Using different ratios of red and blue LEDs to improve the growth of strawberry plants

Transcription

1 Using different rtios of red nd blue LEDs to improve the growth of strwberry plnts M.T. Nznin 1,2,, M. Lefsrud 1, V. Grvel 3 nd X. Ho 2 1Bioresource Engineering Deprtment, McGill University, Cnd; 2 Hrrow Reserch nd Development Centre, Agriculture nd Agri-Food Cnd, Hrrow, Ontrio, Cnd; 3 Plnt Science Deprtment, McGill University, Cnd. Abstrct Red nd blue light emitting diodes (LEDs) re known to be effective for enhncing plnt growth. The im of this study ws to evlute the growth of strwberry plnts under different red:blue light rtios from LEDs compred with high pressure sodium lmps (HPS). In this study, three rtios of red (661 nm) to blue (449 nm) LED light (5:1, 1:1 nd 19:1) were pplied nd HPS ws used s control. Strwberry plnts cultured under different rtios of red to blue LEDs showed higher plnt height, lef, runner, inflorescence nd crown number, fresh mss, nd dry mss ccumultion thn tht of plnts cultured under HPS. The significntly higher fresh nd dry mss ccumultion were observed for strwberry plnts cultured under 1:1 nd 19:1 rtio of red to blue LEDs thn HPS. The tretment 19:1 rtio of red to blue LED ws significntly higher in inflorescences number nd crown number thn the other tretments. These results indicte tht inflorescence production of strwberry plnts is promoted by higher level of red to blue light. Keywords: Frgri nnss, high pressure sodium lmps, inflorescence number, light emitting diodes INTRODUCTION Strwberries (Frgri nnss) present unique combintion of nutrients, phytochemicls, nd fiber, which plys synergistic role in its chrcteriztion s functionl food (Bsu et l., 214). Compring ntioxidnt nd ntiprolifertive ctivities of common fruits, strwberries were rnked fourth, in both totl ntioxidnt ctivity nd inhibitory effects on humn liver cncer cells, while crnberries received the highest score on these prmeters (Sun et l., 22). Thus, while the overll grding of ntioxidnt index in these studies my vry depending on the nlyticl methods used, strwberries consistently receive higher rnking mong other fruits nd vegetbles (Bsu et l., 214). Light is n importnt fctor mong severl environmentl conditions ffecting crop growth, yield nd qulity. Light is the energy source for plnt photosynthesis nd contributes to signl stimulus in plnts, through light intensity, light qulity, nd dylength. Plnts perceive light signls through photoreceptors such s phytochromes, cryptochromes, nd phototropins. Consequently, most developmentl processes tht occur throughout the life cycle of plnts re dependent on light, including seed germintion, phototropism, grvitropism, chloroplst movement, shde voidnce, circdin rhythms, nd flower induction (Jio et l., 27; Crvlho et l., 211; Son nd Oh, 213). In the cse of growing crop under different light sources, ech culturl prctice must be differentited, becuse ech light source hs unique light qulity tht directly impcts plnt growth nd development. Among the electricl lighting sources used in plnt culture, light emitting diodes (LEDs) hve the dvntges of high light conversion efficiency with low rdint het output nd smll mss. LEDs cn be locted very close to the plnt nd the light qulity cn be optimized to improve crop growth (Morrow, 28). The response of plnts to red nd blue light hs been documented extensively (Tibbits et l., 1983; Schuerger et l., 1997). Studies hve shown tht red nd/or fr-red light ffect florl initition (Vince-Prue E-mil: ther.nznin@gr.gc.c Act Hortic ISHS 216. DOI /ActHortic Proc. VIII Int. Symp. on Light in Horticulture Eds.: C.J. Currey et l. 125

2 nd Guttridge, 1973), nd petiole length in strwberries (Vince-Prue et l., 1976). The purpose of this study ws to determine which rtio of red nd blue LED light ws optimum for the growth of strwberry plnt in greenhouse. MATERIALS AND METHODS Plnt culture Strwberry (Frgri nnss Albion ) (June-bering) plnts were plnted in one inch rockwool cubes in trys for soilless hydroponic culture with hlf-strength Hoglnd s solution nd trnsplnted in greenhouse. A m greenhouse room (set in northsouth orienttion) ws used for the experiment. Long wire-mesh tbles (1.2 m high) were used in order to ensure more even irflow. The tbles ( m) were set in the est west orienttion. Only the est wll of the greenhouse ws opened to the outside environment. Ech section ws surrounded by lyer of 2.44 m (8 feet) 6% shde cloth (8MK88, Hrnois, St-Thoms, QC) which limited light from directly reching the plnts nd reduced the cross-contmintion of light between tretments, permitting nlysis of ll sections independently. A shde cloth lyer ws instlled on top of ll the sections, between the roof nd electricl light source. The greenhouse set points were 21 C during the dy nd 16 C during the night. The supplementl lighting ws left on for 16 h dy -1, from 6: AM to 22: PM. A centrl computer in the greenhouse ws used for control. The internl greenhouse temperture ws monitored nd controlled; reltive humidity ws monitored, but not controlled. Strwberry plnts were hrvested fter 16 weeks. Light tretments Plnts were illuminted using different red:blue light rtios from by LEDs. Four light tretments were pplied in this study. Those were 5:1 (83.3% red % blue), 1:1 (9.9% red + 9.1% blue) nd 19:1 (95% red + 5% blue) rtios of red (661 nm) to blue (449 nm) LED light nd HPS light ws used s control. The photoperiod ws t 16/8 h (dy/night) nd photosynthetic photon flux density (PPFD) ws 12±5 μmol m -2 s -1. The LED rrys were prototypes from Generl Electric Lighting Solutions (Lchine, QC). These consisted of 1.78 m 8 cm 2 cm liner fixtures, on which were plced n rry of 16 LEDs. A reflective coting round ech LED permitted for better dispersion of the light. Wvelength distribution ws determined using spectrordiometer (PS-3, Apogee Instruments, Logn, UT, USA). PPFD ws mesured using Li-COR sphericl quntum sensor (LI-193; Lincoln, Nebrsk). Physiology nd biomss Plnt height, length of flowering stem, number of leves, runner, inflorescence, nd crown number of plnts were recorded every four weeks. The fresh mss (FM) of ech plnt ws determined immeditely fter hrvesting, nd their dry mss (DM) were determined fter drying in n oven t 12 C for no less thn 72 h, ASABE stndrd (27). Sttisticl nlysis The sttisticl nlysis ws mde using nlysis of vrince (ANOVA). Lest significnt differences were evluted by the Tukey-Krmer HSD (P<.5). The sttisticl nlysis ws performed by JMP softwre (SAS Institute, Cry, NC, USA). The results were expressed s men vlues nd their stndrd errors (SE) using MS Excel softwre. RESULTS AND DISCUSSION Growth nd morphologicl chrcteristics The tllest plnts were those grown under 1:1 red:blue light rtio but they ws not significntly different from those under 19:1 red:blue light rtio (Figure 1). Height ws 1.1, 1.2 nd 1.2 times higher for plnts under the 5:1, 1:1, nd 19:1 red:blue light rtio, respectively, compred to plnts under the HPS lmps (Figure 1). Plnt grown under HPS 126

3 lmps were significntly shorter those plnts cultured under different red:blue light rtios. Figure 1. Plnt height of strwberry cultured under high pressure sodium (HPS) lmps nd different red:blue light rtios. Vlues with different letters re significntly different from ech other. Vlues re the mens of 6 determintions (n=6). LSD (P<.5) ws determined ccording to Tukey-Krmer HSD tests. Lef number ws 1.3 times higher for plnts grown under the 1:1 red:blue light rtio compred to the HPS lmps (Figure 2A). Lef number per plnt ws 1.1, 1.3, nd 1.2 times higher for plnts grown under 5:1, 1:1, nd 19:1 red:blue light rtio, respectively, compred to the HPS light (Figure 2A). Plnts grown under 1:1 red:blue light rtio produced the gretest number of runners. For exmple, runner number ws 1.1, 1.4, nd 1.2 times higher for plnts grown under 5:1, 1:1, nd 19:1 red:blue light rtio, respectively, compred to plnts under HPS lmps (Figure 2B). Lef number per plnt (A) b b,c b,c Runner number per plnt HPS 5.1 5: : :1 HPS 5.1 5: :1 19: (B) b c b,d Figure 2. Lef nd runner number of strwberry plnts cultured under under high pressure sodium (HPS) lmps nd different red:blue light rtios. Vlues with different letters re significntly different from ech other. Vlues re the mens of 6 determintions (n=6). LSD (P<.5) ws determined ccording to Tukey-Krmer HSD tests. Inflorescences number ws 1.1, 1.2, nd 1.4 times higher for plnts under 5:1, 1:1, nd 19:1 red:blue light rtios, respectively, compred to plnts under HPS lmps (Figure 3A). Similr tendency ws observed in crown number per plnt. Plnts grown under 19:1 red:blue light rtio hd the gretest crown number. For exmple, crown number ws 1., 1.2, nd 1.5 times higher for plnts grown under 5:1, 1:1, nd 19:1 red:blue light rtio compred to plnts under HPS lmps (Figure 3B). 127

4 Figure 3. Inflorescences nd crown number of strwberry plnts cultured under high pressure sodium (HPS) lmps nd different red:blue light rtios. Vlues with different letters re significntly different from ech other. Vlues re the mens of 6 determintions (n=6). LSD (P<.5) ws determined ccording to Tukey- Krmer HSD tests. The longest flowering stems were observed on plnts cultured under LEDs with no sttisticl difference between the LED tretments (dt not shown). Strwberry plnts cultured under LEDs hd flowering stem tht were 1.3 time longer thn those cultured under HPS lmps (Figure 4). Figure 4. Length of flowering stem of strwberry plnts cultured under high pressure sodium (HPS) lmps nd different red:blue light rtios. Vlues with different letters re significntly different from ech other. Vlues re the mens of 6 determintions (n=6). LSD (P<.5) ws determined ccording to Tukey- Krmer HSD tests. Fresh nd dry mss of strwberry plnts cultured under the different red:blue light rtios were higher thn those plnts cultured under HPS lmps (Figure 5). The fresh mss ws 1.1, 1.1, nd 1.3 times higher for plnts under the 5:1, 1:1 nd 19:1 red:blue light rtios, respectively, to plnts under the HPS lmps. Wheres, dry mss ws 1.2, 1.5, nd 1.6 times higher for plnts under the 5:1, 1:1, nd 19:1 red:blue light rtios, respectively, compred to HPS lmps. 128

5 Fresh mss (g/plnt) (A) b b,c c,d Dry mss (g/plnt) (B) 8 c,d c,d 6 b 4 2 HPS 5.1 5: :1 19: HPS 5: : :1 Figure 5. Fresh nd dry mss ccumultion of strwberry plnts cultured under high pressure sodium (HPS) lmps nd different red:blue light rtios. Vlues with different letters re significntly different from ech other. Vlues re the mens of 6 determintions (n=6). LSD (P<.5) ws determined ccording to Tukey- Krmer HSD tests. Results from the present study indicted tht plnt height, lef, runner, inflorescence, nd crown number nd length of the flowering stem were gretest in strwberries grown under different rtios of red to blue light. This mens tht using mixture of red nd blue light resulted in greter plnt growth thn tht of the broder spectrum of HPS lmps. It is known tht different light spectr impct the blnce between growth nd development of the plnts. Previous reserch hs shown positive influence of red nd blue light on the formtion of strwberry runners, inflorescences nd crowns (Brown et l., 1995; Smuoliene et l., 21). According to our dt, the highest fresh nd dry mss ccumultion ws observed under 19:1 red:blue light rtio nd lowest under HPS lmps. Among the three rtios of red to blue we observed tht fresh nd dry mss decresed with incresing of blue LEDs light. This is logicl becuse reltive quntum efficiency of red wvelengths is greter thn tht of the blue wvelengths; for exmple, Smuoliene et l. (21) showed tht the totl dry mss ws slightly lower for strwberries grown under red (64 nm) to blue (455 nm) (R 87% + B 13%) light compred to monochromtic red (64 nm) light. In contrst, Yorio et l. (21) stted tht totl dry-mss ccumultion ws significntly higher for rdish nd spinch when grown under red to blue (R 9%+ B 1%) light thn when grown under red LEDs lone. Perhps, fresh mss nd dry mss ccumultion response under the combintion of red nd blue lights re species specific. ACKNOWLEDGEMENTS This work ws supported by the Fonds de recherche du Que bec - Nture et technologies (FRQNT), Cnd. Literture cited Bsu, A., Nguyen, A., Betts, N.M., nd Lyons, T.J. (214). Strwberry s functionl food: n evidence-bsed review. Crit Rev Food Sci Nutr 54 (6), PubMed Brown, C.S., Schuerger, A.C., nd Sger, J.C. (1995). Growth nd photomorphogenesis of pepper plnts under red light-emitting diodes with supplementl blue or fr-red lighting. J. Am. Soc. Hortic. Sci. 12 (5), PubMed Crvlho, R.F., Tkki, M., nd Azevedo, R.A. (211). Plnt pigments: the mny fces of light perception. Act Physiol. Plnt. 33 (2), Jio, Y., Lu, O.S., nd Deng, X.W. (27). Light-regulted trnscriptionl networks in higher plnts. Nt. Rev. Genet. 8 (3), PubMed Morrow, R.C. (28). LED lighting in horticulture. HortScience 43, Smuoliene, G., Brzityte, A., Urbonvic iu te, A., S bjeviene, G., nd Duchovskis, P. (21). The effect of red nd blue light component on the growth nd development of frigo strwberries. Zemdirbyste-Agri. 97, Schuerger, A.C., Brown, C.S., nd Stryjewski, E.C. (1997). Antomicl fetures of pepper plnts (Cpsicum nnuum 129

6 L.) grown under red light-emitting diodes supplemented with blue or fr-red light. Ann. Bot. 79 (3), PubMed Son, K.-H., nd Oh, M.-M. (213). Lef shpe, growth, nd ntioxidnt phenolic compounds of two lettuce cultivrs grown under vrious combintions of blue nd red light-emitting diodes. HortScience 48, Sun, J., Chu, Y.F., Wu, X., nd Liu, R.H. (22). Antioxidnt nd ntiprolifertive ctivities of common fruits. J. Agric. Food Chem. 5 (25), PubMed Tibbits, T.W., Morgn, D.C., nd Wrrington, J.J. (1983). Growth of lettuce, spinch, mustrd nd whet plnts under four combintions of high-pressure sodium, metl hlide nd tungsten hlogen lmps t equl PPFD. J. Am. Hort. Sci. 18, Vince-Prue, D., nd Guttridge, C.G. (1973). Florl initition in strwberry: spectrl evidence for the regultion of flowering by long-dy inhibition. Plnt 11 (2), PubMed Vince-Prue, D., Guttridge, C.G., nd Buck, M.W. (1976). Photocontrol of petiole elongtion in light-grown strwberry plnts. Plnt 131 (2), PubMed Yorio, N.C., Goins, G.D., Kgie, H.R., Wheeler, R.M., nd Sger, J.C. (21). Improving spinch, rdish, nd lettuce growth under red light-emitting diodes (LEDs) with blue light supplementtion. HortScience 36 (2), PubMed 13