Page 172 - PC2019 Program & Proceedings

PLANT CANADA 2019

S129. Enhancing plant growth using light emitting diode (LED) technology
Scandola, S.; Uhrig, R.G
University of Alberta

Light is essential to plant growth and development. It is required to drive CO2 assimilation into the
building blocks required by plants while also being a key trigger for important plant responses such as
shade avoidance, developmental programs and seed / fruit production. In countries such as Canada,
horticulture is an important component of the food production landscape. An important component of
horticulture is the application of artificial light to facilitate plant growth. Typical light technologies
currently deployed in horticultural plant growth involve high pressure sodium or fluorescent lights which
are energetically and economically expensive, in addition to being technologically limited. Light emitting
diode (LED) light technology represents an alternative to these standard approaches. Generally, LEDs are
used to supplement these standard lighting technologies or glasshouse operations; however, there is
limited knowledge of how plants respond to growth under an LED-only light regime. Advancing our
understanding of LED impact on plant growth and development and how this can be harnessed for
increased horticulture output, represents a timely opportunity given the increasing unpredictability of
weather and climate. Using a programmable LED technology, in conjunction with multiple genetic
resources, we have generated both a molecular and phenotypic understanding of how plants respond to
growth under an exclusive LED-lighting regimen. Together, these findings demonstrate the utility of LED
technologies in horticultural plant growth.

R. Glen Uhrig (ruhrig@ualberta.ca)

S130. Optimizing spectral quality of light emitting diodes light for controlled-environment
microgreen production
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Ying, Q. ; Y. Kong; G.G. Bozzo; Y. Zheng
University of Guelph

Microgreens are becoming highly consumed due to their various colors, attractive flavours, tender
textures, high nutritional values, as well as short growth period. For controlled-environment production,
light is a major factor in controlling microgreens’ morphological, physiological and biochemical
processes. To determine optimal light-emitting diode (LED) spectral qualities for microgreen production,
experiments were conducted in both growth chamber and greenhouse environments using arugula,
cabbage, kale and mustard microgreens from the Brassicaceae family. Under blue and red LED
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combinations with the same photon flux density of ≈300 µmol·m ·s , increasing blue light percentage
(ranging between 5%-30%) proportionally decreased the hypocotyl length and cotyledon area of kale and
mustard, whereas the fresh and dry weight were unaffected except for cabbage. However, the levels of
ascorbate, anthocyanin and total phenolics were higher at blue light percentages of 15%-20%, although
the magnitude of these responses varied with species. In another two experiments (one in growth
chamber, one in greenhouse), low-level monochromatic blue with or without far-red light were applied
throughout the night period. Although both blue and far-red light promoted hypocotyl elongation,blue
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light at 20 µmol·m ·s in the growth chamber and 14 µmol·m ·s in the greenhouse maximally
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increased fresh weight and improved the appearance of microgreens relative to similar levels of far-
red light. These results can be used by growers to determine and manipulate their light quality for high
quality and yield microgreen under controlled environment.
Qinglu Ying (qying@uoguelph.ca)

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