Photosynthesis, Maximized
that influence the production of sugars
for plant growth as well. Maximizing all
the variables that play a role in photosynthesis at the same time can lead to some
fantastic growth rates, but it takes a little
understanding of plant physiology to get
things just right.
What is
photosynthesis?
Indoor lighting can be used to grow a wide range of plants.
6CO2 (carbon dioxide) + 6H2O (water)
in the presence of light turns to
C6H12O6 (glucose) + 6O2 (oxygen
In the equation above we can see that
plants need not only a light source
of sufficient intensity and the correct
wavelengths for
photosynthesis,
but also a supply
of carbon dioxide
and water. What
the equation
doesn’t tell us is
that other factors
play a role in the
rate of this process
as well—temperature, for example,
determines the
rate of photosynthesis; the nutritional status of the
“
plant affects light harvesting; leaf area and
plant pigments such as chlorophyll determine how much light can be intercepted;
and stomata apertures influence the flow
of CO2 into the leaf. Just to complicate
matters even more, the internal flow of
water required for photosynthesis into
the leaf can be affected by drought, high
EC, root damage and other factors, while
CO2 levels directly around the leaf surface are affected by airflow and the use of
CO2 enrichment.
How much light
is needed for
photosynthesis?
Most indoor growers sooner or later
have to grapple with the concept of how
much light needs to be provided for
maximum plant photosynthesis. There is
no hard and fast rule for this, as different
plant species have various optimal lightlevel requirements. A densely planted
growing area will need a higher light
“
The basic principle beh ind photosynthesis is fairly well understood—light
energy is used to synthesize sugars (also
called assimilate) from carbon dioxide
and water. Light is absorbed by pigments
in plants—the most common being chlorophyll—and energy provided by light
is used to combine hydrogen (H) from
water with carbon dioxide (CO2) from
the air to form sugars, such as glucose.
The energy from light is stored within
the sugar molecules, which are then also
used as a raw material for the synthesis
of many other compounds required by
the plant for growth and development.
Photosynthesis is actually a very complex
biochemical process involving many different enzymes; however, the simplified
equation looks like this:
Ideally, all the plants in the growing area
should receive sufficient light to allow them
to reach a point termed ‘light saturation’—
that is, the point when further amounts of
light don’t provide any additional increase in
photosynthesis.
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Maximum Yield USA | March 2012