Thursday, April 14, 2005

Red LEDs to Grow Lettuce


Apparently red LEDs are 60% more efficient than fluorescent light when growing vegetables hydroponically.

According to IEEE Spectrum Online: Of all the colors of the rainbow, red is lettuce’s favorite. Chlorophyll, the electrochemical engine of photosynthesis, runs on red photons. So if you are growing the vegetable indoors in a factory, why waste energy on colors you don’t need?

Using a red LED-based growth process developed by Cosmo Plant Co., in Fukuroi, Japan, instead of a fluorescent lighting based one, cuts a factory’s electric bill by 60 percent, the company told Agence France Press.

Cosmo’s customers uses the technology to produce 7000 heads of lettuce per day all year round in a 10-floor building on just 1000 square meters of space. The lettuce matures more than three times as fast under the LEDs than outdoors. While growing lettuce in an open field is still less costly, growing it inside under LEDs means you don’t have to worry about crop-decimating typhoons and other nasty weather.

Effect of LED-light Stimulation at Specific Frequencies on Lettuce Growth

Accession number;03A0621435
Title;Effect of LED-light Stimulation at Specific Frequencies on Lettuce Growth
Author;NAKABAYASHI KAZUSHIGE(Meiji Univ., Sch. of Agric.) SUZUKI TAKANORI(Meiji Univ., Sch. of Agric.)
Journal Title;Journal of Society of High Technology in Agriculture (J. SHITA)
Journal Code:L1430A
Figure&Table&Reference;FIG.3, TBL.4, REF.13
Pub. Country;Japan
Abstract;Plant growth rate can be controlled by adjusting both the light quality and during light and dark transition. Light intensity and time also have an effect on growth rate. We investigated the effects of low-intensity light irradiation of specific frequency on the growth and inorganic contents of lettuce in the field. Lettuce was cultivated using three types of nutrient solution (complete nutrition, NO3-N-excessive, NO3-N-deficient). Light sources were red and yellow LEDs, which are low-cost artificial light sources used in plant production. Leaves were irradiated by pulsed LED-light for several hours each day. Red and yellow LED-light stimulation of specific frequency (20Hz,50Hz) increased the lettuce yield in nutrient solutions with lower NO3-N concentrations, despite of the fact that the chlorophyll in lettuce does not response much yellow light. Changes in light stimulation frequency affected NO3-N concentrations in lettuce sap. These results suggest that stimulation by red or yellow LED-ligh in the field has a positive effect on photosynthetic activity. (author abst.)

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