I am a research associate in the Department of Horticultural Science at the
University of Minnesota. I have been growing plants under slightly higher
than atmosphere pressure (3kPa) in a chamber I built for plant labeling
with 13CO2. The project I am working on is to develop a method to measure
protein turnover in plants using stable isotope labeling coupling with mass
spectrometry analysis. Because we attempt to enrich our plants with 13C as
high as possible using 99%atom 13CO2, the chamber pressure is maintained
slightly positive to avoid ambient CO2 movement from outside to the chamber.
One interesting thing I noticed from my research was that plants grew
normally under pressure 2-3 kPa higher than the atmosphere but when growing
them under pressure 5-6 kPa higher than the atmosphere they formed brittle
leaves. I didn't try to increase the pressure higher than 6kPa because my
chamber was not built to handle higher pressure. The brittle leaves formed
under higher positive pressure I guessed might be a result of accumulation
of lignin on the cell wall or thickening of cell wall. Just wanted to share
my two cent information. Hope it would stimulate more discussion on this
interesting question.

Wen

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From:
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Sent: Monday, December 22, 2008 2:26 AM
To:
Subject: [Plant-biology] Plantbio Digest, Vol 43, Issue 2

I believe Marine aquatic plant physiology can help also to answer that
question.

Plants growing at 1, 5, 10, 20, or even 50 m undersea have different
hyperbaric conditions and therefore, some effect on marine vegetation
physiology should be observed.

In internet we find any kind of references like the guy who claims that
plants do not stop growing under hyperbaric conditions:

"In two years a
tomato plant grown in a hyperbaric chamber grew to a height of 16 feet
and produced 930 tomatoes! That's not all! It didn't stop growing! "
at this site: http://www.geocities.com/johnh_vanbc.../preflood.html

An interesting question answer we find in this Web site:
http://www.madsci.org/posts/archives...4676.Bt.r.html


Can plants grow at gretaer than atmospheric air pressure
Date: Mon Feb 2 17:18:09 2004

Posted By: David Hershey, Faculty, Botany, NA

Area of science: Botany

ID: 1075527828.Bt

Message:


Growing plants at above normal atmospheric pressure would involve a
hyperbaric
chamber. One recent study on ginkgo found as much as a 250% increase in the
photosynthesis rate when the carbon dioxide was increased 500% and
atmospheric
pressure was increased 25%. I contacted the lead author, Sara Decherd, and
she
kindly told me that they found no significant effect on photosynthesis with
a
25% increase in atmospheric pressure alone. She was also not aware of much
other research on plant growth in hyperbaric chambers. It seems to be an
area
that has not been thoroughly studied. The ginkgo research was recently
featured in a news release, "A Lot of Hot Air: How the Dinosaurs Grew So
Monstrous."

NASA has done work on growing plants at less than atmospheric pressure in
hypobaric chambers. Hypobaric greenhouses with one-sixteenth the pressure of

an Earth atmosphere may be required for Mars colonization.

At normal atmospheric pressures, increasing the carbon dioxide concentration

up to about 1,000 ppm often increases plant growth. Current atmospheric
carbon
dioxide is about 360 ppm. Thus, you might expect a positive effect on plant
growth in a hyperbaric chamber. I doubt a soda bottle would be a
satisfactory
hypobaric chamber. It would be difficult and expensive for a school student
to
maintain an elevated carbon dioxide level in a hyperbaric plant growth
chamber
because a plant can rapidly deplete the carbon dioxide given its low
concentration and the limited chamber volume. Be very cautious if you try to

make your own hyperbaric chamber because an explosion is always a
possibility.

It would be much easier to demonstrate effects of carbon dioxide enrichment
at
normal atmospheric pressures. A soda bottle system to inexpensively induce
carbon dioxide deficiency in plants can be built using rubber stoppers,
aquarium tubing, aquarium valves and an aquarium air pump (Hershey 1992,
1995). The same system could be used to elevate the carbon dioxide level
using
dry ice or acid mixing with calcium carbonate as a source of carbon
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