Hydroponic minituber production in growth room conditions and carry-over effects of the technique on produced minitubers

Jou nal o Ag icul u al Science; Vol. 9, No. 1; 2017 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Cen e o Science and Educa ion 41 Hyd oponic Mini ube P oduc ion in G ow h Room Condi ions and Ca y-O e E ec s o he Technique on P oduced Mini ube s Elina Vi anen 1 & Jussi Tuomis o 2 1 Na u al Resou ces Ins i u e Finland, Oulu, Finland 2 Po a o Resea ch Ins i u e, Ylis a o, Finland Co espondence: Elina Vi anen, Na u al Resou ces Ins i u e Finland, P.O. Box 413, 90014 Uni e si y o Oulu, Oulu, Finland. Tel: 358-29-5326-646. E-mail: elina. i anen@luke. i Recei ed: Sep embe 27, 2016 Accep ed: No embe 7, 2016 Online Published: Decembe 15, 2016 doi:10.5539/jas. 9n1p41 URL: h p://dx.doi.o g/10.5539/jas. 9n1p41 Abs ac The p oduc ion o mini ube s was implemen ed wi h a hyd oponic echnique in g ow h ooms and he ca y-o e e ec s o he echnique on he cha ac e is ics o mini ube s we e s udied. As a compa ison, mini ube s om in i o plan le s we e g own in a pea -based g owing medium. The esul s show ha hyd oponic p oduc ion o mini ube s is success ul in indoo condi ions wi h he cul i a s Desi ee, Van Gogh and As e ix, when day- ime g owing empe a u es o 19.4 °C-26.0 °C and nigh - ime empe a u es o 17.5 °C-22.6 °C we e used. Pho osyn he ically ac i e illumina ion was adequa e a 2383-2509 μmol m -2 s -1 ; ligh ing condi ions consis ed o 14/10-hou day/nigh cycles. The cul i a s Desi ee and Van Gogh de eloped hei i s ube h ee weeks as e han As e ix, and he mini ube yield was 4.5 pe plan o Desi ee, 7.5 o Van Gogh and 4.0 o As e ix. When a pea -based g owing medium was used, mini ube yields we e almos he same bu he size o he mini ube s was smalle han ha o hyd oponically p oduced mini ube s. The esul s o he ca y-o e expe imen s showed ha con en ionally p oduced mini ube s eme ged as e , and in e ms o oliage de elopmen and yielding capaci y pe o med be e han hyd oponically p oduced mini ube s. Keywo ds: Solanum ube osum L., mini ube p oduc ion, hyd oponics 1. In oduc ion Fas e , mo e cos -e ec i e echnical solu ions wi h a highe p oduc ion capaci y a e needed o mini ube and p e-basic seed po a o (Solanum ube osum L.) p oduc ion. P oduc ion e iciency is o en measu ed in e ms o he a e o mini ube p oduc ion and he numbe o mini ube s p oduced. I has been p oposed ha soilless mini ube p oduc ion echniques inc ease p oduc ion olume (Rolo & Seu in, 1999). Va ious soilless, hyd oponic and ae oponic (Co êa e al., 2008; Ri e e al., 2001) and bio eac o - ype (Kämä äinen-Ka ppinen e al., 2010; Aki a & Oh a, 1998) p oduc ion me hods ha e al eady been de eloped and a e in use. The p oduc ion capaci y o hese new echniques is ypically compa ed o he mini ube yields achie ed by con en ional in i o p opaga ion echniques. E en hough i is possible o inc ease con en ional mini ube p oduc ion (Milinko ic e al., 2012; Veeken & an de Lommen, 2009) om in i o plan le s, bu i in ol es clea ly highe p oduc ion cos s and ela i ely low ube yield (Rolo & Seu in, 1999). In hyd oponic p oduc ion, plan oo s a e eely suspended in nu ien solu ion om which hey de i e he necessa y nu ien s and ace elemen s. I has been shown o be possible o inc ease he numbe o mini ube s p oduced by using he hyd oponic p oduc ion echnique (Rolo & Seu in, 1999). The hyd oponic echnique has also been used wi h sand subs a es (No ella e al., 2008). The in oduc ion o new mini ube p oduc ion echniques equi es he op imiza ion o p oduc ion condi ions. A speci ic equi emen o hyd oponic p oduc ion is o achie e a balance be ween he nu ien a ios wi hin he nu ien solu ion, elec ical conduc i i y (EC) alue, and pH as needed o po a o p oduc ion (Chang e al., 2011; No ella e al., 2008; Ri e e al., 2001). Al hough only ew s udies ha e been conduc ed on he e ec o EC on po a o, EC alues om 1.2 o 1.7 dS m -1 a e conside ed no mal (Chang e al., 2011; No ella e al., 2008). In he s udies o Chang e al. (2011), pH luc ua ions be ween 5.0 and 7.2 in hyd oponic p oduc ion co ela ed wi h he EC le els o he nu ien solu ions. In addi ion, empe a u e and illumina ion le els should be aken in o conside a ion in mini ube p oduc ion jas.ccsene . (Le y & V ligh ing ( R Acco din g and, co e ube iza i o p ho osyn h du ing he In no he n con en io n en i onm e al e na i e simula io n al e na i e p oduc io n mini ube s 2. Me ho d 2.1 Hyd o p The hyd o ays, an a h p://engl Each g o w 2500 mm. g ow h o o g ow h o o The oo s (Mu ashi g ha dening cul i a io n ays con a he oo s ube s a e Figu e 1. H The ays w equipped w nu ien s o mic oplan ni ogen l e solu ion 1 ci cula io n o g V eilleux, 200 7 R i e e al., 2 0 g o V eugden h spondingly, h i o n. Le y and V h esis o Eu o p ligh pe iod, n condi ions ( n al mini ube e n al condi io n e . In he p es e n (ligh , emp e e o con en io n n in Finland s ha e no bee n d p onic Mini ub e o ponic p oduc a u oma ic cen ish.li ing ood w h oom had Thi y mic o o m and 100 m om s (4 × 2 × 1 o he mic o p g e & Skoog, able had a c n able in he g a ining a nylon h oughou h e de eloped be H yd oponic p w e e open-en d w i h a pump o lu ions we e le oo ing p h e el was 20- 3 (Ca:K:Mg–0 . n , and solu io n 7 ; V eugdenhi l 0 01) o by m o h il e al. (200 7 i gh illumina i o V eilleux (200 7 p ean po a o c u empe a u es w 64-65°N), en p oduc ion i n n s a e u ilize d e n s udy we e e a u e, humi d n al me hod. T and he ca y n s udied. e P oduc ion ion sys em c o al p ocessing s.nl/). The p o 10 hyd oponi c plan le s we e m ic oplan le s p 00 mic oplan p lan le s o D e 1962) we e w c losed nu ien g ow h ooms ab ic a he b e ay. The sh o ween he nyl o oduc ion ay s d ed, wi h he n a he o he e used in he ci h ase and con 3 0 kg/ha as c o . 7:1.0:0.5) wa n 2 was eplac e Jou nal o A l e al., 2007) . o di ying na u a 7 ), long pe io d o n le els, low 7 ) conside +2 u l i a s. In h e w e e 24±4 °C a i onmen al a n g eenhouses , d . Soilless in d e xamined wh e d i y) o he p he hyd oponi c y -o e e ec s o nsis ed o a m uni , nu ien s o duc ion sys e m c g owing a y e plan ed in e a p e cul i a . T le s/cul i a , o e si ee, Van G o w ashed wi h 3 solu ion cy c (Figu e 1). In b o om o he o o s o he mi c o n ab ic and h s a e ans e V n u ien solu i o e nd, and hen cula ion sys e inuing un il ompa ed o i s eplaced wi e d by 3 (Ca: K A g icul u al Sc i 42 . Hyd oponic a l ligh wi h s u d s o dayligh empe a u es a 0 °C as he o p e s udies o C a nd 12±2 °C b a c o s limi h e , and only o n d oo p oduc i o e he an indo o p oduc ion en c p oduc ion e o he ech n m ic oplan le h a s olu ions, and m s we e plac e y s, each wi h a a ch ay 15 c m T he s udy was o al 800 plan s o gh and As e 3 8 °C wa e a c le. A e 13 d he hyd opo n ay, which en s c oplan le s g o h e plas ic shee o he mic o p V i anen) o n ed o he eci cula ed o e m depending he ini ia ion i eld nu ien l h nu ien so l K :Mg–1.5:1.0: 0 i ence p oduc ion ca n u pplemen al i l and high em p a nd ela i ely p imal empe a C hang e al. ( 2 y day and nig h e u iliza ion o n e p oduc ion o n echniques o hyd oponic i onmen en a e chnique is n o n ique on he a dening abl e anks wi h pu e d in wo g o w a wid h o 22 5 m apa , wi h a conduc ed w i s /cul i a ). ix g own on a a nd ans e e d ays, he mic n ic sys em, h e s u es op imal d o w abo e a p l . p lan le s and b e ay ia a hose o he ay i a on he plan o ube o m e el. A he i l u ion 2 (Ca: K 0 .4) du ing u b n be implem e l lumina ion ( C p e a u es inhi b sca ce nu ie n a u e o ube 2 012) on hyd h , espec i el y illumina ion pe iod is pos he e o e p o p oduc ion s y a ble mini ube o , a p esen , i cha ac e is ic s e , cul i a ion a mps (Li ing F w h ooms 8 m 5 mm, heigh a o al o 300 i ce, in 2012 a n a egula sem i e d o ha deni n oplan le s w e e plan s a e cu l d is ibu ion o l as ic shee an e o e ha es i n a one end an d a a il e sys e de elopmen a m a ion, nu ie n i ni ial phase o K :Mg–0.4:1.0: 0 b e iza ion. Th e Vol. 9, No. 1; e n ed wi h a i C hang e al., 2 b i ube o m n ese es im p o ma ion a n oponic p od u y . and empe a u sible when n a o ide an a a y s em and a i p oduc ion a i n use in mini s o he p o d a bles wi h g o F oods VB, Ho l m 2 and 9 m 2 in 50 mm and l e mic oplan le n d in 2013, in i solid MS me n g condi ions. e e ans e e d l i a ed in g o nu ien solu i n d he oo s a n n g ( igh ) (pho d e u ned o a e m. Th ee di l s age. Du in n solu ions a o ube o m a 0 .3) in he nu e nu ien sol u 2017 icial 0 12). m a ion p o e n d o c ion u e in a u al a c i e icial a s an ube d uced wing l land, a ea. e ng h s pe bo h d ium The o a wing o n o d he o E. a ank e en g he a ied, a ion, ien u ions jas.ccsene . con ained low a e w nu ien s o NMC-P o sys em. I n measu e m com). 2.2 Con e n Hyd opon i mic oplan p lan ed (4 Whi e 42 0 (NPK 14- 4 ni ogen, 5 we e i ig a 2.3 G ow h I was use d plas ic-co a p e g ow h used and g ow h o adia ion ( g ow h o o am) day/n i o bo h g OHM SR L and he P A we e me a 754-O-P M Figu e 2 G ow h o au oma io n b e ween 2 ooms. In in g ow h o g u he mo e P, w as 0.5 l min - o lu ion pH le con olle (N e n addi ion, h e m en s (Bluela b n ional M ini u i c p oduc ion le s we e als o 0 cm × 60 c m 0 W) was use d 4 -20) wi h a p H 5 00 mg kg -1 s o a ed om bel o h Room Cond i d wo g ow h a ed b ick. Th e h oom) (Os a he lamp spe c o oms be ween ( PAR) in he o o ms we e imp i gh illumina i g ow h ooms. L , I aly) equi p A R senso me a a su ed using M T, 754-C, Op . High- p essu o om empe a u n (Ilma eollis u 2 0.9 and 26.0 ° g ow h oom oom 2. Ai h u P, S, Mn, Cu, Z 1 and he lo w els 5.8 ±0.2 e a im TM, N M e pH o he n Combo Me e u be P oduc i o was compa e o plan ed in a p m , dep h 15 c m d as he g o w H o 5.9 and e o luble phosph o o w wi h same s i ions ooms in he e e loo s we e m a m Vialox, G e c um we e h 16,000 and o liage was 23 8 lemen ed day i on. Du ing h e The amoun p ped wi h RA D a su es he pho he OL754 onic Labo a e sodium lam p u es we e adj u u us Oy, Finla n ° C in g ow h 1 day ime e m u midi y in he Jou nal o A Z n, Fe and Na n w cycle was o n and EC 1.3 ± M C-P o-I ig a n u ien solu i e , Bluelab C o o n e d o a con e p ea - b ased g o w m ) a a dis anc e w ing medium. e lec ical cond u o us and 2600 s olu ion as in e sea ch; 8 m 2 m ade o ac yl i e many) wi h h e same in bo 18,000 lx e g 8 3-2509 μmol ime ligh con d e p oduc ion p o illumina i o D and PAR s e osyn he icall y Po able Hi g o ies, Inc., O l p ligh spec u u s ed o 20±2 n d). Tempe a u oom 2. Nigh m pe a u es we e g ow h oom s A g icul u al Sc i 43 n u ien s in h e n e hou a e h ± 0.3 we e adj u a ion, Is ael) o i on, EC and o po a ion Li m e n ional mini u w ing medium . e o 10 cm o The pea was u c i i y 27 m mg kg -1 solu b he hyd oponi c and 9 m 2 in a i c co e ed co n ime con ol ( h g ow h o o g a dless o h e m -2 s -1 (senso d i ions, wi h 1 hase, he spec o n was meas u e nso s. The R A y ac i e adia i o g h Accu acy l ando, FL, US A u m in he g o w °C o day i m u es a ied in - ime empe a e 0.5 °C and n s was adjus ed i ence ei di e en li q h e luid low, u s ed acco di n o guide and c o empe a u e w m i ed, New Z u be p oduc i o . A o al o 16 0 o m he polyp o e ilized wi S m -1 and con b le po assium c echnique. ea. The walls n c e e. High p Schneide El e o ms (Figu e 2 ) e measu ing p measu emen 4 h (07:00 a m um and in e n u ed wi h a H D A D senso m e o n in pho ons p U V -Visible s A ). w h ooms, me a m e and 14±2 ° C g ow h oom a u es we e b e n igh - ime em p o 60-80% us i q uid o ms. T h ollowing a 5 - n g o he a g o n ol he hyd w e e moni o e Z ealand, h p:/ / o n me hod, a n 0 mic oplan le o pylene boxes , h Kekkilä s a aining 1600 m (d y ma e ). T o he ooms w essu e sodiu m e c ic TAC X e ) . Ligh in en s p oin s. Pho o s wa eleng h 4 m -09:00 pm)/1 0 n si y o he lig h D 9021 pho o e asu es adia i o p e squa e me s pec o adiom e a su ed wi h a s C o he nig h 1 be ween 19 . e ween 15.5 a n p e a u es we e i ng a s eam g e Vol. 9, No. 1; h e nu ien sol - minu e pause g e alues usi n oponic p od u e d daily by s e / wwww.ge bl u n d o his e s pe cul i a , and pea (K e e e ilize n m g/kg wa e -s o T he g owing b w e e cons uc m ligh s (4 × 4 0 e n a, Sweden) s i y a ied in s yn he ically a 4 00-700 nm). I 0 h (9:00 pm- 0 h we e de e m o - adiome e ( D o n e iciency i e. Ligh spe c e e (IS-670- L s pec o adiom e h pe iod usin g . 4 and 26.0 ° C n d 22.6 °C in e 0.7 °C lowe e ne a o (Vapa c 2017 u ion . The n g an u c ion e nso u elab. a son, we e kkilä n o. 1 luble b oxes ed o 0 0 W we e bo h a c i e n he 0 7:00 m ined D el a i n lx, c um L ED, e e g AC C and bo h han c LE, jas.ccsene .o g Jou nal o Ag icul u al Science Vol. 9, No. 1; 2017 44 UK) and humidi y le els we e p edominan ly below 60%. Tempe a u e and humidi y eadings we e ollowed wi h da a logge s (Ne a im, Clima e Box, Ne a im, Is ael). 2.4 Obse a ions and Samplings Plan de elopmen and ube o ma ion we e obse ed acco ding o Hack e al. (1993) using p e-ma ked indi idual plan s (10 plan s pe g owing ay), and lea samples we e aken om he same indi idual plan s ou imes du ing he p oduc ion phase. The lea samples we e aken in hyd oponic p oduc ion always be o e changing he nu ien solu ions in ci cula ion, i.e. on 24 May, 30 May, 14 June, and on 7 Augus du ing he ha es ing phase, a which ime ube samples we e also collec ed. D y ma e and nu ien analyses o phospho us (P), po assium (K), calcium (Ca), magnesium (Mg), sulphu (S), sodium (Na), bo on (B), coppe (Cu), manganese (Mn), zinc (Zn) and i on (Fe) we e conduc ed by labo a o y o Suomen ympä is öpal elu Oy. When plan s we e g own in a pea -based g owing medium, samples we e aken du ing he same de elopmen al phases as in hyd oponic p oduc ion, and ha es ing was conduc ed on 7 Augus and sampling and analyses we e conduc ed as in he case o hyd oponic p oduc ion. 2.5 Ca y-O e S udy A e h ee mon hs o cold s o age (4 °C) mini ube s sized 10-20 mm o he cul i a s Van Gogh and Desi ee we e ans e ed o a g eenhouse and plan ed in plas ic g owing boxes (45 cm × 60 cm) in a pea (Biolan, No ag ow) g owing medium. The cul i a As e ix was no included in he ca y-o e s udy due o insu icien amoun o o e 10-20 mm sized mini ube s. A o al o 3,200 mini ube s we e s udied (100 ube s × 2 echniques × 4 eplica ions × 2 cul i a s × 2 imes). The plan s we e i iga ed mechanically wi h a liquid e ilize (Nu i S-A 0.5 ‰ solu ion). The g eenhouse empe a u e was eco ded by an au oma ic wea he s a ion (a-Wea he , AWS -1.04B, Alab, Finland). The eme gence da es o each indi idual plan we e no ed and he de elopmen al s ages obse ed acco ding o Hack e al. (1993) wi h po en ial oliage symp oms eco ded a one-week in e als. Ha es ing was ca ied ou 77 days a e plan ing (DAP). A ha es , he numbe o s ems, he numbe and weigh o he ube s and he ex e nal quali y o he ube s we e assessed indi idually. 2.6 S a is ical Analyses The s a is ical analyses we e conduc ed using he Mixed p ocedu e o he SAS 9.2/SAS En e p ise Guide 4.3 (SAS Ins i u e Inc., Ca y, NC, USA) p og am, using a a iance analysis model in compliance wi h he spli plo s udy design. Fu he mo e mini ube s mean±s anda d de ia ion was conduc ed by Duncan’s mul iple ange es . 3. Resul s 3.1 Mini ube P oduc ion The oliage o Desi ee and Van Gogh de eloped as e du ing hyd oponic p oduc ion han ha o As e ix. Wi hin 37 days om plan ing he mic oplan le s on he ha dening able and ans e ing he plan s o he ays, Desi ee and Van Gogh oliage co e ed he en i e ay. Tube o ma ion (i.e. he i s s olon ends swollen o double hei size) s a ed a e 41 days o mini ube p oduc ion in bo h cul i a s. As e ix oliage de elopmen was almos 3 weeks behind Van Gogh and Desi ee. As e ix ube o ma ion s a ed 62 days a e he mic oplan le phase. When plan s we e g own in g ow h ooms in a pea -based g owing medium, oliage de elopmen occu ed almos 3 weeks la e and also ube o ma ion s a ed app oxima ely 18 days la e in all cul i a s compa ed o hyd oponic p oduc ion. Hyd oponically-g own ube s we e ha es ed 96 days om plan ing he mic oplan le s on he ha dening able. Mini ube yield was 4.5 pe plan o he cul i a Desi ee, 7.5 o Van Gogh and 4.0 o As e ix. The mini ube s we e g aded in size ca ego ies < 20 mm and > 20 mm; 56.1-58.4% o he Desi ee and Van Gogh cul i a s and 95.3% o he As e ix cul i a we e in he size ca ego y < 20 mm. The a e age weigh o he mini ube s was 11 g o he cul i a Desi ee, 13 g o Van Gogh and 6 g o As e ix. In pea -based p oduc ion, Desi ee p oduced 4.4 mini ube s pe plan , Van Gogh 4.6 and As e ix 3.3. Pea -p oduced mini- ube s we e all < 20 mm in size and weighed 5-9 g (Table 1). jas.ccsene .o g Jou nal o Ag icul u al Science Vol. 9, No. 1; 2017 45 Table 1. Compa ison o hyd oponic and pea mini ube p oduc ion me hods on ube numbe and ube weigh in cul i a s Desi ee, Van Gogh and As e ix Me hod Tube numbe pe plan Tube weigh pe plan Mini ube s g ading (%) < 20 mm > 20 mm Hyd oponic 4.5 ± 0.2 b 11.3 ± 1.5 a 58.4 41.6 Con en ional 4.4 ± 0.7 b 7.5 ± 0.8 b 98.9 1.1 Hyd oponic 7.5 ± 2.1 a 13.1 ± 3.6 a 56.1 43.9 Con en ional 4.6 ± 1.2 b 9.2 ± 2.7 b 97.2 2.8 Hyd oponic 4.0 ± 0.9 b 6.1 ± 2.9 b 95.3 4.7 Con en ional 3.3 ± 2.0 b 5.0 ± 2.2 c 100.0 0.0 No e. Values deno e mean±s anda d de ia ion and di e en le e s indica e signi ican di e ences be ween means by Duncan’s mul iple ange es , p = 0.05. The e we e no signi ican di e ences in he nu ien concen a ions o lea o ube samples be ween hyd oponic po a o p oduc ion and po a oes cul i a ed in a pea -based g owing medium. Calcium concen a ions we e sligh ly (no signi ican ly) highe in hyd oponically-p oduced ube s compa ed o ube s p oduced using a pea -based g owing medium. Co espondingly, manganese and i on concen a ions we e sligh ly (no signi ican ly) highe in pea -p oduced ube s ( esul s no shown). EC alues, pH le els and empe a u es in hyd oponic p oduc ion a ied h oughou he p oduc ion season: EC 1.3-1.6, pH 5.8-6.2 and empe a u es 19-23 °C. The pH le els in pea -based p oduc ion a ied pH 6.2-6.4. 3.2 Ca y-O e E ec s o Techniques on Mini ube s Hyd oponically p oduced mini ube s eme ged slowe han pea -based p oduced mini ube s by a di e ence o 5 days (p = 0.000) (Figu e 2), bu no ca y-o e e ec o ei he p oduc ion me hod was ound in oliage de elopmen , numbe o s ems (p = 0.22) o numbe o ube s (p = 0.56) (Table 2). The numbe o s ems a ied om 1.6-1.7 and he numbe o ube s be ween 4.7-5.2 pe plan . Al hough no ca y-o e e ec o he me hods was ound in e ms o he numbe o ube s, con en ional pea p oduc ion had a posi i e e ec on c op yield (g/plan ) (p = 0.005) (Figu e 3), in cul i a Desi ee. Co espondingly, he yield o hyd oponically p oduced mini ube s was 87 g/plan and con en ionally pea -based 104 g/plan . 0 5 10 15 20 25 30 Hyd oponic Con en ional Hyd oponic Con en ional Van Gogh Desi ee DAP Figu e 2. Hyd oponically p oduced mini ube s oliage was de eloped slowe han by mini ube s p oduced in pea jas.ccsene .o g Jou nal o Ag icul u al Science Vol. 9, No. 1; 2017 46 Table 2. The p oduc ion o mini ube s was implemen ed wi h a hyd oponic echnique in g ow h- ooms and he ca y-o e e ec s o echnique on cha ac e is ics o mini ube s we e s udied Me hod Desi ee Van Gogh Hyd oponic Con en ional Hyd oponic Con en ional Hyd oponic Con en ional Eme gence (days a e plan ing) 22.5*** 17.2*** 24.6*** 17.4*** 20.4*** 16.8*** De elopmen ( oliage) 6.7. 20.0 18.0 20.0 18.0 20.0 18.0 19.7. 49.0 47.5 49.0 48.0 49.0 47.0 2.8. 60.5* 55.5* 59.0* 55.0* 62.0* 56.0* 19.8. 67.5 67.0 69.0 69.0 66.0 65.0 No. o s ems 1.6 1.7 1.5 1.7 1.7 1.8 No. o ube s 4.8 5.2 4.7 5.1 4.8 5.2 F esh w . o ube s (g/plan ) 174 208** 154 207*** 194 209 D y ma e con en o ube s (%) 22.8 24.0 20.5 22.0 25.0 26.0 No e. As a compa ison, mini ube s om in i o plan le s (con en ional) we e g own in a pea -based g owing medium. The cul i a s we e Desi ee and Van Gogh. S a is ically signi ican di e ences be ween me hods o cul i a s a *P = 0.05, **P = 0.01 and ***P = 0.001. The e we e no signi ican in e ac ions be ween o he p oduc ion me hods o cul i a s o any o he o he a iables measu ed. 0 20 40 60 80 100 120 Hyd oponic Con en ional Hyd oponic Con en ional Desi ee Van Gogh >50mm 40-50 mm 30-40 mm 15-30 mm g Figu e 3. A ca y-o e e ec o he p oduc ion me hods was ound in yielding, wi h con en ional pea p oduc ion ha ing a posi i e e ec on yield (g/plan ) (p = 0.005) and wi h a g ea e e ec in cul i a Desi ee han in cul i a Van Gogh 4. Discussion I is clea ly impo an ha he me hods used in mini ube p oduc ion a e cos e ec i e, he p oduc ion cha ac e is ics o he mini ube s, such as as a e o oliage de elopmen and high yielding capaci y, a e also desi able. In ou s udy Desi ee and Van Gogh oliage co e ed he en i e ays in he hyd oponic sys em wi hin 37 days a e plan ing and ube o ma ion o he Desi ee and Van Gogh cul i a s s a ed wi hin 41 days om plan ing, simila ly o he s udies o Chang e al. (2012) (wi hin 30-65 days, depending on he cul i a and he p oduc ion echnique). Yields (4.5-7.5 pe plan ) in his s udy a e compa able o he hyd oponic p oduc ion le els ob ained by Ri e e al. (2001); also wi h ega d o ube weigh (11-13 g). Tube o ma ion o he la e-ma u ing cul i a As e ix (63 days) was conside ably slowe han ha o Desi ee o Van Gogh, and also he a e age weigh o he ube s was lowe (6 g). Acco ding o Chang e al. (2008), hyd oponic p oduc ion echniques may no be a ou able wi h la e-ma u ing cul i a s because he nu ien solu ions may e a d oo and s olon g ow h. In he p esen s udy mini ube yield was highe in hyd oponic p oduc ion compa ed o pea -based p oduc ion. In con en ional mini ube p oduc ion (a pea -based g owing medium), oliage de elopmen occu ed almos 3 jas.ccsene .o g Jou nal o Ag icul u al Science Vol. 9, No. 1; 2017 47 weeks la e and also ube o ma ion s a ed app oxima ely 18 days la e in all cul i a s compa ed o hyd oponic p oduc ion. One aim o his s udy was also o in es iga e whe he hyd oponic p oduc ion echnology e ec s on g ow h and yield o p oduced mini ube s as ca y-o e e ec compa ed o pea p oduced mini ube s. In he ca y-o e s udy con en ionally p oduced mini ube s eme ged and de eloped as e and p oduced highe yields han hyd oponically p oduced mini ube s. The ca y-o e e ec s indica e ha mo e esea ch is needed o cla i y which cul i a s a e gene ically he bes sui ed in o hyd oponic p oduc ion and especially compa ison be ween ea ly and la e ma u ing cul i a s. In ou hyd oponic sys em, he pH and EC le els o he nu ien solu ions emained a he au oma ically egula ed le els. A i s lowes , he EC was 1.3 dS m -1 a he ime o igo ous oo g ow h, when he pH le el was a maximum o 6.2. The esul s a e consis en wi h he s udies o Chang e al. (2012) in which dec eased EC le els and inc eased pH le els we e ound o be indica i e o ac i e oo g ow h and apid in ake o nu ien s. The e we e no di e ences in he nu ien concen a ions o lea o ube samples be ween hyd oponic mini ube p oduc ion and mini ube s cul i a ed in con en ional pea -based g owing medium. Po a o does no equi e la ge amoun s o illumina ion o pho osyn hesize e ec i ely (Degaman e & an de Zaag, 1988), bu he amoun o ligh and he ela i e p opo ions o wa eleng hs should be sui able o pho osyn hesis (Ma hews, 2006; Yano sky e al., 1998). In he p esen s udy, he amoun o pho osyn he ically ac i e illumina ion, 2383-2509 μmol m -2 s -1 , p o ided a i icially by he g ow h oom mini ube p oduc ion en i onmen p o ed adequa e. In addi ion o illumina ion, empe a u e is ano he key ac o a ec ing ube o ma ion. Acco ding o Le y and Veilleux (2007), high nigh - ime empe a u es a e mo e damaging han high day ime empe a u es. In he p esen s udy he amoun o hea p oduced by he high-p essu e sodium lamps (4 × 400 W pe g ow h oom) could no be con olled e ec i ely enough wi h he ai condi ioning equipmen in use. This was e iden , in pa icula , as inadequa e di e ences be ween day ime and nigh - ime empe a u es in g ow h oom empe a u es o ca. 19-26 °C by day and 15-23 °C by nigh . Conclusion Ou s udy p o ides signi ican in o ma ion ega ding indoo hyd oponic mini ube p oduc ion sys em and a i icial simula ion o he p oduc ion en i onmen . In no he n condi ions (64-65°N), i a hyd oponic p oduc ion sys em is loca ed in an en i onmen , whe e na u al ligh is u ilized, makes i mo e di icul o achie e a combina ion o ligh in ensi y ha is op imal o plan g ow h and ube o ma ion. Based on he p esen s udy, indoo hyd oponic mini ube p oduc ion needs mo e esea ch, because he ca y-o e e ec s on he cha ac e is ics o mini ube s we e no clea and he o al ca y-o e yield needs o be imp o ed o achie e a leas he con en ional pea -based p oduc ion le el. Also mo e s udies a e needed o choosing cul i a s which a e op imal o be used in hyd oponic mini ube p oduc ion. 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