dark?

I am currently on my 4th day since sprouted 2 seedlings n all is ok, under 2x 20w cfl's and 100w hal, till get my HID on tues but do they need dark as i thot 24/0 was ok for MJ's but some ppl say 18/6 for dark period, is this needed, as i dont want tall spindly plants, but was told that they need to produce sugar etc which is done in dark cycle.?

""During the dark cycle, plants undergo aerobic respiration. Respiration is divided into three parts: Glycolysis, the Krebs or Citric Acid cycle (TCA), and the Electron Transport Chain. Glycolysis is the breakdown of sugars to shuttle smaller sugar molecules and intermediates to the Kreb Cycle.""

"The Krebs Cycle then generates cellular CO2 and energy rich molecules like ATP, NADH and FADH. These energy carriers are then incorporated into the electron transport chain, coupled to the protons and electrons produced during photosynthesis to establish a proton gradient across the chloroplast thylakoid membrane, similar to a battery.?

this is useful info for growing batteries or should i stick to 24/0???

People swear by both. I do 20/4. Pretty much anything between 18 and 24 hours of light will be fine.

but its cold where i am and if i turn off lights then the temp is dropping to like 15-18c max, is this to low for them to be ok as only 3days old, but 1 is 3" and nice and green but one round leave is straight out, the other is pointing up, true leaves are nearly 1", the other plant is shorter not as big leaves, i think i over watered her, but she is perking up and i dont want to risk killing/stunting them by turn off heat as ive been up for the last 3 days checkg temp, then again, then turning plants, then again a bit later, and want to be able to give them maybe 4hrs dark if i can, im best giving it its dark period during the day wen the temp is up?

blimey said:

People swear by both. I do 20/4. Pretty much anything between 18 and 24 hours of light will be fine.

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agreed... i've tried both full light and than some dark, and ime, i've found that they seem to like a dark period of a few hours in veg.. i usually do 18/6, but i'm sure 20 / 4 would do the same..
i once read jeorge cervente's saying that plants grown under 24 hours of light would grow 33% faster than the same plants grown under 18 hours of light, so seeing this i thought, fuck yah, who doesn't want 33% more growth in the same time period?? but after giving it a go with several different strains, i've simply come to the conclusion that this is horseshit, and that they do indeed seem to grow some what better given a few hours of dark in a 24 period..

15-18c is at the bottom of the range you want your plants in. Yea, give them the dark period when it is hottest there.

n im in a cab grow so dont want tall lanky plants, with large spaces between nodes, so will i give them 4 hrs dark during the day, to help the glucose and root production, as i also heard/read that c3 plants absorb more co2 in their dark cycle?