Carbon isotope ratios are correlated with irradiance levels in the Panamanian orchid Catasetum viridiflavum
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Carbon isotope composition (13C/12C) in leaves of the Panamanian epiphytic orchid Catasetum viridiflavum were measured on individuals growing in canopies over a water surface to distinguish the effects of a change in source CO2 and humidity from those of intercellular CO2 concentration in determining isotopic composition. Carbon isotope ratios were observed to vary by over 4 in response to changes in total daily photon flux (PFD, 400–700 nm). Changes in isotopic composition of source CO2 or changes in humidity were not likely to have played a role in determining leaf isotopic composition. Observed changed in carbon isotope discrimination (Δ) of leaves experiencing different light levels ranged from 17 to 21. Because leaf nitrogen contents were similar among all orchids, we suggest that the carbon isotope discrimination data indicated that stomatal limitation to photosynthesis increased with increasing irradiance.
Key wordsCarbon isotope ratio Carbon isotope discrimination Catasetum C3 photosynthesis Gas exchange
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- Benzing DH, Bent A, Moscow D, Peterson G, and Renfrow A (1982) Functional correlates of deciduousness in Catasetum integerrimum (Orchidaceae). Selbyana 7:1–9Google Scholar
- Farquhar GD, Ball MC, von Caemmerer S, Roksandic Z (1982) Effect of salinity and humidity on δ13C value of halophytes-evidence for diffusional isotope fractionation determined by the ratio of intercellular/atmospheric partial pressure of CO2 under different environmental conditions. Oecologia 52:121–124CrossRefGoogle Scholar
- Francey RJ, Gifford RM, Sharkey TD, Wier B (1985) Physiological influences on carbon isotope discrimination in huon pine (Lagarostrobos franklinii). Oecologia 66:211–218Google Scholar
- Leigh EG Jr, Rand AS, Windsor DM, eds, (1982) The ecology of a tropical forest, seasonal rhythms and long-term changes. Smithsonian Institution Press, Washington, District of Columbia, USAGoogle Scholar
- Rand AS, Rand WM (1982) Variation in rainfall on Barro Colorado Island. In: Leigh EG Jr, Rand AS, Windsor DM (eds), pp. 47–59. The ecology of a tropical forest, seasonal rhythms and long-term changes. Smithsonian Institution Press, Washington, District of Columbia, USAGoogle Scholar
- Rundel PW, Ehleringer JR, Nagy KA (1988) Stable Isotopes in Ecological Research. Springer Berlin Heidelberg New YorkGoogle Scholar
- Vogel JC (1978) Recycling of carbon in a forest environment. Oecol Plant 13:89–94Google Scholar
- Zimmerman JK (1989) Evolutionary ecology of Catasetum viridiflavum, an orchid that changes sex. Ph.D. Dissertation, University of Utah, Salt Lake City UT, USAGoogle Scholar