Fig. 5. Simulated soybean net Acan as a function of PPF at six [CO2]. Symbols are from observed data at 5-min intervals (adapted from Campbell et al., 1990), and curves are from simulation by the CROPGRO model using hourly PPF between 0600 and 1700 h, with assumption of PPF transmission of 0.88 (solid lines) or PPF transmission of 1.08 (dashed lines). The PPF on the x axis is external to and above the chamber walls.