Photosynthesis, Maximized
more familiar with these days as it reflects
actual photosynthesis inside plant tissue—not what happens in a test tube, as
was shown in figure one. There is still a
peak in the blue and red wavelengths,
but there is much more photosynthesis
going on in the 500 to 600 wavelength
band—the green and yellow area—than
we generally recognize. Obviously plants
do reflect more green light, which is
why foliage looks green to us; however,
there are pigments present in the plant
trapping this green light and passing the
energy on to chlorophyll for photosynthesis, so green light still drives the
process. This graph is an average response
taken from a large number of common
plant species, so it reflects accurately
what occurs in most crops. It shows that
inside plant tissue the role of green and
yellow light in triggering photosynthesis
is actually surprisingly important. The
reason behind this is that chlorophyll is
not the only pigment that can absorb
light—there is a range of other accessory
or antenna pigments that use green and
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Maximum Yield USA | March 2012
Measurement of light is an important factor when aiming to optimize photosynthesis in an indoor garden.
yellow light as well. For example, much of
the photosynthesis occurring in the green
waveband (540 nm) results from absorption by active carotenoids. Many of the
light-harvesting pigments also make use of
a wide range of light wavelengths and pass
the energy on to chlorophyll for photosynthesis. So while chlorophyll itself might
not absorb much in the way of green or
yellow light, other pigments can—and the
entire spectrum can then be used by the
plant.The use of accessory pigments allows
photosynthesis to use a large proportion of
the spectrum—not just red and blue wavelengths—and for indoor growers that’s an
exciting opportunity to take advantage of.
The Emerson
enhancement
effect and
photosynthetic
lighting
While it’s commonly known that there
are a wide range of wavelengths absorbed