Gas Exchange of CAM Plants

It has long been known that a rhythmic gas exchange in CAM plants can persist under continuous darkness (see Bunning, 1973 see Fig. 5.14). Thus, the gas exchange of certain CAM plants follows a typical circadian endogenous rhythm. The question of rhythms in CAM has previously been reviewed by Wilkins (I960, 1969) and Queiroz (1974). 

The question of CAM plant physiology in situ in natural habitats has recently been studied and increasingly attracts attention. Typical features of CAM plants, such as gas exchange, acid fluctuation, and stomatal behavior, have been measured continuously in the field during day/night cycles and seasonally. Also, isotope composition (5 C value) (see Chap. 3.3) has been determined in samples... 

It was indicated earlier that the gas-exchange data obtained in laboratory experiments suggested that photosynthetic rates of CAM plants were considerably lower than in C3- and C4-species (Table 6.3). This is consistent with the general observation that CAM plants have relatively low growth rates, and supports the view that CAM is more a survival mechanism. 

Neales,T.F. The gas exchange pattern of CAM plants. In Environmental and biological control of photosynthesis. Marcelle,R. (ed.), pp.299-310. The Hague Dr. W. Junk b.v. Publishers, 1975a... 

Fig. 5.2. Schemes of gas-exchange patterns as performed by CAM plants (after Neales,...

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