Cannabis Daily Light Integral
- Thread starter cdgmoney250
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Rahz
Well-Known Member
Those lamps were made to be used with reflectors. I did try to talk him into more cobs at lower amps but 70w each was the sweet spot for him.
Yodaweed
Well-Known Member
mainly genetic and environment based
Slinging PAR
Well-Known Member
It could be. Go at it and run a test.
Nice to see that we are at the stage of researching the impacts of negative conditions on these plants. This run I decided to test for minimal water and nutrients. The plant has some good rebounding capabilities to handle drought conditions and so far just delays veg growth. If done right it can help stagger out full cycles using the same strains.
Randomblame
Well-Known Member
Hmm! Foxtailing is IMO a subsequent flow of growth that occurs when flowers are not fertilized(sinsemilla). These are just attempts to catch pollen. All healthy plants tend to do that over time. That is why we still find fresh flowers on a 60-day strain even after 80 days. They get bigger by the try to catch pollen, so they do not die out. And foxtailing is how it looks like at the end when the flowers are completely bloated.
Rahz
Well-Known Member
Thought I would add some data to the DLI debate. Boosting PPFD from 780 to 1250 increased yield by about 21%. Max yield under multiple runs with 780 = 60g/ft and max yield under first run with 1250 = 73g/ft.
Being able to use more efficient emitters I achieved this using only 5 output watts more per foot. If you did the math you would see the GPW is similar and GPPW is a bit lower. 1250 PPFD for 12 hrs. a day provides a DLI of 54.
Less PPFD spread out more is going to provide a better yield, but when working with limited space there does seem to be some benefit to jacking the PPFD up closer to 1500. How it would affect the yield to move from 1250 to 1500 I can't say for sure but I suspect there would be a small improvement. Likely only a fraction as much as moving from 800 to 1250.
Interestingly, although some have reported a linear yield increase, the increase I experienced moving from 780 to 1250 is close to what the PPFD-vs-growth chart predicts. It's slightly more linear than the curve, but still a curve. Just eyeballing the chart it looks like the prediction would be 17-18% increase from 780-1250.
If we assume the trend will hold up to 1500 PPFD/12 HRS then there would be a 2-3% increase in yield (over 1250 ppfd) and would place the DLI at about 65. When working with limited space, one has to make a decision on what is worth it. In this case, moving from 1250 to 1500 would increase yield about 2g/sqft for an additional 8 output watts per sq/ft. Put another way, about 3% more yield for 20% more electricity. Also, 1500 tends to look better as chip efficiency improves. If emitters were 100% efficient you could get that same 3-4% yield increase for around 12% more electricity.
All based on what to do with limited space, of course. With unlimited space it would be dumb to run DLI of 65... but point being, there's no cut off point at 30-40 DLI where there are no more yield increases. Actual cut off point is likely around 65.
Being able to use more efficient emitters I achieved this using only 5 output watts more per foot. If you did the math you would see the GPW is similar and GPPW is a bit lower. 1250 PPFD for 12 hrs. a day provides a DLI of 54.
Less PPFD spread out more is going to provide a better yield, but when working with limited space there does seem to be some benefit to jacking the PPFD up closer to 1500. How it would affect the yield to move from 1250 to 1500 I can't say for sure but I suspect there would be a small improvement. Likely only a fraction as much as moving from 800 to 1250.
Interestingly, although some have reported a linear yield increase, the increase I experienced moving from 780 to 1250 is close to what the PPFD-vs-growth chart predicts. It's slightly more linear than the curve, but still a curve. Just eyeballing the chart it looks like the prediction would be 17-18% increase from 780-1250.
If we assume the trend will hold up to 1500 PPFD/12 HRS then there would be a 2-3% increase in yield (over 1250 ppfd) and would place the DLI at about 65. When working with limited space, one has to make a decision on what is worth it. In this case, moving from 1250 to 1500 would increase yield about 2g/sqft for an additional 8 output watts per sq/ft. Put another way, about 3% more yield for 20% more electricity. Also, 1500 tends to look better as chip efficiency improves. If emitters were 100% efficient you could get that same 3-4% yield increase for around 12% more electricity.
All based on what to do with limited space, of course. With unlimited space it would be dumb to run DLI of 65... but point being, there's no cut off point at 30-40 DLI where there are no more yield increases. Actual cut off point is likely around 65.
Rahz
Well-Known Member
I was just looking at that chart, which you posted here: https://www.rollitup.org/t/max-ppf-ppfd-with-and-without-co2.921830/page-2
I would have posted it just now if you hadn't. The YOR data is more linear than the Mcree data. YOR is in itself a consensus, but it's nice to get figures first hand to back it up.
I think we've just about got this topic wrapped up.
wietefras
Well-Known Member
Heh.
Either way, from my own grows I also noticed that yield was related to light intensity much more linear than the Chandra chart predicts.
Yeah all those triangles and diamonds are someone's actual yield. I felt that that should be much more realistic data than that Chandra chart based on cannabis leaves in a growth chamber. Although of course there is a lot of potential for inaccuracy with the YOR data too.
Either way, from my own grows I also noticed that yield was related to light intensity much more linear than the Chandra chart predicts.
Slinging PAR
Well-Known Member
I wouldn't call it a cut off. The higher intensity will also reach further down into the canopy and could explain the increased yields. If you aren't running a deep canopy then you might not see an increase.
With your numbers it looks to be a 21% yield increase for a 50%+ increase in optical power. It would be interesting to see the numbers for the top 1/3rd of the plants for comparison. From my experience anything with 200+umols hitting it will produce quite well; even intra-canopy light hitting around 50 umols makes for some good material.
nachooo
Well-Known Member
So..maybe more intracanopy light or well designed sidelighting is the key to better yields...or just some well done defoliation of upper leaves...
Rahz
Well-Known Member
My grows typically have a 14-18" thick canopy (lollypop) with light levels negligible below the canopy. If I measured I suspect the readings below the canopy would be between 5 and 10. So I don't know if my canopies are "deep", but certainly it's worth pointing out the values change as the distance from source changes and there's no such thing as a flat canopy, only an evenly lumpy one. SCROG and SOG should be superior indoors and I do make an effort to keep a flat compact canopy.
I'm unclear on what PPFD (and yield) you're indicating. If you mean 200 PPFD, you should hit some reasonable GPW, but I would expect g/sqft to be fairly low and inline with the YOR curve... although there's plenty of opportunity to beat the prediction at any PPFD. For instance, the average for 1250 PPFD is about 500g/m2 and yet I managed over 700.
Slinging PAR
Well-Known Member
No, I meant any part of the plant getting 200 umols will still produce quite well, eg. those lower branches and sides. So if you are hitting the top at 1200, another 20' down or so might only be 200. That 200 will still produce well, significantly better than 0-50.
To hit high yields you have to maximize use of your available space. Vertical and scrog methods are needed to increase the light surface area. Then you have veg time, different strains, tastes for finish, etc. That 500g/m2 might be typical but there is no reason you can't double or triple that, same as what they do with gourds and pumpkins!
Yeah or tying down the branches for maximum exposure. You could also just hang a a19/e27 bulb in the canopy. The ones these days put off little heat.
ttystikk
Well-Known Member
I found that foxtailing came from an excess of heat in the environment, especially infrared from lamps. Once I went LED, the foxtails vanished for good.
where can i find the data for this chart?
ontopic:
what about sidelighting? anybody follow miami.mango and his #mangotech on IG?
i'm remodeling my room after the current grow based on his rooms. i will have 30 3590 3500k @ 700mA and 20 vero 18 1750k @ 525mA from the top and 52 q-series 27.5cm 3000k stripes @ 700mA from 2 sides over a 4.5x8. should be interesting
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nachooo
Well-Known Member
In my flower room (about 3x3) at middle flowering time I use 10/14 plus far red at the end of day, and 420 watts of high quality leds at the top plus 120 watts of samsung strips as side lighting...all leds driven at half amps so they give less heat and more light...but with such amount of light....and 82F (28C) and 55-60% rh pure indicas are a little stressed , my sativa strain does quite well
With this conditions and sativas my last crop was about 1,95 g per watt....I use some CO2.also.but homemade with sugar gelatine and yeast..
Rahz
Well-Known Member
As I explained, 20 inches down there's almost no light. As for side lighting, the plants are up against the walls. If I used side lighting I would need a bigger tent.
That's quite the claim. If I had tripled that I would have hit about 4 GPW. I'm not saying it's impossible but I'd need some proof.
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InTheValley
Well-Known Member
650PAR looks like the sweet spot?
wonder if youd get a big boost by injecting CO2 to roots at night.
I will do an experiment on that,
wonder if youd get a big boost by injecting CO2 to roots at night.
I will do an experiment on that,