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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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18 vs 24 Hours of Light in the Vegative Cycle
#4843 - 04/21/08 10:40 AM (16 years, 8 months ago) |
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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.
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: ecto]
#4897 - 04/21/08 11:19 AM (16 years, 8 months ago) |
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I thought alot of people would have this question so I started a topic on this specific subject. So this way i wont need to make anymore posts on this subject. sound like a good idea?
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#8556 - 04/22/08 01:58 PM (16 years, 8 months ago) |
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Your thinking of light reaction not dark reaction.
In dark reactions, carbon is broken away from carbon dioxide and combined with hydrogen via the Calvin cycle to create carbohydrates.
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#8566 - 04/22/08 02:13 PM (16 years, 8 months ago) |
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yes it is.. carbon and oxygen from the Co2. The carbon then combines with hydrogen to form carbs, via the Calvin cycle.
Edited by erb (04/22/08 02:24 PM)
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#8620 - 04/22/08 03:10 PM (16 years, 8 months ago) |
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Your still talking about the light reaction not dark reaction.
Notice how it says "carbon is broken away from CO2"
photosynthesis The process by which green plants, algae, diatoms, and certain forms of bacteria make carbohydrates from carbon dioxide and water in the presence of chlorophyll, using energy captured from sunlight by chlorophyll, and releasing excess oxygen as a byproduct. In plants and algae, photosynthesis takes place in organelles called chloroplasts. Photosynthesis is usually viewed as a two-step process. First, in the light reactions, the energy-providing molecule ATP is synthesized using light energy absorbed by chlorophyll and accessory pigments such as carotenoids and phycobilins, and water is broken apart into oxygen and a hydrogen ion, with the electron of the hydrogen transferred to another energy molecule, NADPH. The ATP and NADPH molecules power the second part of photosynthesis by the transfer of electrons. In these light-independent or dark reactions, carbon is broken away from carbon dioxide and combined with hydrogen via the Calvin cycle to create carbohydrates. Some of the carbohydrates, the sugars, can then be transported around the organism for immediate use; others, the starches, can be stored for later use. Compare chemosynthesis. See Note at transpiration. A Closer Look Almost all life on Earth depends on food made by organisms that can perform photosynthesis, such as green plants, algae, and cyanobacteria. These organisms make carbohydrates from carbon dioxide and water using light energy from the Sun. They capture this energy with various pigments which absorb different wavelengths of light. The most important pigment, chlorophyll a, captures mainly blue and red light frequencies, but reflects green light. In plants, the other pigments are chlorophyll b and carotenoids. The carotenoids are usually masked by the green color of chlorophyll, but in temperate environments they can be seen as the bright reds and yellows of autumn after the chlorophyll in the leaves has broken down. The energy gathered by these pigments is passed to chlorophyll a. During the light reactions, the plant uses this energy to break water molecules into oxygen (O2), hydrogen ions, and electrons. The light reactions produce more oxygen than is needed for cellular respiration, so it is released as waste. All of the oxygen in the Earth's atmosphere today was produced as waste by photosynthetic organisms, especially cyanobacteria, which have been producing oxygen for some three billion years, since their first appearance in the Precambrian Eon. During the dark reactions, the plant uses hydrogen ions and the electrons to make carbon dioxide into carbohydrates. Within the leaf of a green plant, photosynthesis takes place in chlorophyll-containing chloroplasts in the column like cells of the palisade layer and in the cells of the spongy parenchyma. The cells obtain carbon dioxide from air that enters the leaf through holes called stomata, which also allow excess oxygen to escape. Water from the roots is brought to the leaf by the vascular tissues called xylem, while the carbohydrates made by the leaf are distributed to the rest of the plant by the vascular tissue called phloem.
dark reaction Any of the chemical reactions that take place during the second stage of photosynthesis and do not require light. During the dark reactions, energy released from ATP (created by the light reactions) drives the fixation of carbon from carbon dioxide in organic molecules. The Calvin cycle forms part of the dark reactions. As long as ATP is available, the dark reactions can occur in darkness or in light. Compare light reaction. See more at Calvin cyclephotosynthesis
Edited by erb (04/22/08 03:26 PM)
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: CaptainKirk]
#8654 - 04/22/08 03:30 PM (16 years, 8 months ago) |
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There is some good info from me in that first post, i wouldn't dismiss it as copy and paste jazz. 18 means less heat. As far as the ballast and bulb go, its better for the longevity if you don't turn them on and off alot.
Edited by erb (04/22/08 03:56 PM)
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#8911 - 04/22/08 05:57 PM (16 years, 8 months ago) |
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It's semantics.. You can say the c02 is reduced or the carbon is fixed to form carbohydrates, same difference.
Edited by erb (04/22/08 10:02 PM)
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#9343 - 04/22/08 08:39 PM (16 years, 8 months ago) |
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Sirius]
#45742 - 06/01/08 06:09 AM (16 years, 7 months ago) |
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Thanks! To bad its cluttered with a bunch of crap.
Edited by erb (06/01/08 06:46 AM)
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Harry_Ba11sach]
#47800 - 06/01/08 11:14 AM (16 years, 7 months ago) |
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Your dense..no i wasnt.
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: m3kgt]
#48747 - 06/02/08 09:06 AM (16 years, 6 months ago) |
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i copied some of it from my others posts under the same screenname (erb) at rollitup as well as from other posts i have made on the subject.I did not plagiarize anyone. some of the scientific info is not mine but gathered from other sources. the second part on photosynthesis is of course not mine.
My point was, its really saying the same thing in two different ways, semantics. I really wasnt trying to cause a big problem, just felt it was nitpicking. peace
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: RustyShaklford]
#127355 - 10/01/08 07:27 AM (16 years, 3 months ago) |
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Quote:
RustyShaklford said: The very first post in this thread was informative. . . As a newb, however, everything else might as well be said in some foreign language. I can't even remember 99% of the words used to describe,,,, something, without scrolling back up.
thank you!
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: t0ad]
#132661 - 10/15/08 09:35 AM (16 years, 2 months ago) |
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If anyone plans on doing a 18/6 - 24/0 comparison remember the other variables involved, heat and Co2.
There is no point in going 24/0 if your not supplying the the plant with enough Co2 and keeping your heat low enough to prevent stretching.
There are other variables that must be taken into account if you want to do a true scientific experiment.
Some people will see better growth with 18/6 for two simple reasons. One is less heat, two is the average Co2 level will be higher. if your not supplementing your Co2 or venting good enough, more hours of light wont make much of a difference, the rest of the plants needs must be met to take advantage the increase in light. This also includes an increase in water and nutrient needs.
Complicated scientific terms are great if they can be understand and utilized, but that is not the case here, it's unnecessary and causes unneeded confusion for the majority of people.
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: erb]
#132682 - 10/15/08 11:12 AM (16 years, 2 months ago) |
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For those that are interested in the scientific aspect, I found this explanation of the Calvin cycle helpful.
The Calvin Cycle:
ATP and NADPH produced by the light reactions are used in the Calvin cycle to reduce carbon dioxide to sugar. The Calvin cycle is similar to the Krebs cycle in that the starting material is regenerated by the end of the cycle. Carbon enters the Calvin cycle and leaves as sugar. ATP is the energy source, while NADPH is the reducing agent that adds high energy electrons to form sugar. The Calvin cycle actually produces a 3 carbon sugar glyceraldehyde 3-phosphate. The Calvin cycle may be divided into 3 steps. Step 1: Carbon Fixation. This phase begins when a carbon dioxide molecule is attached to a 5 carbon sugar, ribulose biphosphate (RuBP).
This reaction is catalyzed by the enzyme RuBP carboxylase (rubisco) one of the most abundant proteins on earth. The products of this reaction is an unstable 6 carbon compound that immediately splits into 2 molecules of 3-phosphoglycerate. For every 3 molecules of carbon dioxide that enter the cycle via rubisco, 3 RuBP molecules are carboxylated forming 6 molecules of 3-phosphoglycerate. Step 2: Reduction. This endergonic reduction phase is a 2 step process that couples ATP hydrolysis with the reduction of 3-phosphoglycerate to glyceraldehyde phosphate.
An enzyme phosphorylates ( adds a phosphate) 3-phosphoglycerate by transferring a phosphate from the ATP. The product is 1-3-bisphosphoglycerate. Electrons from the NADPH reduce the carboxyl group of the 1-3-bisphosphoglycerate to the aldehyde group of glyceraldehyde-3-phosphate. For every three carbon dioxide molecules that enter the Calvin cycle,6 glyceraldehyde-3-phosphates are produced, only one can be counted as a net gain. The other 5 are used to regenerate 3 molecules of RuBP. Step 3: Regeneration of RuBP. A complex series of reactions rearranges the carbon skeletons of 5 glyceraldehyde-3-phosphate molecules into 3 RuBP molecules. These reactions require 3 ATP molecules. RuBP is thus regenerated to begin the cycle again.
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: Yrat]
#132974 - 10/15/08 11:19 PM (16 years, 2 months ago) |
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There are several stages in the progress of the carbon dioxide. It boils down to vocabulary. Just like any chemical reaction you have the reactants and the products. Everything else is just fine tuning.
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erb
Registered: 04/20/08
Posts: 198
Last seen: 13 years, 10 months
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Re: 18 vs 24 Hours of Light in the Vegative Cycle [Re: MFDoom666]
#225587 - 05/12/09 02:32 PM (15 years, 7 months ago) |
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