A higher action spectrum in the red compared to the blue region was found because the quantum efficiency at red light (Fig. 2B) was highest, although absorptance at blue light was slightly lower than in the blue region (Fig. 1C). For getting an impression of the impact of quantum efficiency and scattering being different per wavelength, we did model calculations that showed that 1% change in quantum efficiency increased crop gross photosynthesis by 0.88%, while 1% change in scattering changed crop photosynthesis by only 0.03%. This is confirmed by the rather modest variation in quantum efficiency (ranged from 0.31 to 0.47) which resulted in large variations in photosynthesis (±17.9% from the mean) yet the larger variation of scattering between wavelengths (reflection ranged from 5 to 16%) changed photosynthesis by only±1.7%