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

[Beta Test Team]

When I use 11/13 on my wide leaf types, I get longer
flower times to harvest, adding two weeks, some amber,
mostly cloudy. Leaf shape mostly equal to the same cultivar
flowered at 12/12.

I also noticed growing micro in small pots, 32 oz and less,
leaves grow smaller, but never noticed 5 bladed cultivars
throwing 7 or 9 blades under 11/13.

Phenotype plasticity is there, however, you're not going
to make any dramatic changes to cultivars' expression.

Light spectrum and distance to light also play a role, but it's
a curiosity at best. Navel gazing, so to speak.

Interesting, like the dichotomy of the salts/organic thing.

Very well stated, thank you.

 

[DooDahMan]

DJ:

"After many years of first-hand experience breeding herb indoors as well as outdoors, I am of the opinion that the two most influential factors involving phenotypic variation and expression among current indoor herb breeding projects are the photoperiod (hours of light per day) and the angle of light in relationship to the growing plant."

he's saying (or appears to be saying)

Only in your head. Are you hearing voices?

 

[Beta Test Team]

DooDahMan (aka Bubbleblower), nice job allowing this whole thread to go over your head.

And you're still not posting in context, but doing that makes it easier for you to be disingenuous, I understand.

 

[DooDahMan]

Show us these claims you talk about, because none of us can find them.

You do realise stating an opinion is not the same as making a claim, right?

 

[DooDahMan]

And you're still not posting in context

You really feel quoting only the bolded part took it out of context?

Shaggy, here a few research papers and studies you may want to review if you want more info about these topics. "End-of-day treatment" is also a common use for far-red LEDs

 

[Miraculous Meds]

You seem to suggest he's referring to a single plant in a single season, but he's not (well, he doesn't seem to be).

An hour change in photoperiod I doubt is going to have a similar effect on progeny ("transgenerational epigenetic inheritance") as stressors can (in terms of tags). So I doubt changing the photoperiod by an hour is going to affect the progeny, at all.

I keep referring to genotype (even though epigenetics isn't about changing the DNA sequence, rather gene expression) because DJ wrote about breeding, not growing a single plant, in terms of photoeripod effects on Cannabis.

I simply do not believe, and I won't until I see scientific evidence proving me wrong, that an 11 or 13 hour photoperiod (instead of 12 hours) for flowering can make a Cannabis plant express traits ascribed to specific genotype (like 'indica' and 'sativa') that it doesn't naturally express at a 12 hour photoperiod.

Changes in leaf and flower morphology, and even cannabinoid and teprpene production, can occur from changing the photoperiod (often due to changing the amount of daily radiation), but that's not the same thing as what DJ is suggesting.

If that didn't help clear up any ambiguity from my part I can't do any better. And honestly, this discussion about DJ is going in circles...

Heres how I see it. Dj is referring to bringing out different phenotypic traits by altering the photoperiod. I don't think he is saying that if will change the genotype. But if u have coaxed these plants that express different phenotypic traits, they may pass these traits on, because its obviously in there genotype already.

The point is ur changing the photoperiod to find these examples. If u chose to breed with them, then obviously its a possibility that they may pass these traits on.

 

[bastar]

there is dutch grower use this method

 

[MJPassion]

Here's my stab at attempting to get one to understand the context of DJs article...
#1 The article is about Breeding Tips.
#2 The context of the quotes being referd to are about selection.

The way I see what DJ says:
He is simply refering to techniques used to bring about specific characteristics for the express purpose of selection.
In other words, he is alluding to the fact that light angles & photoperiod times will change the phenotypic expression of a given cultivar, thereby aiding, in some form, the selection process.

 

[Beta Test Team]

I think it's pretty clear there is going to be no agreement on what he wrote unless he comes in and explains what he means (he's far too ambiguous), but even then, there will likely not be agreement on his claims (which are pretty bold, and the whole "angles" thing is has little to no basis in science).

Regardless, his claims have been all this thread has been about for many pages, which is a shame...

 

[Beta Test Team]

there is dutch grower use this method

What method are you referring to, the one Shaggy asked about: Increasing photoperiod in flowering greater than 12 hours? If so, I'm sure he'd like to hear more.

 

[MJPassion]

Nowhere does DJ say that changing the lights will change the genotype. I don't see it. That comes with selection & breeding future generations. F2 & beyond.

 

[MJPassion]

Oh yeah... If that's the same GW study I read a couple years ago it did a pretty fair job of studying the effects of photoperiod v yield.

Most was unndigestible by me. Made me feel like a blond joke. lol

 

[LSWM]

http://www.gwpharm.com/uploads/finalfullthesisdjpotter.pdf

Oh yeah... If that's the same GW study I read a couple years ago it did a pretty fair job of studying the effects of photoperiod v yield.

Most was unndigestible by me. Made me feel like a blond joke. lol

I just finished reading some parts in detail and others I just skimmed.

The author of the paper makes the claim that 11/13 and 13/11 in fact decreased the amount of cannabinoids per g/m^2, and while differences were found in percent cannabinoids by weight, overall there were either more potent but lower overall yield, or less potent but larger overall yield. In both cases overall yield of cannabinoids was down.

Amongst the major findings, from the studies comparing the effect of daylength, it was found that increasing the daylength from twelve to thirteen hours increased energy consumption by at least 8%, but resulted in no beneficial increase in botanical raw material yield. There was sometimes also an unwelcome increase on plant height. Effects of increased day length on cannabinoid yield were variable, with some clones showing a large decrease in cannabinoid production at the longer day length. Conversely, reducing the day length to eleven hours saved energy by approximately 8% but resulted in an economically unacceptable and statistically significant 15 – 20% mean reduction in plant yield (p < 0.01). There was also a significant reduction in the mean cannabinoid yield (p < 0.01 after 10 wks in short days).

He also suggests a mechanism by which 11/13 causes decreased cannabinoid yield.

Plants in the shorter eleven-hour daylength had received 9% less light energy per day. Conversely, these plants spent 9% longer in darkness and would be expected to have lost yet more energy as a result of a longer period of respiration. This would seem a major contributing cause of the yield reduction in the eleven hour daylength and is in marked contrast to the lack of yield difference observed when comparing the twelve and thirteen hour daylengths. In the thirteen hour regime the potential yield benefits of increased energy were not utilised by the plant.

I think this thread needs to change gears. I don't believe most of us are interested in changing light schedules for breeding as DJ is suggesting, I think we are all much more interested in bud formation, cannabinoid profiles, and overall yield vs lighting costs, as it relates to length of lights on, as well as overall flowering time.

In an indoor environment there is no reason to be constrained by a 24 hours day/night length. How does 11/12 or 11/11 effect growth, yield, and total length of flowering time? How about 13/12 or 13/13?

EDIT: What about starting at 14/10 - 12 weeks before harvest, and ending at 11/13 or 11/12? I would imagine you would get larger flowers, and a longer period of stretch, but this would obviously be highly strain dependent.

 

[Snype]

You can't change phenotype without changing genotype in his context...

Phenotype = Genotype + Environment

So if you change the environment, Genotype doesn't change but Phenotype does.

When I look at my plants compared to people that I know that have the same clone, they can be different in many ways.

 

[Beta Test Team]

You can't change phenotype without changing genotype in his context...

Phenotype = Genotype + Environment

So if you change the environment, Genotype doesn't change but Phenotype does.

When I look at my plants compared to people that I know that have the same clone, they can be different in many ways.

See the part I bolded. Your exact point has already been rehashed maybe 3 or 4 times in this thread. There will be no agreement without DJ explaining what he means...and until then I think it's would be good if people started a thread about what DJ wrote and post about it there...kinda off topic for this thread.

 

[Beta Test Team]

I just finished reading some parts in detail and others I just skimmed.

The author of the paper makes the claim that 11/13 and 13/11 in fact decreased the amount of cannabinoids per g/m^2, and while differences were found in percent cannabinoids by weight, overall there were either more potent but lower overall yield, or less potent but larger overall yield. In both cases overall yield of cannabinoids was down.

He also suggests a mechanism by which 11/13 causes decreased cannabinoid yield.

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.

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.

I have used between 12 and 13 hours for a long time for many different cultivars. Really interesting to see how the flowering formation changes, and yields, too.

I think this thread needs to change gears. I don't believe most of us are interested in changing light schedules for breeding as DJ is suggesting, I think we are all much more interested in bud formation, cannabinoid profiles, and overall yield vs lighting costs, as it relates to length of lights on, as well as overall flowering time.

Yes, that's how I see it; the DJ topic should be thread itself, it's not really on topic for this thread.

In an indoor environment there is no reason to be constrained by a 24 hours day/night length. How does 11/12 or 11/11 effect growth, yield, and total length of flowering time? How about 13/12 or 13/13?

EDIT: What about starting at 14/10 - 12 weeks before harvest, and ending at 11/13 or 11/12? I would imagine you would get larger flowers, and a longer period of stretch, but this would obviously be highly strain dependent.

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.

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).

 

[Bubbleblower]

In other words, he is alluding to the fact that light angles & photoperiod times will change the phenotypic expression of a given cultivar, thereby aiding, in some form, the selection process.

F2s in particular:

“Phenotypic expression
The malleability of phenotypic expression among the Sativa/Indica crosses must also be noted. The variability of phenotypic expressionamong the f2 generation of a truly polar (pure Sativa/pure Indica) P1 cross is quite phenomenal. The second generation f2 crosses will exhibit the full spectrum of possibilities between the original parents ? extreme Indica, extreme Sativa, and everything in between.
However, regardless of any particular phenotype selected from among this given f2 cross, future generations may drift radically. Depending on the presence (or lack) of a number of environmental triggers, an f2 Indica phenotype may be coaxed more toward Sativa traits, or an f2 Sativa phenotype may be coaxed more toward Indica expression. The key is environmental conditions.
Inducing Sativa
After many years of first-hand experience breeding herb indoors as well as outdoors, I am of the opinion that the two most influential factors involving phenotypic variation and expression among current indoor herb breeding projects are the photoperiod (hours of light per day) and the angle of light in relationship to the growing plant.
Specifically, I find the single most powerful influence to the Indica dominant phenotype is the traditional 18/6 veggie cycle and 12/12 flowering cycle. The 18/6 veggie and 12/12 flower cycle is an attempt, however poor, to mimic the Indica-producing photoperiod. It is my belief that this light cycle strongly influences for Indica phenotypic expression.
Sativa phenotype characteristics will manifest under a more equatorial photoperiod, closer to a 13/11 veggie cycle and an 11/13 flower cycle. This is the light timing range to use to elicit more Sativa dominant expression from your plants.”

I agree with every word of this.
He is also correct about the importance of angles:

 

[LSWM]

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.

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.

He (David Pate 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.

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.

I have used between 12 and 13 hours for a long time for many different cultivars. Really interesting to see how the flowering formation changes, and yields, too.


Yes, that's how I see it; the DJ topic should be thread itself, it's not really on topic for this thread.


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.

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

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).

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

See my other responses above in blue.

 

[mojave green]

angle of light

 

[Bubbleblower]

angle of light

The angle has a big effect on the spectrum.
Following the same logic more blue light would bring out sativa traits and more red light indica.
To me that is all very interesting as I care more about quality than quantity.

it takes plants a little while to adapt

If you use a dynamic light schedule correctly the plants will not need to photo adapt!
Unlike when you change from 18/6 to 12/12.
Cannabis is smart and very good at math.