by neufer » Sun Jun 28, 2015 11:17 am
Cousin Ricky wrote:Slawomir wrote:
I am wondering whether sunlight being predominantly yellow-green has something to do with chlorophyll having green colour as well.
It doesn’t. It is not to a plant’s advantage to reflect away the predominant wavelengths of its energy source, so the colors are probably just a coincidence. Most plants have such a low albedo anyway, that the fact that they reflect slightly more green than other wavelengths is of little consequence.
- Sunlight being predominantly yellow-green may have something to do
with flowers & fruits having attractive blue/violet & yellow/red colors:
https://en.wikipedia.org/wiki/Anthocyanin wrote:
<<Anthocyanins (from Greek: ἀνθός (anthos) = flower + κυανός (kyanos) = blue) are water-soluble vacuolar pigments that may appear red, purple, or blue depending on the pH. They belong to a parent class of molecules called flavonoids synthesized via the phenylpropanoid pathway; they are odorless and nearly flavorless, contributing to taste as a moderately astringent sensation. Anthocyanins occur in all tissues of higher plants, including leaves, stems, roots, flowers, and fruits.
In flowers, bright-reds and -purples are adaptive for attracting pollinators. In fruits, the colorful skins also attract the attention of animals, which may eat the fruits and disperse the seeds.
In photosynthetic tissues (such as leaves and sometimes stems), anthocyanins have been shown to act as a "sunscreen", protecting cells from high-light damage by absorbing blue-green and ultraviolet light, thereby protecting the tissues from photoinhibition, or high-light stress. This has been shown to occur in red juvenile leaves, autumn leaves, and broad-leaf evergreen leaves that turn red during the winter. The red coloration of leaves has been proposed to possibly camouflage leaves from herbivores blind to red wavelengths, or signal unpalatability, since anthocyanin synthesis often coincides with synthesis of unpalatable phenolic compounds
In addition to their role as light-attenuators, anthocyanins also act as powerful antioxidants. However, it is not clear whether anthocyanins can significantly contribute to scavenging of free radicals produced through metabolic processes in leaves, since they are located in the vacuole and, thus, spatially separated from metabolic reactive oxygen species. Some studies have shown hydrogen peroxide produced in other organelles can be neutralized by vacuolar anthocyanin.
Light absorbance
The absorbance pattern responsible for the red color of anthocyanins may be complementary to that of green chlorophyll in photosynthetically active tissues such as young Quercus coccifera leaves. It may protect the leaves from attacks by plant eaters that may be attracted by green color.>>
[quote="Cousin Ricky"][quote="Slawomir"]
I am wondering whether sunlight being predominantly yellow-green has something to do with chlorophyll having green colour as well.[/quote]
It doesn’t. It is not to a plant’s advantage to reflect away the predominant wavelengths of its energy source, so the colors are probably just a coincidence. Most plants have such a low albedo anyway, that the fact that they reflect slightly more green than other wavelengths is of little consequence.[/quote]
[list]Sunlight being predominantly yellow-green may have something to do
with flowers & fruits having attractive blue/violet & yellow/red colors:[/list][quote=" https://en.wikipedia.org/wiki/Anthocyanin"]
[float=right][img3="[b][color=#0000FF]Superposition of spectra of chlorophyll a and b with oenin, a typical anthocyanin, in an acidic solution. While chlorophylls absorb in the blue and yellow/red parts of the visible spectrum, oenin absorbs mainly in the green part of the spectrum, where chlorophylls do not absorb at all.[/color][/b]"]https://upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Spectra_Chlorophyll_ab_oenin_%281%29.PNG/800px-Spectra_Chlorophyll_ab_oenin_%281%29.PNG[/img3][/float]<<Anthocyanins (from Greek: ἀνθός (anthos) = flower + κυανός (kyanos) = blue) are water-soluble vacuolar pigments that may appear red, purple, or blue depending on the pH. They belong to a parent class of molecules called flavonoids synthesized via the phenylpropanoid pathway; they are odorless and nearly flavorless, contributing to taste as a moderately astringent sensation. Anthocyanins occur in all tissues of higher plants, including leaves, stems, roots, flowers, and fruits.
In flowers, bright-reds and -purples are adaptive for attracting pollinators. In fruits, the colorful skins also attract the attention of animals, which may eat the fruits and disperse the seeds. [b][color=#00BF00]In photosynthetic tissues (such as leaves and sometimes stems), anthocyanins have been shown to act as a "sunscreen", protecting cells from high-light damage by absorbing blue-green and ultraviolet light, thereby protecting the tissues from photoinhibition, or high-light stress.[/color][/b] This has been shown to occur in red juvenile leaves, autumn leaves, and broad-leaf evergreen leaves that turn red during the winter. The red coloration of leaves has been proposed to possibly camouflage leaves from herbivores blind to red wavelengths, or signal unpalatability, since anthocyanin synthesis often coincides with synthesis of unpalatable phenolic compounds
In addition to their role as light-attenuators, anthocyanins also act as powerful antioxidants. However, it is not clear whether anthocyanins can significantly contribute to scavenging of free radicals produced through metabolic processes in leaves, since they are located in the vacuole and, thus, spatially separated from metabolic reactive oxygen species. Some studies have shown hydrogen peroxide produced in other organelles can be neutralized by vacuolar anthocyanin.
Light absorbance
The absorbance pattern responsible for the red color of anthocyanins may be complementary to that of green chlorophyll in photosynthetically active tissues such as young Quercus coccifera leaves. It may protect the leaves from attacks by plant eaters that may be attracted by green color.>>[/quote]