update: lower lights on hours AND higher lights on hours is best for flowering

[dank'd]

these two recent studies compliment each other in an interesting way. the first one (video @17:03, usa) uses various fixed photoperiods to flower three different 8 week varieties, 10L, 11L, 12L and 13L

the second study (article, australia) tests 6 or 7(?) varieties also of the 8 week flowering type but splits the flowering light schedule into 2 four week schedules of varying combinations consisting of 14L>12L, 14L>10L, 10L>14L, 12L>14L, and also straight through for 8 weeks 14L, 12L and 10L

in the first study, 10L straight through for the full 8 week flower cycle produced faster ripening with a more finished, higher quality looking flower, at a loss of yield. in the case of the og variety though they found that raising the light hours to 12L for the last four weeks of flowering increased yield as well as higher quality flower

in the second study we have similar findings but with a unique twist. generally they also found that at low light hours like 10L plants ripened faster at a loss in yield, but in some varieties the photoperiod could be raised to 14L, for an increase in 50% thc(!) and flower weight

BUT!...... ONLY, and i repeat, ONLY, if the 14L period is only for half of the flower cycle (4 weeks for an 8 week variety) and the other four weeks are of a lower daylight duration of anywhere from 10L to 12L

if the 14L photoperiod is continued for the full 8 weeks of flower?... thc yield drops by 2/5! as does trichome density

and here's another kicker. in the case of a high cbd variety, a 14L photoperiod for the full 8 weeks of flower will cause a massive INCREASE in cbd and flower!

so it seems from the two studies we know that like in nature, with the reduction of day length during flower we can [potentially] increase our cannabinoid and flower production in just two phases, AND, it doesn't matter if flowering is initiated with the low daylight hour phase or ends with it, the results should be similar, again, if the variety responds to it

and the australian study

https://www.mdpi.com/2223-7747/12/5/1061

some screen grabs from the first study

 

[Sickofitall420247]

I start with 13 then work my way down to 10.

 

[Rocket Soul]

these two recent studies compliment each other in an interesting way. the first one (video @17:03, usa) uses various fixed photoperiods to flower three different 8 week varieties, 10L, 11L, 12L and 13L

the second study (article, australia) tests 6 or 7(?) varieties also of the 8 week flowering type but splits the flowering light schedule into 2 four week schedules of varying combinations consisting of 14L>12L, 14L>10L, 10L>14L, 12L>14L, and also straight through for 8 weeks 14L, 12L and 10L

in the first study, 10L straight through for the full 8 week flower cycle produced faster ripening with a more finished, higher quality looking flower, at a loss of yield. in the case of the og variety though they found that raising the light hours to 12L for the last four weeks of flowering increased yield as well as higher quality flower

in the second study we have similar findings but with a unique twist. generally they also found that at low light hours like 10L plants ripened faster at a loss in yield, but in some varieties the photoperiod could be raised to 14L, for an increase in 50% thc(!) and flower weight

BUT!...... ONLY, and i repeat, ONLY, if the 14L period is only for half of the flower cycle (4 weeks for an 8 week variety) and the other four weeks are of a lower daylight duration of anywhere from 10L to 12L

if the 14L photoperiod is continued for the full 8 weeks of flower?... thc yield drops by 2/5! as does trichome density

and here's another kicker. in the case of a high cbd variety, a 14L photoperiod for the full 8 weeks of flower will cause a massive INCREASE in cbd and flower!

so it seems from the two studies we know that like in nature, with the reduction of day length during flower we can [potentially] increase our cannabinoid and flower production in just two phases, AND, it doesn't matter if flowering is initiated with the low daylight hour phase or ends with it, the results should be similar, again, if the variety responds to it

and the australian study

https://www.mdpi.com/2223-7747/12/5/1061

some screen grabs from the first study
View attachment 5337858
View attachment 5337859
View attachment 5337860

Its a bit hard to follow: 14L, 10L, is that how many hours the light is on?

Interesting findings but i ask one question to put these findings in perspective: would any serious grower be super happy with any of these results? As in pics of top buds?
Any of these top buds would be deemed a failed crop in our grow, and prompt us to change genetics. Maybe wed run lowest 10 or 11 again if we had no other recourse. All of its smallish buds with a fair bit of leaves, harder to trim.
The point is that its hard to base your grow style on science where their top result doesnt even meet your minimum requirements. But the tendency is interesting.

 

[amneziaHaze]

how many plants where used in the study? maybe it was just genetics or some of the enviormentals, feed...

i know from a guy that got 2.6g/w that he lowered the intensity of the lamps last 2 weeks and still got massive grow. soo your theory about bigger grow might be correct

 

[dank'd]

Any of these top buds would be deemed a failed crop in our grow

oh i most definitely agree, the 4 week photos are not up to my standards either, nor the 6, but then again, i let my plants flower for more than 4 and 6 weeks : )

the og is just about done though there at 8 weeks

 

[dank'd]

in case anybody else is wondering, the 10L/12L/14L means lights on hours

 

[dank'd]

how many plants where used in the study? maybe it was just genetics or some of the enviormentals, feed...

i know from a guy that got 2.6g/w that he lowered the intensity of the lamps last 2 weeks and still got massive grow. soo your theory about bigger grow might be correct

what's interesting is, the first study shows that the short daylight phase can occur either at the second half of flowering or the first. so you could start flowering at 10L or 12L then raise it to 13L or 14L for the second half, or go the more natural evolutionary way and start high and go low

a key finding is, if you just ran 14L for the whole 8 weeks, thc would drop 2/5 along with crystal density, BUT, for cbd varieties this would result in a major increase in cbd and flower mass. so the two phase thing is crucial when going as high as 14L with thc varieties. i guess in nature it is also a two phase situation, but the transition is gradual

it is different for each pheno/strain, but overall they found that doing a two phase flower cycle (for 8 week varieties at least) can POTENTIALLY greatly increase thc and flower mass, if, the strain is responsive to it. if not, it will have no adverse affect

the first study more so seems to highlight the ripening acceleration with lower hours but 10L isn't written in stone some strains might have a sweet spot at 11L or 12L

 

[Rocket Soul]

oh i most definitely agree, the 4 week photos are not up to my standards either, nor the 6, but then again, i let my plants flower for more than 4 and 6 weeks : )

the og is just about done though there at 8 weeks, looks like pure garbage eh!? not fit for pig feed

I didnt catch the week markings on those two top pics. But still at 8wk it dont look very good. It would be nice to see how this worked out on some really nice cuts

 

[ProPheT 216]

Seems like bad science to me. Would mean a lot more if it was all the same strain put thru the different variables. Being different strains for each test doesn't show much. Other than the difference in the seeds

 

[dank'd]

I didnt catch the week markings on those two top pics. But still at 8wk it dont look very good. It would be nice to see how this worked out on some really nice cuts

like i said, the 8 week is almost done, not quite. and yes, these same results would also apply to 'nicer cuts' lol

Seems like bad science to me. Would mean a lot more if it was all the same strain put thru the different variables. Being different strains for each test doesn't show much. Other than the difference in the seeds

don't try to flip this on some q shit please... yes, they did it correctly, these are university studies

yes, each cut/strain was given all of the applications (mkay?). not only did they give each individual cut/strain all the treatments, they repeated this across multiple strains, 3 in the usa study and 6 or 7(?) in the aus study

please actually watch the video and read the article

 

[amneziaHaze]

what's interesting is, the first study shows that the short daylight phase can occur either at the second half of flowering or the first. so you could start flowering at 10L or 12L then raise it to 13L or 14L for the second half, or go the more natural evolutionary way and start high and go low

a key finding is, if you just ran 14L for the whole 8 weeks, thc would drop 2/5 along with crystal density, BUT, for cbd varieties this would result in a major increase in cbd and flower mass. so the two phase thing is crucial when going as high as 14L with thc varieties. i guess in nature it is also a two phase situation, but the transition is gradual

it is different for each pheno/strain, but overall they found that doing a two phase flower cycle (for 8 week varieties at least) can POTENTIALLY greatly increase thc and flower mass, if, the strain is responsive to it. if not, it will have no adverse affect

the first study more so seems to highlight the ripening acceleration with lower hours but 10L isn't written in stone some strains might have a sweet spot at 11L or 12L

i wonder if you just change ppfd do you get same results

Seems like bad science to me. Would mean a lot more if it was all the same strain put thru the different variables. Being different strains for each test doesn't show much. Other than the difference in the seeds

i fought it was clones in each photo and side by side with hours

 

[dank'd]

i wonder if you just change ppfd do you get same results

would be an interesting experiment(!)

 

[Sickofitall420247]

It would be nice if they mentioned d.l.i at all because it sounds like as long as you reach a certain d.l.i. it doesn't matter what you do.

 

[Hollatchaboy]

It would be nice if they mentioned d.l.i at all because it sounds like as long as you reach a certain d.l.i. it doesn't matter what you do.

That's my thinking as well.

 

[dank'd]

It would be nice if they mentioned d.l.i at all because it sounds like as long as you reach a certain d.l.i. it doesn't matter what you do.

they didn't test for d.l.i. no

 

[Sickofitall420247]

Also I'm wondering if they did any far red treatments on the plants to achieve the 14 hours of daylight?

 

[dank'd]

That's my thinking as well.

Also I'm wondering if they did any far red treatments on the plants to achieve the 14 hours of daylight?

nope

 

[dank'd]

these two studies are on light duration changes during flowering only

 

[Sickofitall420247]

That's what I'm asking about is flowering

 

[dank'd]

That's what I'm asking about is flowering

the studies are only about flowering (actually the usa study does a bunch of other experiments also including poinsettia). but no dli or red light augmentation experiments in either study

they did mention the fact that 4 weeks 14L + 4 weeks 10L = 8 weeks 12L

which means that total dli is the same across both regiments yet, some varieties will increase thc/yield under the first regimen while others will produce the same results under both

AND, the short day regiment can occur either at the start or end for similar results