Rahz
Well-Known Member
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.Where did this data come from? Link to the study?
Yields at differant PPFD?
- Thread starter Trippyness
- Start date
Someone asked where the chart came from. It is an image on the page... http://www.tastyled.com/default.asp
Trippyness
Well-Known Member
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
Well-Known Member
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
PDF: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550641/pdf/12298_2008_Article_27.pdf
Rahz
Well-Known Member
4800 PPFD is pretty intense. I'm not sure anything could survive in that environment. Do you have a citation for it?
Trippyness
Well-Known Member
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.
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
Well-Known Member
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
Well-Known Member
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.
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.
Last edited:
Rahz
Well-Known Member
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
Well-Known Member
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.
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.
captainmorgan
Well-Known Member
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
Well-Known Member
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
Well-Known Member
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
Well-Known Member
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
Well-Known Member
Descent. I pull 3.5oz a sq/f with Blue Dream using Blurple. Plan on upgrading.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...
With a better yielder you could surely double your yield.
Abiqua
Well-Known Member
its an impossible question. doh.
Trippyness
Well-Known Member
General guideline. Mainly to see how much difference. Seems i may have to test it in a small run.
nogod_
Well-Known Member
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?
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?
Rahz
Well-Known Member
"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
Well-Known Member
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...