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



## LondonDragon (9 Aug 2020)

Interesting article:

https://www.quantamagazine.org/why-...200730/?utm_source=pocket-newtab-global-en-GB


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## Tim Harrison (10 Aug 2020)

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


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## LondonDragon (10 Aug 2020)

Tim Harrison said:


> 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!!


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## jaypeecee (10 Aug 2020)

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


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## jaypeecee (10 Aug 2020)

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


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## jaypeecee (10 Aug 2020)

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


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## Zeus. (10 Aug 2020)

jaypeecee said:


> They can't both be correct, can they?



I would say no, but they could both be wrong 🤣


But good article, gives one lots to think about 👍


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## LondonDragon (10 Aug 2020)

jaypeecee said:


> 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?


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## oreo57 (10 Aug 2020)

jaypeecee said:


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



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
		
Click to expand...

*


> 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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## dw1305 (11 Aug 2020)

Hi all, 





jaypeecee said:


> I've seen carotenoids described in this way


Look for <"anthocyanins">, we have a few threads that discuss their role in the leaf.

cheers Darrel


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## oreo57 (11 Aug 2020)

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.


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## dw1305 (12 Aug 2020)

Hi all, 





jaypeecee said:


> 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


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## jaypeecee (12 Aug 2020)

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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## jaypeecee (12 Aug 2020)

Hi @Zeus. 


Zeus. said:


> I would say no, but they could both be wrong 🤣



Excellent! 

JPC


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## aripware (15 Aug 2020)

nice info


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