No such thing as dark reactions...

Nitz456

Nitz456

Member
I hear a lot of people here saying that plants need some sort of 'no-light-period' in there cycle in order for the "dark reactions" to take place.

From what I understand from past botany classes, the accepted terms for light and dark reactions are now light dependent and light independent reactions, as the names light and dark reactions were misleading.

Light dependent reactions are reactions pertaining to photosynthesis that take place only when light is present.

Light independent reactions are reactions pertaining to photosynthesis that take place regardless of whether or not light is there.

So basically, what this says is that photosynthesis takes place in its entirety even when the plants are constantly being illuminated.

Would this mean that a 24 hour light / 0 hour dark schedule during veg would be optimal for plant growth? Is people claiming to need dark for "dark reactions" just old habits? Or am I mistaken?
 
I

Illegal Smile

Guest
Dark is needed for flowering but certainly not for veg. whther 24/7 light can be improved upon for veg is debatable. I tend to agree with you and see no reason why darkness would benefit a plant in veg.
 
Supgee3

Supgee3

Well-Known Member
I think the 18/6 promotes faster growth because during the 6 hour dark period your plant will stretch bigger to find more light whereas in 24/7 light it can't.
 
I

Illegal Smile

Guest
Supgee3 said:
I think the 18/6 promotes faster growth because during the 6 hour dark period your plant will stretch bigger to find more light whereas in 24/7 light it can't.
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Perhaps. I just don't know if that kind of stretching translates into productivity or just makes plants lankier.
 
stinkbudd1

stinkbudd1

Well-Known Member
i thought a plant had to have some sort of light or lights to reach out to in order to seek get closer to the light if they are in total darkness what are they reaching for? when your plants streatch for light you notice that it grows in the dirrection of the light.just my opinion..peace pot prosperity
 
AirAnt

AirAnt

Well-Known Member
You are mistaken. Firstly the "dark reactions" and "light independent" terms are merely arguing the difference in semantics between the laymans terminology and the scientifically correct terminology. Secondly, a plant grows more effectively during dark periods. The reason for this is that during light dependent periods a plant is both storing and using energy, during light independent periods a plant merely has to use the energy it has already stored, and is able to do so more effectively because it is not multi-tasking.
 
racerboy71

racerboy71

bud bootlegger
i just goggled this and found an article by ed rosenthal in cannabis culture magazine... he was saying that marijuana is classified as a c3 plant and continues to photosynthesis aslong as it recieves light.. c4 class of plants will only photosynthesis when lights are present.. he went on to say that marijuana that recieves 24/7 hours of light compared to marijuana that only recieves 18 hours of light will grow 33% faster..
now, i always thought that it was better to have an off period for growing marijuana, but after reading ed's article, i take it i was completely wrong.. learn something new everyday huh...
 
J

Jeremy.

Member
Yeah i wouldnt even do the 6 hours off in veg for the fact i have a very tight grow space and i cant afford the plant stretching!
 
Nitz456

Nitz456

Member



I just goggled this and found an article by ed rosenthal in cannabis culture magazine... he was saying that marijuana is classified as a c3 plant and continues to photosynthesis aslong as it recieves light.. c4 class of plants will only photosynthesis when lights are present.. he went on to say that marijuana that recieves 24/7 hours of light compared to marijuana that only recieves 18 hours of light will grow 33% faster..
now, i always thought that it was better to have an off period for growing marijuana, but after reading ed's article, i take it i was completely wrong.. learn something new everyday huh...
Click to expand...
Thanks for some supporting evidence!
 
CaptainDastardly

CaptainDastardly

Member
I was curious a while back when i saw so many people suggesting to at least do 4 hours of darkness...yet, I wasn't convinced, so I started an experiment. On this particular grow I have been doing 2 days where I go 24/0, then on the third day I do 20/4, then cycle the whole thing back around...so basically every 3 days it gets 4 hours of darkness.
So far things are going quite well (Other than a little mishap after moving them to a larger area and having some of my wallboard fall on top of them for a few hours), with the plants standing an average of 8-9" tall and possessing roughly the same number of branch "tiers". (lower branches have 3-4 branch sets each). It started as a CFL grow (~380W), switching over to MH (400W) when I moved them to the larger area. (Oddly enough I think they were growing better with the CFLs but there are a few possible reasons for that)

::shrug:: Anyway...just pointing out that you can do some seemingly odd light patterns, and as long as you don't drop down to 12 or something less, then you shouldn't hit flower (other than the rare oddity we sometimes see in the forums, or perhaps autoflower strains). Stretching has never been an issue with these plants. In fact, I've had to intentionally make them stretch a couple of times because they were getting too bushy too fast, for their proximity to one another.

NOTE: Since they haven't finished, I am only speculating on Veg at this point...for all I know such a pattern may have done something that will cripple flowering. I doubt it...but you never know.
 
I

Illegal Smile

Guest
CaptainDastardly said:
I was curious a while back when i saw so many people suggesting to at least do 4 hours of darkness...yet, I wasn't convinced, so I started an experiment. On this particular grow I have been doing 2 days where I go 24/0, then on the third day I do 20/4, then cycle the whole thing back around...so basically every 3 days it gets 4 hours of darkness.
So far things are going quite well (Other than a little mishap after moving them to a larger area and having some of my wallboard fall on top of them for a few hours), with the plants standing an average of 8-9" tall and possessing roughly the same number of branch "tiers". (lower branches have 3-4 branch sets each). It started as a CFL grow (~380W), switching over to MH (400W) when I moved them to the larger area. (Oddly enough I think they were growing better with the CFLs but there are a few possible reasons for that)

::shrug:: Anyway...just pointing out that you can do some seemingly odd light patterns, and as long as you don't drop down to 12 or something less, then you shouldn't hit flower (other than the rare oddity we sometimes see in the forums, or perhaps autoflower strains). Stretching has never been an issue with these plants. In fact, I've had to intentionally make them stretch a couple of times because they were getting too bushy too fast, for their proximity to one another.

NOTE: Since they haven't finished, I am only speculating on Veg at this point...for all I know such a pattern may have done something that will cripple flowering. I doubt it...but you never know.
Click to expand...
I'm not sure that's a good idea. I think whatever schedule you use should be consistent. I have never done anything but 24/7 so have no comparison to offer. But if they needed dark to grow then they wouldn't grow at all under 24/7, and they do!
 
littlewing

littlewing

Active Member
mmmm....very interesting thread, i also was under the impression dark hrs were impotant for the plant, i also do 6 hrs dark and tended to agree with airant on the multi tasking theory,
but nw interested in reading the article by ed rosenthal, posted by racerboy.
i would tennd to agree with illegal smile on the consistancy thing but nothing wrong with abit of experimentation.
 
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