18hrs Vs. 24hrs

billybob420

Well-Known Member
I took a plant biology in college and yes, plants do need darkness to grow.

The photosynthesis process itself, there is a reaction known as 'dark reaction' pathway or lately known as 'carbon reaction' pathway where the free energy of ATP and reducing power of NADPH, are used to fix and reduce CO2 to form carbohydrate. This is very important process to release Oxygen into the air. This happened in the dark or at night.
That's just not how it works with C3 plants.
 

igorskee

Well-Known Member
18/6 is just enough. Night is important. I noticed that when I grew on 24hrs constantly, the plants grew slower. When you try and compare then you talk. Im sick of heard-said-read.... Try and compare.
 

hyroot

Well-Known Member
I took a plant biology in college and yes, plants do need darkness to grow.

The photosynthesis process itself, there is a reaction known as 'dark reaction' pathway or lately known as 'carbon reaction' pathway where the free energy of ATP and reducing power of NADPH, are used to fix and reduce CO2 to form carbohydrate. This is very important process to release Oxygen into the air. This happened in the dark or at night.

you do know that when plants sleep they release co2 and take in oxygen and then when awake the opposite. that's when they wake the stomatas are open so much causing the leaves to point upwards. they just took in a fat breath of co2.

the respiration of co2 on the leaf surface actually improves in 24/0 and the only thing they do when asleep is break down fibers. they do that when awake too but at a slower rate.

so what you said contradicts what really happens. co2 also does not form carbs, sugars do that. co2 helps produce chlorophyll



http://ceaccp.oxfordjournals.org/content/9/1/19.full.pdf

http://aob.oxfordjournals.org/content/67/supp1/23.abstract

http://jxb.oxfordjournals.org/content/57/11/2687.full.pdf

http://pcp.oxfordjournals.org/content/40/10/999.full.pdf

http://jxb.oxfordjournals.org/content/54/392/2393.full.pdf

http://onlinelibrary.wiley.com/doi/10.1111/php.1987.46.issue-2/issuetoc

http://jxb.oxfordjournals.org/content/61/11/3107.full

http://www.uic.edu/classes/bios/bios100/lecturesf04am/lect10.htm

http://bioap.wikispaces.com/Ch10+Collaboration

http://books.google.com/books?id=wNnu7v9KjCkC&pg=PA15&lpg=PA15&dq=Cultivating+Exceptional+Cannabis&source=bl&ots=rSorVB2NC1&sig=CgINhRfTbamm9rjnW5KlCcP4zVk&hl=en&sa=X&ei=SVf1Tu6mA4eaiALK28T3Bw&ved=0CEsQ6AEwBTgK#v=onepage&q=Cultivating Exceptional Cannabis&f=false
 

hyroot

Well-Known Member
18/6 is just enough. Night is important. I noticed that when I grew on 24hrs constantly, the plants grew slower. When you try and compare then you talk. Im sick of heard-said-read.... Try and compare.
what medium were you growing in, what were you feeding them, how often were they watered, did you use any mycos,was there plenty of oxygen to the roots, what was the temp, any bugs? all these factors can slow growth or speed up growth.

it might not just be the lighting. i do 24/0 and mine grows way faster and more bushy with less stretching.
 

Cloudz2600

Well-Known Member
I've no idea why they called it dark reactions, but dark reactions do not have to take place in the dark! What hyroot said is true, more light=more respiration, more respiration=more photosynthesis, more photosynthesis =bigger plant
 

zuse grower

Member
Well from what I have heard and read, the advantage of 18 hours of light is the plants will show their sex sooner. The advantage of 24 hours is more growing time. I personally grow 24 hours of light and once I get near flowering I go to 18 hours so I can weed out the males.
But how does it weed them out? It seemed worse to me with the 24. I stick with the 16.
 

curiousuk

Active Member
my babies seem happy as hell with 18/6 lighting, then again mine are auto NLs an light times are not that important for them.
 

RawBudzski

Well-Known Member
Well I am back, to 18/6. I went from 18/6 to 24/0 and swore by that & it's worked Great for veg honestly.. it is issues I saw in bloom I was boggled.. so now I must say fk fem seeds and 24/0 lighting.
 

Cloudz2600

Well-Known Member
Wait wouldn't you go 12/12 for bloom anyway? Also, what's wrong with fem seeds? This is random, but I read the thread that you got your quote from Raw...hilarious doesn't even explain it lol.
 

igorskee

Well-Known Member
what medium were you growing in, what were you feeding them, how often were they watered, did you use any mycos,was there plenty of oxygen to the roots, what was the temp, any bugs? all these factors can slow growth or speed up growth.

it might not just be the lighting. i do 24/0 and mine grows way faster and more bushy with less stretching.
Ok. But I wouldnt talk here if all those condition werent applied. I grow for 11 yrs now. But people just get different results, could be because different strains react differently.
 

dvs1038

Well-Known Member
Lol stick with nature.. if humans had stuck with nature wouldnt be global warming
Ummmm well there r places in nature that get 24hrs of sunlight so 24/7 is still considered sticking with nature. And from what I've read regarding MJ and other plants I'm no horticulture major but it was sumptin about the different sugars that plants produce and whether or not a dark period is needed to properly produce that sugar, MJ uses a 4 part sugar that doesn't require a dark period to create it, where other plants that need to create the 6 part sugar need that dark period. Now don't rip me a new one I could be wrong about the 4 & 6 part sugars but I'm almost positive its sumptin like that I might have the numbers wrong.
 

Haydoon

Well-Known Member
if people had stuck with nature, there would no mass production of food, we would have been no more than 2billion tops inhabiting the earth, and we would probably still be with stones and sticks
..and we would all have broken bones but even then names never hurt us bongsmilie
 

hyroot

Well-Known Member
Robbed from another forum :P

Most green plants are classified as either C3 or C4 which represents how carbon(C) is used during photosynthesis.

C4 plants temporarily store carbon dioxide(CO2) over the dark period to use for photosynthesis during the day. C4 plants slow down photosynthesis once the stored CO2 is used up and they need to gather it from the air. Which is why trees slow down photosynthesis in the afternoon even though the sun is still bright. This does NOT apply to cannabis.

C3 plants(cannabis/veggies) gather CO2 only during the light period when they are photosynthesizing. During the dark period these plants only use oxygen for their metabolic life processes. They don't uptake CO2, nor do they use it. As soon and as long as the light is on, C3 plants gather and use CO2 for photosynthesis.

C3 plants also have the ability to use higher concentrations of CO2 than what is found in the air. If the light is bright enough and the plants have sufficient nutes, their growth rate will accelerate from it(2000ppm vs. 400ppm of CO2), which increases yield. They can do this continuously, wihtout a dark period throughout the vegetative stage.

The dark reaction is a process of photosynthesis that takes place in both darkness and light. It uses ATP and NADPH molecules that hold energy absorbed from light to break apart CO2 into it's base components. Because it's called a dark reaction and can occur in the dark, some people(Jorge) have said darkness is needed for this to occur. This Is Not So.

Again people get anthropomorphic with their plant needs. People need rest, so plants must too. This is false as well. Light means growth. Scientifically. Although 18/6 will shock your plants less when you switch to 12/12, it's a personal choice whether you would rather sacrifice a little growth for a quicker adjustment or less photo confusion. If you want to save money or energy that's a personal choice too. Do what you need to do to make your growing scenario work.
 

dvs1038

Well-Known Member
Ty Hyroot, I knew I was wrong about the numbers but I was kinda right. Ohh yeah and one more thing Hyroot, Do the Truffle SHuffle, Do it Now CHunk!!!!!! Do the Truffle Shuffle!!!!!
 

Glider

Member
Robbed from another forum :P

Most green plants are classified as either C3 or C4 which represents how carbon(C) is used during photosynthesis.

C4 plants temporarily store carbon dioxide(CO2) over the dark period to use for photosynthesis during the day. C4 plants slow down photosynthesis once the stored CO2 is used up and they need to gather it from the air. Which is why trees slow down photosynthesis in the afternoon even though the sun is still bright. This does NOT apply to cannabis.

C3 plants(cannabis/veggies) gather CO2 only during the light period when they are photosynthesizing. During the dark period these plants only use oxygen for their metabolic life processes. They don't uptake CO2, nor do they use it. As soon and as long as the light is on, C3 plants gather and use CO2 for photosynthesis.

C3 plants also have the ability to use higher concentrations of CO2 than what is found in the air. If the light is bright enough and the plants have sufficient nutes, their growth rate will accelerate from it(2000ppm vs. 400ppm of CO2), which increases yield. They can do this continuously, wihtout a dark period throughout the vegetative stage.

The dark reaction is a process of photosynthesis that takes place in both darkness and light. It uses ATP and NADPH molecules that hold energy absorbed from light to break apart CO2 into it's base components. Because it's called a dark reaction and can occur in the dark, some people(Jorge) have said darkness is needed for this to occur. This Is Not So.

Again people get anthropomorphic with their plant needs. People need rest, so plants must too. This is false as well. Light means growth. Scientifically. Although 18/6 will shock your plants less when you switch to 12/12, it's a personal choice whether you would rather sacrifice a little growth for a quicker adjustment or less photo confusion. If you want to save money or energy that's a personal choice too. Do what you need to do to make your growing scenario work.
Nice summary Hyroot. This also answers the question I was going to ask about "Does MJ need CO2 at night.". I am still wondering if they need as much CO2 during flowering. So it seems that using th accelerated 14/4 was a waste of time. I wonder if I should rethinking using the 6/12 cycle for flowering?
 
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