4.3. Leaf vs. crop photosynthesis
As far as we know, no action spectra on crop level have been reported before. We achieved the action spectrum on crop level by using a model that explicitly simulates light extinction in a crop and integrates leaf photosynthesis into crop photosynthesis based on measured optical and photosynthetic properties of individual leaves. The model results showed an increased utilization of green light at canopy level relative to leaf level, as indicated by the presented absorptance and action spectra. More importantly, our results indicate that the action spectrum at crop level deviates from that at leaf level. Hence, findings at leaf level should not automatically be extrapolated to crop level without considering interactions within the crop.