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Yolanta Saks, Lilian Sonego, and Ruth Ben-Arie

Mature-green `Anna' apples (Malus domestics Borkh.) reddened after harvest as a result of exposure to continuous cool-white fluorescent light. Color development was most rapid at 20C but most intense at 13C. At 2C, although the induction of red pigmentation was the slowest, a 72-hr exposure rendered color not significantly different from that of red, commercially harvested fruit. The development of color was light-intensity dependent, approaching saturation at 14.5 W·m-2 (at 13 C). No differences in fruit ripening were found between fruit that developed color under artificial light and red fruit from the commercial harvest, in spite of some stimulation of ethylene production during illumination.

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Theoharis Ouzounis, Eva Rosenqvist, and Carl-Otto Ottosen

. 2007 Effect of light wavelength on in vitro organogenesis of a Cattleya hybrid Acta Biol. Cracov. Ser. Bot. 49 113 118 Darko, E. Heydarizadeh, P. Schoefs, B. Sabzalian, M.R. 2014 Photosynthesis under artificial light: The shift in primary and secondary

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Katsumi Ohyama, Yoshitaka Omura, and Toyoki Kozai

Providing continuous light (24-h photoperiod) at a relatively low photosynthetic photon flux (PPF) is one possible way to reduce both initial and operational costs for lighting and cooling during transplant production with an artificial light. However, physiological disorders (i.e., chlorosis and necrosis) are often observed in several species under continuous light with a constant temperature. The objective of this study was to find an effective air-temperature regime under the continuous light to avoid such physiological disorders, and simultaneously enhance floral development, using tomato [Lycopersicon esculentum Mill.] as a model. The seedlings with fully expanded cotyledons were grown for 15 d at a PPF of 150 μmol·m–2·s–1, a relative humidity of 70%, and a CO2 concentration of about 380 μmol·mol–1 (atmospheric standard). Leaf chlorosis was observed when the air temperature was constant regardless of average air temperature (16, 22,or 28 °C). Neither leaf chlorosis nor necrosis was observed when the air temperatures were alternated [periods of high (28 °C) and low (16 °C) air temperatures of 16/8, 12/12, and 8/16 h·d–1]. Faster floral development was observed in the seedlings grown at lower average air temperatures. These results indicated that physiological disorders of tomato seedlings grown under continuous light could be avoided, and at the same time floral development could be enhanced, by lowering the average air temperature through modification of the periods of high and low air temperatures.

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Eva María Almansa, Antonio Espín, Rosa María Chica, and María Teresa Lao

In this work, we present the study of the behavior of 15 tomato cultivars under different grow lights to evaluate the quality of seedlings in the production system. The lamps used are: compact fluorescent, high-efficiency fluorescent, fluorescent, and pure blue light-emitting diodes (B-LEDs). The trial was carried out in a culture chamber with the temperature and relative humidity continuously controlled. Spectral radiation was measured at the canopy level. The following were quantified: fresh, dry biomass partitioning organs (leaves, stems, and roots), the total dry weight/total fresh weight relationship, shoot/root ratio, and indole acetic acid. We found high-efficiency fluorescent light treatment has a very interesting spectral quality for all cultivar applications as a result of it having the lowest photosynthetically active radiation (PAR):near infrared (NIR), blue:red (B:R), blue:far red (B:FR), and red:far red (R:FR) ratios; ‘Conquista’, ‘Velasco’, and ‘Lynna’ are cultivars that show sensitivity to special wavebands (ultraviolet, B, R, and FR). ‘Ikram’, ‘Saladar’, and ‘Delizia’ tolerate the lack of minimum energy and spectral quality.

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Toshio Shibuya, Kaori Itagaki, Motoaki Tojo, Ryosuke Endo, and Yoshiaki Kitaya

, closed-type transplant production systems (CTPS) that use artificial light have been developed as a way to produce high-quality transplants regardless of the weather ( Kozai, 2007 ; Kozai et al., 2006 ). The use of pesticides can be omitted, because the

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Shih-Wei Kong, Hsin-Ying Chung, Ming-Yi Chang, and Wei Fang

of the major differences between plant growth under sunlight and under artificial light. When grown under sunlight, in the same weather conditions, the amount of PPF will not vary too much whether the lettuce was young or matured. However, in a

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Kevin M. Folta and Sofia D. Carvalho

Leaf positioning of Arabidopsis in response to blue light Mol. Plant 1 15 26 Islam, M.A. Kuwar, G. Clarke, J.L. Blystad, D.-R. Gislerød, H.R. Olsen, J.E. Torre, S. 2012 Artificial light from light emitting diodes (LEDs) with a high portion of blue light

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Yuki Sago

Tipburn, a leaf marginal apex necrosis, is a serious problem in vegetable production under controlled environments ( Cox et al., 1976 ), such as in closed plant production systems equipped with artificial light ( Son and Takakura, 1989 ). Tipburn is

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Toshio Shibuya, Junki Komuro, Norio Hirai, Yoshiko Sakamoto, Ryosuke Endo, and Yoshiaki Kitaya

High-performance transplant production systems using artificial light have been developed as a way to produce high-quality transplants regardless of the weather ( Kozai, 2007 ; Kozai et al., 2006 ). The plants grown under the fluorescent lamps used

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Humberto Aguirre-Becerra, Juan Fernando García-Trejo, Cristina Vázquez-Hernández, Aurora Mariana Alvarado, Ana Angélica Feregrino-Pérez, Luis Miguel Contreras-Medina, and Ramón G. Guevara-Gonzalez

-saving because lamps were only activated from 4 to 12 h per day instead of all day long; this is a commonly used strategy in places where daylight provides an adequate amount of solar radiation. Results have suggested that adding hours of artificial light to the