CRASSULACEAN ACID METABOLISM IN KALANCHOE SPECIES COLLECTED IN VARIOUS CLIMATIC ZONES OF MADAGASCAR - A SURVEY BY DELTA-C-13 ANALYSIS

The carbon isotope compositions of samples of Kalanchoe species collected at the natural stands in Madagascar were determined. The results suggest that all species of the genus Kalanchoe are capable of crassulacean acid metabolism. The observed delta-C-13 values cover the whole range from -10 to -30 parts per thousand. This high diversity of the delta-C-13 values was found among the species of the genus as well as, in certain cases, within a single species. This suggest that the CAM patterns in Kalanchoe are generally very flexible. The delta-C-13 values show a clear correlation with the climate of the habitats from where the samples derived. Values indicative of CO2 fixation taking place exclusively during the night were found in the dry regions of Madagascar, whereas delta-C-13 values indicative of mixed CO2 fixation during night and day or of CO2 fixation entirely during the day are distributed in the humid zones.