A
B
Fig. 4 A&B - As LAI includes a concept of depth
(a third dimensional), these two canopies
would likely be measured at 2.160 and 0.735,
respectively, if 3.0 is complete coverage.
Fig. 5 - Though not the only consideration, the amount of light
that is intercepted by plant foliage before it reaches the ground
is at the heart of LAI. It is clear by observing a single canopy such
as this one (dense and low to the ground) that 100 per cent of the
sunlight is intercepted before reaching the soil beneath it.
LAI AND LIGHTING
“WHEN GROWING A CROP THAT
As mentioned, LAI can also
relate to photosynthesis.
Remember photosynthesis
is the power within a plant
to grow and produce, and
this process is driven by
light application. The
MAXIMUM LAI IS THE GOAL.”
more light that falls on
something other than
foliage, the less efficient the use of that light source
(and vice versa). So, there is a direct relationship
between LAI and light interception; as LAI increases,
the percent of light intercepted by (and applied to) a
plant’s leaves increases.
In indoor growrooms, the lights are often stationary.
As such, the garden needs to be carefully planned out
to take full advantage of the non-moving light source.
One benefit of using sunlight in a greenhouse, on the
other hand, is the light’s angle of application moves
throughout the day. Foliage that might be in shade
at one hour is later in sunlight, so more advantage is
taken by all the existing foliage. There are lighting
systems and strategies for indoor grows that also
utilize this same principle of angular light movement.
Sometimes leaves and even branches need to be
removed to allow more light into the center of a plant.
Though this reduces the LAI to some degree, this
type of pruning is desirable for fruiting crops as it
encourages a more thorough production of fruit.
produces leaves for
consumption,
To be a successful grower, one needs to use science
and proven methods to their benefit. Taking notes on
important aspects and observations for each crop,
including the LAI at various points in the cycle, and
recording them for reference in the future can be the
difference between adequate and
maximum yields. For additional
information on LAI, discussion of
how various meters can be used
to measure it, and to review the
reference information for this article,
scan the QR code.
grow cycle
73