So the fluorescence input synthesis
studies in particular are aimed at
providing some baseline information for
one might define an upcoming change
if you would, in an orchard design. We have
been designing orchards and creating bi-
dimensional or three dimensional
canopies basically following a rule that
was worked out and found to be quite
good in the 60s and 70s of the last
century whereby the highest light
interception would give the highest
yield. Where growers an orchard is were
at the time it made a lot of sense. But
now systems like the Tatura V are
clearly harvesting a lot of light, then
one might say where do we go next. And
the next step might be different row
orientations, different row inclinations.
Orchard covers with different materials
to remove a certain amount of light. And
when you do all of these things then
this will also allow us a different
management of irrigation during the day
and during the season, hopefully reducing
the amount of water needed which is very
important for the sustainability of the
fruit growing operations. The
photosynthesis fluorescence instrument,
this is a rather
complicated piece of equipment but very
powerful, It allows us to measure
simultaneously photosynthesis and
transpiration, so the gas exchanges of
the leaf, and also the fluorescence bit
of the light phase of photosynthesis. The
photosynthesis unit, that  will be
using in the trial comes from the
Department, but when it first arrived
here at the lab I could see that one
crucial component was missing which is
this box here. This box houses a
fluorometer. Thanks to the Veski
foundation grant we were able to
actually purchase the fluorometer head
that is now installed on the equipment.
With this addition the instrument really
fulfills its potential for data
collection. In this configuration we are
able to do the biochemistry of
photosynthesis, that is how much carbon
dioxide is taken up by the leaf. We're
also able to do the physics side of
photosynthesis, that is how many photons
of those that the leaf has captured are
actually
being used in the photosynthetic process?
Because surprised to say most people
don't realize only less than 5% of the
incoming light is actually useful for
the synthesis which means 95% and more
the leaf has to deal with. The ways to deal
with that excess energy are more than
one, and in general there is too much
energy and it will damage the leaves.
This part of the instrument allows us to
measure how much damage is is occurring
while the
light is impinging on the leaves. So,
this couldn't get any better than this.
One could really say that with the
fluorometer addition. Now this is one of
the most capable instruments for this
kind of studies in the orchard. So,
basically the leaf will be placed in
this position and then we will close
this chamber. We're actually providing
light of specified quality. There is red
and blue because these are the colors
that photosynthesis is driven by, and in
the intensity that we want. So it is not
as intense as it is coming from the Sun
at the moment but it's way above the
capacity of the leaves to to handle it
in photosynthesis. So we're providing
more energy than is needed to give us
full photosynthesis. One of the important
things that were achieving with this
international effort is the model was
developed in Italy. We're now collecting
data that will allow us to test that
model under Australian conditions
because if it will work here then it's
already good. If it will not work here we
can adjust the model to give us a
response for the local conditions here.
We have, we developed in my lab a model
that
only needs the fluorescence data to tell
us the photosynthesis, which is what
we're interested in. With application of
that model we would not need this much
time as needed for the photosynthesis
measurement, and so we could proceed much
faster. But not only that a fluorometer, a
portable fluorometer technically is very
feasible with today's technology at very
low cost.
Imagine a phone, a smart phone which can
tell you the amount of fluorescence from
a leaf as you just present the phone to
the leaf. This is where we think this
work will lead us in not too long, and
that will be a much powerful tool for
the growers to be able to gauge the
health of the tree and the capacity of
the tree to perform to its maximum.
