Yields at differant PPFD?

[Rahz]

Where did this data come from? Link to the study?

It was extrapolated from the 30C results in this chart. I can't find a link to the study but it is based on vegetative growth of cannabis.

 

[WeedBulbs]

Someone asked where the chart came from. It is an image on the page... http://www.tastyled.com/default.asp

 

[Trippyness]

@Abiqua @Trippyness because it applies so well to what we are talking about here, ill link to the spot in the video where i report the results. its a blue dream dominant strain in 5g canna coco pots.

@churchhaze it looks like I was indeed using more like 750-790 umols of photons per second per square meter.

8:03 mark (wont let me link to that exact spot)

Yeah checked it out. Seems it was around the 800 mark. Nice yield.
One question, why 5g Coco? Seems like overkill. 3G seems like the largest I would go indoors.

 

[Rahz]

They were asking for source data. Here it is: http://www.ncbi.nlm.nih.gov/pubmed/23572895

PDF: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550641/pdf/12298_2008_Article_27.pdf

 

[Rahz]

Note that some commercial growers are using upwards of 4800 PPFD because their fixed assets and personnel costs are more expensive than additional watts.

4800 PPFD is pretty intense. I'm not sure anything could survive in that environment. Do you have a citation for it?

 

[Trippyness]

Really great info here. I may have to test 600 vs 800ppfd in a controlled environment to see which is best.
Seeing as no one has done a test with yields. Im not concered with the cost or electric, if yields are substantialy better than ill go with 800.

 

[Trippyness]

4800 PPFD is pretty intense. I'm not sure anything could survive in that environment. Do you have a citation for it?

Thats way too much light, will burn and kill plants no doubt. Sounds like speculation.
Even with Gavitas they run 800ppfd in about a 5 x 5 so I highly doubt anyone is running that much at all.

 

[Greengenes707]

Let's get something straight...g/w means nothing. (grams/sqft) and (grams/KwH) are the only real metrics to use for comparison.

I refer you to post #416 from me in here for PPFD to yield differences...with pictures...
https://www.rollitup.org/t/have-any-of-you-diy-cob-growers-finished-a-crop-under-1000w-de-hps-poll.883181/page-21#post-12354605

Increase in PPFD is clearly shown in results and seen personally/subjectively. 700-1000µmols has also been shown, talked about, and recommended by others for years. all based on real world and lab studies.
500ppfd, 600ppfd is weak as hell. Of course you are getting good g/w...but g/sqft is what matters.

Look at the standards of growing. hps= 600w for 3x3, 1000w for 4x4...even 400w in 2x2's. That is looking at an average above 1000µmols PPFD for either. That's what the guys getting 2lb+ consistently from a 4x4+space. That is the goal that leds need to live up to. Not some misrepresenting g/w. Professional growers have been growing with 800µmols+...that"+" is key, cause most are over 800.

That is all real world results. Backing what theory says should be the case.


I have added PPFD to my spreadsheet...G/sqft and G/KwH are on there too. As well as your basic g/w.

 

[Rahz]

It is good to see some test data out there. The YOR test data seems to indicate lower PPFD results in notably higher yield per unit of energy. My experience from 500-800 leans much more towards a linear result where the higher PPFD is producing an equally higher yield per area. 600 is relatively weak but to an extent par watts is par watts. Space limitations might lean towards higher density while power use limits might lean towards lower density.

 

[Greengenes707]

There is plenty of data about light density to yield...


Photons are photons. And the main goal pertaining to light of any grower is to get as much light as they can while not going into photoinhibition, which Is upwards of 1500PPFD.

Here is an old conversation between tags and gavita.

I have been chatting with gavita a little about par readings...

"Dear ****,
The ppfd you will read under a lamp depends on the reflector, so it is impossible to compare based on a ppfd measurement at a distance. I have not seen any LED fixtures yet that have a better spectrum and are more efficient than Pro-line HPS, not even at the same power. As said, ppfd at a distance doesn't say anything.
The recommended height from the crop for the pro-1000 is about 80-90 cm, depending is you overlap or not. 2000 umol s-1 m-2 is 30% above the saturation level. We recommend 1000 umol m-2 s-1.
The only thing you can do is measure in a dark room om a given footprint, do a matrix measurement (at least about 40 measurements) and average them over the lit surface.
It would be handy if manufacturers just publish their ppf. We measured Hortilux at a bit lower than 1800 umol s-1 @ 1000W lamp power."



Pretty much goes right with my umol theory.
They are a nice company, and for hps are the best for sure...but honestly they can't think their spectrum is better than led's.

Gavita was quick this time...

The DLI, optimal PPFD and saturation level depends greatly on the crop. I have no public papers to share about this, these are copyrighted research papers we can not distribute. But for a medical cannabis crop you will have a linear increase in yield following the ppfd to about 1000-1100 umol. After that the curve starts to top off with a saturation of the plant between 1400 and 1600 umol m-2 s-1. Beyond that yield decreases.



The standard red an blue narrowband LEDs certainly do not have a better spectrum than HPS. Though HPS lacks blue and green it does have a much wider spectrum of light than the average monochromatic LED, or even 3 at different wavelengths. We have yet to see a fixture (not a lab theoretical maximum output) that is able to beat HPS.



There are plants that thrive under orange and red light. In any case you should ideally not hang only HPS in a climate room. Professional climate rooms use a mixture of HPS and MH or just MH.



The Pro 1000 needs about 80-90 cm distance for an average of 1000 umol m-2 s-1.




Gavita and I differ greatly in ideal spectral performance for sure, obviously they are not up on their white led tech...but there umol levels are right inline with mine so think that I am on the right path for the ultimate light.

 

[captainmorgan]

GPW and GSF can be very strain dependent and not a good way to compare your set up to others unless they're running the same set up and genetics but is more useful comparing runs in your own garden or seeing how new genetics compare to something you've already run. I like the idea of looking at comparing grams per sq/ft at a given watts per sq/ft in my own set up. I've been able to hit 2.2 oz's a sq/ft at just under 30 watts a sq/ft which is about 530 PPFD so it is possible to get a nice GSF at a lower PPFD. My set up is driven by limitations in space and cooling so I'm running higher efficiency and lower watts per sq/ft.

 

[Trippyness]

Let's get something straight...g/w means nothing. (grams/sqft) and (grams/KwH) are the only real metrics to use for comparison.

I refer you to post #416 from me in here for PPFD to yield differences...with pictures...
https://www.rollitup.org/t/have-any-of-you-diy-cob-growers-finished-a-crop-under-1000w-de-hps-poll.883181/page-21#post-12354605

Increase in PPFD is clearly shown in results and seen personally/subjectively. 700-1000µmols has also been shown, talked about, and recommended by others for years. all based on real world and lab studies.
500ppfd, 600ppfd is weak as hell. Of course you are getting good g/w...but g/sqft is what matters.

Look at the standards of growing. hps= 600w for 3x3, 1000w for 4x4...even 400w in 2x2's. That is looking at an average above 1000µmols PPFD for either. That's what the guys getting 2lb+ consistently from a 4x4+space. That is the goal that leds need to live up to. Not some misrepresenting g/w. Professional growers have been growing with 800µmols+...that"+" is key, cause most are over 800.

That is all real world results. Backing what theory says should be the case.


I have added PPFD to my spreadsheet...G/sqft and G/KwH are on there too. As well as your basic g/w.
View attachment 3666768

GG, I usuially agree with you but saying 600 is shit is really stubborn. Yes your right on the g/sf.
I did see your post but nothing conclusive. Your attatchment is blury as well. I have no doubts 800+ppfd increases yield compared to 600 but by how much per sqf?
Thanks for the input.

 

[PerroVerde]

I pulled 1.58 ounces per square foot with 940 PPDF, unproven pheno's and a quite uneven canopy my first time with the Cree 3590 COB's...

 

[Trippyness]

GG, I usuially agree with you but saying 600 is shit is really stubborn. Yes your right on the g/sf.
I did see your post but nothing conclusive. Your attatchment is blury as well. I have no doubts 800+ppfd increases yield compared to 600 but by how much per sqf?
Thanks for the input.

Obviously genetics and veg time are a factor, but in the same conditions how much yield increase from 600 to 800 is all im asking. I love that you attatch real world data. Really helps the community

 

[Trippyness]

I pulled 1.58 ounces per square foot with 940 PPDF, unproven pheno's and a quite uneven canopy my first time with the Cree 3590 COB's...

Descent. I pull 3.5oz a sq/f with Blue Dream using Blurple. Plan on upgrading.
With a better yielder you could surely double your yield.

 

[Abiqua]

Obviously genetics and veg time are a factor, but in the same conditions how much yield increase from 600 to 800 is all im asking. I love that you attatch real world data. Really helps the community

its an impossible question. doh.

 

[Trippyness]

its an impossible question. doh.

General guideline. Mainly to see how much difference. Seems i may have to test it in a small run.

 

[nogod_]

Anyone who doesn't tweak their grow from cycle to cycle isn't worth listening to. That is why you will never find the data you are looking for.

Unless you have some bizarre freak of a strain, 800umols ppfd is going to grow more bud than 600.

more photons = more plant matter

Think about it this way.......blue dream is a great plant to grow in the sun under 2000umols ppfd.
Do you think it is going to grow more bud if you throw a shade cloth over your greenhouse?

Obviously genetics and veg time are a factor, but in the same conditions how much yield increase from 600 to 800 is all im asking. I love that you attatch real world data. Really helps the community

 

[Rahz]

"But for a medical cannabis crop you will have a linear increase in yield following the ppfd to about 1000-1100 umol. After that the curve starts to top off with a saturation of the plant between 1400 and 1600 umol m-2 s-1. Beyond that yield decreases. "

My experience has leaned toward the quote but the quote and the chart seem to disagree. The chart shows flower gram/power ratio is not linear.

 

[PerroVerde]

Descent. I pull 3.5oz a sq/f with Blue Dream using Blurple. Plan on upgrading.
With a better yielder you could surely double your yield.

I'm sure I can and will do better down the road. I was pheno hunting not looking to yield. I think when I'm running full speed I'm still not going to touch 3.5 a sq/f...