Phil Edwards said: "My hypothesis is this: Since a plant produces red
pigments to capture blue
light, then a plant grown under a higher K rating bulb (more blue light)
should be more red than if it were grown under a lower K bulb."
I am sure that you will find this to be true.
The red pigment I believe also absorbs the blueer wavelenghts: violet and
ultraviolet. That explains why many land plants here in sunny Malta turn red
/reddish/brownish at the approach of summer, to protect themselves from
harmful UV rays, much like tourists turn from white to brown. Their melanin
absorbs the harmful UV rays. (Some of the tourists do turn reddish (g), but
that's because their melanin production wasn't activated quickly enough)