Nitty-gritty-cell-rigidity

Elastic Bunch:

We may be going beyond the realm of applicable plant science, but I guess
at least we'll know what is or isn't happening inside our pumpkins.  

Dan:
 Your right that we only really have an option of partial control of one of
the two direct factors of cell expansion, and that is turgor.  By changing
the plants environment we may be able to change the turgor pressure a
little bit.  The elastisity of the cell membrane is a more complicated
process.  First I'll tell you what really goes on in the fruit (at least as
far as I understand it), and then I'll tell you the best and probably the
only way we can help ourselves with this info.  The plant growth regulator
(PGR) that makes this response in the fruit is a common PGR in the plant
and affects numerous other physiological processes.  In the case of cell
expansion inside the fruit the source of the PGR is the seeds.  Every
developing seed in the fruit produces this compound, and serves as the
signal to grow.  Evolutionarily the theory is that the seed needs to signal
the fruit to grow in order for there to be enough nourishment for its own
survival.  This way the more seeds in the cavity, the more PGR produced and
the larger the fruit.  On the other end (inside the cell) the PGR functions
by acidifying the cell membrane.  (The PGR itself is an acid based
chemical)  This acidifying of the components of the membrane make it more
elastic and able to expand.  The bio-chemists have to take over at this
point in the explanation.  

To me the take home message on this information is that we need to hand
pollinate our flowers, and this I believe is the reason why hand
pollination is directly related to larger fruit.  If a flower is open
pollenated the bees and other pollen vectors may pollenate enough embryos
to produce enough seeds to send a strong enough signal to the fruit to
contiue growing.  If we can hand pollenate and do our best to make sure
that every possible seed is going to develope we can make sure that the
amount of this PGR is at its maximum.  

Other ideas:  someone may think that we could artificially increase the
amount of this chemical in the plant somehow.   Maybe its possible, but
there would be a number of complications.  First of all the PGR has its
principle affect with concentrations.   Very minute differences in
concentration affect the response it illicits in the plant.  I know that I
could never measure the concentration needed in my garden.....its roughly
equivalent to peeing in Lake Michigan.  Also if we would put a slightly
different concentration into the plant it could make a different response,
such as fruit abortion(which we don't really want).  Another difficulty is
how could you get this chemical into the plant and maintain its levels
consistently?  Can we put our pumpkins on IV's?   Further this chemical is
very photo-sensitive.  When exposed to light it quickly degrades.  

In conclusion I would say that the best thing for us to do is to make sure
that our flowers are well pollenated and pollenated at the correct time, so
that the pollen is ready and the stigmatic surface is receptive to the
pollen.  Perhaps someone will find a way to manipulate some of the other
factors like RH and temperature to help this process along.  If Dan has the
world record next year I hope he shares is technique with us.....

Best of luck,

Rick

	

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