title: Light-emitting diodes as a radiation source for plants.
abstract: Development of a more effective radiation source for use in plant-growing facilities would be of significant benefit for both research and commercial crop production applications.  An array of light-emitting diodes (LEDs) that produce red radiation, supplemented with a photosynthetic photon flux (PPF) of 30 micromoles s-1 m-2 in the 400- to 500-nm spectral range from blue fluorescent lamps, was used effectively as a radiation source for growing plants.  Growth of lettuce (Lactuca sativa L.  Grand Rapids') plants maintained under the LED irradiation system at a total PPF of 325 micromoles s-1 m-2 for 21 days was equivalent to that reported in the literature for plants grown for the same time under cool-white fluorescent and incandescent radiation sources.  Characteristics of the plants, such as leaf shape, color, and texture, were not different from those found with plants grown under cool-white fluorescent lamps.  Estimations of the electrical energy conversion efficiency of a LED system for plant irradiation suggest that it may be as much as twice that published for fluorescent systems.
authors.affiliation: Department of Horticulture, University of Wisconsin-Madison 53706.
authors.forename: R J
authors.initials: RJ
authors.lastname: Bula
authors.forename: R C
authors.initials: RC
authors.lastname: Morrow
authors.forename: T W
authors.initials: TW
authors.lastname: Tibbitts
authors.forename: D J
authors.initials: DJ
authors.lastname: Barta
authors.forename: R W
authors.initials: RW
authors.lastname: Ignatius
authors.forename: T S
authors.initials: TS
authors.lastname: Martin
mesh_terms: D004780:Environment, Controlled; D018545:Lactuca / Q000254:growth & development* / Q000528:radiation effects; D008027:Light; D017785:Photons; D017440:Photoperiod; D010788:Photosynthesis