You are correct that plant chloroplasts are able to move in the leaf
cells depending on the light level. This movement in response to light
is termed phototaxis. It can maximize light interception under low
light conditions and minimize damage to chlorophyll under high light
conditions.

To determine experimentally if chloroplast phototaxis affects leaf
color as perceived by the human eye would require that you have a
mutant plant with chloroplasts that lack phototaxis. You could then
compare the mutant plant with a normal plant. The following article
describes a mutant tobacco plant that has leaf cells with two to three
large choroplasts per cell. These large chloroplasts lack phototaxis.
A normal tobacco plant has cells with numerous smaller chloroplasts
that do exhibit phototaxis. Thus, you should be able to test your
hypothesis.

http://library.kribb.re.kr/research/pdf-2002/3976.pdf

You would also need to test an inanimate green object to determine if
the human eye sees different shades of green depending on the light
level. It might be that the light level will have a larger effect on
color perception than chloroplast phototaxis.


David R. Hershey



(Jörg Sczepek) wrote in message om...
I´m trying to understand why we perceive colours in nature different
in dependency on the intensity of the illumination. According to this
I read that the chlorophyll cells in leaves can change their position
away from the center to the periphery if the illumination is very
bright. Can anybody tell me if this really the case as, say a kind of
protection mechanism against "overexposure", and if it can lead to a
different colour impression ?