Discussions: Plant growth based on wavelengths

Definition of wavelength: basically in everyday terms, the colour/visible light we see measured in nanometer (nm) except for white which is measured in Kelvin (k)

This is what i saved in my QuickMemo when i started researching my LED build


Views to discuss (and please feel free to add on more)
Can we manipulate plants to grow a certain way?
Theory 1:
Java fern under blue light (400-450nm), will grow short and bushy.

Theory 2:
Java fern under red light (650-700nm), will grow long leaves


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See http://cpl.usu.edu/files/publications/poster/pub__2576523.pdf .

 

The study support my theory that we can manipulate plant grow
"Cryptochrome is a blue light and UV-A receptor that, like phytochrome, controls
many aspects of plant physiology and development. It strongly suppresses stem elongation and contributes to both leaf expansion and plastid processes."
So using blue light we can grow a bushy java fern plant

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I don't have significant knowledge on algea as I was nevwr interested in it but I will look into what promote algea growth besides light duration.

On this note, wouldn't 1 white LED + 1 blue LED = 2 blue leds as white have blue or is made up of mostly blue spectrum? (Please correct me if I'm wrong)

I know you should thrive to create a balance environment but what if you want to create a bushy foreground and longer leaves for the background using java fern (I know it's unnecessary and there are much easier ways to do it, but for debating reasons lets go with java fern)


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This a side, speaking about lights only, CO2 and ferts covered. I'm sure you won't spend thousands on lights and neglect the most important element of photosynthesis

Currently growing java fern with no lights, only fish waste. Don't see much growth in length just alot of smaller leaves

Yip, and knowledge is build on trail and error. Thanks for your input. I hope i didn't struck a nerve with my stupid theories.

I'm sure even this was trail and error.

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This is something I have never been able to get my head around, tips and tricks for the prefect groom.

Later Ferdie

 

I'll do some research and post my finding thanks for everyonce input. Got some great insight.

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You don't need to add a lot of extra blue light to get stimulation of cryptochrome. The white LEDs have low levels of the 400-450 nm range. Supplementation with a little but of 400-430 (violet) light could have a larger effect on plant growth and little on algae. I think Greystoke found that he needed about 1W of violet for every 10W of white light to get his plants to grow under his cheap China LED chips.

If you use blue LEDs (around 450 nm) then you will stimulate the photosynthesis of various algae over and above the light you are already injecting. Most white LEDs have peaks around 450 nm.

 

Yeah i hear you. But my theory is about having blue (400-450nm) to grow bushy plants (no other spectrum) and @Deadpool intelligently told me why it won't work.

As for my LED build, i would of used 46 white and 4 red on a 29 gallon long.

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Without the 400-430 nm input you also won't be able to see pink and purple in your aquarium which means that some plants, eg. Hygro sunset, won't look good. You will need to supplement if you want the full spectrum of colors.

LEDs have high 450 nm peaks... but busy vs elongated stems has more to do about the ratio of wavelengths: http://www.mobot.org/jwcross/duckweed/phytochrome.htm In particular the 660:730 nm ratio. Most LEDs have a high 660:730 nm ratio so there shouldn't be much stem elongation.

 

This is irrelevant as I only want to know if we can manipulate plants. On YouTube people grow the plants in tubs and clear buckets before planting or selling.

This was interesting to read. And in the article they state that plants under the sunlight will promote stem elongation. This will be difficult to replicate in a aquarium environment as you need 6500k and avoid the 660:730 ratio. :Bummer:

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The other issue is minimum dose: http://journal.ashspublications.org/content/115/2/231.full.pdf You need a specific minimum nunmber of photons to see a reaction by the plants. It looks like this is about 19 PPFD for 600-700 nm light. I have about 100 PPFD over my tank and get leggy growth with my neutral white LEDs. With higher PPFD you would get more compact growth due to adequate phytochrome stimulation.

I can't find data for the minimum level of light needed for cryptochrome data but from Greystoke's experiment it seems you need about 9% of the power output in the violet range. I forget how much light he had over his tank in total, but before he added the violet LEDs the plants didn't grow. They just sat there in stasis.

 

Yes theory won't work but the discussion open my eyes and learn quite a lot. To a certain extent you do manipulate the plants, or at least they react to your conditions which could create a plant that look different to the original

Doesn't minimum depend on tank dimensions? Like a shallow tank will require less wattage?


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Depth would make a difference if the tank is much deeper than 30 cm. If the water is clear there is very little loss of light in the first 30 cm of water column.

 

And to combat that, we use lights with higher intensity (lux)? Or do you simply just use more individual bulbs to increase the intensity

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Now that really is the key in LED setup's from experience - if you can keep the water crystal, things tend to grow under LED.
I need to start running purigen again.

Later Ferdie

 

And if you have a dirt set up or tannines in the water? (Do you require more intense light?) Or am I understanding wrong?

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