photosynthesis at high CO2 conc.

Søren Laurentius Nielsen nielsen at
Mon Aug 24 03:02:28 EST 1998

On 23 Aug 1998 15:31:16 -0700, albertov at CRISTINA.CTV.ES ("Alberto
Vilagrosa") wrote:

>I am carrying out an experiment about water stress in sclerophyllus
>plants (quercus coccifera and pistacia lentiscus). I would like study
>limitations at CO2 fixation level related with cell dehydration. For
>this purpose, I will measure photosynthesis with IRGA at normal CO2
>concentration and at 2000 ppm concentration. The reason for high
>concentration is because I think that at this concentration, CO2
>diffuses through cuticle and other leaf barriers when stomata are
>closed. And, I will able differentiate between limitations to
>photosynthesis due to stomatal closure or damage at photosynthetic
>machinery level because of cell dehydration. My question is if 2000
>ppm will be sufficient CO2 concentration to diffuses through cuticle
>when stomata are closed or I will need to use higher concentration?.
>Any comment will be gratefully received. Thanks in advanced.
I do not have any experince with the diffusion of CO2 through the
cuticle, but bear in mind that high concentrations of CO2 seem to have
a negative effect on photosynthesis. This was described as a
"narcotic" effect by Steeman-Nielsen in 1955 (E. Steeman-Nielsen:
Carbon dioxide as carbon source and narcotic in photosynthesis and
growth of _Chlorella pyrenoidosa_. Physiologia Plantarum 8: 317-335,
1955), and was found again by my self much later: S.L. Nielsen & K.
Sand-Jensen: Photosynthetic implications of heterophylly in
_Batrachium peltatum_ (Schrank) Presl. Aquatic Botany 44: 361-371,
1993. This effect (whose cause I am far from certain of) was found at
CO2 concentrations in excess of 1200 ppm.

Søren L. Nielsen
nielsen at

Søren Laurentius Nielsen
Department of Life Sciences and Chemistry
Roskilde University, Denmark
nielsen at
ICQ: 11355525

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