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( Girault et al., 2008 ). Changing red:far-red ratio affects the phytochrome status ( Franklin and Whitelam, 2005 ). The contrast between the current findings (no effect of red:far-red at bud level on budbreak) to literature reporting decreased budbreak when

photosynthetic photon flux ( PPF ) of 160 µmol·m −2 ·s –1 . The subscript values after each LED type represent its percentage of the total PPF , and values in parentheses are the estimated phytochrome photoequilibrium ( Sager et al., 1988 ). Table 1. Actual air

( VvFt) were based on published sequence ( Sreekantan and Thomas, 2006 ). Markers for phytochrome A ( VvPHYA ), phytochrome B ( VvPHYB ), phytochrome C ( VvPHYC ), phytochrome E ( VvPHYE ), cryptochrome 1 ( VvCRY1 ), and CONSTANS ( VvCO ) were based on

). Phytochrome regulates expression of phytoene synthase, a key step on the carotenoid biosynthetic pathway in tomato fruit ( Alba et al., 2000 ; Schofield and Paliyath, 2005 ). Similar results were observed for carotenoids in pepper leaves ( Simkin et al., 2003

). Irradiance levels of 650 and 735 nm were used to calculate the red [R (600 to 700 nm)] to far-red [FR (700 to 770 nm)] ratios because these represent phytochrome action peaks in green plants ( Kasperbauer et al., 1964 ). The R:FR ratio of direct sunlight was

mediate hypocotyl elongation through B radiation regulation of gibberellic acid metabolism ( Zhao et al., 2007 ). Phytochrome, a family of proteins that primarily absorb R and FR (700–800 nm) radiation, signals shade avoidance and flowering control through

( Fankhauser and Chory, 1997 ; Whitelam and Halliday, 2007 ). The main families of photoreceptors identified so far are the phytochromes, cryptochromes, phototropins, and UVR8. Phytochromes (phyA, phyB, phyC, phyD, phyE) absorb principally at the red/far red

). Additionally, Stutte (2009) found that the phytochrome photostationary state, the relative proportion of the active form to total phytochrome, could be manipulated using LEDs to either initiate earlier flowering or promote continued growth in the vegetative

-pressure sodium lamps deliver a higher ratio of red to far-red light than natural sunlight ( Ballare and Scopel, 1994 ). Red to far-red ratio influences phytochrome photoequilibria and phytochrome signaling ( Franklin and Quail, 2010 ) resulting in differential

. All treatments delivered 10% B and 10% G light, with the remaining light quality percentages consisting of O–R–HR of 20–30–30, 0–80–0, 0–60–20, 0–40–40, 0–20–60, and 0–0–80. Predicted phytochrome photoequilibrium ( P FR / P , where P = P R + P FR