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Water use efficiency of two succulents with contrasting CO 2 fixation pathways
Author(s) -
ELLER B. M.,
FERRARI S.
Publication year - 1997
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.1997.d01-16.x
Subject(s) - crassulacean acid metabolism , transpiration , water use efficiency , biology , botany , photosynthesis , carbon fixation , habitat , fixation (population genetics) , dehydration , ecology , agronomy , biochemistry , gene
Two succulents with similar growth forms but different types of photosynthesis, Cotyledon orbiculata (crassulacean acid metabolism, CAM) and Othonna opima (C 3 pathway), were investigated with respect to the modulation of water use efficiency (WUE) during the transition from the rainy season to subsequent drought. Environmental conditions were simulated in a controlled‐environment experiment on the basis of data collected in the habitat of the two species in the southern Namib desert. Experiments included one or more periods of hot bergwind, which frequently occurs in this region. When water was readily available, daily net CO 2 fixation was similar in the two species. This result confirms that the daily CO 2 fixation of CAM plants is as high as that of morphologically similar C 3 plants adapted to the same habitat. As expected, both species reduced CO 2 fixation and water loss through transpiration during simulated hot bergwind periods and their WUE values increased. However, after the second hot bergwind period, nearly identical WUEs were recorded: 41.0 and 40.0 mmol mol −1 for C. orbiculata and O. opima , respectively. Therefore the statement that a CAM plant is a better ‘water saver’ than a C 3 plant does not necessarily hold for CAM and C 3 plants with similar growth forms growing under the same environmental conditions.