This is an interesting question. First, let's
clarify something: the "color" of light doesn't
just consist of the visible colors we can see.
It turns out that the "visible spectrum" is only
a very small part of all kinds of light, or
electromagnetic radiation. When light from the
sun comes into our atmosphere, it's not just a
mix of different colors, but there is also some
UV and infrared light in the mixture. There is
what we would call a certain "distribution" (or
relative amounts) of visible, UV, and infrared
light in this mixture. So I think what your
question comes down to is this: how would
changing the relative amounts of the different
kinds of light affect plant growth?
Let's consider the visible part of the
spectrum first. I think most people would agree
that plants are green in general. They are green
because they reflect green light. So changing
the amount of green light in the distribution
shouldn't really affect how plants grow, since
they don't use it for their metabolic processes.
It turns out that plants use mostly red and blue
light. Let's think about how the color of
sunlight changes over the year. As the days grow
longer in the spring and summer, plants start to
grow. Sunlight is mostly blue in this time of
year, so blue light tends to increase stem and
leaf growth. Later, as summer progresses,
sunlight becomes predominantly red and plants
flower and bear fruit that becomes ripe.
Now let's think about what happens when we
increase UV or infrared. It depends on the kind
of plant we're talking about, but in many cases,
increased UV or infrared tends to damage plants.
I hope this helps!