There was no supplemental CO2 enrichment in all experimental
greenhouses. CO2 enrichment was carried out by natural ventilation
during the four experiments. Therefore, leaf net photosynthetic
rate (Pn) in response to PAR was determined, using Li-6400 (LICOR)
system at a CO2 concentration of 370 ± 20 mol mol−1, on
the newly fully expanded leaves. The measurements were carried
out from 9:00 to 12:00 for three successive sunny days at each
developmental stage.
Data of experiment 2 were used for model development and
those of the rest three experiments were used for model validation.