Page 86 - enLIGHTenment Magazine - April 2017

strategies in light rEport

Unfortunately, supplying the market with appropri-

ate LED lighting isn’t necessarily easy. Bob Koontz of
Venntis Technologies, who has been studying the in-

tricacies, detailed his ndings in the report, Spectral
Control: Impacts of Broad and Narrow LED and Light-

ing Legacy Spectra on Plant Morphology and Yield.

When it comes to measuring the Intensity, Dura-
tion, and Quality of light, what has to be taken into

consideration when evaluating natural sunlight versus
arti cial is that the natural model will have cloudy

days as well as those of only partial sun compared to

the constant sun of arti cial light. “There is still a lot
of work to be done in regard to spectrum,” Koontz

stated, adding, “The light spectrum has to be done in
the right quantities.”

Although the lighting industry has worked hard

to closely replicate natural daylight, the research
demonstrates that when plants are grown under

LED versus natural daylight, the growth rate is not
the same. For example, the LED-grown plants were

smaller, but with more coloration. Theoretically there

might be minute di erences in taste as well nutri-
tional content depending upon the light source.

Finding the right lighting recipe for growing each
individual plant species optimally is still being exam-

ined. “It’s not just red or green or a single frequency

that is needed; it’s a combination,” Koontz said.
West Virginia University conducted broad spec-

trum research in a special indoor test facility where
the lighting intensity and duration were monitored IMPLICATIONS OF SPECTRAL QUALITY

and plants grown under traditional metal halide/
BLUE PHOTONS ORANGE-RED PHOTONS
high-pressure sodium and those grown under LED of
various colors were compared. The results showed (400-499NM)
(600-700NM)

di erences in color and size, depending on the plant • Drive dense plant growth
• Most e cient driving plant
variety. On the plus side, “LEDs can manipulate char- • Support plant health and growth

acteristics in a plant,” explained Nadia Sabeh PhD, appearance
• Best chlorophyl absorption

PE, LEED, AP of Dr. Greenhouse. On the minus side, • Support root development and • Critical for owering and
“Every plant is di erent and every variety of plant is nutrient production
day length control

di erent; that’s a lot of varietal to control,” she added.
• Stimulate chlorophyl
Converting a greenhouse to an LED system is more production and gas exchange

complicated on the engineering/HVAC end, which is

Sabeh’s specialty. The advantages of having a cooler GREEN-YELLOW PHOTONS FAR-RED PHOTONS
light source (LED) such as less heat – and therefore,
(500-599NM)
(701-800NM)
not as large of an HVAC system or energy needed
– has to be balanced with the disadvantages of less • Provide the least amount of • Support total plant function
growth per photon
• Enhance the photosynthetic
heat a ecting humidity levels and air circulation.
• Provide the best penetration e ciency of other wavelengths
The horticulture eld as it relates to LED lighting for subcanopy growth
is still in the early stages. The experts involved a rm • Enable day length control
• Enable visual health
that more de nitive research and ndings will contin- assessment
ue to be released in the months and years ahead.
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84 enLIGHTenment Magazine | april 2017
www.enlightenmentmag.com