Figure 2.

Net CO₂ uptake (A) and g_s responses as a function of changing pCO₂ measured from late afternoon (phase IV) and throughout the dark period (phase I) and into the light (phase II; B). Representative data are plotted as individual response curves for one leaf at selected intervals during the dark period. Gas exchange measurements were made at an irradiance of 300 μmol quanta m⁻² s⁻¹ in the light period, with day/night temperatures of 25°C/20°C and a pCO₂ varied against a background gas mixture of 909 mbar nitrogen and 48 mbar of O₂.