For some time, since I learned from the literature that some orchids
are CAM * plants, I have been interested in the possibility of discovering
which they are. Schnitz's comments don't specifically refer to CAM plants
but seem to imply that he is dealing with some. Having missed earlier
contributions (Zzzzzzz!) on this topic I wonder when the additional CO2
supplement is proposed and whether or not any observations of the stomatal
openings and closures have been made.
I would be most interested to know which commonly cultivated orchids
are CAM plants. Maybe someone can point me at an appropriate website or
printed reference?
Just one thing though; if these plants take up CO2 at night, how do we know
that the limiting factor is not their ability to store the CO2 in their
malic acid until the light of day (and photosynthesis)? In my naive view of
the process, I would imagine that a plant with normal metabolism could
process more or less as much CO2 as the available light would permit.
However, CAM plants would need to anticipate the light levels for the
following day(light) if additional CO2 were to be provided. Sounds a bit of
a tall order! However, I'd be most interested to hear of the results.
Someone out there must have knowledge (better than my surmisings!). Even
better, does anyone know of any explanation for orchids' evolutionary
acquisition of CAM physiology which, in succulents (and some cacti?) is an
adaptation for coping with daytime desiccation. Many, if not most orchids
are not hell-bent on water conservation . . . or are they? Maybe they needed
to be so earlier in their evolutionary history in drier conditions? . . .
Surmise again!
* Oh, just in case it's needed, CAM is an acronym for Crassulacean Acid
Metabolism
John Stanley
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[email protected]>
> Message: 2
> Date: Mon, 13 Nov 2006 09:35:20 -0700
> From: "Schnitz" <[EMAIL PROTECTED]>
> Subject: [OGD] CO2 at night
> To: <[email protected]>
> Message-ID: <[EMAIL PROTECTED]>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> Well, I think this idea of CO2 may be of particular use to me. I have
> read
> that orchids are like cacti, and only open their stomata at night.
> Whereas
> I have plenty of air exchange during the day from my cooler running all
> year, even in freezing weather with some debilitation, I have NO air
> exchange at night. This might not be a problem in a normally populated
> greenhouse (GH), but I am running a temporary green house, 8' X 12' made
> short because of high wind loads on such a flimsy structure, and it has
> been
> going much longer than expected, so it is grossly over crowed at this
> point.
> About 750 plants, not counting duplicates, or those that move to the cold
> frame sometime during winter, with plants growing in 3 levels. To make
> maters worse, I baffle the two louver vents near the top of the GH so that
> the escaping hot air has to travel down to ground level before it is
> exhausted, and this stops the temperature differential from forcing hot
> air
> out the vents, shutting off air exchange there. Only problem may be
> getting dry ice in Prescott, AZ. Anyone try using bottled CO2?
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