New questions arise when considering LEDs for horticultural lighting in view of
studies reported previously.
First, what levels/proportions of red, green, and blue light
will be required for particular crops?
Will these optima change over the life cycle of the
crop, and how should waveband ratios be
modified for optimal production, whether it
be yield or appearance?
Data for the few species already tested already show tolerance
diversity for narrow-band radiation. Better
productivity generally is seen with additional
wavelengths and broadening of the spectrum.
This begs the question of whether we are just
rediscovering the importance of white light.
(Mua -ha-ha-ha-ha ......Welcome to the 'club',guys ...)
White LEDs do exist, but typically are blue
LEDs with phosphor coatings and by their
nature are less efficient than the single-wave-
peak LEDs. Plant studies with these light
sources remain to be performed.
( Yeah,right ...)Perhaps
LEDs used as supplements to sunlight or
other types of lighting in greenhouses or
growth chambers could modify crop growth
or development in a desired direction without
depriving crops of necessary wavelengths.
The trick will be to find the right spectral and
intensity combinations for each crop given
that differences in light response are likely to
exist even at the cultivar level.
Another issue in considering sole-source
narrow-spectrum lighting with LEDs relates
to visualization of plants and early detection
of disease and disorder. Perhaps in species
that have no absolute green light require-
ment, green could be used only when viewing
crops for easier and clearer visualization with
the human eye, and when not under observa-
tion, the energy could be redirected into other
LED wavelengths.
....a lot of maybe. Studies or it didnt happen 
