Figure 3.

Response of CO₂ assimilation rate, stomatal and mesophyll conductance, CO₂ concentration in the intercellular airspaces and chloroplast stroma, the maximum rate of RuBP carboxylation, and electron transport after changing from darkness to high light. A CO₂ assimilation rate (A), stomatal (g_s; dark circle) and mesophyll conductance (g_m; pale triangle) to CO₂, and CO₂ concentration in intercellular airspaces (C_i; dark circle) and chloroplast stroma (C_c; pale triangle) were measured every 100 s under the light condition of (A) a PPFD of 0 and 1,000-μmol photons m⁻² s⁻¹ for 10 min and 50 min in Arabidopsis (blue), and (B) a PPFD of 0 and 1,500-μmol photons m⁻² s⁻¹ for 10 and 50 min in tobacco (red), respectively. The maximum rate of RuBP carboxylation (V_cmax; dark circle) and electron transport (J; pale triangle) were also estimated assuming RuBP-carboxylation or regeneration limiting conditions according to the biochemical model for C₃ photosynthesis. CO₂ concentration and air temperature in the leaf chamber were set to 400 µmol mol⁻¹ and 24°C, respectively. The vertical bars on each plot indicate the standard error with 6–8 replicate leaves for Arabidopsis and 3–6 leaves for tobacco. Grey boxes in each figure indicate the initial period of darkness. The numbers (0, 1,000, and 1,500) in the grey and white boxes at the top of (A) and (B) indicate the light intensity.