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

, to improve the energy use efficiency in PFALs, it is necessary to find the optimal light environment for plant growth ( Kozai et al., 2016 ). Therefore, to investigate the optimal combination of light wavelengths for lettuce ( Lactuca sativa cv

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Yuyao Kong, Ajay Nemali, Cary Mitchell, and Krishna Nemali

., 2017 ). Leafy greens, such as lettuce, are among the group of popular crops for indoor farming ( Kozai, 2013 ). Crops are produced using electric lighting for an average of 16 h·d −1 ( Agrilyst, 2017 ) in indoor farms. Thus, electrical energy-use costs

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Zhengnan Yan, Dongxian He, Genhua Niu, Qing Zhou, and Yinghua Qu

researchers focused on the energy use efficiency for lettuce production in PFALs. The objectives of this study were to figure out suitable DLI and LQ with proper red light amounts created by white plus red light from sole-source LEDs by investigating

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Geoffrey Weaver and Marc W. van Iersel

divided by the number of plants to determine mean shoot dry weight (dry weight). Energy use. Power use by each LED light fixture, one LED driver and five attached LED light bars, was calculated based on a linear relationship between the provided voltage

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Ricardo Hernández and Chieri Kubota

To increase the available photosynthetic photon flux (PPF) for plant growth, greenhouse growers sometimes use electric lighting to supplement solar light. The conventional lighting technology used to increase PPF in the greenhouse is high-pressure sodium lamps (HPS). A potential alternative to HPS is high-intensity light-emitting diodes (LEDs). The objective of this study is to compare supplemental LED lighting with supplemental HPS lighting in terms of plant growth and morphology as well as discuss the energy use efficiencies of the fixtures. There were three light treatments: 1) blue LED (peak wavelength 443 nm); 2) red LED (peak wavelength 633 nm); and 3) HPS, to provide 3.7 ± 0.2 mol·m−2·d−1 (background solar radiation of 6.3 ± 0.9 mol·m−2·d−1). Cucumber (Cucumis sativus) plants at the transplanting stage (26 to 37 days) under HPS had 28% greater dry mass than did plants under the LED treatments. This can be attributed to the higher leaf temperature under the HPS treatment. No differences were observed in growth parameters (dry mass, fresh weight, or number of leaves) between the blue and red LED treatments. Plants under the blue LED treatment had greater net photosynthetic rate and stomatal conductance (g S) than those under the red LED and HPS treatments. Plants under the blue LED and HPS treatments had 46% and 61% greater hypocotyl length than those under the red LED, respectively. The fixture PPF efficiencies used in the experiment were 1.9, 1.7, and 1.64 μmol·J−1 for the blue LED, red LED, and HPS treatments, respectively; however, the fixture growing efficiency (g·kWh−1) of HPS was 6% and 17% greater than the blue LED and red LED treatment, respectively. In summary, supplemental red LED produced desirable plant compactness and HPS had greater fixture growing efficiency than LEDs.

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Lu Zhang, Xiuming Hao, Yonggeng Li, and Gaoming Jiang

improving energy use efficiency in greenhouse crop production. The greenhouse climate is traditionally controlled with an aim to keep the climate at constant pre-set levels, which are assumed to be optimal for plant growth. This approach has not used the

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John C. Majsztrik, Elizabeth W. Price, and Dennis M. King

much to irrigate. At each decision point, regardless of the operation, there are two options, irrigate or not irrigate. The option that is selected at each decision point has cumulative effects on water and energy use, crop growth, fertilizer uptake

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Gioia D. Massa, Hyeon-Hye Kim, Raymond M. Wheeler, and Cary A. Mitchell

radiation capture may need to be reported to take into account parameters such as canopy volume or total energy use/cost. An important issue for LEDs in horticulture concerns their economic viability. Like with any developing technology, as demand

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Athanasios P. Papadopoulos

The greenhouse cover has previously been shown to have large effects upon the greenhouse environment, crop productivity and energy use. However, in most cases, because of inadequate treatment replication, the extent of these effects has been impossible to quantify with confidence. In the fall of 1987, a new greenhouse complex of 9 mini greenhouses (6.4m × 7.2m, each) was constructed at the Harrow Research Station on the principles of the 3×3 Latin Square experimental design and with glass, double polyethylene film and double acrylic panel greenhouse covers as the three levels of treatment in the Latin Square. During the spring seasons of 1988 and 1990 the greenhouse cucumber cultivar Corona was cropped in rockwool in all 9 mini greenhouses, under 3 day air (DAT: 18°C, 21 °C and 24°C) and 3 night air temperatures (NAT: 16°C, 18°C and 20°C), superimposed across the rows and columns of greenhouses, respectively, to estimate yield and energy use response to DAT, NAT and greenhouse cover variation. Early marketable yield was highest at the 18/18 and 18/20°C DAT/NAT combinations and final marketable yield was highest at 18°C DAT regardless of NAT. Yield differences due to the greenhouse cover were insignificant. However, there were consistent differences in greenhouse air RH due to greenhouse cover (60%, 70% and 75% daily averages for glass, double polyethylene and double acrylic, respectively). Also, there were significant energy savings with the use of double polyethylene or double acrylic, as compared to glass greenhouse cover, and with low DAT and NAT (28%, 15% and 12% energy use reduction, respectively).

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Mark Freeman and Dale Handley

Much technology concerning efficient use of agricultural energy and water is available. However, this technology is underutilized by many growers because of inadequate training. This Extension program educates growers about evaluating irrigation systems, soil and water problems, irrigation scheduling, and energy use (of pumps). The program uses different communication tools to create awareness in growers, and then encourage adoption. These tools include in-depth surveys, condensed written material, small group discussions, and videotapes. The program also coordinates efforts among various governmental and private agencies.