Abstract
The quantum requirement (QR) for photosynthesis in Sedum praealtum, a Crassulacean acid metabolism plant, was compared with that of wheat, a C3 plant, and maize, a C4 plant, at 30 C. During the deacidification phase in S. praealtum, approximately 16 moles quanta were absorbed per mole malate consumed. This is equivalent to 16 moles quanta per mole CO2 fixed, assuming 1 mole CO2 is assimilated per mole malate decarboxylated. This QR for Crassulacean acid metabolism is similar to that of the C3 or C4 plant under atmospheric conditions, even though there are considerable differences in the biochemistry of photosynthesis. During late-afternoon C3-like fixation of atmospheric CO2 in S. praealtum, the QR was relatively high with values of 41 under 21% O2 and 19 under 2% O2. During the deacidification phase in S. praealtum, the relatively low QR can be accounted for by the repression of photorespiration and saturation of photosynthesis from the elevated CO2 concentration in the leaves during malate decarboxylation.
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Selected References
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- Campbell W. H., Black C. C. The relationship of CO2 assimilation pathways and photorespiration to the physiological quantum requirement of green plant photosynthesis. Biosystems. 1978 Aug;10(3):253–264. doi: 10.1016/0303-2647(78)90007-2. [DOI] [PubMed] [Google Scholar]
- Cockburn W. Relationships between Stomatal Behavior and Internal Carbon Dioxide Concentration in Crassulacean Acid Metabolism Plants. Plant Physiol. 1979 Jun;63(6):1029–1032. doi: 10.1104/pp.63.6.1029. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ehleringer J., Björkman O. Quantum Yields for CO(2) Uptake in C(3) and C(4) Plants: Dependence on Temperature, CO(2), and O(2) Concentration. Plant Physiol. 1977 Jan;59(1):86–90. doi: 10.1104/pp.59.1.86. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nobel P. S., Hartsock T. L. Resistance Analysis of Nocturnal Carbon Dioxide Uptake by a Crassulacean Acid Metabolism Succulent, Agave deserti. Plant Physiol. 1978 Apr;61(4):510–514. doi: 10.1104/pp.61.4.510. [DOI] [PMC free article] [PubMed] [Google Scholar]