Plant studies and responses with LEDs
Gioia Massa - Purdue University
email: gmassa@purdue.edu
Light-emitting diodes have tremendous
potential as supplemental and sole-source lighting for
crop-production systems, both on and off Earth. Their small size,
durability, long-life, wavelength specificity, relatively cool
emitting surfaces, and linear output in response to input current
make these solid-state light sources ideal for use in
plant-specific lighting designs. Because the output waveband of
monochromatic LEDs is much narrower than that of other sources of
electric lighting used for plant growth, one challenge in
designing an optimum plant-lighting system is to determine
essential wavelengths for specific crops. Work at the Kennedy
Space Center has focused on the proportion of blue light required
for normal plant growth, as well as the optimum wavelength of red
and the red/far-red ratio. Also, the addition of green wavelengths
for improved plant growth as well as for visual monitoring of
plant status has been addressed. Studies on light quality have
shown dramatic effects on crop anatomy and morphology, as well as
nutrient uptake and pathogen development. Work at Purdue
University has focused on light delivery to improve energy
efficiency of a plant-designed lighting system. Additionally,
foliar intumescence developing in the absence of UV light or other
less understood stimuli becomes a serious limitation for some
crops lighted by narrow-band LEDs. Ways to prevent this condition
are being investigated. Automated switching and control systems
that can work only with solid-state lighting like LEDs are being
developed to enhance the energy-saving potential of this evolving
light source for plant growth. This work was funded by NASA.
HortScience, Vol. 42(4), July 2007.
AMERICAN SOCIETY
FOR HORTICULTURAL SCIENCE
