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W. Garrett Owen, Qingwu Meng, and Roberto G. Lopez

et al., 1998 ; Whitman et al., 1998 ). The spectral distribution of photoperiodic lighting influences regulation of flowering in photoperiodic crops. Red [R (600–700 nm)] and far-red [FR (700–800 nm)] radiation can mediate activities of phytochrome B

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Anusuya Rangarajan and Theodore W. Tibbitts

Oedema, a physiological disorder, affects several cultivars of ivy geranium [Pelargonium peltatum (L.) L `Hér. ex Ait) when grown in greenhouses. This study investigated the regulation of oedema on this crop using far-red radiation because these wavelengths inhibited the injury on Solanaceous sp. Plants were exposed to far-red radiation from Sylvania #232 far-red lamps on abaxial and adaxial surfaces of leaves. A far-red photon flux of 15 to 20 μmol·m-2·s-1 (700-S00 nm) was not effective in preventing oedema injury. A far-red abaxial treatment during the light period tended to reduce the amount of injury that developed when photosynthetic photon flux was low (130-170 μmol·m-2·s-1), but this inhibition of the injury was absent with higher photon flux. The results from these studies indicate the use of supplemental far-red radiation treatments in greenhouses would not be justified because adequate and consistent control of the injury on ivy geraniums was not achieved.

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Joshua K. Craver, Jennifer K. Boldt, and Roberto G. Lopez

state for photoperiod-sensitive species. Far-red radiation has a significant effect in the processes of stem elongation and flowering ( Downs and Thomas, 1982 ). For example, a deficiency in far-red radiation has often been found to delay flower

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D. Michael Glenn and G.J. Puterka

) (400–700 nm), and near-infrared radiation (NIR) (700–1100 nm) reflection from a reflective film and a resulting increased air temperature within the canopy and found that the red light/far-red light ratio (R/FR) of the reflective film was similar to

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Kellie J. Walters, Allison A. Hurt, and Roberto G. Lopez

(600–700 nm)], and far-red [FR (700–800 nm)] radiation, total photon flux density ( TPFD ), light ratio, and estimated phytochrome photoequilibria [P FR /P R+FR (the proportion of FR-absorbing phytochromes in the pool of R- and FR

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Steven P. Arthurs, Robert H. Stamps, and Frank F. Giglia

). Fig. 2. Photosynthetically active radiation ( PAR ) measured at solar noon (μmol·m −2 ·s −1 , 400 to 700 nm) in photoselective (red and blue) and color-neutral (black and pearl) nets. Data are means ± sem from four replicate houses. Light quality

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Brian R. Poel and Erik S. Runkle

(peak = 660 nm) at 350 μmol·m −2 ·s –1 for 24 h·d −1 , adding 10% B radiation increased plant growth and seed quantity, resulting in plants that were comparable with those grown under white fluorescent lamps ( Goins et al., 1997 ). Far red LEDs have

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Gary W. Stutte, Sharon Edney, and Tony Skerritt

(LEDs; RGB); red and blue LEDs (RB); red LEDs (R); and red and far-red LEDs (RFr). The photosynthetically active radiation ( PAR ) and the photostationary state ( Φ ) for each treatment are shown. The LED treatment matrices used to determine the effect

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Arend-Jan Both, Bruce Bugbee, Chieri Kubota, Roberto G. Lopez, Cary Mitchell, Erik S. Runkle, and Claude Wallace

all of UV-A (315–399 nm)] and far red (sometimes defined as 700–799 nm) radiation can impact plant growth and development, as can infrared [IR (heat)] radiation (800 nm–1 mm). The latter is more difficult to quantify and primarily influences plant

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

radiation is T 3 > T 1 > T 2 > T 4 . B light affects photomorphogenic aspects of plant growth and their development ( Sundström, 2000 ). Carotene, xanthophylls (orange and yellow), and anthocyanins (red pigments) absorb mainly in the B region of the