Figure 8.

Gas diffusional and biochemical limitations of CO₂ assimilation rate after changing from short or long periods of darkness to high light. The limitations to CO₂ assimilation rate (A) imposed by stomatal conductance (L_gs; dark), mesophyll conductance (L_gm; pale), and biochemical processes were evaluated in tobacco with the dataset shown in Figure 6. Biochemical limitations assumed either RuBP carboxylation (upper panels, L_Vcmax) or RuBP regeneration (bottom panels, L_J) under the light condition of: A, 0, 1,500, 0, and 1,500-μmol photons m⁻² s⁻¹ for 10, 50, 10, and 30 min; B, 0, 1,500, 0, and 1,500-μmol photons m⁻² s⁻¹ for 10, 50, 60, and 30 min preceded by overnight darkness; or C, 2 h of sunlight followed by 5 h of darkness, then 0 and 1,500-μmol photons m⁻² s⁻¹ for 10 and 50 min, respectively. The vertical bars on each symbol indicate the standard error with 3–6 replicate leaves for tobacco. Grey boxes in each figure represent the periods of darkness. The numbers (0 and 1,500) in the grey and white boxes at the top of (A), (B), and (C) indicate the light intensity.