Why Are Plants Green? To Reduce the Noise in Photosynthesis.

Tim Harrison

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Nice article 👍
How would that relate to growing plants in an aquarium and to the design of LED lights, for instance 🤔?
 

LondonDragon

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How would that relate to growing plants in an aquarium and to the design of LED lights, for instance 🤔?
I think its more for those fancy spectrum controllable RGB units, now there is a better understanding of which spectrums the plants utilize so you can start by tweaking them in that way!!
 

jaypeecee

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Hi @LondonDragon (Paulo),

Thanks for drawing our attention to this very interesting article. Having a specific interest in aquarium lighting, I have added this to my list of useful references.

JPC :)
 

jaypeecee

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Hi Folks,

And what would be the optimum spectrum at the water's surface for aquatic plants ? Particularly those that aren't 'true aquatic plants'? Blue light is barely reduced in intensity at one metre water depth but red light is reduced by 75%. Unlike the changing solar spectrum, LED aquarium lighting is constant. Of course, this is not the case for aquatic plants in their natural habitat. Food for thought.

Thanks again, Paulo!

JPC
 

jaypeecee

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Hi Folks,

There's another gem of information in this article of which I was not aware. Here it is:

"There are plants that don’t appear green, like the copper beech, because they contain pigments like carotenoids. But those pigments are not photosynthetic: They typically protect the plants like sunscreen, buffering against slow changes in their light exposure".

The above statement is the first time I've seen carotenoids described in this way. Wikipedia has this to say:

"...there are many non-chlorophyll accessory pigments, such as carotenoids or phycobiliproteins, which also absorb light and transfer that light energy to photosystem chlorophyll. Some of these accessory pigments, in particular the carotenoids, also serve to absorb and dissipate excess light energy, or work as antioxidants".

So, the article referenced by @LondonDragon is saying that carotenoids are not photosynthetic. On the other hand, the Wikipedia article is stating that carotenoids and other accessory pigments have a dual role, one of which is photosynthetic.

They can't both be correct, can they?

The source paper referenced by Wikipedia is:

https://www.tandfonline.com/doi/abs/10.1080/01140671.2009.9687587

JPC
 

LondonDragon

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They can't both be correct, can they?
Maybe the new model superseeds it, a bit like Nitrates are bad for your aquarium! ;)

Comments on the article are also interesting, I did find this one perculiar!

Great article. I had some interesting observations years ago, when I experimented colour intensities with plants. I inferred that red and blue light increased shoot length (tall and thin), while yellow had broader shoot and short.
Wonder if this could have any implications in plant growth in the aquarium?
 

oreo57

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Hi Folks,

There's another gem of information in this article of which I was not aware. Here it is:

"There are plants that don’t appear green, like the copper beech, because they contain pigments like carotenoids. But those pigments are not photosynthetic: They typically protect the plants like sunscreen, buffering against slow changes in their light exposure".

The above statement is the first time I've seen carotenoids described in this way. Wikipedia has this to say:

"...there are many non-chlorophyll accessory pigments, such as carotenoids or phycobiliproteins, which also absorb light and transfer that light energy to photosystem chlorophyll. Some of these accessory pigments, in particular the carotenoids, also serve to absorb and dissipate excess light energy, or work as antioxidants".

So, the article referenced by @LondonDragon is saying that carotenoids are not photosynthetic. On the other hand, the Wikipedia article is stating that carotenoids and other accessory pigments have a dual role, one of which is photosynthetic.

They can't both be correct, can they?
They both are correct.
}
E]
Carotenoids are a class. Both statements are correct
Carotene is usually listed as non-photosynthetic.
As nouns the difference between carotenoid and carotene
is that carotenoid is (organic chemistry) any of a class of yellow to red plant pigments including the carotenes and xanthophylls while carotene is (organic chemistry) a class of tetraterpene plant pigments; they vary in colour from yellow, through orange to red, this colour originating in a chain of alternating single and double bonds[/QUOte]

See table 1
https://www.liebertpub.com/doi/10.1089/ast.2014.1178


Not exactly sure of the conflict about carotene
proper though.

Note: this topic is complex and at the moment possibly wrong or incomplete.
I can't find the paper that (surprising to me) lists carotene as a non-photosynthetic pigment.
Reams of other evidence say differently.
The list of carotenoids is fairly long and not sure all have been thoroughly investigated.

http://www.life.illinois.edu/govindjee/papers/CarFin1.html#intro
V. Conclusions
What is certain is that both b -carotene and the xanthophyll fucoxanthin transfer excitation energy to Chl a; b -Carotene, in addition, protects against photochemical damage of the reaction centers, and the xanthophyll zeaxanthin protects plants against excess light by initiating reactions, in combination with those initiated by pH gradient, that lead to loss of excess energy as heat. Much research is needed to prove the roles of other carotenoids (e.g., lutein, violaxanthin, and others). It is however currently assumed that violaxanthin acts as a light harvester, i.e., transfers energy to Chl a, and that lutein may indeed substitute for zeaxanthin in some systems. Research on both the mechanism of excitation energy transfer from Chls to carotenoids and vice versa is ongoing.
 
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oreo57

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Followup from a source:
. I wrote an article probably 15 years ago on the subject but I don't see it on reefs.com. The role of DD/DT xanthophylls is straight forward. There are several forms of beta-carotene (beta-carotene, beta-beta carotene, etc.) but I don't recall which is functional in zoox. I do know whatever form it is has a weak photosynthetic ability but acts more as an anti-oxidant.
Reef stuff so consider that.
 

dw1305

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Hi all,
So, the article referenced by @LondonDragon is saying that carotenoids are not photosynthetic.
I think they are mainly stored in the cell vacuole, so that would limit their role in photosynthesis.
Plants usually produce the red anthocyanin pigments in high light situations, mainly to protect their chlorophyll from damage by excess sunlight.

This is from Gould, K. (2004) "Nature's Swiss Army Knife: The Diverse Protective Roles of Anthocyanins in Leaves." "By absorbing high-energy quanta, anthocyanic cell vacuoles both protect chloroplasts from the photoinhibitory and photooxidative effects of strong light, and prevent the catabolism of photolabile defence compounds. Anthocyanins also mitigate photooxidative injury in leaves by efficiently scavenging free radicals and reactive oxygen species. J. Biomed Biotechnol. 2004(5): pp.314–320
cheers Darrel
 

jaypeecee

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Hi Folks,

Some good feedback above. Thanks for the responses to points that I had raised. I now need to absorb it all!

JPC
 

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