Lighting Effects of dark period during flowering

[xotorazeko]

Ok, I have read a lot. Really a lot and I couldn't find a clear answer to this. I'm hoping you guys can help me to understand.

Please: Let's put aside the problems with electricity bills and talk about just the lights and how it affects the plants:tiphat:

There are arguments about a dark period of minimum 4 hours (most seem to prefer 6) benefiting the autoflowering plants nonetheless.

So here is what I'm wondering:

1. Do autos benefit from a dark period during flowering? If so, how? Do flowers continue to grow or mature.. what happens?

2. Does it mean the plants are likely to stretch less during flower (If the lights are on for 24/0 instead of 20/4 or 18/6, or 20/4 instead of 18/6 (4 to 6 hours of dark))?

3. Does this (^^ more light hours) mean denser buds but less in quantity (less stretch but more photosynthetic activity)? Or same density but more in quantity thanks to more light hours (more growth due to photosynthesis)?

4. Does more light hours mean getting to harvest quicker (due to photosynthesising more, resting less)?

I would LOVE to understand the effects of light after vegging with a 24/0 schedule.

I appreciate any and all your inputs and comments from your first hand experiences.

A good source I found was:
https://www.autoflower.org/f43/why-not-24-hrs-39831.html

 

[sprinkl]

Those are interesting questions. My belief was that plants do photosynthesis with lights on (= creating sugar out of CO2, H2O and light energy), and during the night those sugars are used by the plant to actually grow, hence the CO2 output(= why they say it's not good to sleep around plants) but I'm not really sure.
Would be really interesting to do a side by side, though you'd have to do big numbers to rule out phenotypical variation as you can't clone... A non-conclusive side by side could be done easily by taking out 1 plant and putting it in the dark for a couple of hours of day...

 

[oldster]

Hi xo, great question.

I have not seen what I would consider a scientifically valid test of the 24/0 vs. other lighting schedules but there does seem to be anecdotal information that plants do benefit from some dark period. There are different physiological process that go on in the dark vs. light and plants have evolved with this situation so some dark period does seem to help.

Not getting enough light will certainly cause excess stretching as will excess red light while plants are in the veg stage but it seems to be more related to intensity than duration.

Turpene development and possibly THC is more active in the dark and then gets broken down during light periods which is why some folks hold plants in the dark for 24-48 hours before harvest.

The time to maturity of autoflowers is pretty much genetically programed and does not seem to be affected by duration within typical light schedules used however low temperatures can slow days to maturity. I have seen some tests that growing autos under 12/12 with photos did reduce harvest amounts but again I would not say these tests were scientifically controlled.

Within the typical 18/6 to 24/0 schedules used light intensity seems to be the key factor rather than duration that drives bud development and harvest weight.