Korean Journal of Environmental Agriculture Korean J Environ Agric (2013) Online ISSN: 2233-4173 Vol. 32, No. 2, pp. 123-127 http://dx.doi.org/10.5338/kjea.2013.32.2.123 Print ISSN: 1225-3537 Research Article Open Access 적색광을이용한국화의개화조절 홍성창, * 권순익, 김민경, 채미진, 정구복, 소규호 농촌진흥청국립농업과학원 Flowering Control by Using Red Light of Chrysanthemum Seung-Chang Hong, * Soon-Ik Kwon, Min-Kyeong Kim, Mi-Jin Chae, Goo-Bok Jung and Kyu-Ho So (Climate Change and Agroecology Division, National Academy of Agricultural Science (NAAS), RDA, 150 Suin-ro, Suwon 441-707, Republic of Korea) Received: 29 April 2013 / Revised: 9 May 2013 / Accepted: 11 June 2013 c 2013 The Korean Society of Environmental Agriculture This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract BACKGROUND: The incandescent bulb and compact fluorescent lamp are widely using as a light sources for daylength extension of chrysanthemum. But, these light sources consume a lot of electricity and have short longevity. A light-emitting diode (LED) is a semi conductor light source. LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime. In this study, we investigated the intensity of red light to control flowering of chrysanthemum (Dendranthema grandiflorum cv. Shinma ) by using LEDs. METHODS AND RESULTS: The red (660 nm) and far-red (730 nm) light were irradiated subsequently to investigate photo-reversible flowering responses of chrysanthemum. The flowering of chrysanthemum was inhibited by night interruption with red light but subsequently irradiated far-red light induced the flowering of chrysanthemum. This photoreversibility, reversion of the inductive effect of a brief red light pulse by a subsequent far-red light pulse, is a property of photo responses regulated by the plant photoreceptor phytochrome B. * 교신저자 (Corresponding author) Tel: +82-31-290-0224, Fax: +82-31-290-0206; Email: schongcb@korea.kr Four different intensity of red light of 0.7, 1.4, 2.1, and 2.8 μmol/m 2 /s (PAR) were irradiated at growth room in order to determine the threshold for floral inhibition of chrysanthemum. Over 1.4 μmol/m 2 /s of the red lights irradiated chrysanthemums were not flowered. The plant length, fresh weight, number of, and leaf area of chrysanthemum irradiated with red light were increased by 17%, 36%, 11%, and 48%, respectively, compared to those of compact fluorescent lamp. CONCLUSION(S): The red light and subsequential far-red light showed that the photoreversibility on flowering of chrysanthemum. The red light (1.4 μmol/m 2 /s of red LEDs) and white light (50 Lux of compact fluorescent lamp) have the same effect on inhibition of flowering in chrysanthemum. Additionally, the red light increased the plant height and dry weight of chrysanthemum. Key Words: Chrysanthemum, Daylength extension, Flowering, Photoreversibility, Red light intensity 서론 신속하고균일하고예측이가능한개화는원예식물재배시중요한요인이다. 원예작물의개화시기를조절하면출하시기를조절할수있고연중생산이가능하게된다 (Armitage and Laushaman, 1989). 일장은식물의생장과개화를조절하며, 식물의개화반응은밤길이에따라분류할수있다 123
124 HONG et al. (Thomas and Vince-Prue, 1997). 국화, 들깨와같은단일성식물의화아형성과개화는장야 ( 단일 ) 조건에서촉진되고 (Wilkins et al., 1990) 페츄니아와딸기같은장일성식물은단야 ( 장일 ) 조건에서화아가유도되거나개화한다 (Blanchard and Runkle, 2010). 원예재배농가들은일몰후또는밤의중간에인공광원을켜주어단일성식물과장일성식물의개화를조절한다 (Mattson and Erwin, 2005; Yamada et al., 2009; Blanchard and Runkle, 2010; Chen et al., 2010). 장일성식물과단일성식물은밤길이의조절로개화를조절할수있다. 인공광원을이용한밤길이조절방법에는일장연장처리, 밤중간에파야처리, 일출직전광처리등이있으며이러한밤길이조절방법들은모두각각의작물들이요구하는밤길이이하로조절될경우효과가동일하다 (Thomas and Vince-Prue, 1997; Hamaker, 1998; Runkle et al., 2012). 백열등 (Cathey et al., 1961; Cathey and Borthwick, 1961; Smith and Langhans, 1962), 형광등 (Canham, 1966), 고압나트륨램프 (Kadman-Zahavi et al., 1987; Blacquie re, 2002) 와같은다양한전기램프들이단일성식물의화아형성을억제하기위한파야처리를위해사용된다. 단일성식물은적색광의파야처리로개화가억제되고연속된초적색광처리로파야처리가무효화되므로단일처리의광은 Pfr형파이토크롬의형성에의존적이다 (Taiz and Zeiger, 2006). 적색광은국화와같은단일성식물의일장연장에의한개화조절에효율이높으나백열등, 형광등, 고압나트륨램프등으로적색광을조명하기는곤란하다. LED (Light-Emitting Diode) 는단일한광파장을방출하는반도체광원으로원예작물의개화조절을위해특정한광파장을선택적으로조명해줄수있는이점이있다. 또한 LED는전구식형광등이나백열등보다전기에너지를적게소비하고수명이길다. 그러나실용적으로사용될수있는적정한적색광강도는검토된바거의없다. 따라서본연구는적색 LED를이용한국화의일장연장처리기술을개발하기위하여국화의개화억제를위한적색광강도를구명하고생육에대한영향을검토하기위해수행하였다. 재료및방법개화의광가역성본연구는 2007년수원시에소재한국립농업과학원시험포장에서수행하였다. 적색광과초적색광의개화조절효과를검토하기위해 1/5,000a 와그너포트에원예용상토 ( 바로커상토, 서울바이오 ) 를균일하게충진한후국화 (Dendranthema grandiflorum cv. Shinma ) 를 9월 20일삽목하여비닐하우스에재배하였다. 각처리구의시험포트는자동관수장치를설치하여동일한수분상태를유지하였다. 파야처리를위해자체제작한적색 LED 장치 (200 6 3cm) 를지상으로부터 200 cm 높이에설치하여삽목직후부터적색광은 0.32 μ mol/m 2 /s, 초적색광은 0.25 0.36 μmol/m 2 /s 강도로처리하였다. 적색광처리구 (R) 는 24:00 부터 15분, 적색광직후초적색광순차처리구 (R-FR) 는 24:00 부터적색광 15분, 초적색광 15분처리되도록설치하였다. 적색광직후초적색광, 적색광처리구 (R-FR-R) 는 24:00 부터적색광 15분, 초적색광 15분, 적색광이 15분간점등되도록전자식타이머등을이용하여조절하였다. 모든처리구는국화의생장이충분히이루어져개화가유도될수있도록 11월 23일까지 90일간광처리한후개화및생육특성등을조사하였다. 시험에사용된적색 LED의중심파장은 660 nm, 초적색 LED의중심파장은 730 nm 이었다. 각처리별적색광과초적색광강도는광센서 SKP-215 (Skyeinstruments, UK) 를이용하여측정하였다. SKP-215 센서의측정범위는적색광은 648 673 nm, 초적색광은 718 743 nm 였다. 한계적색광강도 적색광강도별국화의개화억제효과를검토하기위하여인공광생육실에서 1/5,000a 와그너포트에국화를삽목한후재배하며적색광을처리하였다. 인공광생육실의온도는주 / 야 25 로유지하였고기본생육을위한광원은메탈할라이드램프를이용하여 PAR (Photosynthetic Active Radiation) 500 μmol/m 2 /s 강도로오전 6시부터오후 5시까지 11시간동안점등하여무처리구의기본일장이 11시간으로단일상태를유지하도록하였다. 적색광을이용한일장연장처리구는메탈할라이드램프가소등된직후자체제작한적색 LED 장치 (200 6 3 cm) 를이용하여오후 5시부터 10시까지 5 시간동안점등되어일장시간이 16 시간이되도록처리하였다. 적색광은각각 PAR 0.7, 1.4, 2.1, 2.8 μmol/m 2 /s 강도로처리하여재배하며국화의개화반응, 생육특성등을조사하였다. 각처리구의시험포트는자동관수장치를설치하여동일한수분상태를유지하였으며광차단판을설치하여인접광의간섭이없도록하였다. 각처리구별적색광강도는광센서 SKR-110 (Skyeinstruments, UK) 를이용하여측정하였다. 광센서 SKR-110의측정범위는 400 700nm 였다. 광원별일장연장 일장연장처리의광원별국화의개화와생육반응을검토하기위해비닐하우스에국화를정식한후 6월 1일부터 11 월 20일까지재배하며수행하였다. 일장연장처리는전구식형광등과적색 LED를이용하여각각오후 7시부터 12시까지 5시간동안일장연장처리하였다. 전구식형광등은 50 Lux, 적색광은 PAR 1.4 μmol/m 2 /s 강도로처리하였다. 일장연장처리후국화의개화와생육특성등을조사하였다. 적색광처리구의광강도는광센서 SKR-110 (Skyeinstruments, UK) 를이용하여측정하였다. 광센서 SKR-110의측정범위는 400 700 nm 였다. 통계분석은 R 통계패키지 (Ver 2.3) 를사용하였다.
Flowering Control by Using Red Light of Chrysanthemum 125 개화의광가역성 결과및고찰 국화개화의광가역성을검토하기위하여적색광과초적색광을이용하여파야처리후국화의개화와생육반응을조사한결과는 Table 1과같다. 적색광으로 15분간파야처리한 R 처리구는국화의개화가억제되었고, 적색광처리직후초적색광을처리한 R-FR 처리구는개화되었다. 또적색광, 초적색광, 적색광을순차적으로처리한 R-FR-R 처리구는 R 처리구와같이개화하지않아국화는개화의광가역성을나타냈다. R-FR 처리구는개화되어적색광에의한파야처리구보다국화의엽수는 27 %, 잎생체중은 57 %, 엽면적은 72 % 감소하였다. Table 1. Red and Far-red light reversibility of a night break on flowering and growth characteristics in chrysanthemum. Night-break treatment Height of plant flower bud R 47.0 38.3 0 R-FR 56.4 46.0 12 R-FR-R 61.2 51.8 0 R : Red light (660 nm), 0.32 μmol/m 2 /s FR : Far-red light (730 nm), 0.25 0.36 μmol/m 2 /s, Replication=1 Table 1의결과는 Thomas과 Vince-Prue (1997) 의단일성식물인도꼬마리 (Xanthium strumarium L.), 국화 (Dendranthema grandiflora L.), 콩 (Glycine max L.) 의파야처리와개화의광가역성반응과같은결과이다. 국화는전형적인장야식물이고한계밤길이이상의밤길이가경과될때개화한다. 국화는다른단일성식물들과유사하게짧은적색광파야처리로효과적으로개화가억제된다. 적색광처리후연속된초적색광처리에의해개화작용이무효화되는것은개화작용이파이토크롬이관련되기때문이다 (Borthwick and Cathey, 1962). Taiz과 Zeiger (2006) 는단일성식물이적색광의파야처리로개화가억제되고연속된초적색광처리 로파야처리가무효화되는것은파야처리는 Pfr형파이토크롬의형성에의존적이기때문이라고하였다. 적색광과초적색광은많은식물에서파이토크롬에의해흡수되고개화를조절한다. 파이토크롬은초적색광흡수형인 Pr형과적색광흡수형인 Pfr 형태로존재하며가역적반응을유도한다. 밤동안에 Pfr형파이토크롬은 Pr형으로전환되고 Pfr형파이토크롬이한계치이하로감소되면단일성식물의개화가유도된다 (Thomas and Vince-Prue, 1997). Thomas과 Vince-Prue (1997) 는단일성식물은파야처리하면단야조건이유기되어개화하지않고영양생장을계속하며이반응에는적색광이가장유효하다고하였다. Higuchia 등 (2012) 은국화를적색광으로파야처리하면전혀개화하지않았고, 청색광또는초적색광으로파야처리하면 100% 개화하였다고하였다. 따라서단일광파장을방출하는 LED 광원을이용해국화의개화를억제하기위해서는적색광이적합할것으로판단된다. 한계적색광강도국화의개화억제를위한한계적색광강도를검토하기위하여일몰후 5시간동안적색광을강도별로처리한후국화의개화와생육특성을조사한결과는 Table 2와 Fig. 1과같다. 국화는적색광 0.7 μmol/m 2 /s 처리구에서개화가억제되는경향이었으나화아 (flower bud) 가 1개출현하였다. 국화는적색광 1.4 μmol/m 2 /s 과 2.1, 2.8 μ mol/m 2 /s 처리구는전혀개화하지않았다. 따라서국화의개화억제를위한적색광의한계강도는 1.4 μmol/m 2 /s로판단된다. Matthew 등 (2009) 은고압나트륨램프를이용한국화의순환전조시개화억제를위한한계강도는 2.4 μmol/m 2 /s 이라했다. Cathey 과 Borthwick (1961) 는백열전구를이용한순환전조시국화의개화지연을위한한계강도는 1.1μmol/m 2 /s 이라했다. Armitage과 Laushaman (1989) 은 Velvet sage (Salvia leucantha) 는백열등 2, 3, 6μmol/m 2 /s에서모두개화하지않아한계광강도는 2 μmol/m 2 /s 라하였고 0.05 μ mol/m 2 /s 에서 1.3 μmol/m 2 /s 의광강도에서는모두개화하였다고하였다. Table 2. Flowering and growth characteristics affected by red light intensities for daylength extension in chrysanthemum. Light intensity (μmol/m 2 /s) Height of plant Fresh weight (g/plant) Area of (cm 2 /plant) flower bud Control (No daylength extension) 36.5 a 31 b 38.4 b 668 b 37 a 0.7 42.2 a 54 a 62.4 a 1167 a 1 b 1.4 43.4 a 46 ab 54.5 ab 1029 ab 0 b 2.1 39.7 a 48 ab 57.0 ab 1027 ab 0 b 2.8 44.4 a 49 ab 58.5 a 1365 a 0 b Means values within a columns followed by the same letter are not significantly different (P=0.05) by Duncan s multiple range test. Replication=3
126 HONG et al. Fig. 1. Flowering and growth characteristics affected by red light intensities for daylength extension in chrysanthemum. (From left to right no daylength extension, PAR 0.7, 1.4, 2.1, 2.8 μmol/m 2 /s treatments) Thomas과 Vince-Prue (1997) 는단일성식물은파야처리하면단야조건이유기되어개화하지않고영양생장을계속하며이반응에는적색광이가장유효하다고하였다. 또파이토크롬은초적색광흡수형인 Pr형과적색광흡수형인 Pfr 형태로존재하며가역적반응을유도하는데밤동안에 Pfr형파이토크롬은 Pr형으로전환되고 Pfr형파이토크롬이한계치이하로감소되면단일성식물의개화가유도된다고하였다. 따라서광원별로국화의개화한계광강도가다른것은광원별로파장분포가상이하고이에따라적색광의강도가다르기때문으로추정된다. 국화의개화억제를위한한계적색광강도를검토하기위해적색광을강도별로처리한후국화의개화와생육특성을조사한결과국화의초장과엽면적은적색광 2.8 μmol/m 2 /s 처리구에서가장컸고단일조건인무처리구는개화되어엽생체중과엽면적이적색광처리구보다감소하였다. 일장연장광원별개화특성국화에대한적색 LED의일장연장효과를검토하기위해관행의전구식형광등과적색 LED를이용하여일장연장처리후국화의개화와생육특성을조사한결과는 Table 3과같다. 적색 LED 처리구는관행의전구식형광등처리구와같이국화가개화하지않고영양생장을지속하였다. 전구식형광등 Table 3. Growth characteristics affected by different light sources for daylength extension in chrysanthemum Light source Height of plant Fresh weight of (g/plant) Area of ( cm2 / m2 ) Compact fluorescent lamp 85.0 58.6 718.3 47.3 Red LED 99.8 65.2 977.1 70.4 LSD 0.05 12.8 * ns ns 19.6 * Compact fluorescent lamp : 50 Lux, Red LED : 1.4 μ mol/m 2 /s (PAR) ns : not significant, replication=3 과적색 LED 처리구의초장과엽면적은유의한차이를나타내어적색 LED 처리구는전구식형광등처리구보다국화의초장이 17 %, 엽면적은 48 % 컸다. 국화의엽수와생체중은유의한차이는없었으나적색 LED 처리구가전구식형광등처리구보다엽수는 11 %, 엽생체중은 36 % 증가하는경향이었다. 이와같이적색 LED 처리구의국화의초장과엽면적이전구식형광등처리구보다증가한것은적색광에의한광합성촉진효과와 Pfr형파이토크롬의작용에의한것으로추정된다. 따라서적색광의생리작용과효과에관한추가적인연구가필요하다고판단된다. Saebo 등 (1995) 은적색광은광합성기구의발달에중요하고몇몇식물종에서는광합성산물이잎이외의기관으로이동하는것을억제하여잎에전분의축적이증가되도록한다고하였다. Kasperbauer과 Hamilton (1984) 은적색광을처리한담배잎은그라나가많고전분립의크기가크다고하였다. Higuchia 등 (2012) 은적색광으로파야처리시국화의개화는완전히억제되고국화의엽수는적색광파야처리가청색광이나초적색광처리보다많았다고하였다. Fig. 2. Scene of irradiation of daylength extension by using conventional compact fluorescent lamp (left) and red LED lighting device (right) in chrysanthemum at plastic house. Fig. 2는국화시험포장에서적색 LED와관행의전구식형광등을이용해일장연장처리하는전경이다. 요약 적색광을이용한국화의일장연장처리기술을개발하기위하여국화의개화억제를위한적색광강도를구명하고생육에대한영향을검토하였다. 국화는적색광에의한파야처리로개화가억제되었고연속된초적색광처리로개화하여개화의광가역적반응을나타냈다. 인공광생육실환경하에서적색광 1.4 μmol/m 2 /s (PAR) 로일장연장처리시국화의개화가완전히억제되었다. 적색광 1.4 μmol/m 2 /s 처리는관행의전구식형광등 50 Lux 처리와같이국화의개화를억제시켰다. 적색 LED를이용한일장연장처리로관행의전구식형광등처리보다국화의초장은 17 %, 엽면적은 48 % 유의하게증가하였고엽수와생체중은각각 11 %, 36 % 증가하는경향이었다.
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