Carbon Fixation and Isotope Discrimination by a Crassulacean Plant: Dependence on the Photoperiod

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Science  22 Mar 1974:
Vol. 183, Issue 4130, pp. 1207-1209
DOI: 10.1126/science.183.4130.1207


Variations of more than 1 percent are observed in the carbon-13 to carbon-12 ratio of extracts of leaves of the succulent Kalanchoe blossfeldiana when the photoperiod is changed from long to short days. This indicates that the mechanism of carbon fixation switches from the Calvin (C3) pathway to the Hatch-Slack (C4) pathway of primary enzymic operation. The variations observed in the isotope compositions are tentatively explained by a model.