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Mark G. Lefsrud, Dean A. Kopsell, and Carl E. Sams

and b absorb wavelengths of light strongly in the red (maximum absorption at 663 and 642 nm, respectively) and blue region (maximum absorption at 430 and 453 nm, respectively) with less absorption occurring in the green wavelengths ( Hopkins and

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Heidi Marie Wollaeger and Erik S. Runkle

that red (R; 600–700 nm) and blue (B; 400–500 nm) wavebands are more efficient in eliciting a photosynthetic response than wavelengths between 500 and 600 nm (green and yellow light). The peak RQE of R light is 30% higher than the B peak, and R light

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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

DLI ( Hernández and Kubota, 2012 ). Plant response to light occurs through small chromophore molecules called photoreceptors that are triggered by specific light wavelengths of the spectral range. Five photosensory systems have been identified

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Lie Li, Yu-xin Tong, Jun-ling Lu, Yang-mei Li, and Qi-chang Yang

longevity. Recently, LEDs have been gradually deemed an appropriate light source in PFALs. Furthermore, LEDs can provide special and mixed wavelengths that can be set according to the photosynthetic requirements of plant ( Nelson and Bugbee, 2014

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Venkat K. Reddy and Nihal C. Rajapakse

The influence of removal of specific wavelengths [red (R), blue (B), and farred (FR)] from sunlight on the height of chrysanthemum plants was investigated by overlaying Roscolux™ colored acetate films on 4% CuSO4 or water (control) spectral filters. CuSO4 filters removed FR wavelengths and significantly reduced plant height and internode length compared to control plants that received B, R, and FR wavelengths of light. Plants grown under Roscolux blue filters did not receive R light and were significantly taller compared to plants from any other treatments. Plants grown under Roscolux red filters did not receive B light and were significantly shorter compared to plants from other treatments. Leaf area, leaf dry weight, and stem dry weight were highest in plants grown under Roscolux red and control filter combination. The amount of leaf chlorophyll and the ratio of Chl A: Chl B was highest in plants grown under Roscolux blue filters. In general, plants that received FR light (control + film) were taller than the plants that did not receive FR light in the corresponding (CuSO4 + film) filter combination. The influence of removal of specific wavelengths on plant height control and developmental physiology will be discussed.

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Takeshi Suzuki, Hiroshi Amano, and Toyoki Kozai

The two-spotted spider mite (Tetranychus urticae Koch.) has a worldwide distribution and is one of the most harmful agricultural pests for a variety of plant species. To reveal a visible light wavelength that reduces the population growth rate (as r m, unit: d–1) of the mite, we investigated the r m under wavelength peaks of 468, 515, and 658 nm with half bandwidths of 23, 44, and 22 nm using blue, green, and red light-emitting diodes, respectively. In all treatments, light intensity was set at 2.3 W·m–2 with a light period of 16 h·d–1, and air temperature was set at 25 °C. The survival percentage (l x) and the number of eggs deposited per female (m x) on each age (x, unit: d) were determined to calculate the r m by the following equation: ∑exp(–r m · xl x /100 · m x = 1. The r m and the total m x decreased with increasing wavelength. This result shows that the population growth rate can be reduced under red light (658 nm).

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Dean A. Kopsell, Carl E. Sams, and Robert C. Morrow

radiation is energy associated with wavelengths of visible light (400–700 nm) predominately absorbed by leaf tissues. Photochemistry in plants is initiated by absorbed quanta, which differ in quantum energy level and absorption capacity of photosynthetically

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Haijie Dou, Genhua Niu, Mengmeng Gu, and Joseph Masabni

). With the advancement of light-emitting diode (LED) technology and its customizable nature, the effects of different light wavelengths on plant growth and secondary metabolites accumulation can be characterized ( Darko et al., 2014 ; Mitchell et al

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Gioia Massa, Thomas Graham, Tim Haire, Cedric Flemming II, Gerard Newsham, and Raymond Wheeler

LEDs. Manipulating canopy light attenuation characteristics at different wavelengths could be a mechanism to purposefully deliver additional light to the inner canopy to improve production while reducing overall energy use. More generally, the

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Dean A. Kopsell, Carl E. Sams, T. Casey Barickman, and Robert C. Morrow

[ PAR (400 to 700 nm)] are the wavelengths predominantly absorbed by leaf tissues. However, maximum light absorption by chlorophyll pigments and quantum yield of photosynthesis occur primarily in the blue and red regions of the visible light spectrum