Hey, I was just wondering if keeping the plants in complete darkness when the hps light goes off is necessary during veg stage? Would it stunt growth if its not dark during the off period or does that only apply during the budding stage?
Alright sweet, I've been under 16/8 for about 10 days now, however since today I'm getting a fan I wont be too worried about heat issues so I was thinking about bumping it up to 18/6, would it affect the plants if I bump the light period up by 2 hrs even tho they've been under 16/8 for around 10 days?
You will be fine. Good reason to up the time too. If you have good ventilation, no reason other than theory to do anything other than 24/7.
I do not have a door on my veg cabinet. My cabinet is in my garage and it is not completely dark. I run my veg light on a 18/6 timer and I have not noticed any negative affects.
:icon_scratch: Never heard that befor. No prob bumping to 18/6. Go with what ever makes you happy man. 24/7, 18/6. They both work. Skunky or Useless has a time table experiment with yield ratios posted. Do a thread search and you'll find it. I think it showed an optimum yield at 20/4...but I'm not positive. cheers,
HID lighting Most bulb manufacturers recomend turning the bulb off for at least 15 minutes per weak to avoid a premature rupture of the bulb. The periodic cycling extends the life of the bulb On another note (debatable) heres some scientific jargon explaining why 24/7 might not be the best for the plant. While the chloroplasts are illuminated, protons are being pumped from the main compartment of the chloroplast (stroma) into the photosynthetic membranous sack (thylakoid). This increases the pH of the stroma (good, Rubisco -the mystic C fixing enzyme, has an alkaline pH optimum, and it's in the stroma), but causes some problems. To transport 6C sugars (or 12C like sucrose) across a membrane (to get to the rest of the plant) costs the plant energy, but it has a method of getting around this. Three C sugars (generally called trioses) can be transported across the chlopoplast membrane at no cost and as a bonus, phosphate is shipped in (the triose is actually a triose phosphate, so the phosphate ballance is conserved), but this only happens with any useful rate while the trioses have a charge of -1. While pH is low in the stroma, there are less protons 'floating' around and the trioses have a -2 charge and are VERY slowly transported. The 'trapped' sugar is stored in the chloroplast as starch until dark, when it is broken down and transported out of the chloroplast. If the plants recieve no dark time, net photosynthesis will be inhibited. There is only so much carbon that can be stored in a chloroplast until all of the enzymatic processes that are needed to regenerate all of the Calvin Cycle intermediates start to cause feedback inhibition. Starch filled chloroplasts disassemble their photosynthetic apparatus and become non-photosynthetic amyloplasts. This will happen to some degree, but the plants will still grow ok but they will need to use more metabolic energy to actively transport sugars from the chloroplasts and actively transport phosphate in. assit:
MK- That looks very familiar.....the same piece from cannastats concerning mothers and complex light cycles?? Here's the Useless post I was looking for concerning lighting for veg.
No its not from Cannastats (awesome website btw) Cant think of where I got it at the moment though...
24 hrs veg i set the 1,000 halide on the same timer as the flower rooms hps i just leave the 2 8ft floros on in the veg room it saves on the power bill...
Hmm 5% rly isn't enough to convince me to switch from 18/6 to 20/4, mainly cause it's my first grow and 5% wouldn't be a significant increase so I don't think it's worth the extra $$ on electricity or risk on the hps, Anyways u guys will be glad to hear that I've made huge improvements on my growroom and the plants are responding great!
