FIGURE 7.

CO₂ response curves of canopy photosynthesis during the CO₂ drawdown experiment: Changes in chamber CO₂ concentration (inset, dCO₂ 5s^{– 1}) from drawdown curves measured at constant PPFD were plotted vs. CO₂ concentration, fitted with a logarithmic curve, and converted into photosynthetic CO₂ response curves. Response curves measured during consecutive days are shown as solid and dashed lines. For comparison, the CO₂ response curve measured during PESTO is plotted (BPS 2002, black circles) and P_net of wheat increases at higher light levels (Monje and Bugbee, 1998, blue triangle).