Amount of light?

[Delps8]

@Death The Cultivator was good enough to provide me with this link to a discussion about what pigments in plants. Green light is discussed a bit but it's red and blue light that grab the headlines.

On that point, in one of the Bugbee videos he touches on green light vs red or blue and the comment that he makes is that it's valuable because it makes is easy for growers to look at plants so that they can spot issues. That was interesting to me because I owned a blurple years ago and it did a decent job - I've still got the grow glasses!

 

[Delps8]

Here's another one from Chandra, not free but puts the LSP @ 1800-2000ppfd

https://www.researchgate.net/publication/274095310_Light_dependence_of_photosynthesis_and_water_vapor_exchange_characteristics_in_different_high_D9-THC_yielding_varieties_of_Cannabis_sativa_L

and a study by Bugbee that states at 900ppfd yield was constantly higher than at 700ppfd

I think it was in an interview that he had with the Cornell where I captured some notes

[time passes]

Hmm, it might have been a Mr Growit video. In my defense, I was listening to the video while reading news stories!

Most of his comments were the same info I've heard from him in other places so these are the only notes that I took:

"
two stage adaptation to increased light 300 - 1200 in a few days
Short term and then long term adaptation

1000 or 1200 µmols is economic maximum
even at 1600 yield increases

light goes up 30% yield goes up 15%

"Don't have much margin for error" "all the other things ahve to be co-optimized"

CO2 - 1k ppm is optimal

must remember that water increases with light intensity

CMH is 30% blue
HPS 4% blue good spectrum

3% to 10% blue - 25% blue is too high, not optimal for photosynthesis

prune for disease and air"


What made me think of this was the 30% more light ===> 15% more yield. That sounds like a really rough metric but it's helpful even if it's just in the ballpark.

Something else of interest - from DeBacco.

He states that's from a "4' x 4' table". I assume that's a "drain to waste table."

 

[Delps8]

I started quite a discussion here.
You pros are way over my head but I'm learning. Thank you.

Back before I had LED.
5gal soil grow.
315W CMH
3x3 Gorilla
19.6 zips
Before I new about thinning...or PAR, or PPFD, or LUX, DLI, etc...

View attachment 1483534View attachment 1483535
Lol.

Beautiful plants and a great crop!

"I started quite a discussion here."
I was just thinking the same thing - this is shaping up to be an excellent thread. Hat's off for kicking it off and to everyone who's contributed. I really appreciate reading all of the knowledge that everyone is sharing.

 

[Death The Cultivator]

I think it was in an interview that he had with the Cornell where I captured some notes

[time passes]

Hmm, it might have been a Mr Growit video. In my defense, I was listening to the video while reading news stories!

Most of his comments were the same info I've heard from him in other places so these are the only notes that I took:

"
two stage adaptation to increased light 300 - 1200 in a few days
Short term and then long term adaptation

1000 or 1200 µmols is economic maximum
even at 1600 yield increases

light goes up 30% yield goes up 15%

"Don't have much margin for error" "all the other things ahve to be co-optimized"

CO2 - 1k ppm is optimal

must remember that water increases with light intensity

CMH is 30% blue
HPS 4% blue good spectrum

3% to 10% blue - 25% blue is too high, not optimal for photosynthesis

prune for disease and air"


What made me think of this was the 30% more light ===> 15% more yield. That sounds like a really rough metric but it's helpful even if it's just in the ballpark.

Something else of interest - from DeBacco.

He states that's from a "4' x 4' table". I assume that's a "drain to waste table."

View attachment 1487736

So an average of 500w over a 4x4 equals ~2lbs or ~1000g+- for roughly ~60 grams per sqft. 30% more light equals 650w and an estimated 1150g or 41oz(5oz more than former) or 2.5lbs. Overall 71g per sqft compared to the first example.

I'd agree with staying at 1200umols, looking at higher overall cost compared to having shorter veg times and less load on overall resources while using 30% less energy. In the case of photos, a few extra harvest could be squeezed in

 

[Butrod]

I think it was in an interview that he had with the Cornell where I captured some notes

[time passes]

Hmm, it might have been a Mr Growit video. In my defense, I was listening to the video while reading news stories!

Most of his comments were the same info I've heard from him in other places so these are the only notes that I took:

"
two stage adaptation to increased light 300 - 1200 in a few days
Short term and then long term adaptation

1000 or 1200 µmols is economic maximum
even at 1600 yield increases

light goes up 30% yield goes up 15%

"Don't have much margin for error" "all the other things ahve to be co-optimized"

CO2 - 1k ppm is optimal

must remember that water increases with light intensity

CMH is 30% blue
HPS 4% blue good spectrum

3% to 10% blue - 25% blue is too high, not optimal for photosynthesis

prune for disease and air"


What made me think of this was the 30% more light ===> 15% more yield. That sounds like a really rough metric but it's helpful even if it's just in the ballpark.

Something else of interest - from DeBacco.

He states that's from a "4' x 4' table". I assume that's a "drain to waste table."

View attachment 1487736

Yeah some studies suggest the increase in harvest is rather a linear metric, others describe it with a diminished return. I suspect it has alot to do with interrelated factors like CO2, veg time, training and genetics.
Though even at a diminished return the cost return may be there, especially if all things considered like extra space, hardware & working hours. Having an extra tent is way more of than just to power up 3 tents by +30%.

I'm still searching for a chinese study done on UVB where they measured the LSP no higher than 1000ppfd and even commented on Chandra's 1500ppfd. That guy used mostly Mexican Sativa which is a very good photosynthesizer, much better than indoor polyhybrids.

 

[SHRED]

Update

I'm at about 18" and 100% power.

37 days old.

 

[Talonxracer]

Yeah some studies suggest the increase in harvest is rather a linear metric, others describe it with a diminished return. I suspect it has alot to do with interrelated factors like CO2, veg time, training and genetics.
Though even at a diminished return the cost return may be there, especially if all things considered like extra space, hardware & working hours. Having an extra tent is way more of than just to power up 3 tents by +30%.

I'm still searching for a chinese study done on UVB where they measured the LSP no higher than 1000ppfd and even commented on Chandra's 1500ppfd. That guy used mostly Mexican Sativa which is a very good photosynthesizer, much better than indoor polyhybrids.

I can not remember what study I was reading, but in that research study it showed a bell curve rather than a linear or diminished returns. The initial gains as light is increased are substantial(increasing gains) until it starts to plateau and then you start seeing diminished returns.

 

[Butrod]

The initial gains as light is increased are substantial(increasing gains) until it starts to plateau and then you start seeing diminished returns.

suspect the range defined from what fluxlevel the measurements start and end should put that into shape
if it's 0-3000 then it should look like that but 400-800 should resemble linear
always in the context of the study itself

 

[Delps8]

So an average of 500w over a 4x4 equals ~2lbs or ~1000g+- for roughly ~60 grams per sqft. 30% more light equals 650w and an estimated 1150g or 41oz(5oz more than former) or 2.5lbs. Overall 71g per sqft compared to the first example.

I'd agree with staying at 1200umols, looking at higher overall cost compared to having shorter veg times and less load on overall resources while using 30% less energy. In the case of photos, a few extra harvest could be squeezed in

Thanks for running the math. Granted that there's no "standard" grow site but, since you've been involved at the commercial level, would the extra 11 gm/ft2 be economically sound?

 

[Delps8]

Yeah some studies suggest the increase in harvest is rather a linear metric, others describe it with a diminished return. I suspect it has alot to do with interrelated factors like CO2, veg time, training and genetics.
Though even at a diminished return the cost return may be there, especially if all things considered like extra space, hardware & working hours. Having an extra tent is way more of than just to power up 3 tents by +30%.

I'm still searching for a chinese study done on UVB where they measured the LSP no higher than 1000ppfd and even commented on Chandra's 1500ppfd. That guy used mostly Mexican Sativa which is a very good photosynthesizer, much better than indoor polyhybrids.

I suspect Bugbee was talking in very general terms. His own videos who that the yield curve starts to roll off at about 500 µmols (non-CO2).