EL [yank]'tensile strength' of ultra pure water?
Ken S. Tucker
EL this subject has deviated from s.p.research, but it is still
physics, the reference thread is there, but your excellent post
must be replied to!
Dear EL,
>Dear ken.
>On this news group I never assume authority but...
>Well, plant cells maybe categorised as dead or alive.
>The green colour usually indicates life but water and cell organelles
>are the critical factor here.
>There are many vacuoles within a living cell and the cell wall is
>somehow elastic and may tolerate deformation without changing water
>content.
>Regarding your experiment with subjecting plants to soft breeze and
>its relation to growth as a factor, I would say that it is true that a
>soft breeze shall help growth exactly as it would help drying your
>cloths, which you hang on the line, so how is that! I shall tell you.
>A soft breeze shall renew the air shells around the leaves, which (air
>shells) would be highly saturated with water in still air and humidity
>shall be distributed by a gradient. The mechanical action of a breeze
>is not on the xylem or phloem but on the air shells, and the
>consequence shall be a higher transpiration rate, which in tern shall
>increase the negative pressure in the high end of the plant, which
>helps the rising of the sap and consequently carrying nutrients needed
>for growth. As you may see and conclude, that by raising the rate of
>transpiration, negative pressure, nutrient sap uptake and consequently
>the growth rate factor, we shall never agree that it was a mechanical
>pluming issue and for yet some other reasons.
We'll see, I'm optimistic...your transpiration theory would mean
a tree would thrive in low humidity conditions, when well watered,
but in high humidity would be stumped. However we know for a
fact that tropical jungles thrive, but desert conditions even with
abundant ground water makes only an oasis, that is not
characterisized by enhanced growth rates, your theory predicts.
Many trees and plants regularily drip, for example, expose a
philadendrum to humid moving air and it drips. Consider
further the Weeping willow and their desire for ground
water, and lake fronts.
>So firstly, please realize that strong enough wind might be rather
>essential to some trees with heavy foliage density because the trapped
>air would be vapour saturated, and wind is the only way to renew that
>air for that reason and yet for supplying CO2 by day and O2 by night.
>A plant needs to breath you know.
>So wind is good for plants but it never pumps water mechanically for a
>very simple reason:
>The cell-walls' molecular biochemistry and biological morphology has
>no provisions for a one-way valve.
>Swaying motion in fact helps to break up the dead bark to give room
>for horizontal growth in bigger trees.
>Therefore, no one should argue about the usefulness of wind effects on
>the growth of trees, but no one may assume that cells would develop
>mechanical one-way-valves at the top and the bottom to account for
>water direction by varying shape volume and pressure of cells. Those
>alleged and assumed OWV simply do not exist in the cell wall
>structure.
>But I have to say that you do have a very sharp observation to realise
>that air currents are factors of growth.
>Thank you for your keen observation and your love to the plant
>kingdom. :)
>
>Former Molecular Biochemistry and Molecular cell Biology professor.
>EL
Thanks EL that was excellent....
I don't know if you read threw the thread, but the issue has to do
with moving water (sap in this case) up a column that measures
50 to a 100 metres, and a tree was introduced into this experiment.
Every ~10 meters of water depth produces 1 atmosphere of
pressure, so a 100 meter column would produce 10 atmospheres
of pressure or about 150 PSI. Somewhere a One Way Valve is
(OWV) required to prevent the sap running downward just as
we need capillaries. And a significant amount of energy is
required to move the sap up this height. Your fine essay
contained neither the mechanism nor the energy source to do
this, although everything else you wrote I agree with, but it
pretains to wind effects on leaves.
Facts about healthy trees..
1) The sap flows between the bark and the wood,
removing some bark, and moisture is apparent.
(the trunk interior is deadwood).
2) Removing a strip of bark around the circumference
of a tree, kills it.
3) The greatest tension/compression force due to wind
is at or near the bark/wood interface.
4) The compression and tensile strength of wood is
equal.
It's the relative relation of the inner bark and the outer
wood that forms the OWV, ie, the required capillaries.
This is easy to confirm, as there is a variable (up/down)
relative friction, on the inner bark and the exposed wood.
It's also the point of maximum pumping potential.
Experiment: Given two identical trees, sway one
mechanically but slowly, subject the second tree to the
breeze the first gets from swaying, and note difference
in growth rates.
Given that you are a, "Former ...Biology professor",
you can confirm these two experiments for yourself.
Except for girls, trees are my favorite living thing, (I may
have even invented the saying, "If you were a tree, what
tree would you be?", I'd be a grape-vine, and take up
200 acres, have beautiful French women gather my seed,
stomp on it (bit of S&M), and then get eveybody loaded!
What a life....)......
Ken S. Tucker