Photosynthesis efficiency was calculated as mol of CO2 assimilated
per mol of incident light for the action spectrum and as
mol CO2 per mol of absorbed light for the spectral quantum
yield. As quantum yield was very similar at both light intensities,
the quantum yield was calculated as the average of yields at 30 and
at 60molm−2 s−1 narrow band light. All values are expressed as
a fraction of the maximum value, recorded for both the treatment
at 680 nm.