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Brian R. Poel and Erik S. Runkle

increase and costs decrease ( Bourget, 2008 ; Wallace and Both, 2016 ). Unlike conventional lamps and excluding LEDs coated with phosphors, LEDs emit narrow wavebands based on their chip composition and can therefore emit specific wavebands of interest for

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W. Garrett Owen and Roberto G. Lopez

during propagation. Previous research has investigated the effects of DLI and SL from high-pressure sodium (HPS) lamps and LEDs during AR development and subsequent rhizogenesis of numerous genera of vegetatively propagated annual bedding plants ( Currey

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

, were inexpensive, and were commonly available ( Craig and Runkle, 2013 ). However, incandescent lamps have been phased out of production because of their short life span and energy inefficiency ( Waide, 2010 ). Currently, fluorescent and LED lamps are

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Devdutt Kamath, Yun Kong, Chevonne Dayboll, and Youbin Zheng

, there is a lack of information on their use for the production and maintenance of stock plants for cutting production. Light-emitting diodes (LEDs) are replacing traditional light sources (e.g., high-pressure sodium and fluorescent lights) as SSL in

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Neil C. Yorio, Gregory D. Goins, Hollie R. Kagie, Raymond M. Wheeler, and John C. Sager

Radish (Raphanus sativus L. cv. Cherriette), lettuce (Lactuca sativa L. cv. Waldmann's Green), and spinach (Spinacea oleracea L. cv. Nordic IV) plants were grown under 660-nm red light-emitting diodes (LEDs) and were compared at equal photosynthetic photon flux (PPF) with either plants grown under cool-white fluorescent lamps (CWF) or red LEDs supplemented with 10% (30 μmol·m-2·s-1) blue light (400-500 nm) from blue fluorescent (BF) lamps. At 21 days after planting (DAP), leaf photosynthetic rates and stomatal conductance were greater for plants grown under CWF light than for those grown under red LEDs, with or without supplemental blue light. At harvest (21 DAP), total dry-weight accumulation was significantly lower for all species tested when grown under red LEDs alone than when grown under CWF light or red LEDs + 10% BF light. Moreover, total dry weight for radish and spinach was significantly lower under red LEDs + 10% BF than under CWF light, suggesting that addition of blue light to the red LEDs was still insufficient for achieving maximal growth for these crops.

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

-efficient LEDs allows for a wide array of adjustable spectral distributions relevant to regulation of flowering. Lighting manufacturers have developed LED lamps emitting varying intensities of B, R, or FR radiation for flowering applications of photoperiodic

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Gioia D. Massa and Jeff Norrie

The use of Light Emitting Diode (LED) technology for research and commercial horticulture has undergone exponential growth in the past decade. In 2007, the American Society for Horticultural Science (ASHS) held a workshop on “LED Lighting for

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Kazuhiro Fujiwara, Toshinari Sawada, Yoshikatsu Kimura, and Kenji Kurata

A light-emitting diode (LED)-low light irradiation (LLI) storage system was developed for suppressing the change in dry weight and maintaining the quality of green plants during long-term storage. In this system, the carbon dioxide (CO2) exchange rate was maintained at zero by automatically adjusting the photosynthetic photon flux density (PPFD) with a proportional-integralderivative (PID) controller. The voltage supplied to the LEDs was controlled by the difference between the inflow (400 μmol·mol-1) and outflow CO2 concentrations in the storage case. Grafted tomato (Lycopersicon esculentum; scion = `House Momotaro'; rootstock = `Anchor T') plug seedlings were stored at 10 °C for 35 days under four different LLI conditions as a system operating test: fixed red light irradiation at 2 μmol·m-2·s-1, PID-controlled red light irradiation with no blue light, and PID-controlled red light irradiation with blue light at 0.2 or 1.0 μmol·m-2·s-1. The results showed that the automatic PPFD control during LED-LLI helped suppress changes in dry weight during storage as expected. Furthermore, it was found that addition of a low percentage of blue light improved the morphological appearance of the seedlings and reduced the PPFD required to suppress the change in dry weight.

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Mengzi Zhang and Erik S. Runkle

-emitting diodes (LEDs) with an R:FR ≥0.66 at a photon flux density of 1.3 to 1.6 μmol·m −2 ·s −1 compared with SD control ( Craig and Runkle, 2013 ). The inclusion of FR with R radiation, delivered as EOD or NI lighting, had little to no effect on regulating

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Angela O'Callaghan*, Florence Brown, Denise McConnell, and Robert Morris

Southern Nevada Master Gardeners (MGs) donate 50 hours annually to educational and service projects. These volunteers respond to community needs by developing and staffing horticultural projects under UNCE supervision. In Las Vegas, 20 such projects exist. Some are more energy and information intensive than others. Mojave Guides are docents at the Desert Demonstration Garden, a part of the Las Vegas Springs Preserve, not Extension. They commit to a shift at the garden, providing information to visitors. While they are directly supervised by garden staff, the hours they contribute are Master Gardener hours. These volunteers receive training in desert flora from gardens staff and participate in seminars on selected topics. The MG Orchard Team operates a teaching orchard at the Center for Urban Water Conservation in North Las Vegas. These volunteers maintain hundreds of fruit trees and grape vines. They receive training on topics related to fruit trees and orchard management. This project began in 1996. Since 2002, they have been formalizing their organization using the logic model and SWOT analysis. Many members work weekly at the orchard and take the produce to a local farmers market. This raises funds for the orchard and is an opportunity to teach the community about desert horticulture. Project PLANT volunteers work at the Red Rock National Recreation Area visitor center and grounds. They are docents who also learn about and maintain the native plants there, and prevent infestations of invasive weeds which threaten the area. Their monthly meetings include training on topics related to the project. These projects are successful because of the MGs themselves. They grew out of interest and continue because the volunteers have drawn commitment from others.