Table 1.

Integrated net CO₂ uptake for the times of each of the four CAM phases (mmol CO₂ m⁻² phase⁻¹) by young fully expanded leaves of Aechmea ‘Maya’ under ambient (380 μmol mol⁻¹) and elevated (700 μmol mol⁻¹) CO₂ concentrations

CO2 (μmol mol−1)	Phase I 2200–0600	Phase II 0600–0900	Phase III 0900–1800*	Phase IV 1800–2200*	Total 24 h 1200–1200
380	52·5 ± 6·1	7·2 ± 0·6	−2·5 ± 4·7	10·5 ± 2·0	67·7 ± 6·9
700	55·4 ± 2·6	16·1 ± 1·3	−3·7 ± 2·5	42·5 ± 3·7	109·5 ± 10·5
P-value	>0·05	<0·05	>0·05	<0·05	<0·05

The data are means ± s.e. for five leaves, each from a separate plant and were compared for each phase between the two treatments by two-sample t-test (α = 0·05).

*Due to elevated CO₂ phase IV extended by starting 3 h earlier at 1500 h compared with controls; concomitantly phase III reduced by the same extent.