730nm, Photoperiodism, Emerson Effect and Photosynthetic Artificial Darkness

[WhatDoYouDo]

Hey all,

I want to get your feedback on the 730nm spectrum and how that is affecting your plants. I am new to this field but I think it is important for everyone to understand. (Especially me). One thing that I find interesting is a lack of conversation on this.

Far Red (730nm) it is useful for a few things.

1. Emerson Effect: The combination of Red and Far Red (670nm and 700nm) creates an effect where the photosynthesis is doubled.

Q: Can 730nm also be used? (many articles suggest yes, anything over 700nm will work) Does it work just as well, and what ratio do you want of red/far red? The sun seems to use a ratio of about 1:0.8, That is to say, if you have 10 watts of red 660, you should have 8w of far red? Any input?

Q: At what state and for how long do you want to run this Far Red cycle?

2. Photoperiodism: It cancels out any red light (660nm) that the plant receives during the dark period if you follow that interruption with far red (730nm). This tricks the plant into thinking it never saw any light instead of interrupting the dark period.

This means that, if you turn on a light during the dark period, you will wreck the dark period. If you turn on a light but then turn on 730nm, you will cancel out the light the plant saw and it does not affect the dark period.

Q: Does anyone have experience with this? I have read plenty of articles on it but wanted real feedback.

* Note, that in Morning glory (and I assume other plants) the opposite can be true. Does anyone know why?

3. Far red (730nm) given to your plants at the begging of the dark period shortens the critical dark period by about 2 hours. So instead of a 12/12, you can go to something like 13.5/10.5. This is because you shaved off that time it takes for the plant to change from Pr to Prf. In nature, when the sun is setting, a far red spectrum does this. If the plant does not see this far red, it takes about 2 hours to make the switch after it first see the dark. That means for 2 hours, your plant does basically nothing. By running Far Red, you convince the plant the sun has set and it will begin the dark phase faster.
Q: Does anyone do this? What are the results, and how long do you run the lights before the Dark period?


4. Phytochrome: Pr (660nm) and Pfr (730nm). These are the relationships.
a. Absorption of red light by PR converts it into PFR
b. Absorption of far red light by PFR converts it into PR.
c. In the dark, PFR spontaneously converts back to PR.


This jumps into Photosynthetic Artificial Darkness, (PAD)
Some people suggest that only the Red affects the dark phase (660nm is a night interrupter). Some suggest that the blue could be run all night, allowing 24/0.

Q: Has anyone does this? How does it work, and were the results good?

Q: could Far Red and Blue be run at night? Far Red could be absorbed at night and so could blue. In theory, could we run a deep blue and far red at night to promote growth?


Last question, is 730nm the best, or should it be a range of 720 — 740 to do everything mentioned above?



So, in theory, If we had lights that we could control each spectrum, (Blue, green, red, and far red), how should we go about doing this for optimal results?

It sounds like we would want a full blast, wide spectrum during the day, including far red for the Emerson Effect. Before the dark period, it sounds like we want to turn all the lights off expect the Far Red, and allow that to run 15 — 30 minutes into the dark phase. Shut that off and give it 10.5 hours of dark.

Some people suggest running the Far Red 15 minutes before you switch to the light phase (since that is what the sun does). Does any science back that up and improve results?


Thanks a lot guys. Any other suggestions are great.

 

[Hosebomber]

1. Emerson Effect: The combination of Red and Far Red (670nm and 700nm) creates an effect where the photosynthesis is doubled.

Q: Can 730nm also be used? (many articles suggest yes, anything over 700nm will work) Does it work just as well, and what ratio do you want of red/far red? The sun seems to use a ratio of about 1:0.8, That is to say, if you have 10 watts of red 660, you should have 8w of far red? Any input?

The original study was done in the 50's and used 658 and 723nm. There have been hundreds if not thousands of repeat studies using everything from 620 and 680 to 680 and 750. The key is to have at least 60nm split between high and low wavelengths. The amount of far red is about 8% in nature or .08 not .8.

The effect is not exactly doubled, but it is greater than the sum of the two wavelengths alone. Meaning if there is 10 carbon molecules fixed using only 660nm light and 10 using only 730nm light, if you used the same amount of 660 and 730 at the same time you would get <20 carbon molecules fixed.

Q: At what state and for how long do you want to run this Far Red cycle?

The angle of the sun in the day/ time of year mandates how much far red plants receive. Just as the sky looks more red in the evening, that's when the majority of plants grown outdoors would get it more. There is a lot of debate on this, but the Pf conversion leads me and many others to believe that you would have better results with it being used at all times.

2. Photoperiodism: It cancels out any red light (660nm) that the plant receives during the dark period if you follow that interruption with far red (730nm). This tricks the plant into thinking it never saw any light instead of interrupting the dark period.

This means that, if you turn on a light during the dark period, you will wreck the dark period. If you turn on a light but then turn on 730nm, you will cancel out the light the plant saw and it does not affect the dark period.

Q: Does anyone have experience with this? I have read plenty of articles on it but wanted real feedback.

This statement is completely false. Feel free to turn a crop hermie and see for yourself.

3. Far red (730nm) given to your plants at the begging of the dark period shortens the critical dark period by about 2 hours. So instead of a 12/12, you can go to something like 13.5/10.5. This is because you shaved off that time it takes for the plant to change from Pr to Prf. In nature, when the sun is setting, a far red spectrum does this. If the plant does not see this far red, it takes about 2 hours to make the switch after it first see the dark. That means for 2 hours, your plant does basically nothing. By running Far Red, you convince the plant the sun has set and it will begin the dark phase faster.
Q: Does anyone do this? What are the results, and how long do you run the lights before the Dark period?

There is some truth to this, as the setting sun is skewed by the atmosphere to show more far red than other spectra. I have seen people successfully do 13/11 cycle with 15 min of 730nm+ only light after lights out. I've seen people try 14/10 using the same method and the plant dropped balls... So... could be weak genetics or it could be some strains are more tolerant of lighting.

4. Phytochrome: Pr (660nm) and Pfr (730nm). These are the relationships.
a. Absorption of red light by PR converts it into PFR
b. Absorption of far red light by PFR converts it into PR.
c. In the dark, PFR spontaneously converts back to PR.

There are more wavelengths to both Pr and Pfr
a. correct
b. correct
c. It is not spontanious... roughly 15 min for most up to 2 hours for some anad never for others. (not all Pfr gets reverted to Pr)

This jumps into Photosynthetic Artificial Darkness, (PAD)
Some people suggest that only the Red affects the dark phase (660nm is a night interrupter). Some suggest that the blue could be run all night, allowing 24/0.

Q: Has anyone does this? How does it work, and were the results good?

Q: could Far Red and Blue be run at night? Far Red could be absorbed at night and so could blue. In theory, could we run a deep blue and far red at night to promote growth?

I have seen an attempt at it. No it didn't work. the test lasted 60 days with the plant never going into flower.

No any red light at all would interrupt the night cycle.

Last question, is 730nm the best, or should it be a range of 720 – 740 to do everything mentioned above?

730nm just happens to be the peak wavelength that most diodes are made at.
I personally run my far reds for the entirety of my light cycle with no extra on either end. The longer my lights are off the cheaper they are to run. I actually shorten my lights on period over the course of flowering down to 9/15
The suns angle in the mornings (at sunrise) does not generate more far red than any other spectra, that occurs in the evening.

 

[WhatDoYouDo]

Sounds good man, Thanks a lot for your input! Very helpful, you have no idea.

As for the 730nm being the peak wavelength, I have access to nearly any Red/Far-Red wavelength; 670, 720, 730, 740, 745, 750, 850, and 940. Thanks for the input on the 60nm difference.

I am still working on a full spectrum light, the heatsink is killing me though. (off topic) Trying to dissipate 100watts of heat without a fan is hard. Haha, Had to pull out a few heat transfer books.

 

[Hosebomber]

Check out Makrolon® TC8030 and CoolPoly... both are on my list to try in the very near future.

 

[WhatDoYouDo]

Thanks, I am very interested in this material. A natural-convection heat sink for this wattage is not an easy design tho. The only flaw I see so far is the Thermal Conductivity of this plastic is still awful. Some of coolpoly's are only 10W/mk - 100W/mk (but I did not see a data sheet for anything higher than 50), but Aluminum is about 200W/mk (T6061 is about 150W/mk)

The added benefit is in the design. We planned on doing Aluminum Extrusions but that limited our design to 2D. It is surely doable but the design can not dissipate heat as well and I am limited in how I can increase the effectiveness. I have 2 great ways that would significantly increase heat dissipation but they require us to use a CNC machine, and that would be very expensive.

This plastic, even tho it has awful thermal conductivity properties, could make up for the fact that I can make sure cool designs with so much surface area that the thermal conductivity doesn't mean anything.

Thanks for sharing that find with me. very useful information.

 

[WhatDoYouDo]

Hosebomber

How much far red are you using for the flowering stage? Is it safe to go up to 10 or 20% Far-red if my Red is only at say, 60% overall?

I forgot to mention (since you recommended I look into this about a month ago) We are now connected with a group of master students who are focused on Aquaponics systems and will do all our testing with those systems.

In the near future, we are going to use our 'umbrella' nonprofit and pull them in under our wing. Our ultimate plan is to use their aquaponic systems with our LED lights to create portable community gardens. They are already retrofitting the systems in shipping containers (which they are getting for free at the local Port/Dock).

Once everything is figured out and tested, we will be dropping these guys off in developing countries to make small greenhouses/gardens for small towns and villages. We have access to 3 warehouse (one is ours with a 3 ton crane, 2 are the universities with 15ton cranes on the ceiling) and 1 indoor swimming pool, should be an interesting few months for everything.

The reason we are on these forms is because we figure if people can grow Cannabis, they can grow nearly anything. And lets face it, this market is our biggest market until indoor growing really takes off. =p

Thanks for all your help

 

[Hosebomber]

I try to stay under 7% of total lighting power in the far red.

The best part about the aquaponics is that it only uses about 10% of the water that regular farming requires. Clean water is one of the hard things to get access to in developing countries.

Believe it or not, I came to these forums for the same reason. Some of the best testing and research in grow lighting happens in the cannabis community. I started messing with LED lights about 3 or 4 years before we moved to Cali and my wife didn't get her card until we had lived here nearly 2 years. We went another few years before ever growing her meds but was still growing plants indoors with aquaponics and LEDs.

 

[WhatDoYouDo]

Thanks again for the information. I only see one company using high amount of far red, so I had my doubts but I figured I would ask. Our Aquaponics team really wants a product to test now, so they are on my back about getting something soon that they can tweak and improve on.

Anyway, I really appropriate your time and knowledge man. I will certainly keep you and this community updated as we go about testing new ways of growing plants with different systems. Now that we have a University sponsor and a few private sponsors (the Aquaponics team does anyway, and they are doing all of our testing/growing), we can hopefully add a significant amount of research to this field.

 

[Light Addict]

OK let's wake this threads back up, as we have a few of us now running Emerson lights!