Fig. 3.

The relationship between net CO₂ assimilation rate A and the lumped variable I _incΦ₂/3 (mean of four replicates) from irradiance response curves under non-photorespiratory conditions (i.e. at 2% O₂ combined with high CO₂) at six leaf temperatures. Open circles are for I _inc ≤500 μmol m⁻² s⁻¹ and filled triangles come from the three levels of I _inc >500 μmol m⁻² s⁻¹. The lines represent linear regression based on data with I _inc ≤500 μmol m⁻² s⁻¹, in which the slope gives the estimate of calibration factor s′ and the intercept gives the estimate of day respiration R _d (see the text).