Does anybody know which kind of photosynthesis cycle most waterplants use??
I guess it's mainly the C3 cycle.

But I remember to read something on the net, but don't remember where
:-(( about waterplants using the CAM-cycle (Crassulacean Acid Metabolism).
This would mean those plants would store CO2 at night and use the stored CO2
for the photosynthesis proces at daylight.

If they use the CAM-cycle I guess it would make sense to keep dosing CO2 in
the night period??
--

Mazzeltov, Adriaan Briene
http://members.lycos.nl/brieneoord/aqua/

Adriaan Briene wrote:
This would mean those plants would store CO2 at night and use the stored CO2
for the photosynthesis proces at daylight.

According to Diana Walstad some water plants convert CO2 at night into
malate, which is used during the day to generate CO2 for photosynthesis.
She also says this strategy is not as common in aquatic plants as it is in
terrestrial ones. ("The Ecology of the Planted Aquarium" pp. 96-97)

--
Victor M. Martinez | The University of Texas at Austin
| Department of Chemical Engineering
http://www.che.utexas.edu/~martiv | Austin, TX 78712
If we knew what we were doing it would not be called research, would it?

If they use the CAM-cycle I guess it would make sense to keep dosing CO2 in
the night period??

No, these are slow growers and have lower CO2 needs as a rule.
There's also no algal or C3 plant uptake during the night so there's
no competition except among themselves which is not that much unless
you have a tank packed with Isoetes and little else etc. As slow
growers, they tend to be mixed with other fast species that dominate.

The only common CAM plant kept is Isoetes which is a heterosporus fern
and it's weird even in a weird group. They also get most of the CO2
from roots(60% up to 100%) substrate.

One plant in the family has no stomata at all and gets 100% of the CO2
from the roots. It's rare and lives up in the Andes of South American.
Stylites andicola.

C4 is more prevalent in aquatics(Hydrillia, Orcutt grass etc).
There is also bicarbonate usage which differes from C4, the effect is
rather similar. It suppresses the oyxgenating activity of Rubisco(the
enzyme that fixes the Carbon) and lowers the CO2 compensation point.
CAM plants do this _temporally_ within each cell. C4 is _spatial_
within the plant rather than temporal.

But adding CO2 during the day is the only thing folks need to do.
Regards,
Tom Barr

Thanx for the info Tom and Victor !

So it seems it makes no sense even if I had plants capable of CAM and I can
keep on dosing like I use to do it.
(Regulating the CO2 on the pH value measured in the morning when the lights
are still out, gives a "natural" level of about 5-10 mg/ltr)


It was very interesting to read some aquatic plants even use the C4 cycle,
didn't expect that :-)).


--

Greetings from, Adriaan Briene

Aquariumhobby, Nijverdal www.aquariumhobby.nl

" schreef in bericht
om...
snip /snip
C4 is more prevalent in aquatics(Hydrillia, Orcutt grass etc).
There is also bicarbonate usage which differes from C4, the effect is
rather similar. It suppresses the oyxgenating activity of Rubisco(the
enzyme that fixes the Carbon) and lowers the CO2 compensation point.
CAM plants do this _temporally_ within each cell. C4 is _spatial_
within the plant rather than temporal.

But adding CO2 during the day is the only thing folks need to do.
Regards,
Tom Barr