CO2 Exchange in Continuous Darkness

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). 

According to Pittendrigh (1954 see also Wilkins, 1969), true endogenous rhythmic phenomena obey the following  

The rhythm persists under constant environmental conditions 

The rhythm phase can be shifted by environmental perturbation, and the new rhythm will persist if kept under constant conditions 

Since rhythms depend on energy (for example, oxidative phosphorylation), anaerobiosis will inhibit. 

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