For Advanced Hobbyists - Importance of Green Light in Photosynthesis

[oreo54]

o/t (sort of) paper of interest..

The LUXEON SunPlus Lime + Purple LEDs performed best in terms of yield (fresh weight) and antioxidant levels. The spectrum of
this light source includes output in the far red range (700-800 nm) that can boost lettuce yields. The Valoya PC LEDs produced
greens of comparable yield but statistically lower levels of antioxidants, indicating that the spectral photon distribution of
phosphor down conversion can have different effects on crop quality. In summary, these data suggest that growth and nutrition
are optimized using PC LEDs with strong royal blue, green, deep red and far red components found in the combination of
LUXEON SunPlus Lime + Purple LEDs.
The spectra that performed best for both yield (fresh weight) and nutrient concentrations were the LUXEON SunPlus Series Lime
+ Purple and Purple + Green LEDs. To effectively grow Rouxai red lettuce and similar crops in indoor environments, the use of
Lime + Purple and Purple + Green LEDs from Lumileds demonstrated significant advantages

https://www.lumileds.com/uploads/702/WP34-pdf

 

[Dana Riddle]

So why are green houses still using primary blue and red lighting?
Would they have not experimented with green?

As oreo5457 said, the science is relatively new. Another reason could be the relatively low output of green LEDs (the 'green slump' if I recall, someone correct me if I used the wrong term.) Since green light would make the output appear brighter (if green LEDs really produced) and 'bright sells lights' it would make sense, from a marketing perspective to include green. But the popular opinion is that green light is practically worthless in promoting photosynthesis in terrestrial plants.

 

[oreo54]

Luxeons "selling" their lime pretty heavily..
Pretty interesting..
Also the value of IR..
https://www.lumileds.com/horticulture/calculator/

Need to make one of these for coral....

 

[ReefBeta]

This will have more impact to refugium grow light, the purple type, like kessil H380 for example. They are absolutely absence of green light. Coral LED usually get some amount of green from either dedicated green LED, or from part of the white LED.

 

[sikorskys]

I've read a series of articles about the same recently. The bottom line of the series: 4000K/6000K LEDs is the cheapest and better way to grow lettuce (work as good as pink LEDs, but much cheaper).

Unfortunately, available in Russian language only:
https://geektimes.ru/post/293045
https://geektimes.ru/post/298287
https://geektimes.ru/post/297333

 

[Lasse]

Green wavelengths penetrate deeper into plant tissue and its reflected by green leaves further down of the canopy. There is also plenty of this wavelengths in both white low Kelvin LEDs and in sunlight. This together will probably make plants to utilize green wavelengths better in spite of that fact that green light - per photon - is not so effective as blue and red wavelengths. Look at this pictures that show how much green light penetrate a leave. I use a flashlight with phosphorus coated white LED (6500 K). The upper side of the leaf

The back side - all wavelengths except of green and yellow/orange was filtered out (been taken up)

I have done the same experiment with blue and red LED and in the case of blue - the backside of the leave its completely black - no photons penetrate the leaf. With red wavelengths – the backside become slightly orange – some photons in the orange range penetrated.

So why are green houses still using primary blue and red lighting? Would they have not experimented with green?

For terrestrial plants - the importance of green wavelengths is established - high end growth fixture today include phosphorus coated white LEDs. The reason why not use green LEDs - as explained by others - efficiency and cost

However - the question is - is it the same for corals?

Sincerely Lasse

 

[Dana Riddle]

Your photo is worth a thousand words.

Green wavelengths penetrate deeper into plant tissue and its reflected by green leaves further down of the canopy. There is also plenty of this wavelengths in both white low Kelvin LEDs and in sunlight. This together will probably make plants to utilize green wavelengths better in spite of that fact that green light - per photon - is not so effective as blue and red wavelengths. Look at this pictures that show how much green light penetrate a leave. I use a flashlight with phosphorus coated white LED (6500 K). The upper side of the leaf

The back side - all wavelengths except of green and yellow/orange was filtered out (been taken up)

I have done the same experiment with blue and red LED and in the case of blue - the backside of the leave its completely black - no photons penetrate the leaf. With red wavelengths – the backside become slightly orange – some photons in the orange range penetrated.




For terrestrial plants - the importance of green wavelengths is established - high end growth fixture today include phosphorus coated white LEDs. The reason why not use green LEDs - as explained by others - efficiency and cost

However - the question is - is it the same for corals?

Sincerely Lasse

 

[Lasse]

I know All of this years I´ll try to understand this - and not coming up with such a simple experiment in order to understand what´s happen befor now

Sincerely Lasse

 

[Dana Riddle]

Benefits of radiation at 800nm? What of the 'red edge effect?' Very interesting. Thanks!

o/t (sort of) paper of interest..

https://www.lumileds.com/uploads/702/WP34-pdf

 

[peterj66]

Green wavelengths penetrate deeper into plant tissue and its reflected by green leaves further down of the canopy. There is also plenty of this wavelengths in both white low Kelvin LEDs and in sunlight. This together will probably make plants to utilize green wavelengths better in spite of that fact that green light - per photon - is not so effective as blue and red wavelengths. Look at this pictures that show how much green light penetrate a leave. I use a flashlight with phosphorus coated white LED (6500 K). The upper side of the leaf

The back side - all wavelengths except of green and yellow/orange was filtered out (been taken up)

I have done the same experiment with blue and red LED and in the case of blue - the backside of the leave its completely black - no photons penetrate the leaf. With red wavelengths – the backside become slightly orange – some photons in the orange range penetrated.




For terrestrial plants - the importance of green wavelengths is established - high end growth fixture today include phosphorus coated white LEDs. The reason why not use green LEDs - as explained by others - efficiency and cost

However - the question is - is it the same for corals?

Sincerely Lasse

These pictures seems to imply that the green light is not absotbed/used by the plant at all. It is either reflected or passes right through.

 

[Dana Riddle]

These pictures seems to imply that the green light is not absotbed/used by the plant at all. It is either reflected or passes right through.

I think the point is that green light penetrates deep into, and through, the leaf much better than red or blue light, where it can be used in photosynthesis.

 

[Lasse]

Yea - I want to show that some photons can penetrate so much that they travel through the leave - and its rather easy to say - it looks like one wavelength is better than others. From other studies - its known that photons of the green wavelengths will be adsorbed - the % its much lower than blue and red photons. But if the amount of green photons is higher than blue or red photons - the amount of poorly working photons in the green range will contribute more to the photosynthesis than blue or red because - there can be more active layers. This simple experiment shows that there could be a green photon effect in the photosynthesis.

But it´s true that it is a need to quantify the different wavelengths in order to see what´s happen.

Sincerely Lasse

 

[Dana Riddle]

Yea - I want to show that some photons can penetrate so much that they travel through the leave - and its rather easy to say - it looks like one wavelength is better than others. From other studies - its known that photons of the green wavelengths will be adsorbed - the % its much lower than blue and red photons. But if the amount of green photons is higher than blue or red photons - the amount of poorly working photons in the green range will contribute more to the photosynthesis than blue or red because - there can be more active layers. This simple experiment shows that there could be a green photon effect in the photosynthesis.

But it´s true that it is a need to quantify the different wavelengths in order to see what´s happen.

Sincerely Lasse

Genius in its simplicity. As Jimmy Buffet once said "It was so simple it plumb evaded me."

 

[User1]

Two of my DIY multi-channel LED's have 12 lime green lights each Been that way for 3 years and love them.

 

[ksed]

Turning up my greens 100%. Kinda like the color, it give a aqua blue color.

 

[Lasse]

Hi

Together with David and Björn (from the Maritime Museum & Aquarium Gothenburg) can I present some rather primary results according to oxygen production of three different species hard corals. The oxygen production is a result of photosynthesis; hence you can use production during a certain time as an estimate of photosynthesis rate. We use small enclosed plastic containers with water and corals inside. Before closing – oxygen level was measured. The container was placed below 6 monochrome LED sources (400, 420, 450, 530, 630 and 660 nm) and below a white LED of 6500 K. PAR level for all 7 tests was adjusted to 90. After 2.5 Hour – The containers was open up, and a new measure of oxygen take place. For Seriatopora hystrix and S. caliendrum the weight was taken and for Montipora – the area was calculated. From this – an oxygen production per weight and hour (S. hystrix and S. caliendrum) was calculated and for Montipora sp oxygen production per square cm and hour was calculated. The result are shown in the graphs below.

Montipora sp

​

Seriatopora hystrix

​

S. caliendrum

The results is in some way rather unexpected but give some indications. However this is only 3 experiments - the results shall be taken quite cautiously. They give an indication for these three species in this type of short time test. But for sure - the green wavelength is not of no concern as the thoughts has been in the past. It has been shown for green plants and now also for at least three coral species! We are now going to do some experiments with combined wavelengths and probably do some experiment with far red too.

This test does not give any long time effects - only show the respond of the photosynthesis in short time below different light sources.

Sincerely Lasse

 

[ReefBeta]

Hi

Together with David and Björn (from the Maritime Museum & Aquarium Gothenburg) can I present some rather primary results according to oxygen production of three different species hard corals. The oxygen production is a result of photosynthesis; hence you can use production during a certain time as an estimate of photosynthesis rate. We use small enclosed plastic containers with water and corals inside. Before closing – oxygen level was measured. The container was placed below 6 monochrome LED sources (400, 420, 450, 530, 630 and 660 nm) and below a white LED of 6500 K. PAR level for all 7 tests was adjusted to 90. After 2.5 Hour – The containers was open up, and a new measure of oxygen take place. For Seriatopora hystrix and S. caliendrum the weight was taken and for Montipora – the area was calculated. From this – an oxygen production per weight and hour (S. hystrix and S. caliendrum) was calculated and for Montipora sp oxygen production per square cm and hour was calculated. The result are shown in the graphs below.

Montipora sp

​

Seriatopora hystrix

​

S. caliendrum

​

The results is in some way rather unexpected but give some indications. However this is only 3 experiments - the results shall be taken quite cautiously. They give an indication for these three species in this type of short time test. But for sure - the green wavelength is not of no concern as the thoughts has been in the past. It has been shown for green plants and now also for at least three coral species! We are now going to do some experiments with combined wavelengths and probably do some experiment with far red too.

This test does not give any long time effects - only show the respond of the photosynthesis in short time below different light sources.

Sincerely Lasse

Your images were broken

 

[Lasse]

Is it better now?

Sincerely Lasse

 

[Pny]

How much does the graphs change if you repeat the experiment with the exact same piece of coral a few times in a row?

 

[Sallstrom]

How much does the graphs change if you repeat the experiment with the exact same piece of coral a few times in a row?

We don't know yet It takes some time to do these experimets with all preparation etc(and we don't do it under work hours). Every thing is done so it can be repeated, so hopefully we will do more with same settings and species. But not with the same coral in the same place, all corals have to be randomly(not sure if thats a word but I hope you understand) placed.

We have 3 corals in 3 plastic containers in every go in the experiment already.

/ David