RESEARCH ARTICLE https://doi.org/10.12972/kjhst.20170047 Growth of Runner Plnts Grown in Plnt Fctor s Affected b Light Intensit nd Continer Volume Seon Woo Prk 1, Yurin Kwck 2, nd Chnghoo Chun 1,3* 1 Deprtment of Plnt Science, Seoul Ntionl Universit, Seoul 08826, Kore 2 Division of Eco-Friendl Horticulture, Yonm College, Cheonn 35, Kore 3 Reserch Institute for Agriculture nd Life Sciences, Seoul Ntionl Universit, Seoul 08826, Kore *Corresponding uthor: chnghoo@snu.c.kr Abstrct Received: Revised: HORTICULTURAL SCIENCE nd TECHNOLOGY 35(4):439-445, 2017 URL: http://www.kjhst.org pissn : 1226-8763 eissn : 2465-8588 Mrch 13, 2017 M 8, 2017 Accepted: M 31, 2017 OPEN ACCESS This is n Open-Access rticle distributed under the terms of the Cretive Commons Attribution NonCommercil License which permits unrestricted non-commercil use, distribution, nd reproduction in n medium, provided the originl work is properl cited. Coprightc2017 Koren Societ for Horticulturl Science. This stud ws supported b the Ntionl Joint Agriculturl Reserch Project (Project No. PJ907003082015) of the Rurl Development Administrtion, Kore. Trnsplnt production in plnt fctor with rtificil lighting provides severl benefits; (1) rpid nd uniform trnsplnt production, (2) high production rte per unit re, nd (3) production of disese free trnsplnts production. To improve the growth of runner plnts when strwberr trnsplnts re produced in plnt fctor, we conducted two experiments to investigte (1) the effect of different light intensit for stock nd runner plnts on the growth of runner plnts, nd (2) the effect of different continer volume for runner plnts on their growth. When the stock nd runner plnts were grown under nine different light conditions composed of three different light intensities (, 200, nd 400 μmol m 2 s 1 PPF) for ech stock nd runner plnts, incresing the light intensit for stock plnts promoted the growth of runner plnts, however, the growth of runner plnts ws not enhnced b incresing the light intensit for runner plnts under sme light intensit condition for stock plnts. We lso cultivted runner plnts using plug trs with four different continer volumes (21, 34, 73, nd 150 ml) for 20 ds fter plcing the stock plnts, nd found tht using plug trs with lger continer volume did not enhnce the growth of runner plnts. These results indicte tht providing optiml condition for stock plnts, rther thn the runner plnts, is more importnt for incresing the growth of the runner plnts nd tht the efficienc of strwberr trnsplnt production in plnt fctor cn be improved b decresing light intensit or continer volume for runner plnts. Additionl ke words: Frgri x nnss, photosnthetic photon flux (PPF), plug tr, trnsplnt production, vegettive propgtion. Introduction A form of sexul reproduction in strwberries is clonl growth, in which runner plnts derive from runners nd remin ttched to their stock plnts until their roots re sufficient to support themselves (Alpert nd Moone, 1986). The runner plnts originte t runner tips; their leves grow first, nd then their roots nd runners re formed (Nishiw, 1994; Sito et l., 2008). The runners between the stock plnts nd the runner plnts trnsfer resources from the stock plnts to the runner plnts to support growth Horticulturl Science nd Technolog 439
(Roilo et l., 2007). When stock nd runner plnts grow in heterogeneous environments, the shre resources with ech other to procure insufficient resources in their respective environments (Alpert nd Stuefer, 1997). The runners in short-d cultivrs grown in Kore re generted under long d conditions nd high tempertures (Verheul et l., 2006; Zhedi nd Srikhni, 2016), nd their production rtes increse under high photosnthetic photon flux (PPF) nd CO 2 concentrtions (Chen et l., 1997; Kim et l., 2010). Using plnt fctor with rtificil lighting tht specilies in trnsplnt production, in which environmentl conditions cn be esil controlled, is pproprite for rpid nd er- round trnsplnt production. However, it is difficult to ppl the conventionl strwberr propgtion methods to plnt fctor becuse the sie of stock plnts used in the conventionl propgtion method is too lrge. Koi (2016) suggested tht the pproprite height of trnsplnts produced in plnt fctor should be less thn 15 cm to mintin dequte ir current nd reltive humidit, while the height of stock plnts used in the conventionl propgtion method is pproximtel 25 cm nd the length of their lef blde nd petiole re c. 5 nd 20 cm, respectivel (Kim et l., 2010; Konsin et l., 2001). To overcome the limittions of the conventionl propgtion methods for trnsplnts production in plnt fctor with multilered shelves, Chun et l. (2012) developed propgtion method clled the utotrophic trnsplnt production method (ATPM). This method is performed s follows: (1) stock plnts whose sie (crown dimeter: c. 5 mm) is smller thn tht for conventionl methods (9-13 mm; RDA, 2013) re used, (2) runner tips tht hve unfolded their brct (generted from the stock plnts) re fixed on medium in 150 ml pots, (3) runner plnts derived from the runner tips re seprted from their stock plnts when their crown dimeter reches the initil sie of the stock plnts (c. 20 ds fter plcing stock plnts), nd (4) the re then used s new stock plnts for next propgtion ccle. We hpothesied tht, if ll of the runner plnts nutrients nd wter cn be received from stock plnts nd unfvorble environmentl conditions for runner plnts do not ffect their growth while the re still connected with their stock plnts, the efficienc of trnsplnt production b ATPM in plnt fctor cn be improved b decresing the light intensit or continer volume for the runner plnts. To confirm these hpotheses, we investigted (1) the effect of different light intensities pplied to both stock nd runner plnts on the growth of runner plnts, nd (2) the effect of different continer volumes for runner plnts on the growth of runner plnts. Mterils nd Methods Plnt Mterils Used for Stock Plnts Strwberr plnts (Frgri nnss Duch. cv. Mehng) used for stock plnts were selected bsed on crown dimeter of 5.0 ± 0.5 mm. Selected stock plnts hd two compound leves nd one runner with n unfolded brct. The were plnted into 150 ml continers using 32- cell cutting plug tr (Bumnong Co. Ltd., Jeongeup, Kore) filled with commercil medium (Plnt World; Nongwoo Bio Co. Ltd., Suwon, Kore). Growth of Stock Plnts nd Runner Plnts s Affected b PPF Level Six stock plnts, plnted in 150 ml continers, were rrnged in row on the bed nd their runners were fixed in 150 ml continers filled with commercil medium for the formtion of runner plnts. The distnce between plnts in row ws 120 mm nd between rows ws 240 mm. Nine different tretments composed of three different light intensities were pplied to both 440 Horticulturl Science nd Technolog
stock nd runner plnts; PPF (104.8 ± 6.9 µmol m -2 s -1 ), 200 (192.5 ± 5.6 µmol m -2 s -1 ), nd 400 (391.7 ± 12.8 µmol m -2 s -1 ). Light intensit ws controlled b chnging the number of 32W cool white fluorescent lmps or using tinted films. Air temperture during the light/drk-period ws mintined t 27 C/23 C, nd the photo-period nd CO 2 concentrtion were 16 h nd 800 µmol mol -1, respectivel. A closed irrigtion sstem ws used in the plnt fctor nd plnts were sub-irrigted with Ymki nutrient solution for strwberries (EC 0.7 ds m -1 ; Ymki, 1982) for 10 minutes once d. At 20 ds fter plcing (DAP), six stock nd runner plnts from ech tretment were selected, nd the number of compound leves nd runners, crown dimeter, lef re, nd dr weight were mesured. Growth of Runner Plnts s Affected b Continer Volumes Six stock plnts, plnted in 150 ml continers, were rrnged in row on the bed nd the distnce between plnts in row ws 120 mm. We set four tretments with different continer volumes (21, 34, 73, nd 150 ml) using 32, 50, 72, nd 128-cell cutting plug trs (Bumnong Co. Ltd., Jeongeup, Kore) for runner plnts. Runner tips from stock plnts were fixed into continers with different volumes nd cultivted for 20 ds in plnt fctor. The light intensit nd photo-period were 210 µmol m -2 s -1 nd 16 h, respectivel. Air temperture during the light/drk-period ws mintined t 27 C/23 C nd CO 2 concentrtion ws 800µmol mol -1. A closed irrigtion sstem ws used in the plnt fctor nd plnts were sub-irrigted with Ymki nutrient solution for strwberries (EC 0.7 ds m -1 ; Ymki, 1982) for 10 minutes once d. At 20 DAP, 15 runner plnts from ech tretment were selected, nd the number of compound leves nd runners, crown dimeter, lef re, nd dr weight were mesured. To investigte the subsequent growth of runner plnts fter being seprted from their stock plnts, ten runner plnts seprted t 20 DAP were trnsplnted into plstic pots (ø 90 mm) filled with the commercil medium nd grown for 35 ds in greenhouse locted in Suwon, Kore (E 127.0, N 37.3 ). 35 ds fter trnsplnting, the number of compound leves nd runners, crown dimeter, lef re, nd dr weight were mesured. Dt Anlsis The experimentl dt ws nled using SAS 9.2 (SAS Institute Inc., Cr, NC, USA) with Duncn s multiple rnge tests. Tretment differences were considered significnt t level of 5% probbilit. Results nd Discussion Growth of Stock Plnts nd Runner Plnts s Affected b PPF Levels Tbles 1 nd 2 show the growth of stock plnts nd runner plnts, respectivel, s ffected b PPF level t 20 DAP. The growth of both stock nd runner plnts ws gretest when both were grown under 400 µmol m -1 s -1, nd those incresed s PPF elevted. The growth of the runner plnts ws ffected b the PPF of their stock plnts regrdless of their own PPF level. The dr weight of leves in the stock plnts ws ffected b PPF regrdless of their runner plnts PPF levels; however, their root, runner, nd totl dr weights were ffected b the PPFs of both the stock nd their runner plnts. When considering the sum of the PPF pplied to both stock nd runner plnts [ 600 (400 + 200 or 200 + 400; stock plnt + runner plnt), 500 (400 + or + 400), 300 (200 + or + 200)], the totl dr weight of stock nd runner plnts incresed s the PPF of the stock plnts incresed. Kim et l. (2010) reported tht incresing PPF levels promoted the formtion of runners nd runner plnts in closed trnsplnt Horticulturl Science nd Technolog 441
Tble 1. Growth nd develpment of stock plnts in Mehng strwberr s ffected b photosnthetic photon fluxes (PPFs) for ech stock plnts nd runner plnts t 20 ds fter plcing the stock plnts in plnt fctor. PPF No. of leves No. of leves Crown dimeter Dr weight (g / plnt) S R per plnt per plnt (mm) Leves x Crown Roots Runners Totl P400 P400 5.0 w 4.0 7.1 1.56 0.09 0.26 0.42 2.35 P200 4.5bc 2.7b 6.7 1.38b 0.09 0.22b 0.21b 1.90b P 4.2bc 2.2bc 6.7 1.38b 0.08b 0.21b 0.16c 1.83bc P200 P400 4.5bc 1.8bcd 6.3 1.26b 0.08b 0.21b 0.13cd 1.68c P200 4.2bc 1.2cde 6.4 1.09c 0.08b 0.20b 0.10de 1.47d P 4.7 b 1.8 bcd 6.2 b 1.06 c 0.08 b 0.17 c 0.07 ef 1.39 de P P400 4.7 b 0.8 de 6.1 b 0.98 cd 0.08 b 0.17 c 0.05 fg 1.27 e Significnce P200 4.2 bc 0.8 de 6.1 b 1.01 c 0.08 b 0.14 d 0.02 g 1.26 e P 4.0 c 0.5 e 5.5 b 0.85 d 0.07 b 0.11 d 0.02 g 1.06 f S ns v ** ** ** ns ** ** ** R * ns ns ns ns ** ** * S X R * * ** ** ns ** ** ** PPF levels for stock plnts. PPF levels for runner plnts. x Lef bldes + petioles. w Men seprtion within columns b Duncn s multiple rnge test t 5%. v ns: non-significnt; *: significnt t p < 0.05; **: significnt t p < 0.01. production sstem until 280 µmol m -2 s -1. In this stud, the number nd dr weight of runners derived from runner plnts were not significntl ffected b the runner plnts PPF level. However, the number nd dr weight of runners from stock plnts incresed s their PPF level incresed. In clonl plnts, such s strwberr, ssimiltes nd nutrients tend to move from older to ounger plnts becuse the diffuse from higher to lower concentrtions until the sstem equilibrtes, nd ssimilte nd nutrient pools of older plnts re commonl greter thn those of ounger plnts (Crco nd Kell, 1991). Fig. 1 shows tht proportion of ech orgn in totl dr weight of the stock plnts. Proportion of leves decresed s the PPFs pplied to both stock nd runner plnts incresed while tht of crown decresed s PPF for stock plnts incresed. Strwberr plnts connected to ech other m overcome light deficienc b trnslocting ssimiltes from plnt with high suppl to plnt with low suppl b enhncing the lef growth of the plnts exposed to higher light intensit (Roil et l., 2007). However, ssimiltes produced b the runner plnts might be used for estblishment of them until 20 DAP s the could not grow independentl, nd the might ttrct ssimiltes nd nutrients from connected stock plnts due to ounger thn the stock plnts (Alpert, 1996; Friedmn nd Alpert, 1991; Svini et l., 2008). As ssimiltes increse under higher light intensities (Kinet et l., 1985) nd runner plnts under lower PPF might ttrct more ssimiltes from their stock plnts, the proportionl weight of leves in the stock plnts might be higher when the PPF pplied to the runners is lower. Proportion of runner enhnced s the PPFs on both the stock nd runner plnts incresed (Fig. 1), nd the dr weight of their runners lso promoted s both PPFs incresed (Tble 1). However, proportion of the runner plnts ws not significntl different b both PPF levels, while totl dr weight of them incresed when onl the PPF for stock plnts incresed (Tble 2). Runner growth depends on the mount of surplus resources for propgules becuse new runner ppers onl when plnts hve sufficient resources (Alpert, 1991). Therefore, propgtion rte will enhnce s PPFs on both the stock nd runner plnts until c. 442 Horticulturl Science nd Technolog
400 µmol m -2 s -1, nd runner plnts under unfvorble environment conditions such s low light intensit b shding cn be grow sufficientl b receiving ssimiltes or nutrients from stock plnts growing under fvorble environment conditions. Tble 2. Growth nd develpment of stock plnts in Mehng strwberr s ffected b photosnthetic photon fluxes (PPFs) for ech stock plnts nd runner plnts t 20 ds fter plcing the stock plnts in plnt fctor. PPF No. of leves No. of leves Crown dimeter Dr weight (g / plnt) S R per plnt per plnt (mm) Leves x Crown Roots Runners Totl P400 P400 2.6 w 2.2 6.1 0.66 0.06 0.14 0.28 1.15 P200 2.3 1.8b 5.7b 0.61 0.06b 0.13b 0.23b 1.04b P 2.2 1.7bc 5.7b 0.59 0.05bc 0.12b 0.24b 1.00b P200 P400 2.3 1.5bc 5.6b 0.47b 0.05bc 0.09c 0.23b 0.83c P200 2.3 1.5bc 5.6b 0.46b 0.05bc 0.08cd 0.23b 0.81c P 2.5 1.2 bc 5.3 bc 0.45 b 0.05 bcd 0.07 de 0.20 b 0.78 c P P400 2.3 1.3 bc 5.5 bc 0.39 bc 0.05 cd 0.06 ef 0.12 c 0.62 d Significnce P200 2.2 1.2 bc 5.1 bc 0.38 bc 0.05 cd 0.05 f 0.11 c 0.59 d P 2.1 1.0 c 4.8 c 0.34 c 0.04 d 0.03 g 0.10 c 0.51 d S ns v ** ** ** ** ** ** ** R ns ns ns ns ns ns ns ns S X R ns ** ns ** ** ** ** ** PPF levels for stock plnts. PPF levels for runner plnts. x Lef bldes + petioles. w Men seprtion within columns b Duncn s multiple rnge test t 5%. v ns: non-significnt; *: significnt t p < 0.05; **: significnt t p < 0.01. 120 Runners Runner plnts Leves Crown Roots % orgn dr weight 80 60 40 b bc cd bc bc cd d 20 b bc bcd d cd d 0 Runner plnt Stock plnt b b b b b b b 200 400 200 400 PPF ( µmol m -2 s -1 ) Fig. 1. Proportion of ech orgn in the totl dr weight of stock plnts in Mehng strwberr s ffected b the light intensit pplied to stock nd runner plnts 20 ds fter plcing in plnt fctor. Letters, -e indicte significnt differences ccording to Duncn s multiple rnge test t p 5% (n = 6). 200 400 Horticulturl Science nd Technolog 443
Growth of Runner Plnts s Affected b Continer Volumes We found tht the growth of runner plnts ws dependent on the light intensit pplied to the stock plnts but not on the light intensit pplied to the runner plnts. We hpothesied tht using smll volume continers for runner plnts, which would decrese the distnce between stock nd runner plnts nd might decrese the light intensit for runner plnts due to shding, would not negtivel ffect their growth. To confirm this hpothesis, we investigted the effect of different continer volumes on the growth of runner plnts. The numbers of leves nd runners, crown dimeter, lef re, nd dr weight of runner plnts were not significntl ffected b continer volume (Tble 3). We fixed runner tips whose brct hd just unfolded nd where the root hd not et been estblished. The roots emerged fter pproximtel 6 DAP nd grew s much s possible until being seprted from the stock plnt t 20 DAP (Prk et l., 2008). Until this point, the might receive wter nd minerl nutrients from their stock plnts due the immturit of their own roots (Alpert nd Moone, 1986; Friedmn nd Alpert, 1991). Moreover, s strwberr is clonl, runner plnts connected to their stock plnts cn overcome stress induced b environmentl conditions through support from the stock plnts (Crco nd Kell, 1991). In prticulr, potentil wter grdient m exist from stock plnt to runner when the runner plnt hs not rooted (Alpert nd Moone, 1986). As roots of the runner plnts grew for just 14 ds nd runner plnts cn receive wter from their stock plnts, those grown in the smllest continers (21 ml/cell) did not show reduction in growth due to the smll continer volume. Runner plnts seprted from their stock plnts t 20 DAP were trnsplnted into pots nd grown until 35 ds fter trnsplnting. Tble 4 shows growth nd development of runner plnts 35 ds fter trnsplnting. The growth of runner plnts fter trnsplnting into lrger continers ws not reduced b decresing the continer volume before seprting. Therefore, until 20 DAP, runner plnts connected with their stock plnts cn be grown in 21 ml continers, which will both reduce the quntit of medium consumed nd increse spce efficienc when strwberr trnsplnts re produced in plnt fctor. Tble 3. Growth of runner plnts in Mehng strwberr s ffected b continer volumes t 20 ds fter plcing the stock plnts in plnt fctor. Cell volume Dr weight (g/plnt) No. of leves No. of runners Crown dimeter Lef re per plnt per plnt (mm) (cm 2 Crown + /plnt) Leves Runners Roots Totl petioles 21 ml 2.7 1.2 5.24 59.9 0.30 0.25 0.15 0.05 0.74 34 ml 2.7 1.2 5.26 62.9 0.30 0.25 0.15 0.05 0.76 73 ml 2.6 1.3 5.11 63.0 0.30 0.24 0.16 0.06 0.76 150 ml 2.8 1.3 5.27 66.7 0.31 0.24 0.15 0.06 0.76 Volume of the runner plnt continer while connected to their stock plnts. Men seprtion within columns b Duncn s multiple rnge test t 5%. Tble 4. Growth of runner plnts in Mehng strwberr t 35 ds fter trnsplnting in greenhouse s ffected b continer volumes during connecting on their stock plnts. Cell volume Dr weight (g/plnt) No. of leves No. of runners Crown dimeter Lef re per plnt per plnt (mm) (cm 2 Crown + /plnt) Leves Runners Roots Totl petioles 21 ml 6.9 3.0 9.41 385.2 1.56 1.81 0.40 0.71 4.23 34 ml 6.8 3.2 9.06 366.2 1.42 1.76 0.37 0.63 3.81 73 ml 6.9 3.3 9.30 369.0 1.38 1.56 0.35 0.68 3.86 150 ml 6.6 3.1 9.13 357.1 1.39 1.58 0.40 0.61 4.24 Volume of the runner plnt continer while connected to their stock plnts. Men seprtion within columns b Duncn s multiple rnge test t 5%. 444 Horticulturl Science nd Technolog
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