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Does Blue Light Shrink Aquatic Plants?

jaypeecee

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Hi Everyone,

Since first seeing a YouTube video by Dr Bruce Bugbee of Apogee Instruments, I have often wondered if blue light shrinks aquatic plants? Please take a look at the following:


Fast forward the video to around 4 mins 45 secs and watch from there. Now, it may be that what Dr Bugbee is saying only refers to terrestrial plants. Does anyone know if blue light also shrinks aquatic plants?

Thanks in advance.

JPC
 

plantnoobdude

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HI, i don't think it shrinks plants, but i do beilieve it leads to more compact growth.I believe i read a study a while ago, but i forgot what it was. i'm not too well versed on this topic, and will keep an eye on this thread as the experts chime in.
 

erwin123

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When it's access to CO2/O2 is cut off sharply by submergence. This leads to rapid accumulation of the hormone ethylene in the plant meristem, which induces rapid stem elongation in an attempt to break back up the water surface to access air.
However, most aquatic plants do not respond as directly to blue light as stem elongation is more affected by the flooding response
One of the main factors in determining internodal distance is actually growth speed. Plants in faster growth mode tend to have longer internodes than plants in slower growth mode. Temperature is one significant factor that determines the rate of plant metabolism - cooler tanks with lower temperatures lower plant metabolism and give rise to more compact plants.
 

oreo57

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Heavy blue spectrum will shorten internodes in some aquatic plants at least from my personal experience.

Hard to see but hygrophylla leaves became more dissected and internodes "disappearred"
Rotala tightened up as well.
Granted extreme color shift.
tankblueonlyCROP.jpg
 
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jaypeecee

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Hi Everyone,

Thanks for the feedback.

I'd forgotten about the article on the 2Hr Aquarist website. I'd read this some time ago but forgotten about it.

In what way will a lot of light in the blue part of the spectrum affect rosette plants?

JPC
 

EA James

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I've read before that blue light can contribute/cause algae? I'm not sure where but I don't think it had any scientific backing, more of a rumour!! Any thoughts on that?

Cheers
 

oreo57

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Oh yea thanks for that. There is the "thing" about the "reverse spectrum effect" i.e deep water less light, more blue/green light, shallow water more light, more red light.
Exact opposite of terrestrial spectrum.

Soo possibly species or intensity or mix differences..
If people want to run more plants under reef lights to see which do what.. hey I'm all for it.
Like I said my few plants I tried it on exhibited "normal" terrestrial responses though the light was 10000k/royal blue 1:2 ratio
 

oreo57

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Looking at this from a quantum mechanical perspective blue light has vastly more energy per photon than red and photosynthesis is a quantum process.

:)
Yea don' t think that applies.
Statistics 8 photons are used per 1 O2 produced. For every O2 produced 4 ATP are made and 2 NADPH. 1 NADPH can produce 3 ATP.
Doesn't in photosynthesis.
Just depends in the absorption characteristics of pigments/ proteins that regulate hormones ect
Just fir fun
 

jaypeecee

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I've read before that blue light can contribute/cause algae? I'm not sure where but I don't think it had any scientific backing, more of a rumour!! Any thoughts on that?
Hi @EA James

There should be some truth in what you read. It's related to iron availability in the water column. As stated by @Wookii, blue light has higher energy* than the other colours of light in the PAR spectrum. As a result, blue light is known to convert ferric iron to ferrous iron which, as I understand it, is the form of iron preferred by plants and algae/cyanobacteria. The process is known as the photoreduction of iron. Diana Walstad discusses this in her book Ecology of the Planted Aquarium.

*Planck's Law E = hf

JPC
 

oreo57

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If it's preferred by plants and algae why do you think it favors algae?
 

jaypeecee

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If it's preferred by plants and algae why do you think it favors algae?
Hi @oreo57

I'm not sure that I understand your question. I simply stated that ferrous iron, as I understand it, is the form of iron preferred by plants and algae/cyanobacteria. Is that not correct?

JPC
 

jaypeecee

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Hi Folks,

As we're discussing lighting spectrum, some of you may find it useful to get an idea of the RGB relative intensity being emitted from your aquarium lighting. If you're interested, you may find the following to be worth a try:


The image below shows how the data is presented.

Screenshot_20210702-193730.png

JPC
 

oreo57

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Hi @oreo57

I'm not sure that I understand your question. I simply stated that ferrous iron, as I understand it, is the form of iron preferred by plants and algae/cyanobacteria. Is that not correct?

JPC
Thought you were linking it to blue favoring algae since you were sort of answering this statement.
My mistake.
I've read before that blue light can contribute/cause
algae?

Our results show that algae grows the best under white light
.I don't have access to the complete paper .
Anyways it isn't conclusive either way really including red light favors algae in saltwater
Blue light helps with the plant’s production of chlorophyll–the green pigment that traps light energy and is integral to photosynthesis

In other words, blue light is easier for a plant to absorb and use the energy in photosynthesis.
 
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