Cannabis, the effect from increasing photo-period by only 15 or 30 min.

mojave green said:

angle of light

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Hocus pocus my friend!



That's more of DJ's ambiguity to which I was referring. And nowhere does he seem to think it important to reference his claims, which is why he makes the points that it's his guess (it isn't even a valid hypothesis).

In fact, DJ makes the point to mention he's referring to angles (incident photons striking leaves), not spectrum (wavelengths).

And it's not like there's no diffuse portion of sunlight, nor diffuse or reflected radiation in a grow room (mylar, Orca, etc.), so not sure where DJ's logic is coming from. Nowhere does he write about spectrum, that I see.

I find it odd DJ doesn't even mention one of the most (or the most) important factors: irradiance.

I think someone needs to start a thread for DJ's claims, where like minded folks to DJ can discuss his claims in peace.

LSWM said:

Beta Test Team said:

Yup, that's why I keep writing about DLI, which is the total sum of irradiance per day, which is affected by photperiod. Changing the photoperiod without accounting for DLI is not wise.

And his work is not stellar in terms of plant science, so we can't draw conclusions form his work, for example, he used irradiance much lower than most Cannabis growers use, and his experiment was a bit flawed, as well. But it does provide solid evidence and a good starting place for future research.

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I noticed this as well. 75w/m^2 in the greenhouse test and 70w/m^2 in the indoor test. Neither is very high compared to what most would run indoors. My donuts are 4 feet wide and plants cover 3-4 ft vertically giving a number closer to 150-200 w/m^2. I'm sure the numbers are higher for people running 1000w over a 4x4 or 5x5.

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Yes, and with our spreadsheet we can calculate exactly how much PPFD he used, which was in the ballpark of around 400 or 500. Another work of his related to that one is a published study on energy (radiation) effects on Cannabis (as optic PAR watt which can be converted to PPFD, and was electrical watt as growers use it).

LSWM said:

Beta Test Team said:

He (David Potter and GW) care more about cannabinoid yield, not flower yield. And if flower yield is greater, while keeping cannabinoid yield on par, that means greater cannabinoid yield as well.

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It seemed they were looking at both factors to decide overall cannabinoid yield, and I see no reason why anyone else should look at it differently. If you can grow 1 lb of cannabis that is 15% THC or 1/2 lb that is 30% THC, you should be able to sell the latter for twice the price and the difference in yield shouldn't matter. At the highest level of growing and consumption, testing should be mandatory.

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He did study both, but they care most about cannabinoid yield per gram and overhead costs, not flower gram per photon or watt or whatever. My point was that likely it's not necessary not suffer the tradeoff you wrote about, i.e. instead grow 1 pound of Cannabis with 30% THC. This goes back to the flaws in his work and his low irradiance I wrote about.

GW doesn't sell flowers, so they don't care about that really, to them, less flowers is better I'm sure, less headache.

Most growers care about yield of flower and yield of cannabinoids, not one or the other. So I'm just saying it's best to try and optimize both, and that's not what GW does, nor what David Potter wants to do, he makes that point pretty often (that's why they use low irradiance). GW cares about cannaboinds per gram, and electricity costs.

That study I posted is a good starting place, not a good ending place.

LSWM said:

Beta Test Team said:

Using something other than 24 hours has not proven to be useful in my experience, but that's not to say there's no there, there. I've tested greater than 24 hour dinural periods. It's not only (or even mainly) about the photoperiod changing by a couple of hours, it's about DLI.

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Have you tested cycles less than 24 hours? Do you have any pictures to help explain your findings?

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No, never used less than 24 hours as I see no reason (not that there isn't a valid reason). In my mind all that does is lower DLI unless PPFD is pretty high which isn't good for various reasons.

Now if one's main goal was to keep electricity low, not have the best quality and quantity of harvest, shorter than 24 hours could be something to consider. That said, using EOD far-red treatments to reduce nightlength so daylength (and therefore DLI) isn't greatly reduced would be interesting...

I don't have any pics, I wish I did, this was years ago. And like wrote, my word isn't the last word, and we'd be willing to carry out more rigorous experimentation on atypical diurnal periods in the future (like we are with continuous light and night-break studies).

LSWM said:

Beta Test Team said:

Also, there's a good study on the effects of changing the nightlength on carbohydrate partitioning and storage of plants. Another reason to not get too creative with changing light periods too often (it takes plants a little while to adapt).

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I would love to see any links to papers you have regarding DLI and night lengths.

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There are at least two other published studies on Cannabis I know of, but most of the data and science comes from other species at this point. (Something we're going to rectify in the ensuing years.)

I'm post some of those studies over the next day or two for you.

LSWM said:

I noticed this as well. 75w/m^2 in the greenhouse test and 70w/m^2 in the indoor test. Neither is very high compared to what most would run indoors. My donuts are 4 feet wide and plants cover 3-4 ft vertically giving a number closer to 150-200 w/m^2. I'm sure the numbers are higher for people running 1000w over a 4x4 or 5x5.

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I just wanted to mention I think you're confusing "PAR watts" (as in irradiance, energy from the lamp that hits the leaves) with "electrical watts" as used by Cannabis growers. They aren't the same thing.

So this is one reason I wrote his work is a bit flawed, he uses PAR watts (joule/s/m^2 from 400 to 700 nm), not PPFD (umol/m^2/s from 400 to 700 nm), to measure the amount of radiation (light) his plants are getting.

So where you wrote 150 w/m^2, I assume you mean that's 150 watts from the lamp's rated wattage (like 600W, 1000W, etc.) over a meter squared. If so, that's not the same thing as listed in that study.

You can't compare electrical watts per m^2 to energy emitted from the lamp per m^2 without working with the lamp's SPD and math. Our spreadsheet were writing does just that thing, though.

If you're using 150 watt per m^2, and that's lamp wattage draw, you're using a lot more radiation than he was, which is a good things for our goals vs. GW's goals.

Beta Test Team said:

I just wanted to mention I think you're confusing "PAR watts" (as in irradiance, energy from the lamp that hits the leaves) with "electrical watts" as used by Cannabis growers. They aren't the same thing.

So this is one reason I wrote his work is a bit flawed, he uses PAR watts (joule/s/m^2 from 400 to 700 nm), not PPFD (umol/m^2/s from 400 to 700 nm), to measure the amount of radiation (light) his plants are getting.

So where you wrote 150 w/m^2, I assume you mean that's 150 watts from the lamp's rated wattage (like 600W, 1000W, etc.) over a meter squared. If so, that's not the same thing as listed in that study.

You can't compare electrical watts per m^2 to energy emitted from the lamp per m^2 without working with the lamp's SPD and math. Our spreadsheet were writing does just that thing, though.

If you're using 150 watt per m^2, and that's lamp wattage draw, you're using a lot more radiation than he was, which is a good things for our goals vs. GW's goals.

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Yes you are correct. I am confusing the two, but the paper does not make this explicitly clear either. It basically just says "70 watts/M^2 of HPS lighting". He mentions irradiance but that's not a term I was familiar with.

I see what you mean by not making it clear. Without being used to reading these types of papers with this lingo I can see why it's not clear. Sorry for any confusion coming from me.

See Table 5.4 as an example of "W m-2 PAR." And page 22 where he writes "17 W m-2 PAR" and "55 W m-2 PAR." Those are examples of where he explained he was referring to irradiance, not power consumption.

To make matters even more confusing, PAR watts isn't used in plant science, we use PPFD as irradiance (the true definition of PAR as photons, not joules per second). That's one way I know David Potter isn't a plant scientist (or at least doesn't work with radiation often).

Being as I skimmed over a good portion of the paper and simply read what was interesting/applicable to me, it's no wonder I was confused. I essentially skipped over much of his explanation of his methods and jumped straight into the meat of his findings, and in some cases straight to the conclusion.

LSWM said:

Being as I skimmed over a good portion of the paper and simply read what was interesting/applicable to me, it's no wonder I was confused. I essentially skipped over much of his explanation of his methods and jumped straight into the meat of his findings, and in some cases straight to the conclusion.

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I'm sometimes guilty of that too! Especially now that the current trend in some journals is to have the intro, results, and discussion sections first, then the materials & methods section, etc.

By the way, I don't know how old you are, but if you know Pink Flyod (and I assume you do ) these lyrics popped into my head: "If you don't eat yer meat, you can't have any pudding."

Beta,
It's already been mentioned that DJs article IS relevant to this conversation.

If you think he is sooooo wrong in what he's said, proove it instead just flappin your gums or fingering the keyboard!!!

You need to realize that YOU have derailed the thread with your constant bickering about a simple sentence that YOU are failing to comprehend.

...book smart don't mean shit when you haven't any common sense.

& you two reveling in how smart you are is...
FUCKING HYSTERICAL!!!

MJPassion said:

Beta,
It's already been mentioned that DJs article IS relevant to this conversation.

If you think he is sooooo wrong in what he's said, proove it instead just flappin your gums or fingering the keyboard!!!

You need to realize that YOU have derailed the thread with your constant bickering about a simple sentence that YOU are failing to comprehend.

...book smart don't mean shit when you haven't any common sense.

& you two reveling in how smart you are is...
FUCKING HYSTERICAL!!!

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Bingo!

MJPassion said:

Beta,
It's already been mentioned that DJs article IS relevant to this conversation.

If you think he is sooooo wrong in what he's said, proove it instead just flappin your gums or fingering the keyboard!!!

You need to realize that YOU have derailed the thread with your constant bickering about a simple sentence that YOU are failing to comprehend.

...book smart don't mean shit when you haven't any common sense.

& you two reveling in how smart you are is...
FUCKING HYSTERICAL!!!

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I have proven it using science, you just don't agree and/or understand (such as his "angles" hogwash). Which is fine.

And by the way, the person making the claims (DJ) is the one who has to prove it, not the skeptical person asking for proof (me)...

And it's also been mentioned that his work is off topic for this thread, as well, by others than myself.

Yes, you are "fuc*ing hysterical," please stop. And while you're at it, start a DJ thread, please, where you can discuss his breeding claims about light.

Beta Test Team said:

I have proven it using science, you just don't agree and/or understand (e.g. his "angles" hogwash). Which is fine.

And by the way, the person making the claims (DJ) is the one who has to prove it, not the skeptical person asking for proof (me)...

And it's also been mentioned that his work is off topic for this thread, as well, by others than myself.

Yes, you are "fuc*ing hysterical," please stop. And while you're at it, start a DJ thread, please. So how about you start a DJ thread where you can discuss his breeding claims about light?

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If u quit claiming shit that isn't there then u wont get people saying ur full of shit.

U don't see that?

U keep taking statements dj made out of context and keep this argument going on.

Quit assuming that u think dj meant this or that. Those are just ur incorrect assumptions.

For somebody that bases their statements on science how can u keep claiming u think dj meant this or that. Read it for what it is and give up on ur assumption that he is just basing his findings on magic. that's really what u think, but u making shit up to defend ur position isn't going to fly.

not sure how angles of light are relevant to a vertical bulb. i run 11/13, sort of, for convenience sake. 1 hour is for working, so there is generally a small fluorescent on for that hour. have no fooking idea bout all this mumbo jumbo.

i think you read that wrong. he wasn't saying you can turn a indica to sativa by changing the photoperiod. he was saying you see more of the plants natural expression by giving them more than 12 hours dark. i've been running 11/13 since about a year and a half now. it seems to keep sativa's shorter, but my indica types seems a lot more compact than in the past too. but i'm also using an MH bulb these last few grows too so the jury still out on that one. but it certainly seems to help them finish a little bit faster. talking days to a week here not weeks with an S.

Riddleme said:

No problem as I have pics to show exactly what you said and DJ is referring to Sativa/Indica hybrids I doubt it would change a pure indica to a sativa lol

ist pic is my CTF in veg, you can see the wide hybrid leaves

second pic is 2 weeks after being fipped to flower, you can see the wide leaves on the bottom and new growth comin out thinner

3rd pic is right before harvest, all leaves very Sat looking

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in your case i think you might be experiencing a placebo effect. even my sativa's start off with wide leaves that eventually get thin.

here's for instance a plant i just started it's at about 3-4 weeks. it's been under 18/6 till about 5 days ago when i put it into my flower which is 11/13.


the leaves started off wide and are progressively getting slimmer. i don't have a pic from today or i could show you this plant is very NLD lol or whatever sativa leaning.


this one is a good example.

clearly a sativa right?

but here's his baby pictures.




clearly an indica right?

mojave green said:

not sure how angles of light are relevant to a vertical bulb. i run 11/13, sort of, for convenience sake. 1 hour is for working, so there is generally a small fluorescent on for that hour. have no fooking idea bout all this mumbo jumbo.

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Do the research or don't, that's up to u.

If u quit claiming shit that isn't there then u wont get people saying ur full of shit.

U don't see that?

U keep taking statements dj made out of context and keep this argument going on.

Quit assuming that u think dj meant this or that. Those are just ur incorrect assumptions.

For somebody that bases their statements on science how can u keep claiming u think dj meant this or that. Read it for what it is and give up on ur assumption that he is just basing his findings on magic. that's really what u think, but u making shit up to defend ur position isn't going to fly.

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MM, and others, if you want to hold tight to your ideas about DJ feel free, don't let my posts stop you. But please take it to a different thread.

Does it not seem rude to you to keep posting about DJ in this thread? I've asked many times that you all stop, and make a new thread (where I won't be there to bother you), but you won't...

LSWM and I had a good thing going talking about the tread topic, but then you and MJ Passion just had to bring DJ back up...so, who's the one that keep this DJ malarkey going? Hmmm.

beta test team,

fella u talked out ur butt about an assumption, own it, admit it, or at least quit defending it and no one will say another word.

Otherwise putting words in a respected members mouth isn't going to fly. Don't respond about ur incorrect accusations anymore and no one will tell u ur full of crap and making stuff up.

Beta Test Team said:

It's my understanding, and maybe I'm wrong, that DJ was referring to making for example, WLDB into NLDB, that is, the leaves would change, too. Like poof! Now it's a new genotype due to a photoperiod change.

If that's not the case then I stand corrected about that specific claim of his, though I'm not sure that's not the case. I will wait to be proven wrong by someone who can post his words in full context. It would help to remove the ambiguity of his claims.

Regardless, I provided science to show what happens in some cases, and from my reading it's not what DJ is claiming...

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Stand corrected! U are wrong to assume. Hes never stated that. If so prove it by quoting it here, and I will eat my words.

But I don't think that's going to happen because this is just crap u made up in ur head to support ur opinion.

let it go.

Look, it's obvious you don't comprehend what I wrote and you are a cherry picker; I'm the one that keeps pointing out his ambiguity. It's obvious you admire him, and that's why you can't accept he may be wrong.

I'm wasting my time with you and others in this thread. Feel free to mud-sling me in the following posts of yours as much as you like, you won't hear another peep from me. But don't think that means I agree with your "appeal to authority" (Google that term, btw ), or your personal insults toward me.

Beta Test Team said:

So from reading his article again (it's been years), it still seems to me like he's suggesting photoperiod will affect genotype (as relating to phenotype from parental stock to progeny), and I still disagree. It seems like he's conflating simple breeding by phenotype with changing genotype and therefore phenotype by photoperiod over generations.

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Wrong assumption again!

If he said this prove it. Which u cant because he didn't say it. U thought it, and held on to it, and made it true in ur head. Don't pass on ur conjecture as what he is saying. Its not true.

Beta Test Team said:

Look, it's obvious you don't comprehend what I wrote and you are a cherry picker; I'm the one that keeps pointing out his ambiguity. It's obvious you admire him, and that's why you can't accept he may be wrong.

I'm wasting my time with you and others in this thread. Feel free to mud-sling me in the following posts of yours as much as you like, you won't hear another peep from me. But don't think that means I agree with your "appeal to authority" (Google that term, btw ), or your personal insults toward me.

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I can admit my own mistakes and own them, I do it all the time. I don't claim to be correct all the time. I can accept someone I appreciate and admire being wrong too.

Maybe its u who needs to own the fact they are wrong. lol