Hmmmm...but its a very good idea, at the end. Equipment that measures instant O2 flux from a leave is not so expensive....

It would be needed to use a dark period of 30min between each light quality, but using large steps, like 20% for each waveband, we may identify the bext mixes in a rough way and then work in fine tuning it.

Using the same irradiances of differnt SPD needs some work, but its doable. A single testing array with 1 or 2 LEDs of each color and current adjustement for each color is all we need.

I think its a very good idea. At least in order to identify the best photosynthetic respones. Long term (whole grow under a given quality and irradiance) would be still needed to study which matter at the end, the carbon fixation, morphology traits, to understand the final relation between light and yield. But it would be experimenting in far narrower settings.