Why go 24 hours lights on??

[U~know~who]

Truth is in the gardens, not in the books.

 

[spurr]

So you're saying that vegging plants on 24h are constantly photosynthesizing?

Nope, plant rate of photosynthesis is reduced after about the 17th-18th hour of non-stop light. At that point much of the active rubisco has been converted into inactive rubisco, which means the plants can't keep up high rate of photosynthesis, because rubisco activase is less able to 'do it's job' under 24/0. Also under 24/0 C assimilate/partitioning goes down past the 17th-18th hours, as well as Co2 fixation, etc.

You described it well when you wrote about how plants need to 'switch' modes (excuse my simple description) to carry out light independent reactions such as starch conversion, cellular repair, etc., if light is provided 24/0. Plants simply can't use light to photosynthesize and carry out other needed reactions simultaneously, and keep up a high rate of photosynthesis.

Below is a good read you will like (if you haven't read it yet), it's about rubisco activase. So-called rubisco activase is what converts inactive rubisco into active rubisco so plants can photosynthesize (re: plants need active rubisco for photosynthesis). After 17-18 hours of non-stop light active rubisco gets mostly converted into inactive rubisco, and if no dark period is given, rubisco activase is less efficient and effective in converting inactive rubisco back into active rubisco.

This topic is also why using Co2 over ~1,200 ppm is bad, as well as temps over ~89'F. In both instances the amount of rubisco activase is reduced, thus the plant is less able to convert inactive rubisco into active rubisco. That means the rate of photosynthesis goes way down and the plant suffers (just like if using 24/0 of light). I have a few studies on cananbis that looked at ideal level of Co2, along with PPFD and temp, all found Co2 saturation at ~> 1,000 ppm, just like most other C3 plants. Thus using more than 1,000 ppm is a waste, and using more than 1,200 ppm can/does hinder rate of photosynthesis due to reduction of rubisco activase. That is another area of BS in the cannabis world, i.e. claims that 1,500 ppm of Co2 is ideal (that has never been proven, it's only more conjecture and anecdotal evidence from 'first hand experience' so loved by some in this thread). Check out this thread for more info I wrote on that topic: "A simple question for growers that use CO2"

"Robust Plants' Secret? Rubisco Activase!"
Steven J. Crafts-Brander and Micheal E. Salvucci
Agricultural Research Magazine, Nov. 2002, Vol. 50, No. 11
http://www.ars.usda.gov/is/ar/archive/nov02/plant1102.htm
​

So to go where your going, I would need to have X[watts] for 24hr lighting and Y[watts] for 18h lighting. With Y>X.

Yes, but that doesn't really tell about the photons hitting the plant. That is why using a quantum sensor is better. Or at least using a lux meter to make sure the lux is the same between X and Y.

So they each get the same, roughly, amount of photons over the two week period.

Yup!

I still think my experiment is of use, due to the abilities of the plants observed in flower following 24h compared to those of the plants with 18h (in terms of just changing light hours, nothing else),

Me too.

but I see what you're saying and it is the more proper method. Thanks for the insight, I'm going to draw up another experiment with that adjustment. Probably will have to use all CFL's to get an accurate supplement for 18h. hmm...

Cool, keep us in the loop!

Ok I see what you're saying now too. I got too concerned about isolating variables to realize what I was overlooking.

Happens to the best of us, I learn something new each day.

 

[spurr]

Spurr, from what I can tell, you've read lotsa scholarly journals and have tried to attempt to "connect the dots" from different studies and draw conclusions from that - insofar as I can tell (please, correct me if I'm wrong), you have not linked to one study yet where the variable tested was hours of light per day on marijuana plants in vegging - again, please correct me if I'm wrong here.

Nope, you're not wrong, I wrote that already. And that I plan to study that very topic, but, I am not merely connecting dots where there is not direct, and proven, very large body of science. I.e. light independent reactions that use night periods, as I, and many others have listed many times, like circadian rhythm, calvin cycle, starch conversion, etc.

I realize you've linked to similar papers regarding plants that are similar in many ways to weed, but have yet to do so with weed -

Only because I haven't uploaded them, as I wrote many times, there are many studies that studied cannabis with PPFD, Co2, temps, etc., for rates of photosynthesis, Co2 fixation, yield, etc.

therefore, any conclusions that you claim to draw ARE WHOLLY DEPENDENT ON THE ASSUMPTION THAT WHATEVER PLANT WAS STUDIED IN THAT PARTICULAR STUDY IS IDENTICAL IN EVERY WAY TO WEED, which I find to be a "stretch" at best.

Please don't YELL!

As I have written many times, there are many studies on cannabis. If some of you want to read them so badly, then look them up, it's not hard. I tend to slack on uploading files because I know very few people bother reading them, so I feel little need to upload them. Hell, most people dont' even read the studies I have already posted and provided links for, some people see it as badge of honor to not read studies, lol.

If people really wish to read said studies they would find them themselves, or ask me to upload them, which has yet to happen

There is no "stretch" taking place, all studies on cananbis and irradiance came to the same conclusion, that ~1,500 PPFD is ideal. Other studies on C3 plants, that are wholly applicable to cannabis, esp. studies on "model organism", all come to the same conclusion: that C3 plants benefit from dark period. That is irrefutable and it's complete valid to use them to state cannabis benefits from a dark period.

I dont' understand why people think cannabis is some magical plant that operates on a different set of rules than other C3 plants in terms of a dark period...that is just ignorant to think so.

The scary part here is that you have had no formal academic studies, nor have had a mentor to oversee your work and let you know what correlations/conclusions are relevant to plant biology and which are simply spurious (no pun intended).

I have no need for a formal academic degree, there is no need for one in plant biology is a person is willing and able to do the work on their own. Stop trying to pretend someone needs a fancy title to know what they are talking about.

FWIW, I am getting a Masters in plant physiology, but I'm in no hurry. And I do have contacts in the world of academia whom I work with, and correspondent with, and have plans to work with on a peer basis in the future.

Also, for all my claims I have provided full references, or at least told you were to find them, thus, it's on you to read them and decide if I am relating the info held within them correctly, or not. That is how it works. When you read a study, if you feel the authors didn't correctly portray the info from their references, you read the references to make your own determination. Let me ask you: have you bothered to read any of my references to see if I am full of hot air, or not? (yea, I didn't think so, from what you have told me thus far [re: my "boring" references]...thus you have no grounds to complain, I am being 100% transparent and you are being disingenuous.)

From this, you have FORMED AN OPINION OF WHAT YOU THINK.

Please stop YELLING. I have not formed an opinion of what I think, I formed my opinion based on the same things a person with an advanced degree uses to form their opinions. I study the same books as they do. Have you not seen "Good Will Hunting"? That is pretty much what I do, I have full access to a great University (where I currently attend as an undergrad even tho I'm older than everyone else in my classes at 33 yrs old) and all their professors, libraries, etc., even though I dont' have a Masters (yet).

Admittedly, you lack the required capital (although you seem to be saving up) for the equipment necessary to test your hypothesis, so unless I'm missing something, I FAIL TO SEE HOW YOU CAN POSSIBLY MAKE THE CLAIMS YOU MAKE WITH ANY DEGREE OF SERIOUSNESS.

Please stop YELLING. True, I lack the funds to get the tools I want, however, I have (nearly) full access to said tools at the University, but, they would never let me us them to study cananbis, thus I need to buy my own. And I am not "saving up", I hope to back full financial backing soon (fingers crossed).

If you fail to see the logic and sound, proven science I am delivering, then it's your fault, and loss...

If you continue to want to espouse these beliefs, please, please, please make sure that everyone knows THAT IT IS YOUR OPINION BASED ON YOUR KNOWLEDGE, AND HAS YET TO BE TESTED OR VERIFIED.

Please stop YELLING.

Everything I have written about, has been tested and verified and proven for ages, <face palm>.


I think I need to take some other Icers opinion and just ignore you, and your ilk like DH, and others from now on...just like I do with a few members already.

 

[Dave Coulier]

Spurr, please do upload the studies on Cannabis you have. Its guaranteed that I will read them.

 

[spurr]

Spurr, please do upload the studies on Cannabis you have. Its guaranteed that I will read them.

Hey bro,

I know you will, I will do so tomorrow, I promise

 

[mrpotatohead]

I do it in the winter time because it's cheaper to run 1800 watts of light than run the heat in my veg room.

 

[spurr]

@ Anyone interested,

Here are a few of the papers I have on PPFD, also info about UV-b and Co2 and temp and stomatal conductance, etc. I will upload others tomorrow...

All papers show ideal PPFD is ~1,500.


1. "Effect of light intensity on photosynthetic characteristics of four high THC yielding varieties of cannabis sativa"

2. "Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions"

3. "UV-B RADIATION EFFECTS ON PHOTOSYNTHESIS, GROWTH AND CANNABINOID PRODUCTION OF TWO Cannabis sativa CHEMOTYPE"

4. "Thidiazuron-induced high-frequency direct shoot organogenesis of Cannabis sativa L."

 

[Dave Coulier]

@ Anyone interested,

Here is a few of the papers I have on PPFD, also info about UV-b and Co2 and temp and stomatal conductance, etc. I will upload others tomorrow...

All papers show ideal PPFD is ~1,500.


1. "Effect of light intensity on photosynthetic characteristics of four high THC yielding varieties of cannabis sativa"

2. "Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions"

3. "UV-B RADIATION EFFECTS ON PHOTOSYNTHESIS, GROWTH AND CANNABINOID PRODUCTION OF TWO Cannabis sativa CHEMOTYPE"

4. "Thidiazuron-induced high-frequency direct shoot organogenesis of Cannabis sativa L."

Thanks for the links. For those who do not want to read the full articles, at least read the abstracts.

 

[spurr]

No prob. bro, and I agree, "at least read the abstracts".

 

[Rumpleforeskin]

Any views on this subject that are not the same as the admins are being deleted or edited. No way to have dialog or learn. I may be wrong, but I see no reason to silence me as long as I am being polite and staying within the guidlines of this forum.

The term uncool comes to mind.

 

[jeffie]

Rumpleforeskin sure it works but next time try 18/6 I am sure you'll save on electricity (unless u got other factors like heating or smthn) and get the same or even better results. Not to mention plants will kick into bloom soon after switch to 12/12. I've also found in general clones root faster with some dark hours. But u know, if u don't care for hydrobills and all that global warming cooling and no relays around then sure its fine.

i got way with words. come on, let me see... not sure there's enough food in my kitchen to kill the munchies... perhaps i should go read some credibol scientifocal papers on how much is enough.. oh wait.. i have a better way of finding out, an old fashioned one

 

[VerdantGreen]

nice looking plants rumple, i also have a gallery full of nice looking plants - that were vegged at 18/6. im sure my final yields would compare favorably with anyones

.....
I realize you've linked to similar papers regarding plants that are similar in many ways to weed, but have yet to do so with weed - therefore, any conclusions that you claim to draw ARE WHOLLY DEPENDENT ON THE ASSUMPTION THAT WHATEVER PLANT WAS STUDIED IN THAT PARTICULAR STUDY IS IDENTICAL IN EVERY WAY TO WEED, which I find to be a "stretch" at best.

The scary part here is that you have had no formal academic studies, nor have had a mentor to oversee your work and let you know what correlations/conclusions are relevant to plant biology and which are simply spurious (no pun intended).
.....

Bob, i dont know how much botany you have studied - you might like to check out the new forum - i myself am by no means an expert, but the fact is that C3 plants, (the grouping covers most plants, over 90%) may all look very different, once you get inside the leaf and look at the basic functions such as photosynthesis, they are all pretty much identical. think about it. the earth has a day and night - why would plants have evolved to not make use of both light and dark to perform various functions. there would be no evolutionary advantage to a plant that couldnt perform some of it's functions efficiently during the dark.
and before you cite polar day/night as an exception, you have to realise that light levels are very low during this 3 month long day period.

if the scientific word can agree upon this categorization then it seems churlish that weed growers think their plant is somehow unique in it's basic internal functions

and to suggest that someone cant be an expert on something without formal qualifications is ludicrous. information is available to everyone these days. all you need to do is put in the hours and study - something that many people cant be bothered to do. when someone who has clearly dedicated themselves to learning as much as they can comes here and shares information, then that is something we should all be grateful for.

VG

 

[Silence]

Re: C3 plants

I keep seeing it mentioned that cannabis is classed as a C3 is this just based on the fact Ed said so?

http://www.cannabisculture.com/v2/articles/3127.html

I have it as a C4 type myself?

Kopite

Ps: Gojo hows the book coming along?

 

[DHF]

You know Gojo.......You don`t haveta ignore me , cuz I`ve been over your attempt at shovin academic drivel down folk`s throat before you got banned here AND the Cabana .......

Now you`re back and still shovin.......For the record , I deleted the part about text meaning very little compared to "Hands-on" knowledge and experience when growin dope , tryin ta be more amicable , but you snatched it and twisted everything while still shovin shit down folks throats that as a whole mostly don`t have a fukin clue what you`re sayin........all for the purpose of discrediting me and my opinion on yrs and yrs of doing this instead of talking about it......

I`ll not bother to post again on a subject that`s been debated as long as I`ve been on weedsites back when they first popped up on the internet back in late `94.........

And guess what.......18/6 is what works best......guaranteed.....from many many expert and well versed "hands-on" growers that`ve done all the test trials you speak of yrs ago..........

Now , carry on with your experiments and research while posting outrageous amounts of shit most folks don`t care to read or understand as it seems to consume you more than the actual growing of said dope.......

I`m sure there`s SOMEBODY here that`ll glean SOMETHIN from your verbal diahrrea.....I`ve seen a few here actually interested...very few......

My apologies again.....Call em like I see em...Now back to your waste of bandwidth.....film at 11.......

Peace....DHF...........

 

[h.h.]

I find 6 hours of darkness every 3rd day seems to be enough. They seem to trigger quicker after the light is cut back when they are use to the long days. They also need less hours of dark to flower. I can set them outside in late spring when the days are a bit longer than 12 hours and get good bud. At least with the strain I have.

 

[qdavid]

One good way to trigger hermies is to vary the light schedule with most strains.

 

[Silence]

Kopite, ive never seen Cannabis classified as c4 - what makes you say that?

VG

I'm fairly sure i have read it, but would have to dig the info out...

 

[spurr]

It's simply.

It's called a typo , I tend to make them from time to time because I type fast and tend to type a lot. I try to check my spelling and grammar, but sometimes things slip through. I really couldn't care less, considering this is an Internet forum and that you knew what I meant. I also tend to write "your" when I mean "you're", and "dont'" when I mean "don't", and even "teh" when I mean "the".

But please, continue pointing out typos, that is just what this thread needs, finally we have someone posting worthwhile info /sarcasm

Re: C3 plants

I keep seeing it mentioned that cannabis is classed as a C3 is this just based on the fact Ed said so?

http://www.cannabisculture.com/v2/articles/3127.html

I have it as a C4 type myself?

FWIW, yes, cannabis is a C3 plant due to how cannabis fixes Co2 - carbon (re: RuBP). Cannabis is not a C4 plant. No one should be citing Ed.R.

 

[spurr]

I'm fairly sure i have read it, but would have to dig the info out...

If you read that then your sources are wrong.

 

[Silence]

If you read that then your sauces are wrong.

HP is never wrong