Seasonal effects on carbon isotope composition of cactus in a desert environment
| Autor: | Irwin P. Ting, J. H. Troughton, B. G. Sutton |
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| Rok vydání: | 1976 |
| Předmět: | |
| Zdroj: | Nature. 261:42-43 |
| ISSN: | 1476-4687 0028-0836 |
| DOI: | 10.1038/261042a0 |
| Popis: | IN plants with crassulacean acid metabolism (CAM), CO2 is fixed in the light by ribulose-l,5-bisphosphate carboxylase1,2 and in the dark by phosphoenol pyruvate (PEP) carboxylase2,3. Because these two enzymes fractionate the stable isotopes of carbon (12C and 13C) in the atmosphere and discriminate against 13C to different extents4, the wide range of values of carbon isotope discrimination ratios (δ13C) found in these plants5 has been attributed to different contributions of dark and light fixation to carbon gain6. The proportion of total carbon fixed at night can be altered by environmental variables such as temperature7, water status8 and photoperiod5. Predictable changes in δ13C values have been observed when these environmental conditions have been varied. With one exception, all such studies have been performed in artificial conditions. Because the δ13C ratio of CAM plants has been used as an indicator of environment in palaeoecological investigations9, we have examined the sensitivity of these δ13C ratios to seasonal environmental influences in a natural system. Using Opuntia acanthocarpa, O. basilaris and O. bigelovii, we found that the carbon isotope composition of the plants did not change during the experiment, indicating the insensitivity of this measurement to short term seasonal influences in this environment. |
| Databáze: | OpenAIRE |
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