18/6 vs 24/0

[jmd1109]

I plan on experimenting with the duration of "lights on" cycle during grow.

In my limited research I've done to date, I've come across this a few times:

There is no scientific proof that the plant benefits from anymore than 18hrs of light during the grow (Veg) cycle...

As mentioned above, I do plan on finding an experimental truth to this very question, "Does the plant benefit from more than 18hrs of light during grow period"...

Even we can be force fed -

Enjoy!

:rasta:

[Xelatoth]

I am a biology major currently taking a plant physiology course and I can tell you, at least according to my botanist professor, that plants will not benefit from the extra 6 hours of light in any meaningful way.

Their stomatic gas exchange occurs during the dark period and while they may induce this behavior during constant light anyhow, there is something they can NOT do in 24 hour light:

Their "dark" reactions!!!

A plant has 2 photosystems and both light and dark reactions!

The plant's electron transport chains will be active during light periods to "harvest" the light into chemical energy...

Now, this energy will be stored for use at night!

At night, the plant uses that stored energy for input into the Calivin Cycle!

The Calvin Cycle is the MOST IMPORTANT metabolic pathway in a plant and it finally can convert the chemical energy into useable sugars with the waste byproduct being O2.

Basically, 18/6 is really the only choice

*** 24/0 will allow for a forced Calvin Cycle, but the plant will need to expend MORE ATP and NAD+ to get the same singular glucose molecule... more work for same result = less vigor!

Fo' real.. let us put this to rest as Mother Nature is the best scientist there is!

Peace

:smokin:

[the image reaper]

I am a biology major currently taking a plant physiology course and I can tell you, at least according to my botanist professor, that plants will not benefit from the extra 6 hours of light in any meaningful way.

Their stomatic gas exchange occurs during the dark period and while they may induce this behavior during constant light anyhow, there is something they can NOT do in 24 hour light:

Their "dark" reactions!!!

A plant has 2 photosystems and both light and dark reactions!

The plant's electron transport chains will be active during light periods to "harvest" the light into chemical energy...

Now, this energy will be stored for use at night!

At night, the plant uses that stored energy for input into the Calivin Cycle!

The Calvin Cycle is the MOST IMPORTANT metabolic pathway in a plant and it finally can convert the chemical energy into useable sugars with the waste byproduct being O2.

Basically, 18/6 is really the only choice
24/0 will allow for a forced Calvin Cycle, but the plant will need to expend MORE ATP and NAD+ to get the same singular glucose molecule... more work for same result = less vigor!

Fo' real.. let us put this to rest as Mother Nature is the best scientist there is!

Peace

The plant's Calivin Cycle will be active during light periods, but its

this is an excellent, educated explanation :thumbsup: ... there will still be some growers that insist they get better results from a 24/0 cycle, but I've tried every conceivable cycle imaginable, and I have never seen any advantage over 18/6 ... as I say to growers that insist on 'experimenting' with everything, " your plants survive your efforts, because they are WEEDS, and they don't thrive BECAUSE of your 'ideas', but, IN SPITE of your 'ideas' " ... when in doubt, 'imitate nature' ...

[Mr. Clandestine]

I'm partial to the 18/6 schedule for two reasons: 1) As Image Reaper suggested, in nature, plants don't get 24 hours of sunlight. I've never had substandard results from imitating nature, and don't know anyone who has. 2) Your power bill will thank you for that extra 6 hours of downtime if you're running 1k of lights or more, several ventilation fans, humidifier/dehumidifier, etc.

One upside to keeping a 24 hour schedule is that you don't have to worry about fluctuating temperatures. With fluorescent setups, the 24/0 schedule for vegging plants, clones, and mothers seems a bit more feasible. But still not entirely necessary.

[orangecommunist]

I am a biology major currently taking a plant physiology course and I can tell you, at least according to my botanist professor, that plants will not benefit from the extra 6 hours of light in any meaningful way.

Their stomatic gas exchange occurs during the dark period and while they may induce this behavior during constant light anyhow, there is something they can NOT do in 24 hour light:

Their "dark" reactions!!!

A plant has 2 photosystems and both light and dark reactions!

The plant's electron transport chains will be active during light periods to "harvest" the light into chemical energy...

Now, this energy will be stored for use at night!

At night, the plant uses that stored energy for input into the Calivin Cycle!

The Calvin Cycle is the MOST IMPORTANT metabolic pathway in a plant and it finally can convert the chemical energy into useable sugars with the waste byproduct being O2.

Basically, 18/6 is really the only choice

*** 24/0 will allow for a forced Calvin Cycle, but the plant will need to expend MORE ATP and NAD+ to get the same singular glucose molecule... more work for same result = less vigor!

Fo' real.. let us put this to rest as Mother Nature is the best scientist there is!

Peace

:smokin:

I know this is a very old thread but i would just like to clarify for any future readers that the 'dark' reactions, that occur in the Calvin cycle, are NOT reactions that only happen in darkness. The term 'dark reactions' refers to the fact that they occur independent of light. That is to say that these reactions can continue day or night until the plants stored energy is depleted. This is a very common misconception and i hate how many text books refer to them as 'dark reactions' as this confusion often arises with many of my students.

However, with some hardy plants, that grow in arid environments, the opening of the stomata (pores in the leaf) that allows for the intake of CO2 occurs only during darkness. This is so that there will be as little water loss as possible. I am not sure if this is the case for the marijuana plant but it would seem that knowing some of the evironments that it naturally occurs in and having read of its strong drought tolerence i would guess this may be the case. So though the above comment may have been technically innacurate in its information the practical application for what was said still remains solid.

18/6 may infact allow for faster growth as regardless of how much energy a plant has stored it cannot convert this energy to plant material without sufficient CO2 which it collects and stores during the cooler hours of the evening. But as always strain, genetics and individual environment will determine what is best for a plant. There are no universal rules as to what is best for marijuana plants.

[Dutch Pimp]

Hi OC...we kick this puppy about every six months...we don't get anywhere with it.

grower's choice

[oldmac]

..."Amen"


..

[wraithe]

I found this to be good reading, I also noticed someone mentioned the Marijuana Horticuture-Indoor-Outdoor Medical Growers Bible. I have the electronic version if anyone needs it its about 140megs and I can post it on a anonymous site like rapidshare or something, if anyone is in need. Thanks for all the work put into this thread

[M.B.A.]

oldy but goody thread aye

[daihashi]

My vote is still the same.

24/0 is a waste; plants create their own photocycle if forced into 24/7 light anyway and will rest on their own. Save the electricity and put extra cash in your pocket.

18/6 is where it's at