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#1
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Do leaves change their colour according to the brightness ?
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 ? |
#2
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Do leaves change their colour according to the brightness ?
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 ? |
#3
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Do leaves change their colour according to the brightness ?
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#4
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Do leaves change their colour according to the brightness ?
In article ,
Mike Lyle wrote: (David Hershey) wrote in message . com... You are correct that plant chloroplasts are able to move in the leaf cells depending on the light level.[...etc...] OK, you've answered the intelligent question. Now, how about a naive one? I've sometimes wondered if the reactions involved in green vegetation's sensitivity to light could have been exploited to form the basis of a photographic process not dependent on silver compounds. Well, you can put a stencil on an apple and when it ripens, the part that was covered will not have turned red. This has been recommended to delight little kids by putting their names on apples. I think you can do this with dark green winter squashes too - the covered part is orange. Maybe I should try it this year - I could get on the front page of the National Inquirer (Face of Jesus Appears on Woman's Squash! Cucurbit Apocalypse Predicted!) It's more like old fashioned blueprints than photography, though. OK, I said it was naive. But if it goes on to get you a Nobel Prize, try to remember me in the speech of thanks! I like the idea: dynamic videos on rhubarb leaves, perhaps. A new goal for genetic engineering! |
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