Question about lighting schedule.

[cadlakmike1]

In another thread(http://www.marijuanapassion.com/forum/showthread.php?t=48822) Hick had mentioned that 12 hours of light will nearly double the THC content as compared to only ten hours of light. I was amazed by that statistic, and it got me to thinking.

Let's say you switch to a 12/12 schedule and flowering is induced. Once the plant is flowering, can you then increase the light schedule for better results? I realize that if the light schedule is increased too much the plant will revert back into a vegetative state and stop flowering, but what if you just increased the light by an hour or two? I'm sort of a traditionalist about a lot of things, and believe that if it's not broke, don't fix it, but I am interested in what studies have been done and what results where achieved.

I would imagine(and I might be way off here) that an increased amount of light would increase yield(assuming you can increase the light and keep the plant in flowering), because the plant would have more time to grow, create photosynthesis, uptake nutes, etc., but would there be and adverse affects on THC content? Would the plant stress out and turn hermie? If decreasing the lights by just two hours can have such a dramatic negative effect, you have to wonder if there is some magical number slightly greater than 12 that can just as drastic consequences, but in a positive manner.

Any opinions are welcome, I'd love to hear what some other people on this site think about this, even if it is just an opinion or thinking out loud. Also. any personal experiments from any users, please share, or point me in the direction if you've read about others.:48:

 

[Locked]

Good question...it makes me wonder how this applies to autos that don't need the reduction in light to flower...does the added amount of light help the thc content get up to speed with regular strains? I don't live in Cali and hve access to the great genetics that are out there but the autos I hve grown hve been some potent little monsters....

 

[cadlakmike1]

Good question...it makes me wonder how this applies to autos that don't need the reduction in light to flower...does the added amount of light help the thc content get up to speed with regular strains? I don't live in Cali and hve access to the great genetics that are out there but the autos I hve grown hve been some potent little monsters....

I can't really comment on that too much, but I can say this. I have done a few runs on auto's(Lowryder 2), and the first time I grew them I snuck them into my grow room right before I flowered a very time consuming strain. They were on 18/6 for 2 weeks, and then went to 12/12 right along with my normal strain. They took longer to finish, greatly reduced yield, and really didn't seem as potent. So not having them on a longer light schedule definitely has negative results as far as auto's are concerned. That has been my experience at least.

 

[BBFan]

Hey Mike-

Good to see you. In my opinion you still win the best pumpkin contest- I never knew your avi was a pumpkin. Very cool indeed. Have you done anything new for this year?

I've never done autos, so I can't comment on that.

The statistic Hick quoted is from RC Clarke's "Marijuana Botany". In the text, Clarke cites the source. If you'd like to read more about it, I'll dig up the link for you.

The important thing to remember about flowering is not so much the hours of light, but rather the hours of dark. The issue about additional light seems to get hung up on the circadian rhythm, the cycle that affects most living things based on a 24 hour day. Can you tweak it? I don't know- I haven't been able to find any studies on it, particularly as it relates to mj. But I think the maintenance of dark is what is crucial as it relates to the creation of florigens. Too much light though, would destroy the florigens, so you're probably only talking a few additional hours at most while maintaing the 12 hours of darkness.

Be very interesting to see if a few extra hours of light (which would create a crazy schedule- based perhaps on a 26 hour day) would make any difference. I for one would be very interested in your results were you to attempt it.

 

[cadlakmike1]

:bump: Just wanted to bump this up and hopefully get some more input on my original post. There have to be some users on this site that have experimented!!!

Hey Mike-

Good to see you. In my opinion you still win the best pumpkin contest- I never knew your avi was a pumpkin. Very cool indeed. Have you done anything new for this year?

Thank you for the kind words, and yes, I just posted some new pics in that same thread.

Be very interesting to see if a few extra hours of light (which would create a crazy schedule- based perhaps on a 26 hour day) would make any difference. I for one would be very interested in your results were you to attempt it.

That would be interesting, if I had the room to run several grows simultaneously I would definitely try more experiments, but only having the space to run one room I keep it fairly traditional and conservative. I know what works and just repeat it over and over again, growing just enough to hold me over to my next grow. Maybe on my next grow, I'll bump up my quantity to grow enough to last me a while and then try a run doing some experiments. It's just been years since I actually bought a bag of pot, and I'd hate to ruin a grow and then run out and have to buy a bag. I had quit smoking for a while a few months ago, and I shut down my grows till I started back up. I wish I had used that time to try different things.

 

[cadlakmike1]

My only thought on this is how would you tell if it does increase THC? Do you have the equipment to test the level of THC in bud? This just seems like an experiment that would end in an opinion instead of a fact...

I agree, and no I do not have the ability to do a gas chromotography test. I guess I could try that Cannalyse, but I'm not sure how accurate those are, or if they are even still around. I remember reading about them back in '06, but I haven't seen anything on them in a long time. Even though I do not have the equiptment to run these tests, I'm also wondering if these tests have already been conducted by any greenhouses that do have access to gas chromotography.

Some things could be reliably tested at home though, such as overall yield. If you ran ten clones in a controlled enviroment, and ten in a variable enviroment, you could accuratly compare the average of the yields. And also, while it would just be opinion, you could compare overall quality. If you took ten smokers on seperate occasions, and had them each try bud from both grows, but never told them which grow the bud was from, if they all consistently said one bud was better than the other it would be fairly definitive that it had more of something(probably thc).

It would be interesting though to be actually able to compare thc, thcv, cbg, cbc, cbd and cbn from lots of grows, not just this experiment! I would love to be able to put those numbers on my grows and be able to compare it other people's, just for bragging rights. Sort of like trying to grow the biggest tomatoes every summer to talk trash on your friends gardens!

 

[smokingjoe]

hXXp://www.onlinecannabisseeds.com/cannalyse-cannabis-fingerprint-test-p-180.html?osCsid=pfrhgrxhisrikj]There you go cadlakmike1

Jeez it's pricey!

 

[cadlakmike1]

]There you go cadlakmike1[/URL]

Jeez it's pricey!

Thanks man, guess it does still exist. I remember reading about that exact thing a few years ago. That price is really not that bad considering what it does, assuming it's not a one time use!!! I would like to see the results of it compared to a gas chromotography test though, I would hate to buy it just to find out it is innacurate. Assuming it is accurate, now if you were to do some tests with lighting schedules, you could test it and verify the results without having to worry about opinions.

If anyone wants to check it out and was worried about clicking a link here it is in full length, just change the xx to tt.

hxxp://www.onlinecannabisseeds.com/cannalyse-cannabis-fingerprint-test-p-180.html?osCsid=pfrhgrxhisrikj

edit: After reading that I started doing some research and found it at a few other places too. It says it contains enough for 12 tests, so a little over $13 a test. That's really not that bad, especially when you consider how valuable the information could be when researching different grow techniques.

It's $162 here-->hXXp://www.paradox.co.uk/acatalog/Cannalyse-Fingerprint-THC-Test-Kit.html

 

[BBFan]

My only thought on this is how would you tell if it does increase THC? Do you have the equipment to test the level of THC in bud? This just seems like an experiment that would end in an opinion instead of a fact...

You raise a very good point Mindzeye. Great thread CadalakMike.

However, IMHO (and it is only my opinion) I believe that the impact of photoperiod manipulation would have more of an effect on yield and little to no effect on potency. IMHO a strain is genetically predisposed, under optimal conditions, to produce a specific amount of thc and there is nothing we can do through normal or modified growing techniques (I am not discussing breeding here) that will result in a higher percentage of thc content in the end product. Our goal as growers is always attempting to provide those optimal conditions.

The original research referenced by Clarke in Marijuana Botany suggests thc production is greater under a 12 hour light period versus a 10 hour light period in a specific strain and was not verified across multiple strains and genetics. The mitigating factor here though is still the reliance upon a 24 hour day. And again, it is not suggested in the research that any more thc was produced than the strain was genetically capable of producing.

Ultimately though, in the final analysis, the end result is the increase of maturation time, increased production costs per gram, and the inherent risks brought on by increased stress. Is it worth it? Would an increased veg cycle produce better results? Perhaps.

Indoor growing has been going on for many years now and I know there are many growers out there smarter than us (no offense intended to anyone) who have thought through and possibly even attempted these experiments in an effort to improve / increase final results. If any of it worked to a noticeable degree, we most likely would have heard about it by now.

Happy Growing and Thanks for letting me share my view.

 

[umbra]

Wow guys there is some thoughtful insight here. Good posting Mike. BB you are sooo on target. Big problem with a lot of questions like this have not been researched, or at least the test results never repeated and verified. I did a couple of autos. Diesel ryder and a sour bubble ryder. I used 20/4 lighting schedule. I felt that this was about optimal for those plants. IMO, I really think that genetics really takes a big part of that equation. We already know that(in terms of pure strains) that equatorial sativas take longer flowering times, and indica shorter. With all the various hybrids, it is impossible to know how every strain will react to changes in the dark period. The biggest risk here to doing this research is that at some point between a dark period that induces flowering, and one that continues to maintain veggin', is a dark period that stresses the plant. This stress could very well induce hermi's. In terms of what is a dominant trait and a recessive trait is hard to ascertain with cannabis without mapping genes. The possibilities are endless. Maybe someday we will get to the point that the pack seeds will say something like....10 hrs darkness, 800-1000 ppm, ph 6.1.

 

[BBFan]

Hey Umbra and all-

Good points Umbra- I've never done autos- actually never even researched them so I don't even know how they do what they do.

Frankly though, I've never been overly impressed with auto grows I've seen in journals here- no disrespect intended in regards to growing skills, but rather the end result even from experienced and talented growers like you, Umbra, or HippyinEngland and many others have not wowed me- but I guess they serve their purpose. Perhaps I need a bit of education.

I think if anything though, irrespective of day light length manipulation, the constant would need to be 12 hours of darkness for the proper influence on florigens.

So that would bring us to the manipulation of the Circadian Cycle: That may be something worth investigating- and one I can't find any data on. Certainly over a long term it may have an effect at the genetic level, but I would imagine that on a grow by grow basis, the effects wouldn't be too dramatic as far as quality goes- and that perhaps quantity may be improved marginally or who knows, perhaps exponentially. It would however be a real pita to manage a 26 or 27 hour day as we all are so chained to a 24 hour day.

 

[umbra]

Hey Umbra and all-

Good points Umbra- I've never done autos- actually never even researched them so I don't even know how they do what they do.

Frankly though, I've never been overly impressed with auto grows I've seen in journals here- no disrespect intended in regards to growing skills, but rather the end result even from experienced and talented growers like you, Umbra, or HippyinEngland and many others have not wowed me- but I guess they serve their purpose. Perhaps I need a bit of education.

I think if anything though, irrespective of day light length manipulation, the constant would need to be 12 hours of darkness for the proper influence on florigens.

So that would bring us to the manipulation of the Circadian Cycle: That may be something worth investigating- and one I can't find any data on. Certainly over a long term it may have an effect at the genetic level, but I would imagine that on a grow by grow basis, the effects wouldn't be too dramatic as far as quality goes- and that perhaps quantity may be improved marginally or who knows, perhaps exponentially. It would however be a real pita to manage a 26 or 27 hour day as we all are so chained to a 24 hour day.

There is a reason I don't grow them anymore. For me, it didn't meet my expectation in regards to uniformity, quality, or quanity. I'm not trying to slam auto's either. Just not my cup of tea. If you look at how much we have learned about cannabis in the last 20 years. Just scratching the surface in my mind.

 

[IRISH]

ok mike. before i read what other posters say, so it don't influence my answer, i'll say, why would you want to extend what we've figured to be optimal lighting hours, over the past 20 years? this is already a proven fact, time , and again...

if you've got the crucial space, go for it. i can't afford to lose ANY bud, on any grow myself. besides, i would think you would be standing in a vast sea of hermies' by trying to pro-create a time line. jmo...

remember the days of the phototron?... ...