Lighting wanna get yer geek on? Here's a scientific paper on cannabis and light for you.

[Mañ'O'Green]

@damien50 You know about all of the other spectrum lights I have in the space don't you?

2 Far Red Pucks
2 Royal Blue Pucks
2 50w LED w/blue
2 - 48" t5 Agromax UVA Plus 10,000K florescent lamps
1- 48" t5 Agromax Pure UV 75% UVB 25% UVA florescent lamps

If I could bite off a piece of the sun and throw it in there I would do it.

 

[Mañ'O'Green]

@elcoloan recently purchased an Apogee and was astounded at the difference between his LUX and Apogee.

Not to discourage you, I would watch the grow lol, but the benefits of the Emerson Effect are lost over 750-800ppfd but I believe that plant size has a certain degree of influence on the maximum DLI.

I believe the sun hits around 9-1500ppfd but plants are being hit with 300-799nm while the vast majority of manufacturers only cover the 400(barely) to 730nm(again, barely) range. I wonder how much yield could be achieved capitalizing on the Emerson Effect, supplementing the whole spectrum send providing side/intra lighting.

You know I swore I had seen the research paper before but I couldn't remember where. I first saw it on another forum and some members pointed out issues with the study

Are CRI and luminous efficacy influencing the photosynthetic photon efficacy?

Customers ask for high CRI LED for their plant growth projects at times, and sometimes this confuses us that why a well color rendered LED for human vision is also desired for plant growth? In order to understand this, we process relevant experiments and calculations for analyzing the reason...

store.yujiintl.com

I found this article by a lighting manufacturer on b high cri - the last paragraph was the most important but I've heard that the reds over 600nm improved the SPD by various degrees when supplementing.

Curiously, most lights have individual SPDs that have to be measured with a spectrometer to give an accurate conversion of ppfd to LUX but lux meters don't capture the full spectrum that we want for our needs. Think an Apogee is expensive, spectrometer are in the 2k+ range.

Enabling Accuracy | Präzision in der Lichtmesstechnik | Gigahertz-Optik

Wir ermöglichen höchste Präzision in der Messung optischer Strahlung und Lichtmesstechnik von UV bis IR. Innovationen Made in Germany mit ISO 17025.

www.gigahertz-optik.de

This is a fun topic

Geez every time I re-read this I see another question. The high CRI is for me. My eyes are the best instrument I own. It helps me see the health and/or problem in a plant. I would think this to be really important in a commercial grow as well? The plant may not be using that energy but it is better for it.

 

[Death The Cultivator]

Geez every time I re-read this I see another question. The high CRI is for me. My eyes are the best instrument I own. It helps me see the health and/or problem in a plant. I would think this to be really important in a commercial grow as well? The plant may not be using that energy but it is better for it.

Efficacy is the top priority in most commercial operations so high cri isn't a priority. I was speaking with a Bridgelux rep that was baffled that I wanted a 90+ cri and 2.6+umol/j - realistically I wasn't expecting the high efficiency but it didn't hurt to try. The reds are less efficient than blues so reaching those higher cri numbers hits your bottom line harder for initial investments.

I totally get wanting to see your plants more clearly but it has also been shown that to reduce flowering time, shade avoidance, and improve yields. Worth the initial investment and drop in efficacy imo.

I love your setup, I am aiming for something similar. My goal is full intra/side/top canopy lighting at 92+cri and average efficiency of 2.4umol/j. 4000k for intra/side and 2700k for top - enough red that I can run 730nm for EoD/BoD treatments.

I have a theory that running UVA from seed/clone to harvest is going to be highly beneficial over current methods that suggest a little bit every day towards the end of harvest. Sourcing UVA LEDs has been difficult price wise but the benefits I've seen in studies to Ca uptake, hardening off, and cannabinoids have me sold on running it the whole grow.

IMHO, I don't think we're too far from the sun if not doing it more efficiently in our particular hobby. There's so much still not understood in regards to light and plant physiology but we're cannabis cultivators - being pioneers and industrious is part of the culture.

 

[Death The Cultivator]

Vesta® Thrive™ | Bridgelux, Inc. LED Lighting

Vesta® Series Tunable White products deliver adaptable light in a solid-state lighting package, tapping into the powerful emotional elements of light and color to influence experience, well-being, and human emotion. Vesta Series Tunable White COB arrays and modules are now available with...

bridgelux.com

Those are 98 cri but only 138L/w compared to Gen 2 bridgelux at 180l/w or Samsung 301b/h reaching 200l/w. Bridgelux EB Gen 3 92cri hit 2.4umols/j but they can't take more than 15w. High cri is high dollar plus those Thrives are tunable from 2700-6500k

 

[Olderfart]

@elcoloan recently purchased an Apogee and was astounded at the difference between his LUX and Apogee.

Not to discourage you, I would watch the grow lol, but the benefits of the Emerson Effect are lost over 750-800ppfd but I believe that plant size has a certain degree of influence on the maximum DLI.

I believe the sun hits around 9-1500ppfd but plants are being hit with 300-799nm while the vast majority of manufacturers only cover the 400(barely) to 730nm(again, barely) range. I wonder how much yield could be achieved capitalizing on the Emerson Effect, supplementing the whole spectrum send providing side/intra lighting.

You know I swore I had seen the research paper before but I couldn't remember where. I first saw it on another forum and some members pointed out issues with the study

Are CRI and luminous efficacy influencing the photosynthetic photon efficacy?

Customers ask for high CRI LED for their plant growth projects at times, and sometimes this confuses us that why a well color rendered LED for human vision is also desired for plant growth? In order to understand this, we process relevant experiments and calculations for analyzing the reason...

store.yujiintl.com

I found this article by a lighting manufacturer on b high cri - the last paragraph was the most important but I've heard that the reds over 600nm improved the SPD by various degrees when supplementing.

Curiously, most lights have individual SPDs that have to be measured with a spectrometer to give an accurate conversion of ppfd to LUX but lux meters don't capture the full spectrum that we want for our needs. Think an Apogee is expensive, spectrometer are in the 2k+ range.

Enabling Accuracy | Präzision in der Lichtmesstechnik | Gigahertz-Optik

Wir ermöglichen höchste Präzision in der Messung optischer Strahlung und Lichtmesstechnik von UV bis IR. Innovationen Made in Germany mit ISO 17025.

www.gigahertz-optik.de

This is a fun topic

The comments on the research paper seem spot on to me, thanks for forwarding them. A fun topic indeed.

I think you have a point about the Emerson effect. I am a bit surprised not to see more discussion of it given its strength. There are obviously some sort of interdependent processes going on in the two wavelength bands, and figuring out how to optimize spectrum accordingly seems like high priority stuff, and not just for cannabis. I imagine the better grow light companies are working on this, but are not that inclined to reveal details.

i am curious why the effect would disappear over 800 ppfd. Presumably one of the channels is saturated so cannot assist the second channel further. By any chance do you have a link to research on it?

Happy growing Damian.

 

[Olderfart]

No the first auto grow with the lights had other problems.

No, I do not have a meter. I just do the math. The information provided by the vendor is very thorough. There was a little difference in an independent test but not enough to change the numbers.

I have an inline watt meter on each of my 500w ChilLed GrowCraft so I can dial-in the watts used with the dimmer. This chart displays the information on 1 of the 6 light bars in the space (3 per Fixture). In order to achieve 39 DLI in 12 hours each light bar needs to run at 300 PPF . To produce that much light takes about 100w per bar or 300w per fixture or 600w total.

View attachment 1246168

View attachment 1246169

Nice process! Now if I just had data like that for my screwins...

You will be amused that I now have some uvb bulbs to add to the mix. And I’m checking out red bulbs too...

Happy growing MOG.

 

[Death The Cultivator]

The comments on the research paper seem spot on to me, thanks for forwarding them. A fun topic indeed.

I think you have a point about the Emerson effect. I am a bit surprised not to see more discussion of it given its strength. There are obviously some sort of interdependent processes going on in the two wavelength bands, and figuring out how to optimize spectrum accordingly seems like high priority stuff, and not just for cannabis. I imagine the better grow light companies are working on this, but are not that inclined to reveal details.

i am curious why the effect would disappear over 800 ppfd. Presumably one of the channels is saturated so cannot assist the second channel further. By any chance do you have a link to research on it?

Happy growing Damian.

I haven't been able to find research papers on it but I presume that the reason is as PPFD increases the efficiency of photosynthesis isn't as pronounced

For the average grower, there isn't a huge increase in photosynthesis from 700 to 1200. Looking at the 1500 range you aren't receiving nearly three huge boost one would assume.

Anyways, when I see the chart I see a money sink in attempting to push high PPFD values plus there is inherent savings when trying to maintain VPD compared to pushing PPFD higher.

While I was browsing I did find tidbits of info on green wavelengths and their benefit to denser canopies. It could be reasoned, and I'm fine being wrong, that modern grow lights lack green especially in lower CRI that if this was rectified would improve canopy penetration. Shade avoidance would be reduced and the idea that defoliation is necessary because leaves are 'blocking' bud sites could disappear in peace even though sugar leaves and calyxes don't photosynthesize to begin with.

 

[Olderfart]

More brain burning on this topic... Since I posted the link to the Chandra et. al. article, I ran into a good analysis of the article over at Cocoforcannabis.com. (https://www.cocoforcannabis.com/how-much-light-ppf-do-you-need-for-indoor-cannabis/) The article revealed to me that I had mis-interpreted the data from the Chandra et. al. paper. The article explained that the data in that paper show that at ambient CO2 levels, CO2 starts to become the limiting factor at ~500 micromoles/m2/s, and that photoinhibition starts at ~1000 micromoles. Photosynthesis continues to rise above ~500 micromoles, but returns diminish. The authors conclude that the optimum PPFD is ~ 700 micromoles, not the ~1500 that I had originally thought. As the post earlier in this thread points out correctly, the Chandra et. al. paper does have its limitations, but according to the Cocoforcannabis authors, it still stands as the best currently available measurement of light requirements of Cannabis.

To my mind, one of the most important observations made in the Cocoforcannabis article is that by the time we see visible symptoms of excess light, especially chlorosis, the light level has already been significantly too high for a while. Damage to efficiency and plant health start before symptoms are visible. So if we see mischief at all, it is beyond time to dial the light back. Bottom line to me is that we should start at the expected lower level of effective illumination, dial things up gradually, and dial them back as soon as the first signs of mischief occur.

Overall, I find the discussion of this issue over at Cocoforcannabis very informative and apparently reliable. Anyone new to this and wishing to take their understanding a notch higher should have a look.

 

[Bigg Al]

Good to read!! Thanks!! But my thing is I grow autos, these papers are for photoperiod grows. How does this go for autos. It's not legal in my state yet, this is why I grow in a closet.

I also use a Co2 bag, my light is a Spider Farmer SF-1000, the space I grow in is a 2x2x48(this is only 1 side of the closet). I dont have lux meter or
any other meter and they are expensive. I just cant afford it right now. The only thing I dont have for the closet is an extraction fan. Other wise I have everything the tent grower have. My temps are 78(lights off) and 81-83 day time temps, RH is 40-50.
So how can I use this knowledge for my autos.

Thanks!

 

[Death The Cultivator]

Good to read!! Thanks!! But my thing is I grow autos, these papers are for photoperiod grows. How does this go for autos. It's not legal in my state yet, this is why I grow in a closet.

I also use a Co2 bag, my light is a Spider Farmer SF-1000, the space I grow in is a 2x2x48(this is only 1 side of the closet). I dont have lux meter or
any other meter and they are expensive. I just cant afford it right now. The only thing I dont have for the closet is an extraction fan. Other wise I have everything the tent grower have. My temps are 78(lights off) and 81-83 day time temps, RH is 40-50.
So how can I use this knowledge for my autos.

Thanks!

I think all you can do is read your plants, maybe rent a PAR meter, and maintain VPD.

Realistically is there any reason why autos couldn't grow at 12/12 with elevated ppfd to reach 45ish DLI? @automan grows at 12/12 and seems to do fine.

Imo, it's applicable to cannabis whether auto or photo especially considering the amount of photo genetics contained in autos.

Rental: Apogee MQ-510 Par Meter: Full-Spectrum Underwater Quantum Meter + Wand

Rent the newest Apogee MQ-510 Par meter specially designed to measure the blue light emited from LEDs. Rental price starts at $15 and shipped directly to your door. Don't settle for cheap inaccurate equipment anymore. Find out exactly what par your coral needs.

www.podyourreef.com

They rent out meters for cheap.