Effect of Vegetative Propagation Materials on Globe Artichoke Production in Semi-Arid Developing

18 Pages·2017·3.62 MB·English

agronomy
Article
Effect of Vegetative Propagation Materials on Globe
Artichoke Production in Semi-Arid Developing
Countries: Agronomic, Marketable and
Qualitative Traits
JouhainaRiahi1,CarloNicoletto2,* ID,GhaithBouzaein3,PaoloSambo2and
KarimaKoukiKhalfallah1
1 DépartementdeProductionVégétale,InstitutNationalAgronomiquedeTunisie,43AvenueCharlesNicolle,
Tunis1082,Tunisia;[email protected](J.R.);[email protected](K.K.K.)
2 DepartmentofAgriculture,Food,NaturalResources,AnimalsandEnvironment,UniversityofPadova,
CampusofAgripolis,Vialedell’Università16,35020Legnaro(PD),Italy;[email protected]
3 Stationd’AppuideManouba,GroupementInterprofessionneldesLégumes(SAM),Manouba1120,Tunisia;
[email protected]
* Correspondence:[email protected];Tel.:[phone]
Received:31August2017;Accepted:21September2017;Published:24September2017
Abstract: InTunisia,globeartichokeismainlypropagatedbyundergrounddormantaxillarybuds
(ovoli),whichareremovedfromthefieldinAugustduringthequiescenceperiod. Thehighcost
ofinvitro-plantsandtheabsenceofspecializednurserieswereamongthereasonsfortheriseof
heterogeneity and spread of diseases. The aim was to help farmers to improve artichoke yield
andqualitybyamelioratingtheirvegetativepropagationtechniquewithlowcostmethods. Three
plant cuttings management methods were tested: summer ovoli (T0); spring offshoots nursery’s
cuttingsforcedtopassavegetativerestperiodbystoppingirrigation(T1);andoffshootsnursery’s
cuttings not forced (T2). The cuttings management can affect both yield and qualitative traits of
artichoke. T1nurseryplantsproducedtheheaviestprimaryheads,7%and23%higherthanT2and
T0,respectively. T1plantsexhibitedthehighestyieldduringtheharvestseason,with+17.7%and
+12.2%comparedtoT0andT2,respectively. T0andT1showedthehighesttotalantioxidantcapacity
andinulincontent;thepropagationmethodalsoaffectedtheshort-chainsugarsratio. T1isaviable
andsustainablealternativetothetraditionalonethatdoesnotheavilyimpactongrowingcostsand
improvesyieldandqualityofartichoke.
Keywords: Cynarascolymus;cuttings;yield;antioxidant;phenolicacids;fructans;sugars
1. Introduction
Globeartichoke(CinaracardunculusL.subsp. scolymus(L.)Hegi)isoneofthemostimportant
cultivatedspeciesintheMediterraneanBasinandiscontinuingtobeplantedandadaptedinother
partsoftheworldduetoitshealthbenefits[1,2]. InTunisia,thecultivationofglobeartichokeismainly
concentratedinthelowMadjerdavalley. In2016,thetotalareainvolvedwiththiscropreached3850
hectares, and the total production was approximately 19,000 tons [3]. Around 75% of this area is
representedbythecultivar“Violetd’Hyères”whichisthemostappreciatedpurplevarietyinTunisia
foritsfastcommercializationinlocalandinternationalmarkets. Inthelastfiveyears,Tunisianglobe
artichokeexportationshaveincreasedinaremarkableway,andreached1222tonsin2014[4]. Dueto
thelargequantityofpropagationmaterialpresentinaplant,globeartichokesaregenerallypropagated
vegetativelybyoffshoots,stumps,ordriedshootsharvestedfromcommercialfieldsattheendofthe
growingcycle[5]. Inrecentyears,thepropagationofartichokeshasundergoneconsiderableevolution
Agronomy2017,7,65;doi:10.3390/agronomy7040065 www.mdpi.com/journal/agronomy
Agronomy2017,7,65 2of18
toavoidsoilbornediseasesfollowingthedevelopmentofmicro-propagationsystems[6,7],grafting
techniques[8–10],andbyusinghybridseeds[11]. Alloftheseagronomicinnovationsarecommonly
appliedindevelopedcountries, wheretherearenursery techniques andtechnologicalequipment.
Inothercontexts,suchasTunisia,vegetativepropagationisthemostwidelyusedtechniquethatcan
easilybeadoptedbyproducers.
ForTunisianfarmers,earlinessisoneofthemostimportantfactorsfortheproduction,andit
is directly linked to the export period which extends from November to January. The absence of
specializednurseriesforartichokeplantletproduction,especiallyforthelocalvarieties,hasleadtothe
growersproducingtheircuttingsbythemselves,ininappropriateconditions. Asaconsequenceof
thisuncontrolledpractice,thenationalaverageyieldofglobeartichokehasneverexceeded7tha−1
duringthelastyears[3].Yet,manyresearchersinsomecountries,suchasItaly[5,12,13],Turkey[14,15],
and the US [16], conducted several experiments to improve the vegetative propagation materials
andproductiontechniquesofglobeartichoke;however,theydidnotrefertotheavailablevegetative
materialofthefarmers,buttheyfocusedtheirattentionontheuseofmicro-propagatedplants. Then,
they started to promote the nurseries’ establishment, and to schedule the cuttings’ propagation.
This strategy seems to be quite difficult and inadequate in the case of Tunisia, for several reasons.
Thefirstoneislinkedtotheabsenceofnurseriesfortheinvitro-plantproduction. Thesecondreason
is related to the harvest time, that starts at the end of February or in March. As a result, Tunisian
farmersarenotabletoexporttheirproductionandthisaffectsnegativelytheirincomes. Inadditionto
that,headproductionofmicro-propagatedartichokescouldbelowerthantheordinaryplantsand
instablefromoneseasontoanother[17,18].
In the last three decades, artichoke breeding programs have produced some hybrids, which
started to be considered in the main artichoke producing areas as an alternative to the traditional
ones[19]. Yet,hybridsarefreefromthemainendemicdiseaseslikevirusesandfungi,andshowed
goodyields[20–22],buttheystarttoproduceheadslaterifcomparedtothestandardcultivars[23]
andtheyarestillnotwidelycommercialized. Indeed,thecostofhybridseedsisoftenveryhighand
notallfarmerscandealwithit.
Consideringthequalitativeaspectsofartichoke,therearemanysourceswhichclearlydescribe
thenoticeablehealthpropertiesandqualityofthisvegetable[1,24,25]. Untilnow,themainresearch
lines evaluating the effects of agricultural practices on artichoke quality, are concerned with seed
propagation[21,26,27],stresseffects[28],differentfertilizationtechniques[29,30],mycorrhizause[31],
theapplicationofbio-regulators[32],andtheuseofsustainablefarmingsystems[33]. Regardingthe
managementofvegetativepropagationmaterialandartichokequality,thereislittleinformation.
Earliness,highyield,andgoodqualityoftheproductionarethemaincriteriatargetedbythe
farmers. Theseobjectivescouldbereachedjustbyimprovingthequalityofcuttingsbyupgradingthe
rootingofoffshootsinthenursery[12],scalingtheproductionofearlytransplants[34],orconditioning
thetransplantstomitigateheat,droughtstress,andbioticstresses[15].
Themainobjectiveofthisworkistoimprovethequalityofartichokecuttingsonthebaseofthe
simpletoolsthatTunisianfarmerscanafford. Inthistrial,plantsderivedfromnursery’scuttingswere
evaluatedfortheiragronomic,marketable,andqualitativetraits,comparedtothetraditionalplants
originatedfromfield’sovoli(undergrounddormantaxillarybuds).
2. Results
2.1. VegetativeGrowthandYieldParameters
Following the plants’ vegetative growth 70 to 190 days after planting, nursery transplants of
163 days (T2) showed the lowest elongation rhythm (Figure 1) but the highest extension width
comparedtotheplantsderivingfromthetwotypesofovoli: thetraditional,andthenursery’sones
(Figure2). Thepre-germinationofovoliwasefficientforT0andT1afterarestperiodfortheactivation
oftherootsystemandlateralbuds,obtainingagoodstartforvegetativegrowth.
AgronoAmgAryogn2roo0mn1o7ym ,2y70 ,2160751, 77,, 675, 6 5 3 o3f o1f8 1 38o f18
1.41.4 aa
T0T0 T1T1 T2T2 aa
1.21.2 aa aa aaaa bb
)m( thgieh tn)m( thgieh tn001...680001...680abababab baabaa baabaa baabaa baabaa baabaa baabaa baba baba bb baabaa baabaa
alPalP0.40.4
0.20.2
0.00.0
7070 8080 9090 101000 111010 121020 131030 141040 151050 161060 171070 181080 191090
DDayasy asf ateftre pr lpalnatnattaiotinon
FigurFeiFg1iug.ruePr e1la . 1nP. tlPahnlaetn ihgt ehhigtehiegtvh eotv leouvltuoioltuinotnioa nac ccacocorcrdodirindnggin gttoo totthh teeh cecu uctuttittnitnginsgg’s st’’y tptyyepp uee suuesdse edfdo rfof otrh rteht hae reatircathricothikcoehk ove kevgeeegvtaeettigavteeitv aet ive
proppargpoarptoaipoganagt.iaotWnio. niWt.h Wiitnhitinhth itneh tesh aseam smaeem ppee eprriieoordido,, ddd, adataata twa wewreeer raeen aaannlyaazllyeyzdze edbdy b Ayb yNAONAVONAVO,A aV,n Aadn, dvaa nvluadleusve wasl iwutheit snho wn loiet thlteetnrt eoirn ilne tter
incocmocmmommonomnoa nrae raes risegi gsnniigififnicicfaaicnnattnllyyt lydd iidffffieferfreeenrentn tata t atpt p p<< <0 .000.5.00 55a caacccoccroodrridndgiinn gtgo ttoTo uTkTueukyke eyHy SHDHS DSTD eTsetT.s etSs. ttaS.ntaSdntaadrnadrd dear rredorrrose rrasr roaer rse are
repreoproterdte. dT. 0T: 0s:u smummemr eorv oovlio; lTi; 1T: 1s:p srpinrgin ogf fosfhfsohootso tns unrusersryer’sy ’csu ctutitntginsg fso rfocercde dto tpo apsas sas va evgeegtaettiavteiv ree sret st
reported. T0: summerovoli;T1: springoffshootsnursery’scuttingsforcedtopassavegetativerest
peprieordio bdy b syt osptoppipngin igr riirgraigtiaotnio; nT;2 T: 2s:p srpinrgin ogf fosfhfsohootso tnsu nrusersryer’sy ’csu ctutitntginsg nso nt ofto rfocercde. d.
periodbystoppingirrigation;T2:springoffshootsnursery’scuttingsnotforced.
1.81.8 aa
1.61.6 T0T0 T1T1 T2T2 aa aaaa aaaaaa aaaa
)m( htdiw tnalP )m( htdiw tnalP011...1824011...1824bacbac bacbac bacbac abababab aaaaaa bbabba aaaaaa abababab abababab abbabb aa
0.60.6
0.40.4
7070 8080 9090 101000 111010 121020 131030 141040 151050 161060 171070 181080 191090
DDayasy asf ateftre pr lpalnatnattaiotinon
FigurFeiFg2iug.ruePr e2l .a 2nP. ltPawnlatn idwt tiwhditdehvt heo vleouvltuoiltouiontnioa nac ccacoocrcrdodriindnggin gttoo totth hteeh eccu uctuttittnitnginsgg stsy tptyyepp eue suuesdse edfdo rfof otrh rteh thea reatircathricothikcoehk oev kevgeeegvtaeettgiavteeitv aet ive
proppargpoarptoaipoganagt.iaoWtnio.i ntWh. Wiinthititnhh ienth steah smea smeaemp eper epiroieodrdi,o, ddd,a adttaaa twwa ewerreee raean naanalyalyzlyezzdee ddby bb yAy NAAONNVOOAVV AaAn adan ndvda vluavleausle uwse iwsthiwt hni otn hloe ntlteoetrtl eeirnt tine rin
cocmommomno na rae rsei gsnigifniicfaicnatnlyt lyd idffiefrfeenretn at t apt p< <0 .005.0 5a caccocrodridngin gto toT uTkuekye yH SHDS DT eTset.s tS. taSntadnadradr der reorrros ras rae re
common are significantly different at p < 0.05 according to Tukey HSD Test. Standard errors are
repreoproterdte. dT. 0T: 0s:u smummemr eorv oovlio; lTi; 1T: 1s:p srpinrgin ogf fosfhfsohootso tns unrusersryer’sy ’csu ctutitntginsg fso rfocercde dto tpo apsas sas va evgeegtaettiavteiv ree sret st
reported. T0: summerovoli;T1: springoffshootsnursery’scuttingsforcedtopassavegetativerest
peprieordio bdy b syt osptoppipngin igr riirgraigtiaotnio; nT;2 T: 2s:p srpinrgin ogf fosfhfsohootso tnsu nrusersryer’sy ’csu ctutitntginsg nso nt ofto rfocercde. d.
periodbystoppingirrigation;T2:springoffshootsnursery’scuttingsnotforced.
ThTeh me monointoitroinrign go fo of fofsfhfsohooto fto fromrmataiotino nre rveevaeleadle dsi gsinginfiicfaicnatn dt idffieffreernecnecse bs ebtewtweeene nth teh ter etraetamtmenetns.t s.
AThtA etth tmeh eeon nedni tdoo fro iJfna Jngaunoaurfayor y(f1f (5s1h05 o0do adtyasfy oasr fmateftrae ptri lopannlatnarettaivoteinoa)n,l e)t,hd teh seeim genmisisfisiiocsianon not fo dnf ienfwfeew roe fonfsfchfesohsootbose tsstt wastreateertdne.d tT.h 1Te 1at nraden adTt 0mT 0e nts.
Atthweweerneedr feao fifraliJyral yncl uoclsaoers,y ea,(n 1adn5 0dsh dsohawoywesdea dtfht etehr hep ihglaihgnehtsaet stnito unnmu)m,btebhre eor feo mof fofissfhfssiohooontoso twsf wintheitw han ao naffv asehvreoargoaetgs oesf ot aafl rmatlemodso.t sT5t 1s5h asonhoodtosT tas0t a wt ere
thteh een edn do fo tfh teh he ahravrevsetisntign gse saesaosno n(F (iFgiugruer 3e) 3. )T. 2T d2 idspislpaylaeyde dth teh leo lwowere or fofsfhfsohootos tps rpordoudcuticotino,n 1,4 1.74%.7% le sless s
fairlyclose,andshowedthehighestnumberofoffshootswithanaverageofalmost5shootsattheend
thtahna nT 1T. 1.
oftheharvestingseason(Figure3). T2displayedtheloweroffshootsproduction,14.7%lessthanT1.
Agronomy 2017, 7, 65 4 of 18
Agronomy2017,7,65 4of18
a
a ab
6 a b
t
n T0 T1 T2
a a b
lp 5 ab
r
e b
p s 4 a
t ab
o
oh 3 b
s
f
fo a
fo 2 a
re a
b 1
m
u
N 0
January February March April May
Harevst time

FiguFreig3u.reN 3u. mNubmerboerf ooff fosfhfsohootostsf oformrmeedd aaccccoorrddiinngg ttoo ththe ecuctutitntignsg tsyptye pueseuds feodr tfhoer athrteicahrotkiceh voekgeetvateigvee tative
proppargoaptaigoant.ioWn.i Wthiitnhitnh ethsea smameep peerrioiodd,, ddaattaa wweerree aannaalylzyezde dbyb AyNAONVOAV, Aan,da nvadluveasl uweitshw niot hletnteor lient terin
commcoomnmaorne asrieg nsiigfinciafincatlnytlyd idffifefreernentta att pp << 00..0055,, aaccccoordrdinign gtot oTuTkuekye HySHDS TDesTt.e Sstta.nSdtaarndd earrrdorse rarroer s are
reporretpedor.teTd0.: Ts0u: msummemreor voovloi;liT; T11::s spprriinngg ooffffsshhooootst snnuursresreyr’ys ’csucttuinttgisn gfosrcfeodr cteod ptaossp aa svsegaevtaetgiveet aretisvt erest
periopderbioyds btoyp sptoipnpginirgr iigrraigtiaotnio;nT; 2T:2s: psprriningg ooffffsshhoooottss nnuurrseseryr’ys’ scuctutitntgins gnsont footrcfoedrc. ed.
First heads were harvested on 14 January 2016, and their height, diameter, and fresh weight were
mFierasstuhreedad (Tsawbleer e1)h. aTr1v neustresedryo npl1a4ntJsa pnruoadruyc2ed01 t6h,ea hnedavtiheesitr phriemigahryt, hdeiaadmse wteirth,a an mdefarens whewigehigt hoft were
meas2u69r egd, 7(T%a balned1 2)3.%T 1hniguhresre trhyanp lTa2n tasnpd rTo0d, urceespdetchtievehlye.a Ivni etsetrmpsr iomf ahreyighhet aadnsd wdiiathmeatemr,e parnimwaeryig htof
269gh,e7a%dsa pnrdod2u3c%edh ibgyh pelratnhtas ndeTr2ivainngd fTro0m,r ensuprescetriyv’es loyv.oInli taenrdm tsraodfihtieoingahl tfiaenldd’sd oiavmolei twere,rpe rsiimmailrayr.h eads
prodTuhcee dflobwyepr liannittisatdioenri ovfi nTg1 fprloamntsn buergsuenry e’asrolivero tlhiaann dthter aodthietiro pnlaalntfise’ ltdre’satomveonltisw, aenrde tshimis irleasru.lTt hweasfl ower
initiaptrioovnedo fbTy1 thpel aensttismbaetigoun nofe tahreli perertcheanntatghee oof tehaerlry pyliaenldt,s s’otr tehaet mpreimntasr,ya hnedadths iwserrees uadltvwanatasgperoouvs edby
to grow and to gain more weight before the first time of harvest.
theestimationofthepercentageofearlyyield,sotheprimaryheadswereadvantageoustogrowand
togainmoreweightbeforethefirsttimeofharvest.
Table 1. Characterization of primary harvested heads according to the cutting type used for the
artichoke vegetative propagation.
Table 1. Characterization of primary harvested heads according to the cutting type used for the
Treatment Height (mm) Diameter (mm) Weight (g)
artichokevegetativepropagation.
T0 95.3 ± 1.5 a 92.5 ± 0.6 ab 208 ± 8 c
T1 96.9 ± 1.9 a 94.8 ± 0.7 a 269 ± 11 a
Treatment Height(mm) Diameter(mm) Weight(g)
T2 89.9 ± 2.2 b 89.2 ± 0.4 b 249 ± 6 b
T0 95.3±1.5a 92.5±0.6ab 208±8c
Within each parameter, data were analyzed by ANOVA and different letters indicate significant
T1 96.9±1.9a 94.8±0.7a 269±11a
differences according to the Tukey’s HSD test at p < 0.05. Standard errors are reported. T0: summer
T2 89.9±2.2b 89.2±0.4b 249±6b
ovoli; T1: spring offshoots nursery’s cuttings forced to pass a vegetative rest period by stopping
Withineachparameter,datawereanalyzedbyANOVAanddifferentlettersindicatesignificantdifferencesaccording
irrigation; T2: spring offshoots nursery’s cuttings not forced.
totheTukey’sHSDtestatp<0.05.Standarderrorsarereported.T0:summerovoli;T1:springoffshootsnursery’s
cuttingsforcedtopassavegetativerestperiodbystoppingirrigation;T2: springoffshootsnursery’scuttings
notfoTrhceed .yield of the local cultivar “Violet d’Hyères” was evaluated progressively through the
measurement of heads weight per plant in each harvest for all treatments. As a consequence,
cumulative yield per hectare (Figure 4) was monthly estimated along the growing cycle, from 14
The yield of the local cultivar “Violet d’Hyères” was evaluated progressively through the
January to 15 May 2016. T1 plants, deriving from nursery’s ovoli, exhibited the highest head
measurementofheadsweightperplantineachharvestforalltreatments.Asaconsequence,cumulative
production during the harvest season, with a final cumulative yield of 29.21 t ha−1 against 24.03 t ha−1
yield per hectare (Figure 4) was monthly estimated along the growing cycle, from 14 January to
(−17.7%) and 25.65 t ha−1 (−12.2%), respectively, for T0 and T2.
15May2016. T1plants,derivingfromnursery’sovoli,exhibitedthehighestheadproductionduring
theharvestseason,withafinalcumulativeyieldof29.21tha−1 against24.03tha−1 (−17.7%)and
25.65tha−1(−12.2%),respectively,forT0andT2.
AgronoAmgryon2o0m17y ,270,1675, 7, 65 5 of 18 5of18
a
ab
a
35 b
T0 T1 T2 a b
1) 30 b b
-a b
h
t 25 a
( d b
le 20
iy e a b
vit 15 b
a
lu 10 b
m
u
C 5
0
January February March April May
Harvest time
Figure4.Cumulativeyieldevolutionaccordingtothecuttingstypeusedfortheartichokevegetati ve
propFaiggautrieo n4.. CWumithuilnatitvhee ysiealmd eevpoelurtiioodn, adccaotardwinegr teo athnea lcyuztteindgbs ytyApeN uOseVdA foar nthde varatliucheoskwe vitehgentoatilveett erin
commproonpaagraetisoing. nWifiitchainn ttlhye dsiafmfeer epnetriaotd,p d<ata0 .w05eraec acnoarldyiznegd tboy TAuNkOeyV’As HanSdD vTaleusets. wStitahn ndoa rldetteerrr ionr sare
reporctoemdm. Ton0 :asrue msigmneifricoavntolyli ;dTif1fe:rsepnrt iantg po <f f0s.h0o5 oatcsconrudrinsegr tyo’ sTcuuktetyin’sg HsSfoDr cTeedst.t oStpanadssarad veerrgoertsa atirvee rest
periordepboyrtsetdo. pTp0i:n sgumirmrigera toivoonl;i;T T21:: sspprriinngg ooffffsshhooootsts nnuursresreyr’ys ’csuctutitntgins gfosrnceodt ftoor pceadss. a vegetative rest
period by stopping irrigation; T2: spring offshoots nursery’s cuttings not forced.
TheTphreec porceitcyocaitsys eassssmesesnmte(nTta (bTlaeb2le) t2h) rtohuroguhgthh ethteh rthereepe epreioridosd:s:e aearlryly( b(beeffoorree 1155 JJaannuuaarryy)),, mmiidd--early
(betweaerelny (1b6etJwaneeuna r1y6 Jaanndua1ry5 aMndar 1c5h )M, aarncdh),l aatned( alafttee r(a1ft5erM 15a rMcha)rcrhe)v reeavleeadledth tahtatt htheer reellaattiivvee yyiieelldd rate
obtairnaeted obbetafoinreedm biedfo-Jrae nmuiadr-yJanwuaasryr ewlaatsi vreellaytilvoewly floowra flolrt raella ttrmeaetnmtesn,tasn, adnndo ntoht ihgihgehrert hthaann 55..22%% ooff total
yieldtointatl hyeieblde sint cthaese be(Tst1 c)a.se (T1).
TableTa2b.lYei e2l. dYdieilsdt rdibisutrtiibounti(otnh (at− h1a)−1a)n adndp eprecrecnentataggeep peerr ttrreeaattmmeenntt aaccccoorrddiinngg ttoo ththee cucutttitnign gtytpyep uesuesde dfor
for the artichoke vegetative propagation.
theartichokevegetativepropagation.
Treatment T0 T1 T2
Harvest Period Treatment t ha−1 T0 % t ha−1 T1 % t ha−1 T2 %
HarEvaerslyt Pyieerlido (d<Jan 2015 0.60 ± 0t.h15a −b 1 2.5 % 1.52 ±t 0h.1a1− a1 5.2 % 1.00 ± 0t.1h2a c− 1 3.9 %
Mid-Early yield (Jan–Mar
Earl2y01y5i)e ld(<Jan2015 11.603. 6±0 0.±230 b. 15b 48.42 .5 13.15.55 2± 0±.209 .a1 1a46.4 5.212.121 .±0 00.3±1 c0 .12c47.3 3.9
MidL-aEtae rylyielydi e(>ldM(aJra 2n0–1M5)a r2015) 11.8101 .±6 30.1±9 b0 .23b49.14 8.4 141.134.5 ±5 0±.170 a.2 9a48.4 46.412.5132 ±. 102.1±6 c0 .314c8.8 47.3
LateToytiaell dyie(>ldM ar2015) 24.1013±.8 00.1±5 b0 .19b1004 9.1 291.421.1±4 0±.150 a.1 7a100 48.425.6152±. 503.15± c 0.161c00 48.8
Totalyield 24.03±0.15b 100 29.21±0.15a 100 25.65±0.15c 100
Within the same period, data were analyzed by ANOVA and values with no letter in common are
Withisnigtnhiefiscaamntelyp derififoedr,endta taat wp <e r0e.0a5n aTluykzeeyd’sb yHASDN TOeVsAt. Satnadndvaarldue esrrwoirtsh anroe rleetptoerrtiendc. oTm0:m suomnmareers oigvnoilfii;c antly
differTen1:t saptrpin<g 0o.f0fs5hTouoktse yn’usrHseSryD’sT ceustt.tinSgtasn fdoarcredde tror oprassasr ae vreepgeotratetidv.e Tre0s:t spuemriomde rbyo vstoolip;pTin1:g siprrriignagtioofnf;s hoots
nursery’scuttingsforcedtopassavegetativerestperiodbystoppingirrigation;T2: springoffshootsnursery’s
T2: spring offshoots nursery’s cuttings not forced.
cuttingsnotforced.
The mid-early yield recorded between 16 January and 15 March was 46% higher than total yield
fTohr ealml tirdea-etmarelnytsy,i welidthr ethceo rhdigehdebste htweaede npr1o6duJacntiuona riyn aTn1 dtr1ea5tmMeanrtc (h13w.5a5s t4 h6a%−1 ahgigaihnesrt 1th2.a1n2 tto htaa−l1 yield
foralalntdre 1a1t.m63e tn htas−,1,w reitshpetchteivheliyg,h feosr tTh2e aandd pTr0o).d Tuhcet sioamnein teTn1detrnecayt wmaesn otb(s1e3r.v5e5dt inh ath−e1 laatgea yiinesldt,1 w2.h1e2ret ha−1
and 1T11. h63ast thhea h−i1g,hreesst pperocdtiuvcetliyo,n fionr teTr2mas nodf toTn0s) .peTr hheecstaarme,e butet nndote nthcey bwiggaessot pbesrecrevnetdagien oft hthee ltaottealy ield,
wheryeieTld1 choamsptahreedh tiog thhee srtelpatriovde upocrttiioonn oinf Tt0e rymielsd oinf tthoen ssampeer phereicotda trhea,tb rueatcnheodt 4th9.e1%b.i gAgs ecsotnpseeqruceennctea geof
of these different rates, total yields cumulated at the end of harvest season were always significantly
the total yield compared to the relative portion of T0 yield in the same period that reached 49.1%.
higher for plants deriving from nursery’s ovoli.
As consequence of these different rates, total yields cumulated at the end of harvest season were
The calibration of the harvested heads (Table 3) was done on the base of precocity scale (early,
alwayssignificantlyhigherforplantsderivingfromnursery’sovoli.
mid-early, and late). In the three periods, the harvested heads of T1 treatment were the heaviest ones
Thecalibrationoftheharvestedheads(Table3)wasdoneonthebaseofprecocityscale(early,
compared to T0 and T2, and they ranged from 304 g in the early harvest to 260 g in the late one. In
mid-early, and late). In the three periods, the harvested heads of T1 treatment were the heaviest
ones compared to T0 and T2, and they ranged from 304 g in the early harvest to 260 g in the late

one. Inaddition,thehighestmeanheadweightwasrecordedintheearliestharvestperiodbefore
mid-January,independentlyfromthetreatments.
Agronomy2017,7,65 6of18
Table3. Meanweight(g)andmeandiameter(mm)ofheadspertreatmentaccordingtothecutting
typeusedfortheartichokevegetativepropagation.
Treatment
T0 T1 T2
HarvestPeriod
Meanheadweight(g)
Earlyyield(<Jan2015) 304±5b 322±2a 287±6c
Mid-Earlyyield(Jan–Mar2015) 299±2b 314±4a 285±4c
Lateyield(>Mar2015) 260±3b 277±5a 247±3c
Meanheaddiameter(mm)
Earlyyield(<Jan2015) 99±3ab 109±2a 89±1b
Mid-Earlyyield(Jan–Mar2015) 85±2ab 92±3a 73±1b
Lateyield(>Mar2015) 69±1ab 74±2a 62±2b
Withinthesameperiod,datawereanalyzedbyANOVA,andvalueswithnoletterincommonaresignificantly
differentatp<0.05,accordingtoTukey’sHSDTest.Standarderrorsarereported.T0:summerovoli;T1:spring
offshootsnursery’scuttingsforcedtopassavegetativerestperiodbystoppingirrigation;T2: springoffshoots
nursery’scuttingsnotforced.
Thebiggestheadsizewasobtainedintheearlyharvestseason,withamaximumof109mmof
diameterinthetreatmentT1,andthesmalleroneinthelateharvest,withanaverageof62mmfound
inthetreatmentT2. AccordingtoTable4,morethan65%ofharvestedheadswereclassifiedbetween
thetwosizes75mmand110mmofdiameterinalltreatments. T2wasthemostadvantageous,witha
rateof71%,followedbyT0(69%)andT1(68%)ofheads. Forthesmallestsize,T2presentedabout
4.10tha−1withthehighestrateoftheproduction(16%). AccordingtoUNECEstandardclassification
ofcommercialqualityartichokes(Table5),morethan50%oftheproductionwasclassifiedasanextra
qualityonlyforplantsderivingfromnurseryandtraditionalovoli. T1wasthemostadvantageous
treatment,withmorethan18tha−1fortheclassExtra,followedbyT0with12.25tha−1,andsofar,
T2with3.09tha−1. FortheclassI,34%oftheT2totalproductionwasthehighestratecomparedto
T0andT1. Concerningthelowestqualityclass,T1expressedthelowesttotalyieldwith4.38tha−1
converselytoT2,thatshowedthehighestportionofthetotalyieldwithanaverageof13.84tha−1.
Table4.Yielddistribution(tha−1)anditspercentageclassifiedbydiameteraccordingtothecutting
typeusedfortheartichokevegetativepropagation.
Treatment T0 T1 T2
HeadDiameter tha−1 % tha−1 % tha−1 %
D≥130m 1.44±0.01a 6 0.51±0.05c 2 0.77±0.01b 3
110m≤D<130mm 3.84±0.07ab 16 4.62±0.30a 18 2.57±0.31b 10
90mm≤D<110mm 8.65±0.18c 36 11.39±0.23a 39 9.49±0.07b 37
75mm≤D<90mm 7.93±0.28b 33 8.47±0.23c 29 8.72±0.15a 34
6mm≤D<75mm 2.16±0.08b 9 3.51±0.05b 12 4.10±0.06a 16
Withinthesamediameter,datawereanalyzedbyANOVAandvalueswithnoletterincommonaresignificantly
differentatp<0.05accordingtoTukey’sHSDTest.Standarderrorsarereported.T0:summerovoli;T1:spring
offshootsnursery’scuttingsforcedtopassavegetativerestperiodbystoppingirrigation;T2: springoffshoots
nursery’scuttingsnotforced.
Table5.Totalyielddistribution(tha−1)anditspercentageaccordingtothecuttingtypeusedforthe
artichokevegetativepropagationinrelationtoUNECEclassification.
Treatment T0 T1 T2
MarketableClasses tha−1 % tha−1 % tha−1 %
ClassExtra 12.25±0.06b 51 18.11±0.24a 62 3.09±0.17c 12
ClassI 7.68±0.03b 32 6.72±0.14c 23 8.72±0.17a 34
ClassII 4.09±0.02b 17 4.38±0.04c 15 13.84±0.17a 54
Withinthesamemarketableclass, datawereanalyzedbyANOVAandvalueswithnoletterincommonare
significantlydifferentatp<0.05accordingtoTukey’sHSDTest.Standarderrorsarereported.T0:summerovoli;
T1:springoffshootsnursery’scuttingsforcedtopassavegetativerestperiodbystoppingirrigation;T2:spring
offshootsnursery’scuttingsnotforced.
Agronomy2017,7,65 7of18
2.2. QualitativeTraits
Duringtheintermediateperiod(mid-early)ofheadharvest,thequalitativetraitsofmarketable
product and leaves were evaluated for each treatment, in order to highlight any changes in the
nutritionalprofileoftheplant. Thedataobtaineddemonstratethattheplantpropagationmethodcan
significantlyaffectqualitativeaspects.
Regardingpigmentcontent(Table6),T1andT2hadsignificantlyhighervaluesthanthecontrol
treatment. In particular, the content of chlorophyll a, b and xanthophyll + carotenoids in T1 was
higherof24.5%, 24.7%, and18.0%, respectively, ifcomparedtoT0. T0andT1showedthehighest
totalantioxidantcapacityvaluesincontrasttoT2thatalsopresentedthelowestlevelsoftotalphenols.
Regardingthephenolicacidcontent,thechemicalanalysesidentifiedthepresenceofchlorogenicacid
andcaffeicacid. Forthefirstone,thehighestvalueswererecordedinT0andT1,respectively29.6%
and30.2%greaterthanT2. Nosignificantdifferenceswerefoundwithcaffeicacid. Thequalitative
parameters so far reported were also assessed in the plant leaves (data not reported), however,
nosignificantdifferenceswereobserved,withtheexceptionofthechlorogenicacidcontent. Thelatter
washigherinT0(91.2mgkg−1dw)andT2(89.0mgkg−1dw),whereasT1presentedthelowervalues
(53.6mgkg−1dw). Thechlorogenicacidcontentintheleaveswasmuchlowerthanthatofthehead
(−97.7%onaverage).
Table 6. Effect of cutting type used for the artichoke vegetative propagation on pigments and
antioxidantcompounds.
Xanthofills+ Chlorogenic
Chlorophylla Chlorophyllb TP TAC CaffeicAcid
Carotenoids Acid
µgg−1dw µgg−1dw µgg−1dw k(mg−g1GdAwE) k(mg−g1Fdew2+) (mgkg−1dw) (mgkg−1dw)
artichokehead
T0 221±3b 92.5±2b 29.5±1.5b 8361±56a 7636±43a 3873±25a 79.4
T1 293±4a 122±5a 37.4±2.4a 9068±78a 6827±72ab 3905±48a 69.2
T2 293±6a 124±7a 35.4±2.1a 6569±29b 6033±37b 2724±32b 54.3
** * * *** * *** n.s.
Withinthesametrait,datawereanalyzedbyANOVAandvalueswithnoletterincommonaresignificantlydifferent
atp<0.05accordingtoTukey’sHSDTest.Standarderrorsarereported.T0:summerovoli;T1:springoffshoots
nursery’scuttingsforcedtopassavegetativerestperiodbystoppingirrigation;T2: springoffshootsnursery’s
cuttingsnotforced;TP:totalphenols;TAC:totalantioxidantactivity.n.s.:notsignificant;*:significantatp<0.05;
**:significantatp<0.01;***:significantatp<0.001.
Also,sugarcontentwasaffectedbytheplant’spropagationmode.Ingeneral,inulinconcentration
was significantly higher than the other sugars considered (Figure 5), and was found only in the
marketableproduct.
Concerningthemarketableheads(Figure5A),thesucroseandinulincontentswereconditioned
bythetreatmentsevaluatedinthisexperiment. T0andT1showedinulinvalueshigherthan180gkg−1
dw,whereasT2significantlydifferedfromT0,presenting12.8%less. Alwaysinthemarketablehead,
eventhesucrosecontentwasaffectedbypropagationmethod,andT1andT2showedthehighest
concentrations;nosignificantdifferenceswereobservedinglucoseandfructoseload. Interestingly,
thepropagationmodealsoaffectedtheshort-chainsugarsratio. Thesucrose/glucoseratioranged
from0.35to0.44,respectively,forT0andT1,whereasfructose/glucoseratio(0.7)wasratherconstant.
Theleafbiomass(Figure5B)presentedsignificantlyhigherconcentrationsofglucosethanfructose
andsucrose;moreover,treatmentssignificantlyinfluencedtheglucosecontent. T2suppliedthehigher
responses,with19.7%and25.0%morethanT0andT1,respectively.
Agronomy 2017, 7, 65 8 of 18
than fructose and sucrose; moreover, treatments significantly influenced the glucose content. T2
Agronomy2017,7,65 8of18
supplied the higher responses, with 19.7% and 25.0% more than T0 and T1, respectively.
220 220
A B
200 aab 200
180 b 180
T0 T1 T2 T0 T1 T2
160 160
)w140 )w140
d120 d120
1-g100 1-g100 a
k g( 80 k g( 80 b b a a a
60 a a a 60
40 a a a 40
b a a
20 20 a a a
0 0
sucrose glucose fructose inulin sucrose glucose fructose

FiguFreig5u.reE 5ff.e Ecftfeocft couf tctuinttgintgy tpyepeu useseddf foorr tthhee vveeggeettaatitvivee pprorpoapgaagtiaotnio onno snugsaurg caorntceonnt tienn atritnichaortkiec hhoeakde head
(A)a(nAd) alenadv leeasv(eBs) (.BW). iWthiitnhitnh tehes asmameet rtraaiitt,, ddaattaa wweerree aannalaylzyezde dbyb AyNAONVOAV, aAn,da vnadluveas lwueitsh wnoit hletnteor letter
incoimn cmomonmaorne asrieg sniigfincifaincatnlytlyd idffifefreerenntta att pp << 00..0055, ,aaccccoordrdinign gtot TouTkueky’esy H’sSHD STDestT. eSstta.nSdtaarndd earrrodrse rarroe rsare
reporretpedor.teTd0.: Ts0u: msummemreor voovloi;liT; T11::s spprriinngg ooffffsshhooootsts nnuursresreyr’ys ’csucttuinttgisn gfosrcfeodrc teod ptaossp aa svsegaevtaetgiveet arteisvt erest
period by stopping irrigation; T2: spring offshoots nursery’s cuttings not forced.
periodbystoppingirrigation;T2:springoffshootsnursery’scuttingsnotforced.
The mineral profile of the plant is another parameter that was affected by the propagation mode
oTfh eartmicihnoekrea. lRpergoafirdleinog fmthaerkpetlaabnlte isheaando t(hTearblpe a7ra),m cehtleorridthesa,t pwhaosspahfafetecst,e dsublfyateths,e spordoiupmag, ation
modpeootafsasirutimch, oaknde. cRalecgiuamrd iwnegrem saigrnkiefticaabnltelyh edaifdfer(eTnatb. lTe07 )e,xcphrelossreidd etsh,ep hhiogshperh arteessu,ltssu flofar taelsl ,tshoed ium,
potascosimupmo,neanntds lcisatelcdi uambovwe,e Tre1 swigasn infiocta dnitflfyerednitf fferroemn tT.0 Te0xceepxtp rfoers scehdlortihdeesh aigndh esrodreiusmul tcsonfoternta, ll the
compwohneerenatss Tli2s taendd aTb0o svheo,wTe1d wthaes sanmote dcoifnfteernetn otff rpohmospTh0ateexs.c eAps tpfaorrt ocfh ltohrei dleeasveasn, dthes ocdoniutemnt coofn tent,
wherseoadsiuTm2, apnodtasTsi0umsh, oawnde dmtahgenessaiumme nciotrnattee nwtaos fspighnoifsicpahnatltye slo.wAers inp aTr2t. oRfetghaerdlinega vneistr,attehse, Tco0 ntent
presented the highest concentration.
of sodium, potassium, and magnesium nitrate was significantly lower in T2. Regarding nitrates,
T0presentedthehighestconcentration.
Table 7. Effect of cuttings type used for the vegetative propagation on mineral content in artichoke
head and leaves.
Table7. Effectofcuttingstypeusedforthevegetativepropagationonmineralcontentinartichoke
hea dandClela− ves. PO43− SO42− Na2+ NH4+ K+ Mg2+ Ca2+ NO3−
(g kg−1 dw)
T0 12.4 aC l− 6.8P7 Oa 43− 2.6S9O a4 2− 2.N58a Aa2 +rticho0Nk.3eH3 h14e +ad 30K.2+ a M1.g821+ C3.a422+ a NOn3d−
T1 12.3 a 5.41 b 2.16 b 2.67 a (g0.k34g7− 1dw2)8.3 b 1.75 2.78 b nd
T2 10.6 b 6.69 a 2.28 b 2.03 b 0.385 29.2 ab 1.85 2.39 b nd
Artichokehead
*** *** *** *** n.s. * n.s. ***
T0 12.4a 6.87a 2.69a 2.58Aarticho0k.e3 3le1af 30.2a 1.81 3.42a nd
T0 T1 61.91 2.3a 3.352. 41b 4.23.01 6b 192..06 7a a 10..3304 7 4228..13 ab 21.9.785 a 2.788.52b n7d.34 a
T1 T2 57.11 0.6b 3.260. 69a 5.20.02 8b 127..80 3a b 10..2398 5 4219..02 aabb 2.19.78 5ab 2.399.61b n5d.72 b
T2 49.2 *** 3.45 *** 4.30** * 15.7** b* 1n.2.3s . 39.1* b 2n.5.3s .b *8*.*22 5.22 b
n.s. n.s. n.s. *** Artichonk.se. leaf * * n.s. ***
Within the same trait, data were analyzed by ANOVA, and values with no letter in common are
T0 61.9 3.32 4.30 19.0a 1.30 42.1a 2.98a 8.52 7.34a
significantly different at p < 0.05, according to Tukey’s HSD Test. T0: summer ovoli; T1: spring
T1 57.1 3.20 5.00 17.8a 1.29 41.0ab 2.97ab 9.61 5.72b
offshoots nursery’s cuttings forced to pass a vegetative rest period by stopping irrigation; T2: spring
T2 49.2 3.45 4.30 15.7b 1.23 39.1b 2.53b 8.22 5.22b
offshoots nursery’s cuttings not forced. nd: not detected; n.s.: not significant; *: significant at p < 0.05;
n.s. n.s. n.s. *** n.s. * * n.s. ***
**: significant at p < 0.01; ***: significant at p < 0.001.
Withinthesametrait,datawereanalyzedbyANOVA,andvalueswithnoletterincommonaresignificantly
differentatp<0.05,accordingtoTukey’sHSDTest. T0: summerovoli;T1: springoffshootsnursery’scuttings
3. Discussion
forcedtopassavegetativerestperiodbystoppingirrigation;T2:springoffshootsnursery’scuttingsnotforced.nd:
notdetected;n.s.:notsignificant;*:significantatp<0.05;**:significantatp<0.01;***:significantatp<0.001.
Vegetative propagation methods on globe artichoke significantly affected the yield, and the
marketable and qualitative characteristics of the product. Under the production point of view, the
3. Discussion

Vegetative propagation methods on globe artichoke significantly affected the yield, and the
marketable and qualitative characteristics of the product. Under the production point of view,
thelowestgrowthrhythm,registeredinT2,couldbeduetothetransplantage[27]. Thiscaninfluence
thevegetativedevelopmentofartichokeplants,modifyingthedevelopmentstageoftheauxiliarybuds
thatwereactivatedduringthenurseryphaseandtheaerialpartofT2cuttingsgrewuplaterallyusing
Agronomy2017,7,65 9of18
theaccumulatedreserves. TheheightdevelopmentofT2plantswasaffectedbytheslowemission
ofnewadventitiousroots,andthedamageoftheexistedrootsduringthenurseryphase,afterthe
removalofplantsfromthenurserytothefield. Infact,tissueagecanaffecttheabilityofcuttingsto
formnewadventitiousroots,anditisalsolinkedtoontogeneticphases;thesemarkthedifferentiation
of the tissue from meristem that is getting physiologically older and more mature [35]. The slow
growthrateofT2plantalsoaffectedthereproductivephaseofthecrop,andthisresultisconfirmed
byT1, whichproducedtheearliestandtheheaviestprimaryheadscomparedtoothertreatments.
Theseresultsprovethatovolitypologycaninfluencethenumberofearlyharvestedheadsandhead
weight,asreportedinliterature[36]. Overall,T1providedthehighestyieldresults,withmorethan
29tha−1,whichareinlinewiththoseobtainedfromotherexperiments. In2013,anexperimental
essaywasconductedinKaâlatElAndalousinArianagovernateinthenorthofTunisia(37◦ N,10◦ E,
altitude238m). Assuggestedinotherstudies[37],thebiggestheadsizewasobtainedintheearly
harvestseason. Inaddition,theharvestperiodsignificantlyinfluencedthephysicalqualityofheads.
Thelowestmeanweightandmeandiameterofheadswereobtainedinthelateharvestingperiod.
Similarresultswerepresentedbyanotherexperiment[38],wherethehighestheadweight(253g)and
headdiameter(74mm)wereobtainedon15January,whereasthelowestvalues(179gforheadweight
and67mmforheaddiameter)wereregisteredon15March.
Asreportedforagronomicandmarketableparameters,thequalitativeoneswereinfluencedby
thevegetativepropagationmethods. Takingintoconsiderationheadcolorcharacteristics,different
pigmentcontentswereobserved. Asknown,pigmentcontentdependsonthephotosyntheticcapacity
ofleavesandleafarea[39]. Thisinformationcanbelinkedtoourexperiment,whereleavesofT1and
T2plantswerewiderthanT0, infact, significantdifferenceswereobservedinplantwidthduring
thevegetativephase. Thevaluesmeasuredforantioxidantcapacityweregenerallylowerthanthose
observed for other artichoke varieties, like “Violetto di Chioggia” and “Violetto di S. Erasmo” [2];
ifweconsider“ViolettodiToscana”,instead“Violetd’Hyères”,thetotalantioxidantcapacity(TAC)
valuesareonaverage50%higher. Thisvariabilityintheconcentrationofantioxidantcompoundsis
mainlyduetogeneticaspects,agronomicpractices,andenvironmentalconditions[1,40]. Furthermore,
the high content of antioxidants and total phenols in T0 and T1 may also be connected to more
stressfulconditionsthattheplantcuttingshaveexperiencedbeforetransplantingintheexperimental
field. The drought stress, that was induced for 60 days, at least for T0 and T1 plants to obtain
cuttingswithquiescentbuds,hasinfluencedthequalityofproducedheadsduringthegrowingcycle.
As previously reported [36], ovoli management has an important impact on the head production.
Asknown,astressexperiencedbytheplantduringthegrowingseasoncansignificantlyinfluencethe
antioxidantamount. Infact,plantstresstolerancemaybeimprovedbytheenhancementofinvivo
levelsofantioxidant[41,42]. Thelowerorslowerrootsystemdevelopmentreduced,forsomeperiods,
the nutrient and water availability to the plant, by inducing such responses. The low antioxidant
content in T2 is probably due to the lower stress condition that the plant has suffered during the
cropcycle. Asaresult,theconcentrationofchlorogenicacid(caffeoylquinicacid)waslowerinT2by
29.6%and30.2%comparedtoT0andT1. Basedontotalcaffeoylquinicacidcontents,caffeoylquinic
acidisthemostabundantsinglecomponent(39%),followedby1,5-O-dicaffeoylquinicacid(21%),
and3,4-O-dicaffeoylquinicacid(11%). Cynarin(1,3-O-dicaffeoylquinicacid)contentisusuallyvery
low(about1.5%)inmethanolicextractsofartichoke[1]. Thechlorogenicacidcontentintheleaves
was much lower than that of the head. This result is similar to what reported for the “Violetto di
Toscana”artichokevariety(−82.9%)[43]. Moreover,itshouldberememberedthatthecaffeoylquinic
derivatives content in artichoke tissues highly depends on the physiological stages of the plant.
The total caffeoylquinic acid content can range from about 8% in young tissues to less than 1% in
senescenttissuesondrymatterbasis[44].
Asknown,theartichokeisaspeciescharacterizedbyahighamountoflongandshortchainof
sugars. Inadditiontosimplesugars, thefructangroupisofgrowinginterestasafunctionalfood
ingredient,becauseoftheirpotentialbenefitsforhumanhealth[45–47]. Ashumanenzymescannot
Agronomy2017,7,65 10of18
digestfructans,theyreachthecolonandserveasasubstrateforenterobacterialgrowth[1]. Fructan
containing diets selectively stimulate bifidobacteria and make them the predominant species [48].
Consequently,anincreasedfecalcontentofshort-chainfattyacidsandadecreasedconcentrationof
tumor-promotingsubstances,suchasammonia,wereobserved[49]. Theinulinvaluesmeasuredfor
“Violetd’Hyères”artichoke,commonlygrowninTunisia,areinlinewiththoseobtainedforother
varietiesofartichoke(LeCastelandGreenGlobe)[47]. Thesugarratioisalsogreatlyinfluencedbythe
varietalcharacteristics. Thesucrose/glucoseratiorangesfrom0.46to2.29forthevarietiesPoivrade
andBuette,respectively[47]. Otherauthors,instead,foundlowersucrose/glucoseratios(0.07–0.1),
respectively, for“ViolettodiS.Erasmo”and“ViolettodiChioggia”[2]. Thehighconcentrationof
glucose,comparedtofructoseandsucroseinleafbiomass,weresignificant. Treatmentsremarkably
influencedtheglucosecontent,andT2suppliedthehighestoutcomes. Thisresultismainlylinkedto
thebiggersizeoftheleavesinT2inthefirstpartofthecropcycle,thuspromotingthephotosynthetic
activity.Thisconfirmsthatthehighartichokeleafareapositivelyinfluencedthephotosynthesisactivity,
asalreadyreported[50].
Themineralprofilewasalsoaffectedbytheplantpropagationmode. Ingeneral,mostofresults
areattributabletothedifferentabilityofoffshootsandovolitoformnewroots,andtotheirability
toexplorethesoil. Somesignificantchangeshavebeenrecordedforpotassiumandsodium. Infact,
thesemineralsarethemainindicatorsforplanttolerancetomitigatedroughtstress[51,52]. During
thenurseryphase,thecuttingsofT2werecontinuouslyirrigateduntiltheirtransplantationinthe
experimentalfield,whereascuttingsofT1andT0wereforcedtoenterinavegetativerestperiodby
causingdroughtstressthroughstoppingofirrigationformorethan2months. After80daysfromfield
transplantation,T2plantsemittednewsecondaryroots,mainlyinthe0.25mofthetopsoil,whereas
T0andT1plantsdevelopeddeepersecondaryroots. Thiscouldexplainwhytheabsorptionofmineral
nutrientswaslowerinT2thantheothertreatments. Ingeneral,themineralcontentwassignificantly
higherintheleavescomparedtothemarketableyield. Sucharesponseisinagreementwithother
findings[43]. Inthehead,themostabundantelementwaspotassium,withvaluescloseto30gkg−1
dwandto40gkg−1dwintheleaves. Ontheotherhand,thecontentofchloridesisparticularlyhigh,
probablyduetotheirpersistenceinthesoil,becauseoftheuseofpotassiumchlorideasafertilizerfor
previouscultures. Comparedtothemineralcompositionofothervegetablesreportedintheliterature,
theglobeartichokerepresentsagoodsourceofK[53]. Inaddition,theNa/Kratioofglobeartichoke
isoneofthelowestratios,followingpotato. Thisparameterisveryimportant,sinceahighlevelis
involvedinincreasingbloodpressureandcardiovasculardiseases[54]. Therefore,theconsumptionof
globeartichokemightalsobesuggestedtoovercomethesediseases. Moreover,theincreasedmineral
contentintheleavescanbeexplainedbythecapacityofglobeartichoketocompartmentalizeexcess
ionsinthevegetative,ratherthanthereproductive,partsoftheplant[55].
4. MaterialsandMethods
4.1. ExperimentalSite
TheexperimentwasconductedintheSupportStationofManouba(SAM),whichisunderthe
supervision of the Inter-professional Group of Vegetables (GIL). It is located in Manouba region,
situatedinthenorthofTunisia(36◦48(cid:48) N;10◦03(cid:48) E,altitude469m). Thelocalclimateofthisareais
characterizedbyanuppersemi-aridstage,withanaveragedailytemperaturerangingfrom9◦Cas
minimuminJanuary,to25◦CasmaximuminAugust. Therainfallisirregular,withanaverageof
450mmperyear. MeteorologicaldatarecordedduringthetrialperiodarereportedinFigure6.