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18 VS 24 Hours Of Light Veg Cycle

I DID NOT WRITE THIS AND KNOW PRETTY BASIC KNOWLEDGE OF LIGHTING. DO YOU AGREE WITH THIS?


"""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, without 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.

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.

Another factor to consider, your bulb life will be shorter the more you turn it on and off.

Don't confuse internode stretching in the dark cycle with plant growth.
Under 18/6 you may get a taller plant, but the end weight is less than a plant grown under 24 hours of light.
At 18/6 you will save some money on electricity,
but like i said before, 24 hour light means 24 hour growth
as long as the plants other needs are met.

24/0 will always show faster growth
as long as you are providing for the plants other needs.
Marijuana does not need rest.
It does not get tired from to many hours of light.
its keeps on photosynthesizing at the same rate through the entire light cycle.

Although more hours of light does mean higher temp. issues.
I think some people have better luck with 18 hours because of the drop in temps it provides the plants, especially to the root-zone.

Water, CO2 and nutrient requirements are increased under 24/0 .

The daily voltage spike at startup contributes a large portion of the wear on a lighting system.

One week before flowering you can reduce the photo-period to 18/6 to reduce the stress on the plants.
Normally, under ideal conditions you can flower plant about a week earlier when grown under 24/0."""
 

NOKUY

Active member
Veteran
24/0 and 12/12 for me works best


prolly need to debate this in the growers forum tho...this is the den, and we have our hands full w/ kids who have parents squashing seedlings...lol
 
G

Greyskull

DO YOU AGREE WITH THIS?


"""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, without 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.

...

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.

Another factor to consider, your bulb life will be shorter the more you turn it on and off.

Don't confuse internode stretching in the dark cycle with plant growth.
Under 18/6 you may get a taller plant, but the end weight is less than a plant grown under 24 hours of light.
At 18/6 you will save some money on electricity,
but like i said before, 24 hour light means 24 hour growth
as long as the plants other needs are met.

24/0 will always show faster growth
as long as you are providing for the plants other needs.
Marijuana does not need rest.
It does not get tired from to many hours of light.
its keeps on photosynthesizing at the same rate through the entire light cycle.

Although more hours of light does mean higher temp. issues.
I think some people have better luck with 18 hours because of the drop in temps it provides the plants, especially to the root-zone.

The daily voltage spike at startup contributes a large portion of the wear on a lighting system.

Normally, under ideal conditions you can flower plant about a week earlier when grown under 24/0."""


yes i agree.


ha ha squashing seedlings ha ha
 

Sheriff Bart

Deputy Spade
Veteran
c3 plant
ribulose biphosphate (RuBP) is used to bind co2, then it breaks up into two 3-carbon moleules
hence the 'c3'

c4
the plants have overcome a difficulty faces by the c3 plants, photorespiration
RuBP can bind oxygen as well as co2 though, and when this happens its not only produces something slightly toxic to the plant (glycolate) but it takes even more energy to get back to where RuBP can bind co2 again
when plants evolved long ago, there was little oxygen in the air, so RuBP was evolved in high co2, low o2 environment so it didnt care so much about o2, as photorespiration didnt matter so much in the environemnt
nowadays, the dry hot climates have forced the plants to become more effcient in how they photosynthesize

in a c4 plant, photosynthesis occurs but co2 is instead fixed into a 4-carbon acid which is transported to the bundle sheath cells, co2 is frees form the 4-carbon acid and then RuBP binds
this allows the plant to create an oxygen deprived high co2 environement so that binding of Co2 to RuBP is more effeicient
however its only more effeient in high light, low water ocnditions,

CAM plants are like c4 plants, in that they make a 4-carbon acid (malic acid) and store it, but they do that at night and then free the co2 during the day to photosynthesis. they seperate the dark and light reactions by time, rather than by space in c4 plants
 

MrBaker

Member
^ Good explanation on C3 C4 and CAM plants

Other thoughts on 24/0: Plants have circadian rhythm for a reason, and I'm not sure if taking away that rhythm is the best thing for every cannabis plant. Although the "dark reactions" are really more "light independent reactions" I still have an inkling that plants have evolved to somehow use their night time.

Or maybe my gut feeling is wrong, and cannabis doesn't do anything at night time. Need more research.
 
C

cyberwax

from experience and with little techical preaching, plants seem to grow better at 24/0, roots might be longer/bigger at 18/4, if you need to save power 18/4 will do just fine.
 
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