Nick Maclaren wrote:
In article ,
"Jeff Layman" writes:

Has anyone ever tried growing under sealed polythene and increasing
the carbon dioxide concentration in the air surrounding the plant?
There is no point in all the sophisticated stuff if the carbon
dioxide level is insufficient. Perhaps it is somewhat simplistic
to say so, but plant weight is basically added through
photosynthesis, water, and carbon dioxide. It seems to me that the
first two are often controlled carefully, but nobody appears to
experiment by increasing CO2. I assume there would be an effect,
and maybe there is a critical concentration.

Has anyone ever looked into this over here? Seems that it has been
investigated on the other side of the pond:
http://gvgo.ca/mb/index.php?topic=433.msg1954#msg1954

It has been looked into scientifically, because it is relevant to
global warming. The executive summary is that most plants do grow
faster with slightly higher levels of carbon dioxide, but more than
a very small increase is toxic to them. They have, after all,
adapted over many millions of years to an environment low in carbon
dioxide.

The only thing that surprised anyone was how small an increase was
needed to cause toxicity. After all, almost all foods are toxic to
almost all organisims in very high concentrations.

Note that this does not apply to some of the unicellular plants,
just as with nitrates etc. in water courses.


Regards,
Nick Maclaren.

Thanks for the info.

There is no doubt that plants which have evolved environmental adaptations
to low concentrations of a particular molecule, gas, ion, or whatever often
suffer when exposed to high concentrations (such as many Western Australian
Proteaceae and soil phosphate levels). I wonder what makes CO2 toxic?
Perhaps it simply lowers pH in the cell, or maybe makes some metallic ions
less available as carbonate increases.

Something for the gene manipulators to get their thinking caps into if CO2
really is going to increase excessively. Will the heat or famine get us
first?...

--
Jeff
(cut "thetape" to reply)