role in food provision and tackling global challenges such as water scarcity, food security,waterpollution,highenergyuseandexcessivefoodtransportmiles[5]. IfAPisoperatedin aclosedwaterloop,ithaslittleenvironmentalimpactbecausethefoodisproducedwithlowwater consumption [6,7]. Plant production yields in AP have been reported to be higher than for crops grown in soil [8,9], however data are scarce. In AP, nutrients enter the system in the form of fish feed. Thefeedisingestedandmetabolizedbythefish. Theremainsofthefeedandthemetabolic productsfromthefishdissolveinthewatercreatinganaquacultureeffluentthatprovidesmostof thenutrientsrequiredforplantgrowthinaHPpartofthesystem. Microorganismsinthebiofilter,on plantroots,andintherecirculatingwaterreleaseandconvertthenutrients(e.g.,phosphatesfromthe debris,andammoniumtonitrate)andtheplantsassimilatethem,thustreatingthewater,whichflows backtotheaquaculturecomponentofthesystem[5,8]. InAP,fish,plants,andbacteriacoexistinthe samewater,albeitindifferentcompartmentsofthesystem[10]. DifferenttypesofHPsystemshave beenusedforgrowingcropsinAP:(i)dripirrigation;(ii)floatingraftculture;(iii)gravelbed;and (iv)nutrientfilmtechnique(NFT)[5–8,11–14],howeververyfewstudieshavecompareddifferentHP productionsystemsinanAPcontext. TheonlypaperweareawareofisbyLennardandLeonard[15] comparesfloatingrafts,gravelbeds,andNFTforgrowinglettuceinAPandfoundthatNFTproduced significantlylessbiomassandremovedthenutrientsfromfishwaterlessefficientlythantheother twosystems. Generally, all plant species that can be adapted to growth in HP systems can also be grown inAP[16], meaningthereisanextremelywidevarietyofchoices. Savidov[17]reportedgrowing over 60 different types of plant species in AP. Lettuce, specialty greens and herbs (chives, basil, spinach, and watercress) have low to medium nutritional requirements and are well adapted to AP[16]. Fruityieldingplants(tomato,bellpepper,cucumber,andsquash)haveahighernutritional demandandperformbetterinheavilystockedAPsystems. Inindoorsystems,themostcommonly used tomatoes are greenhouse varieties which are better adapted than field cultivars to low light andhighhumidityconditions[16]. AccordingtoFAOstat[18],tomatoesareworldwidethesecond most important vegetable crop after potatoes. Tomatoes are rich in nutrients and vitamins which are associated with healthy food, i.e., carotenoids, flavonoids and lycopene [19,20]. Leaf nutrient concentrationscanbeusedtodetectthemineralnutritionalstatusoftheplantsandthusmighthelpto revealdifferencesinnutrientavailabilityindifferentgrowingsystems,whereasfruitnutrientcontent indicates the nutritional value for human consumption [21]. Graber and Junge [5] compared four varietiesoftomatoes(Grapella,RoseofBerne,FrogKingGoldenOrb,andSweetfromHungary)in AP,andincommercialHPcultivationwithapplicationsofmineralfertilizeraccordingtoResh[22]. TheyfoundthatallvarietiesperformedbetterinAP. Thepurposeofthisstudywastocomparetomatoyields,morphological(external)andbiochemical (internal)quality,andoverallplantvitalityinthreedifferentHPsystems(NFTsystem,dripirrigation system, andfloatingraftculture). Inaddition, nutrientuptakeanddistributionwithinthetomato plantswasalsotobedetermined. 2. MaterialandMethods Theexperimentwasconductedfrom31Marchto5November2014(220days)inadoubleplastic coveredgreenhouseattheZurichUniversityofAppliedSciences(ZHAW)inWädenswil,Switzerland. From31Marchto11June,thesystemswereoperatedasHPsystems,withnutrientsupplementsadded directlytothesump(Figure1). Therequiredamountofnutrientsupplementswascalculatedbasedon Water2016,8,533 3of21 thewatervolumeintheHPunit. On12June,theHPunitswereconnectedwiththeaquacultureunit Wanatdert 2h0e16s, y8s, 5te33m startedtoworkasaquasi-closedloopAP. 3 of 21 FFiigguurree 11.. PPlalanno fotfh etheex peexrpimereinmtaelnstualb usnuibtsuninittsh eina qtuhaep aoqnuicalpaobnoirca tloarbyo,frraotmory3,1 fMroamrc h3t1o 5MNarocvhe mtob e5r N20o1v4e,mwbitehr t2h0r1e4e, rwepitlhic tahterese( Are,pBl,icaantdesC (A)a, tBt,h aenZdu Cri)c hatU thneiv Zerusriitcyho UfnAipvperliseitdy Socfi eAnpcepsliiend WScäidenecnessw iinl, WSwäidtzeenrslwanild, .SFwraimtzienrglalninde. sFtyraleminindgic altinese wshtyiclhe siunbduicnaitteiss cwonhnicehct esdutbouwniht icihs ccoomnpnoecnteendt .tWo hwilehtichhe ceolemmpeonntsenatr.e Wdrhaiwle nthteo eslceamlee,nthtse adries tdarnacwesnb teot wsceaelen, tthheem diasrteanncoetst boestcwaelee.n them are not to scale. 2.1. The Aquaponic System 2.1. TheAquaponicSystem Three identical experimental recirculating AP systems (A, B, and C) were installed in a ThreeidenticalexperimentalrecirculatingAPsystems(A,B,andC)wereinstalledinagreenhouse, gcoreveenrhinogu2se7,0 cmov2eirnintgo t2a7l0(F mig2u irne t1o)t.aEl a(FchigAurPe s1y)s. tEeamch(F AigPu sreys2t)emwa (sFcigoumrep o2s) ewdaosf caofimsphohsoedld ionf ga tfainshk holding tank (2700 L), a solids removal unit (drum filter) with water level sensor (230 L), solids (2700L),asolidsremovalunit(drumfilter)withwaterlevelsensor(230L),solidsthickeningunit, thickening unit, i.e., radial flow settler (45 L), a moving bed biofilter (580 L), an oxygenation zone (30 i.e.,radialflowsettler(45L),amovingbedbiofilter(580L),anoxygenationzone(30L),acollection L), a collection sump with water level sensor (470 L), piping (65 L) and a HP unit (730 L). The HP unit sumpwithwaterlevelsensor(470L),piping(65L)andaHPunit(730L).TheHPunitineachofthree iAnP earecph loicfa ttherseye sAtePm rsepcolincasitset esydsotefmthsr ceoenssuisbtuendi tosf: t(hi)reNe FsTubcuhnaintsn:e (li)( 4NmFT× ch0a.2nnme)l (w4 imth ×fo 0u.2r mco)c ownituht ffiobuerr csolacbosnfuotr fpiblaenr tsslaubpsp oforrt; p(ilia)nflto sautipnpgorratf; t(ciiu) lftluoraetibnags inra(f6t 5c0uLlt;u4rem b×asi1nm (6×500 L.2; m4 m)w ×it h1 amn ×a e0r.a2t imon) wpiipthe taon pareorvaitdioena dpdipitei otnoa lprooxvyigdeen atdodtihtieonraolo tosx(y2g5enL ·tmo inth−e1 )raonodts fl(2o5a tiLn∙mgirna−f1t)s a(nDdr yfhloyadtrinopg ornaifctss, (Dryhydroponics, BV’s‐Gravenhage, The Netherlands); and (iii) a drip irrigation system (4 m × 2 m) BV’s-Gravenhage,TheNetherlands);and(iii)adripirrigationsystem(4m×2m)withfourcoconut with four coconut fiber slabs for plant support and 20 narrow tubes delivering water directly to the fiberslabsforplantsupportand20narrowtubesdeliveringwaterdirectlytotheplants. Eachreplicate pAlPanstyss. tEeamchh aredpaliwcaatete ArvPo slyusmteemo fh4a.d8 5a mw3ataenrd vaolsuumrfea coef o4f.8355 mm32 a.nd a surface of 35 m2. The climate in the greenhouse was controlled and recorded by a greenhouse climate computer Theclimateinthegreenhousewascontrolledandrecordedbyagreenhouseclimatecomputer (MasterClim 4 Zones, Anjou Automation, Mortagne‐sur‐Sèvre, France). During the day (start 1 h after (MasterClim 4 Zones, Anjou Automation, Mortagne-sur-Sèvre, France). During the day (start 1 h aasftterornaostmroincaolm siucnalrissuen),r itshee) ,htheaethinega tiwnagsw aacstiavcattievda teifd tihfet hiensinidseid teemtempepreartuatruer ewwasa sbbeeloloww 1188 °◦CC aanndd aeration (openings in the greenhouse roof and additional ventilation) started if the temperature was aeration(openingsinthegreenhouseroofandadditionalventilation)startedifthetemperaturewas aabboovvee 2200 °◦CC.. 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Teh hee pTpuhupmemuppppmup uu❸m p❸mm p❸ ppc c❸o ❸o ncnos cs tnccoatoosanntnnnsatslsttnyltatyata nlp nnyptutlt uylplmyym up pppmupeuumepdmmde pw pdpweea edwadtd etwa ewrwtr aei aanitrntet teieortnror itt i niohtnnht etotteo ho f tlf ethtolh hofeaelea tof itfllfaniolnotogaigana trt itgraininan fgrtfgga t cr f rcrautaua flcftftltu tutc uclcruturueulel,tlrt u,taue uarn,r rneeade,d,n ,aN a daNnnnF dNdFdT TNF NNc TcFhFhF TacTTahn cn canchnhnheaealnan lnane nannlne neadeldln l af a darfnnron dfodmdr mof fr fmrt rohotohm metmerh ret eteht hrvh eveeier arivreae e i va vi aia thvthietae hd ttedhthr hradeeaei rnddi andarriaraangagiieannie gnapa epaggo goepeinei opnp tpio tonb oiibtnani ancbttck tbabk cabta kcotacok cktt kohtt hto eotte oht s ht esuhteu hmsemseu sup msupm.u m.pT mpT.hp .hTpe.T e .hT rh Terehee htreutree uerr trtrneuunet ruprt nupnru runpmpn muup ppmmup u❹m pp❹m p❹ pp ❹p u❹ uppm muup pmpmupeumpepdmdee pwd dpwe aewdwadt eatwa ertwter aeb ratbraetb aecbrackr acbk cbkta kotacot ckott koht tht ehotteo he s t esohtso hloseileold iisd ldssois odslr ilrserdie emdrsmmes or moorevevmvoamaalvo llao vlva al l uuunnnuitiin utta uinaatnn nniadtidd nt a t dahtnthhn udtuudhs tss uhte heesnu nnusesssusn euu rsenrreuneesdrsudde uar daare c e daccodo o nac nnao scss tncoattosaanntnnnast ttstnw atwwtan anwaatt tettwa eerwtrr ael aelltreeetv elvvreer eellv elllie evniilvnne ite lnhtt lhhi eniteen h s t essuhtuu hmsemmeu sp msupp.u m..pD mDD.pu Dpuu.r .rriDu niiDnrnugiuggnr a rigaanuin uugatgott uoao mtaummouatmaoattoittmaciimcc tadi dcadtr itrrudciuuc mrd mmudr mfru iffiulmi tllmfetti eelrf trr iferl irrtirlnetii nnerrsir ssinr niirisnnngiinggns ws igwwnin igwtiightt hhwi tw hiti hth ccclellceealaanecnnclaeeleedneadde an sdnsesy eyydssdsst yetst seesmytmymes stm wetwwem amwaat ettw aeerwtr,rae ,,a stresstm, emmrsr,a m,aals llslma llm alaaalm amlmallo lmooa uaumuonmnnutosttonus sut onsoonft ffsot ws wfwo aowfaat fettw aeerwtr rae watrwwet ierwtiirh tthw hi tw shisosti oohtlsihll odiis ddlssois dosl (ilsf(d(iif fidsis(shsfs ih(h sf( mhifmmsi sahmahan nm naumuunrareuranee nru aeauanr nnreaded dn a rdanrern eedsrsdis ediir dsdrueiuedusesieuesdis sdeu osuoofe fefso fs ifffio si oshsffhi hf sf fhifeffsie eeshfeehde ddf e)ef ))de e)ed d) ) wwweweerrreweee wrr erereeere mrremmee orm oorevevvmoemeedvoddeo vi dnivienn etditotdnoo it s niossontoo lostilloodi isdd lssoiss dolt ithltsdhih idtsciihcsc ktk ikhtecehenkincniieckniinknnegieggnn nu iguuninn nnguigtii nt,ut ,,uia ntaans,is s taid ,tdds ,ea eeadsssscs edcc rsdrriecbiiesbbrescieedcbrddrie bii dnibienn e diM dnMM i anMiaany yyM eaMeeryarr e[a y[2[ry22e 3[e3r3]2r ].][3 ..2T[ ]T2T3.h 3hh]Ti.]cii h.Tcck Tikkhecheenkicnnieeckeednkedde enf dnlffleol edoofadlaa tof ittlfaniiolnntogaiggna,t ,,itag niaann,g nnadg,ddn ,as dassnenee tdstttdel ttsell tseeetdleddte tt ldtel edd sslulsudldusgslgdeuleu gdwdewg agwease s wa mwsma aamsans nm aumunaaaulanllnayulylu alryaelrll emyrlmye or morevemvoemedvodeo vfdvrfeor edfomdr mof r fmtrohtomh emte h st eysht yhssetsey est sesmytymes stmtethtemh rmterh eet rhte ehtreitremi etmeiee mt esit msieamsa ew easws eaw eea ekwe wk eaekeane enkadk dn a cdanocn odlcldlo elc clecoltceoletlcldeeltedce ictdneitn e diadn ani nnia no naou anuotnd uto dootudooutoordt doruorouno ounritr ni.u t ui.ntn.i ti.t . sludge was manually removed from the system three times a week and collected in an outdoor unit. SSooSlilodiSdlSsois-odlf-ilsrfdire-dsfeers-e ef-wrfwere aeweate etwa erwtr aewawtret aewarsr s wa rwrseae tarstueus rr trrneuneteruetdnudre rntdntoeo e dttdtoh ht eotte ho sts eohto hlselieoid ds lssois dolrirlesdie mdrmses orm orevvemoamavlol uaovulvna nuailit lnt.u . uintn.i ti.t . Solids‐free water was returned to the solids removal unit. In IonIr nIdon reo dorr erdtdore etrmor t aotmok m aemk aaaek ck aeoe acm ao c pmcooampmriapsproaiarsnrio sitnsooo n tcno ot otcmoo c mmcoomemmrmcemiraecelri rcapcilrai paol ldrp opurdrocoudtdicuoutncicot,it nfoioo,n unf,o r,f u oftooru umtror ta mottomoam tpaoatl aotpon lp aptlsnal aotnsnft osttsh fo oetfh fst ehtah mseea s emsa acmemu celetu ci vclutuailvtlrit avivra arr IInn oorrddeerr toto mmakaek ae caomcopmarpisaorins oton ctoomcmomercmiaelr pciraoldpurcotidounc, tfioounr, tfoomuartoto pmlaantots polfa tnhtes saomf teh ceulstaivmaer wewrweew regeerr reoge wrg ogrnwro owhnwy nhnd yh rhdoyyprdodorpronoopipcnoaoinlcnliaycilca loayllln yloy rno oo ncrn okr c rowkoc ckowk ow olw oouolos ouiln lsu guisn sidgninr gdigp rd idirprri rpiipir gir raiirrgtriiagoigtaniaot itinoino n inan i nicano a cma oc mmcoomemmrmcemiraecelri rcagcilari aegl lerg negrehreneeoehnunohshueoo su(ueMs se(eeM ( iM(eeMrie eeirei err wcuelrtiev garrowwenr ehgyrdorwopnohnyicdarlolyp oonni craolclyk ownorool cukswinogo dlruispi nirgridgraitpioinrr iigna ati oconminmaerccoimalm greerceinahlogureseen (hMoeuiseer GeGmGeGümesemüem,sü Pües,ase Peu, ,aPl P uuaalun uuld lnu uRdnnu dRde uRd Reuiu dMeeid deMii iMe eMrie,e eRirei,eü rRr,t ,iüR hRtüoiühtfit,ohi Shfo,wo fS,fi w,St Szwiewtzritileztarzenleradrlnal)a.dn Fn)d.od )Fr.) o.Ft Fhro oitrshr t cihtsohi cmsiso c pmcooampmriapsproaiarsnrio signsoro nogn urg ogpruro,o putuo,p mpt,o ,ta mottomoam tcaoaut otclotu ci vclutuailvttlitiavoivtaniaot itnoio nn (GMemeieürseG, Peamuül suen,d PRauueldiu MndeieRr,u RedütiihMofe,i Sewr,itRzüertliahnodf,). SFwori ttzheisr lcaonmd)p.arisFoonr gtrhoiuspc, otommpaatrois counltigvraotiuopn, memamesmuaeseraueasssru eurssreu esscs u hssc uuhacc shh a psa aespss tepipscetiesidscteiticid cieadid peaep palaippcplapiptcliilaocitcaniaot itnowio nenw r weew reeper reeper fepoprerfermorfrofemordrmem daee dcdca o cacracdoccrciondorgirdnd igntino g gt oe t sotote as ebtesalstibastalhbibselihldsiesh hdmee ddam n maamngaaanengmaaegegmenemetm neetn nt t mtoemaasutorecsu lstiuvcaht ioans mpeesatsiucirdees saupcphliacsatpioesnt icwideerea pppelrifcoartmioendw aecrceoprderinfogr mtoe deastcacbolridshinegd tomeasntaagbelimsheendt prpacrptapriccrataecicscti teicisnce e siSns iw niSni wSt zSwiewtzritileztarzenleradrlnal [adn2n d4[d2] [. 4 2[I]24n.4 ] I.]an .I d nIand da iatddidoidtdniioti,it notiow,n nt,ow ,t wtdowi ofdof eid fdrfieefiffnrefeter nrecetnh ncte thrc rcehyhre retryorr rymtyo t amottomoam tacoaut otclot uci vclutuailvtlritsavi vrwasar erswsr w eew reaeerl sreaeo la s abloslo sobuo ob gbuohogutu hgignth h itn ti nin pmraancatigceems ienn tSwpriatzcteircleasnidn [S2w4]i.t zIenr laadnddit[i2o4n],. tIwnoad ddiiftfieorne,nttw cohedrirfyfe troenmtacthoe crruylttiovmarast woceurelt iavlasors bwoeurgehatl sino a sau aspa ues spurumeppreamerrrmkameraktar erkokten eot t1no 5o n1 n O51 1c5O5t oO cObtcoectbrot oebtbroe e rtcro ot otcmo oc pmcooampmreapp raieanr retieen i rtninentraetnler arnfnrla uaflr iltf u rfqirutuu iqtia tuq liqautuylai atltyilrti ayttyir tt asrti ratfasirti ostfsmr f orf mrotohm meth t eehtxh eepe xee perxxiepmpreieermrinmietmaneletn anstlyat assl lyts essymtysest metem m ab osuugphetrminaarkseutp oenrm 1a5r kOecttoobne1r5 toO cctoombepratroe cinotmerpnaarle firnutietr nqualaflrituyi ttrqauiatsl itfyrotmra itthsef reoxmpetrhiemeexnptaerl ismyestnetmal wiwthwiw tdhitii htfdhf eid fdrfieefiffnrefeter nrecetun ncltt tuci vclutuailvtrlitsavi vrgasarr rosgs wrg ogrnwro owinnw n iann ni nia nu na na nunk nu nuknonnkwkonnnwo owcnwo ncmn oc mmcoomemmrmcemiraecelri rcascilyai assly tls essymtysest.m etem.m . . wsyistthe mdifwfeirtehndt icfufelrteivnatrcsu gltriovwarns ignr oawn nuninknaonwunn kcnomowmnecrcoimalm syesrcteiaml.s ystem. Water2016,8,533 5of21 Water 2016, 8, 533 5 of 21 Figure3.FWigeuerke l3y. Wmeeeaknly vmaelaune vsafluoerst feomr tpemerpaetruatruere(T (T),),a anndd rreellaatitvive ehuhmuimditiyd i(RtyH()R inH th)ei ngrtehenehgorueseen, ahnodu se,and electrical conductivity (EC) in the system water; n = 1 for RH and T and n = 3 for EC. electricalconductivity(EC)inthesystemwater;n=1forRHandTandn=3forEC. 2.2. Stocking of the System 2.2. StockingoftheSystem In spring 2014, the AP system was stocked with tomato plants (Solanum lycopersicum L. cv. In sp“Grianrgden2b0e1r4ry, Fth1”e (HAiPld)s) yansdte Nmilew tilaaspisat (oOcrkeoecdhrowmiist hniltootimcusa)t. oTopmlaatno tssee(dSlionlgasn wumerel oybctoapineerdsi ocun m L. cv. 28 February from Tozer Seeds Ltd. (Pyports, UK) and were supplied by Max Schwarz AG (Villigen, “GardenberryF1”(Hild))andNiletilapia(Oreochromisniloticus). Tomatoseedlingswereobtainedon Switzerland) before being cultivated further in the greenhouse. Seedlings were transplanted into the 28FebruaryfromTozerSeedsLtd. (Pyports,UK)andweresuppliedbyMaxSchwarzAG(Villigen, HP units on 31 March. Initially, each HP unit hosted seven tomato plants with 24 shoots (31 March– Switzerla1n2d J)ubneef)o. rOenb 1e2in Jgunceu, lotinvea rtaenddfoumrt hheearltihnyt hsheogorte peenrh HoPu suen.iSt eweadsl irnemgsovweedr etot raasnsessps ltaontatle dgrienetno theHP unitson3b1ioMmaarscs hin. eInacihti aHlPly u,neiat,c lheaHviPngu 2n3i tshhooostste pders uenviet.n Ttoo emnsautroe peqlaunaltistyw bietthw2ee4ns HhoPo utnsit(s3, 1onM 2a5r Jcuhly–,1 2June). On12Junoen,eo snhoeorta pnedr cohmanhneela wltahsy resmhoovoetdp, leeravHinPg u22n hitewaltahsy rsehmoootsv, ewdithto eaacshs etosmsatotot apllagnrte oecncubpiyoinmga asns ineach average area of 1.1 m2. The tomato plants were cultivated using a high wire system [25], with the HPunit,leaving23shootsperunit. ToensureequalitybetweenHPunits,on25July,oneshootper supporting wire at a height of 4.20 m. The growth period after transplanting was 31 weeks. The channelwasremoved,leaving22healthyshoots,witheachtomatoplantoccupyinganaverageareaof tomato plant tips were cut nine weeks before the end of the experiment to prevent further elongation. 1.1m2. ThPelatnot mpraottoecptiolann wtsithw beerneecfiucilatli voargteadnisumssin (Egnacahrsiiga hforwmiorsea,s Iychsnteeummo[n2s5, ]a,nwd iPthhytthoseeisuulups ppeorrstiminilgis)w ireata heightofa4n.d2 0pemsti.ciTdhese (gNraotuwratlh, Ppeegraisouds, aanftde Erntvraidnosrp) wlaanst pinergfowrmaesd3 d1epwenedekenst. oTnh tehet onmeedast o(Tpablalen At1ti)p swere cutninewanede kacscboredfionrge ttoh ienteengrdatoedf tpheeste mxpaneargimemeenntt tporipncriepvleesn utsfiungr tbheenrefeilcoianl goargtiaonnis.mPs laanndt pprroodtueccttsi onwith registered for organic production as standard pest control measures. Other chemical pesticides were beneficialorganisms(Encarsiaformosa,Ichneumons,andPhytoseiuluspersimilis)andpesticides(Natural, only applied to control high pest pressure situations. Bumblebees provided by Andermatt Biocontrol Pegasus,andEnvidor)wasperformeddependentontheneeds(TableA1)andaccordingtointegrated AG (Grossdietwil, Switzerland) were used to support pollination. In June, a high occurrence of spider pestmanamgietems wenats pobrisnercvipedle isn uthsei nggrebenehnoeufiscei, awliothr goanne iosfm thsea rnafdt cpurlotudrue cHtsP rseugbiusnteitrse (dC9f)o breoinrgg athnei cmporsot duction asstandaarfdfepcteedst cchoannntreol l(Fmigeuarseu 1r easn.dO Ftihguerrec Ahe1)m. Hicoawlepveesrt, iac idraetisngw oefr espoindelyr mapitpe ldieadmatogec oonn tlreoavlehsi ghpest sampled for nutrient analysis did not show severe damage or significant differences between the pressuresituations. BumblebeesprovidedbyAndermattBiocontrolAG(Grossdietwil,Switzerland) treatments. Towards the end of September blossom‐end rot was observed on some fruits in all of the were used to support pollination. In June, a high occurrence of spider mites was observed in the HP units (Figure A2). From July onwards regular cutting of the roots in the NFT channels was greenhouse,withoneoftheraftcultureHPsubunits(C9)beingthemostaffectedchannel(Figure1and necessary. Inside the channels, increasing root biomass was blocking the water flow, causing FigureA1le)a.kHagoews, eavnedr c,laogrgaitnign gtheo fpisppeisd. eTrhem roitoetsd waemrea cguet oonn bleotahv seisdessa omf pthlee dchfaonrnenl uotvreire an tpearnioadly osfi as didnot showsevfeerwe ddaayms atog ceaousres liegsns isfitrceassn ttod tihfefe prleannctse, sasb sehtwowene nint Fhiegutrree aAt3m. Renotttse.nT roowotsa rwdesret hoebseenrvdedo fafSteerp tember removing roots from the raft culture and NFT channels in November. The most damaged roots were blossom-endrotwasobservedonsomefruitsinalloftheHPunits(FigureA2). FromJulyonwards found in the corners of the raft culture (Figure A4), probably resulting from insufficient aeration, and regularcuttingoftherootsintheNFTchannelswasnecessary. Insidethechannels,increasingroot in the NFT channels under the coconut fiber slabs (Figure A5). biomasswasNbliolec tkilianpgiat lhaervwaea wteerrefl oobwta,inceadu fsrionmg Tleila‐Akqaugae sIn,taenrndatciolongalg (iVnegldtehne, Tphiep Nese.thTehrleanrdoso)t. sOwn 1e2r ecuton bothsideJsunoef, tehacehc fhisahn tannekl wovase srtoackpeedr wioidth o30f0a tifleapwiads (aaypsprtooxicmaautse e67l.e8s gs psetrr efisssh)t.o Ththe efisphl wanertes ,feads asdh ownin FigureA3li.bRituomtte (in.er.,o too taspwpaererneto sbatsiaetrivone)d tharfetee trimreems ao dvaiyn g(8:r0o0o, 1ts3:0fr0o, amndt h17e:0r0a)f wtcituh lat uswreimanmdinNg pFeTllectheda nnelsin feed (Table A2). While nutrient uptake by the tomato plants remained more or less stable after 12 November. Themostdamagedrootswerefoundinthecornersoftheraftculture(FigureA4),probably resultingfrominsufficientaeration,andintheNFTchannelsunderthecoconutfiberslabs(FigureA5). Nile tilapia larvae were obtained from Til-Aqua International (Velden, The Netherlands). On 12 June, each fish tank was stocked with 300 tilapias (approximate 67.8 g per fish). The fish were fed ad libitum (i.e., to apparent satiation) three times a day (8:00, 13:00, and 17:00) with a swimmingpelletedfeed(TableA2). Whilenutrientuptakebythetomatoplantsremainedmoreor lessstableafter12June,thefishbiomassincreased. Gainedfishbiomassovertheentireaquaponic experimentwas59.0±5.0kg. Water2016,8,533 6of21 To balance the feed input demand of the fish with nutrient demand of the plants, fish were harvestedthreetimesbetween12Juneand5November,accordingtotheZHAWinternalstandard operatingprocedure. 2.3. SystemMonitoringandDeterminationofNutrientSupplementationfortheHPSystem Electricalconductivity(EC),pH,dissolvedoxygen,andtemperatureweremeasuredcontinuously in the fish tank and logged every 15 min with SC1000 sensors from HACH Lange (Loveland, CO, USA).CalciumhydroxideandpotassiumhydroxidewereusedtoadjustpHduringtheexperiment. Weeklysystemwateranalysesoftotalphosphorus(TP),nitrate-nitrogen(NO -N),nitrite-nitrogen 3 (NO -N),ammonium-nitrogen(NH -N),potassium(K),iron(Fe),calcium(Ca),magnesium(Mg),and 2 4 boron(B)wereperformedwithaDR3800VISSpectrophotometerandLCKtests(HACHLange). Each week(1April–5November),onesamplefromeachfishtank(A,B,andC)wastakenin500mLplastic bottles. Nutrient target values for system water (Table 1) were determined according to standard tomatonutrientrequirements[26]. Inmid-September,theparameterswereadjustedtolowertarget values. HydroBuddyfreesoftware[27]wasusedtocalculatetheamountofnutrientsupplementation neededtoreachsystemwatertargetvaluesusingIronDTPAandMultiMicroMix(ÖkohumGmbH, Herrenhof,Switzerland),KristaSOP,KristaMKP,andYaraLiva®Calcinit(YaraUKLimited,Grimsby, UK),andEPSOTOP® (K+SKaliGmbH,Kassel,Germany). ThetargetvaluesforECandpHwere 2500µScmand6.5,respectivelythroughouttheentireexperiment. Table1. Targetedlevels(mg·L−1)foreachmeasuredparameterintheaquaponicsystem,andthe correspondingHACHLangeLCKtestnumbers. Parameter TP NO3-N NO2-N NH4-N K Fe Ca Mg B HACHLangetestnumber 349 339 341 304 328 321 327 326 307 31March2014until14September2014 40 160 0 0 250 3 200 50 0.2 15September2014until5November2014 40 160 0 0 234 3 130 24 0.2 2.4. TomatoHarvestandBiomassSampling The fresh weight of removed biomass (pruned biomass, unripe tomato fruits, and roots) was recordedfrom31Marchto5November. Ripe(i.e.,fullyred)tomatoeswereharvestedtwiceaweek from 15 May till 5 November. Harvested fruits were classified into three categories according to thecurrentmarketrequirementsforcherrytomatoes(Table2)[28],andsubsequentlycountedand weighedforeachHPunitseparately. Startingfrom6June,thetomatoplantswereprunedweekly by removing the side branches and old leaves, leaving 12–15 completely developed leaves on the shoots,andshorteningtheflowerclustersto15tomatoespercluster. Theprunedbiomassdryweight wasdeterminedtwice,on12Juneand25July. Afterthefinalharveston5November,theremaining biomasswasweighed. Todeterminethedryweight,onetomatoplantfromeachHPunitwasused. Freshsampleswerecutintopiecesofapproximately2–4cmwithgardenscissors,andoven-driedat 105◦Cuntiltheyreachedaconstantweight(24–48h). Thedriedsamplesweregroundintoapowder, whichwaslaterusedtodeterminethetotalbiomassnutrientcontent,asdescribedbelow. Todetermine theleafchlorophyllstatus(aplantvitalityparameter),theleafandfruitmineralnutrientconcentrations, theinternalfruitquality,theleavesandthefruitsweremeasuredandsampledonthreedates(12June, 7 August, and 16 October), after the respective fruit harvest. To analyze the leaf mineral nutrient content,theleaveslocatedbetweenthetwotrusses,whereactualharvestingtookplace,weresampled fromfourplants. Thechlorophyllstatuswasestimatedusingachlorophyllmeter(SPAD-502,Minolta Corporation,Ramsey,NJ,USA)measuringthefiveleafletsatthetipofeachleaf. Subsequently,leaves werecutandstoredinacoolingboxforlaterprocessingonthesameday. Leafstomatalconductance andtemperatureweremeasuredwithasteadystatediffusionleafporometer,SC-1(DecagonDevices, Pullman,WA,USA)onthetipleaflet. Chlorophyllfluorescencewasmeasuredonthesamefiveleaflets wheretheSPADmeasurementsweretakenusingaportablechlorophyllfluorometer(MiniPAM,Waltz Water2016,8,533 7of21 GmbH,Effeltrich, Germany). Fluorescencewasonlymeasuredforthesecondandthirdsampling harvest. Toanalyzethefruit,16randomfirstcategorytomatofruitswereselectedfromeachHPunit andwereanalyzedasdescribedbelow. Toestimatethecumulativetomatofruitnutrientuptakefor thetomatofruitsharvestedfrom15Mayto10July,resultsfromtheharveston12Junewereused. Samplestakenon7Augustwereusedfortheperiodfrom11Julyto12September,andsamplestaken on16Octoberwereusedforthelastharvestperiodfrom13Septemberto5November. Table2.TomatoqualityclassificationsaccordingtoSwissmarketqualitynormsforcherrytomatoes[28]. Category Criteria FruitQuality Category1 diameter:20–35mm marketable Category2 diameter:>35or<20mm non-marketable,edible rotten,cracked,damaged,blossom-endrot, Category3 non-marketable,notedible greenoryellowcolored(compost) 2.5. LeafandFruitAnalysis Toanalyzetheleafmineralnutrients,thefoursampledleavesandfourfruitsfromeachHPsubunit channelwerepooledanddriedinanovenat60◦Cuntilaconstantweightwasreached.Priortodrying thefruitswerecutintohalvesandthedriedsamplesweregroundtopowder.Todeterminephosphorus (P),K,Ca,copper(Cu),sulfur(S),Mg,manganese(Mn),zinc(Zn)andFe,200mgofdriedpowderwas weighedintoaTeflontubeanddissolvedin15mLofnitricacid(HNO ,70%)at120◦Cfor90min.After 3 coolingdownfor30min,3mLofH O wasaddedandthesolutionswereincubatedforanother90min 2 2 at120◦C.Aftercoolingdownforafurther30min,thesolutionsweretransferredinto50mLtubes andfilledupto50mLwithnanopurewater. Formeasurementpurposes,thesolutionswerediluted tenfoldandanalyzedwithanaxialICPOES(VarianVistaMPX,Waldbronn,Germany). Toobtainthe carbon(C)andnitrogen(N)concentration,2.5mgofdriedpowderwasweighedoutintotincapsules andanalyzedinaCHNSOanalyzerEUROEA(HEKAtechGmbH,Wegberg,Germany). Forsugarand aciditymeasurements,twofreshlyharvestedtomatofruitsweresqueezedandblended(Moulinex, Glattpark,Switzerland)infourreplicatesforeachHPsubunit. Thesugarcontentwasthenmeasured byareflectometer(HR75,Fa. A.KrüssOptronicGmbH,Hamburg,Germany)usingnanopurewater asablank. Acidity(fruitpH)wasmeasuredwithapHmeter(Metrohm632,Herisau,Switzerland). Theremainingfourtomatofruitswerefreeze-dried(ChristFreezeDryers,Beta2–8LDplus,Osterode am Harz, Germany). Prior to freeze-drying, several tiny holes were pierced into the tomato fruit skin to allow better evaporation. Afterwards, the tomatoes were ground up. The measurement of the fruit lycopene content was adapted from the protocol by Anthon and Garrett [29]. For this purpose,25mgoftomatopowderwasdissolvedin1.5mLHEA(Hexane:Ethanol:Acetone,2:1:1)and centrifuged. Aftercentrifugation,thesupernatantcontainingthelycopenewasremoved. Toobtain all of the potential lycopene, this extraction step was repeated. Then, 0.45 mL of H O was added 2 tothepooledsupernatanttoreachphaseseparation. Fromtheupperpart,containinghexanewith dissolvedlycopene,200µLwasplacedinatransparent96-wellplateandmeasuredintheEnspire 2300multimodeplatereader(Perkin-Elmer,Schwerzenbach,Switzerland)at503nm. Acorrection functionfortheorganicsolventsusedwasestablishedusingcuvettespectrophotometer(UV-1800, ShimadzuManufacturingInc.,Canby,OR,USA)andacrystalglasscuvette. Theopticalabsorbanceof thelycopenesolutionisproportionaltothelycopeneconcentration,whichwascalculatedforeach sampleweightusingtheEquation(1)establishedbyAnthonandGarrett[29]. (cid:16) (cid:17) 1.717×A ×V Lycopene mg·kg−1 = 503 (1) W whereVisavolumeofHEAsolution(mL)andWisasampleweight(mg). Oxygen radical absorbance capacity (ORAC) was adapted from the protocol developed by Garrett et al. [30] For this purpose, 25 mg of tomato powder was dissolved in 1.5 mL MetOH Water2016,8,533 8of21 (MetOH:H O, 1:1), mixed and centrifuged. The supernatant that contained the antioxidants was 2 removed. Thisextractionstepwasrepeatedthreetimes. Theremovedsupernatantswerepooledinto onesample. Formeasurementpurposes,20µLofthesamplewereaddedto200µLofFluorescein (Fluorescein Sodium Salt) and incubated at 37 ◦C for 10 min. After the incubation step, 75 µL of 2,2(cid:48)-azobis(2-amidino-propane)dihydrochloridewereaddedbeforetheabsorptionwasmeasuredin anEnspire2300multimodeplateatawavelengthof485nmusinganemissionwavelengthof528nm. AcalibrationcurvewascreatedusingTrolox(Trolox(±)-6-Hydroxy-2,5,7,8-tetramethylchromane-2- carboxylic acid, 97%). The ORAC concentration is given as mmol TE L−1 where TE is the Trolox equivalent.Themethodfordeterminingthetotalphenoliccontent(TPC)wasadaptedfromthemethod developedbyWaterhouse[31],usingpooledextractsfromtheORACmeasurement. Thirtymicroliters ofthesamplewasaddedto30µLH Oand50µLofFCR(Folin-Ciocalteau,10%). After1min,80µL 2 Na CO wereadded. Theplatewasincubatedfor2hatroomtemperaturebeforemeasuringat765nm 2 3 in an Enspire 2300 multimode plate reader. A calibration curve was made using Gallic acid and measuredtogetherwiththesamples. 2.6. StatisticalAnalysis The data were statistically analyzed in R-project using the R-studio software (R version 3.0.2, 2013)[32]. Thetotalfruityieldandbiomassparameterswerecalculated,usingaone-wayAnalysis ofVariance(ANOVA)withtheHPsystemasafactor. Fortheleafandfruitanalysisandtheplant vitalityparameters,atwo-wayANOVAwasperformedusingHPsystemandtimeofharvestasfactors. Ifsignificanteffectswerefound,aTukey’stest(HSDtest)withap-valueofp<0.05wasperformed. 3. Results 3.1. TomatoYieldandExternalFruitQuality Thetomatofruitsmeasuredapproximately25mmindiameter,hadastrawberryshapeanda deepredcolor,asweetflavorandfirmconsistency(FigureA6). Themarketableyield(fruitsofthe category1)wassignificantlyhighestinthedripirrigationandthenon-marketableyield(category2) wassignificantlyhigherintheraftculturesystem(Table3). ThetotalcumulativeyieldperHPunit showed significantly better performance for the drip irrigation system (Figure A7). This was also observedforsingleharvestswherethedripirrigationsystemoftenhadthehighestweeklyyieldsand theraftcultureprovidedthelowestones(however,notalwayssignificantlydifferent). Thenumberof tomatofruitsincategory1wassignificantlyhighestinthedripirrigationsystemandthecategory2 yieldwassignificantlyhigherintheraftculture. Fruitfreshweightdecreasedsignificantlyduringthe seasonbutnodifferenceswereobservedbetweentheHPsystems. Thenegligibledifferenceindry matterwasonlydetectedincategory1wheremeanweightwashighestinthedripirrigationsystem (19.4±3.2g)andlowestintheraftculture(18.8±4.3g). Table3.Averagecumulativeandtotalyield(g·m−2)andaveragenumberoftomatofruits(±SD)shown forthreequalitycategories(Table2)indripirrigationsystem,raftculturesystem,andnutrientfilm technique(NFT)system.Differentlettersindicatesignificantdifferences(Tukey’sHSD,n=3,p<0.05). FruitQualityClass DripIrrigationSystem RaftCultureSystem NFTSystem Averagecumulativeyield(g·m−2) Category1 18,323±667 16,857±341 17,176±364 Category2 86±220 b 156±290 a 73±110 b Category3 248±108 371±177 255±650 Total 18,657±568 a 17,383±242 b 17,503±339 b Averagecumulativenumberoffruits Category1 936±350 877±500 869±350 Category2 11±400 b 20±4.00 a 10±200 b Category3 15±7.00 21±900 16±400 Total 963±350 918±580 895±340 Water2016,8,533 9of21 Water 2016, 8, 533 9 of 21 3.2. InternalFruitQualityParameters 3.2. Internal Fruit Quality Parameters ThefruitsugarcontentwasatitslowestinJune,andsignificantlyhighestintheAugustharvest The fruit sugar content was at its lowest in June, and significantly highest in the August harvest (Figure4A).ThesignificantlyhighestsugarcontentwasmeasuredintheNFTsystem,andthelowest (Figure 4A). The significantly highest sugar content was measured in the NFT system, and the lowest inthedripirrigationsystem(Figure4A).ThesugarcontentofthefruitsfromcommercialHPcontrol in the drip irrigation system (Figure 4A). The sugar content of the fruits from commercial HP control wawsains itnh ethsea msaemrae nrgaengaes faosr ftohre thder idpriirpr iigraritgioanti.oTnh. eThfreu firtusiut gsaurgcaorn ctoenntteonft tohfe tOhec tOobcteorbhearr hvaersvtewsta swnaos t menaostu mreedabsuecreadu sbeeocfauloswe onfu lmowbe nruomffbrueri tosfa nfrduiotsth aenrdfr outihtearn afrluysite sanwaelyresepsr iwoerirteiz perdi.oFrirtuizietdp.H Fr(uaciti dpiHty ) wa(sacsiidgintyifi) cwanatsl ysilgonwifeisctanintltyh eloOwcetsotb ienr thhaer vOecstto.bPerro nhoaurvnecsetd. Pdrifofneroeunncceesdb edtiwffeereenntchees HbePtwsyesetne mthsew HePre onslyysotebmsesr vweedrei nonthlye fiobrssterhvaerdv eisnt ,thweh feinrstt hhearrvafetstc,u wlthueren sthhoe wraefdt csuigltnuirfiec ashnotlwyehdig shigenriffriucaitnptlHy hviaglhueers thafrnuNit FpTH( vFaigluuerse t4hBa)n. NFT (Figure 4B). FigFuigreur4e. F4r. uFitruinitt eirnntaelrnqaula lqituyapliatyra pmaertaemrsestuergsa rsucognatre ncotn(Ate)n;tf r(uAit);p Hfru(Bit );psHu g(aBr)–;a csuidgraart–iaoc(iCd );ralyticoo p(Cen);e conlyteconpt(eDne); ctootnatlepnht e(nDo)l;i ctocotaml ppohuenndoslic(E c)o;amnpdoouxnydgse n(Er)a; daincadl aobxsyogrebna nrcaedcicaapla caibtyso(rFb)acnocme pcaarpeadciftoyr r(Faf)t culctoumrep,adrreidp ifrorirg artaifot nc,unlututrriee,n tdfriilpm itrercighantiiqoune, (nNuFtrTi)enatn dfialmc otnetcrhonligqruoeu p(NcuFlTti)v aatnedd ian acocnotmroml egrrcoiaulply opceuralttievdatehdy dinr oap coonmicmseyrsctiaelmly aotpethrarteeeds haymdprolipnognipco siynsttsemin astu tmhrmeee sr.amEprlrionrg bpaorisntrse ipnr esusemnmt setra. nEdrraorrd debvaiartsi orne.pDreisffeenrte nsttaunpdpaerrdc adseevainadtiolonw. eDricfafeserelnett teurpspinerdciacsaete asnigdn ilfoiwcaenrtcdasifef elreetntecress (inTudkiceayt’es sHigSnDi,finca=n3t , differences (Tukey’s HSD, n = 3, p < 0.05) for harvests and hydroponic systems, respectively. The p<0.05)forharvestsandhydroponicsystems,respectively.Thefactors,harvest(H)andtreatment(T), factors, harvest (H) and treatment (T), and their interaction (H*T) were reported by “***” for p < 0.001, andtheirinteraction(H*T)werereportedby“***”forp<0.001,“*”forp<0.05and“.”forp<0.1. “*” for p < 0.05 and “.” for p < 0.1. Water2016,8,533 10of21 The fruits from commercial HP control had pH values similar to the aquaponically grown tomatoes. Theratioofthesugartoacidityratio(Figure4C)showedsimilartendencies,beinglowestin JuneandhighestinAugust;theNFTsystemdeliveredhighervaluesandthedripirrigationsystem significantly lower values. Again, commercially produced tomato had similar values to the drip irrigationsystem. ThefruitlycopenecontentwasobservedtobesignificantlyhighestintheAugust harvest(Figure4D),whileonlyintheJuneharvest, werepronounceddifferencesbetweentheHP systemsobserved. At this time, the NFT system had significantly lower values compared to the raft and drip irrigationsystems. Thelycopenecontentmeasuredinthecommerciallyproducedtomatoeswashigher thanintheaquaponicallygrowntomatoesthroughouttheentireseason. TheTPCwassignificantly higher in the October harvest compared to the June and August harvests. However, only in the Augustharvest,weresignificantdifferencesbetweenHPsystemsobserved,whenthedripirrigation systemhadthehighestTPC(Figure4E).ThecommerciallyproducedtomatoeshadalowerTPCin theJuneandAugustharveststhaninOctober. TheORACchangedsignificantlybetweenharvests, with the highest ORAC observed in August and the lowest in October. No significant differences betweenHPsystemswereobserved(Figure4F).However,commerciallyproducedtomatoeshadlower ORACvalues. ThecomparisonoffruitqualityparametersfromAPgrowntomato(thisstudy)andtomatoes boughtinthesupermarketwithSwissandDutchoriginrevealedsimilarsugarcontents,fruitpHand sugarcontenttopHratios(Figure5). ForlycopeneandTPC,weobservedslightlyhighervaluesinthe supermarkettomatofromtheNetherlands,whereasSwisssupermarketandtheAPsystemgrown tomatoeshadsimilarvalues. IntermsofORAC,weobservedslightlyhighervaluesintheAPsystem growntomatoes. Intermsoffruitmineralconcentrations,themostvariancewasfoundbetweenharvests(Table4). WhileC,N,PandSconcentrationsinfruitsdecreasedovertime,theconcentrationsofK,Mg,Fe,Ca, Cu,Mn,andZnincreasedsignificantly. SignificantdifferencesbetweentheHPsystemswereonly foundforMn,wheretheraftcultureexhibitedsignificantlyhigherconcentrationsinallthreeharvests comparedtothedripirrigationandtheNFTsystems(Table5). Table4.Averagefruitmineralconcentrations(±SD)shownforthethreeharvestsandthecorresponding ANOVAresults. Differentlettersindicatesignificantdifferences(Tukey’sHSD,n=3,p<0.05)for harvests. Thefactors,harvest(H)andtreatment(T),andtheirinteraction(H*T)werereportedby “***”forp<0.001,“**”forp<0.01,“*”forp<0.05and“.”forp<0.1. MineralNutrient 1stHarvest 2ndHarvest 3rdHarvest ANOVAResult C(mg·g−1) 397.6±2.20 A 408.5±2.20 B 408.3±3.10 B H:*** N(mg·g−1) 17.4±0.8 A 15.4±0.6 B 14.6±0.5 B H:*** P(mg·g−1) 1.6±0.1 A 3.8±0.1 B 3.8±0.1 B H:*** K(mg·g−1) 10.6±0.3 B 28.6±0.40 B 34.9±2.5 A H:*** S(mg·g−1) 0.6±0.0 A 1.5±0.1 AB 1.4±0.1 B H:**,HxT:. Mg(mg·g−1) 0.3±0.0 B 1.1±0.1 A 1.1±0.0 A H:*** Fe(µg·g−1) 4.0±2.0 C 24.7±2.80 B 39.2±15.3 A H:***,T:. Ca(mg·g−1) 0.3±0.1 AB 1.0±0.3 A 0.6±0.2 B H:*** Cu(mg·g−1) 1.2±0.3 B 8.5±4.6 A 8.9±1.4 A H:** Mn(µg·g−1) 4.1±0.8 B 22.6±9.6 A 27.3±10.3 A H:***,T:***,HxT:* Zn(µg·g−1) 6.0±0.5 B 16.2±1.9 A 18.3±1.60 A H:*** Table5.Averagemanganesefruitmineralconcentrations(±SD)inµg·g−1shownforthethreeharvests fromeachofthethreehydroponicsystems.Differentlettersindicatesignificantdifferences(Tukey’s HSD,n=3,p<0.05)betweenHPsystems. Harvest DripIrrigationSystem RaftCultureSystem NFTSystem 1st(12June2014) 2.6±0.1 b 4.2±0.1 a 2.6±0.1 b 2nd(7August2014) 12.0±5.1 b 31.4±3.0 a 24.3±5.8 b 3rd(16October2014) 20.2±2.3 b 39.6±6.7 a 22.2±4.4 b

Tomato Productivity and Quality in Aquaponics

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