What does 6500K actually provide for plants?
(Or any color temperature, but 6500K is the most relevant.)
I understand the concept of color temperature ratings: the color of the light produced by a light source --- whether or not it emits thermal radiation --- is rated based on its resemblance to the temperature of a theoretical black body emitting that color. (So a bulb rated for 2700K is emitting the same color of light as a true black surface that is 2,700° Kelvin hot.) And I more or less understand that 6500K is the nearest color temperature to the sun at the time it is optimally bright for plants.
What I don't understand is, what nutrition does a plant actually derive from that color of light? Is 6500K just the point at which the most PAR is available for plants? If so, if PAR ratings became more widespread (or PAR readers become affordable!), would there no longer be a need to look for color temperature ratings on lights, at least for growing purposes?
Or does the color temperature of light provide some other parameter of nutrition to plants, that is totally unrelated to PAR?
Thanks for your consideration.