(Forgive me if this is terribly off-topic or circuitous. My ADD is kinda in overdrive today.)
(Not sure if this link is gunna work so if not:
doi:10.1111/j.1556-4029.2011.02024.x The Effect of Electrical Lighting Power and Irradiance on Indoor-Grown Cannabis Potency and Yield )
These dudes are averaging a little over a p per square meter with plain ol’ philips HPS across three different light intensities. 3 week veg, 8 flower, ambient co2 only. They report intensities at W/m2 but after checking some references for the bulbs in question:
600w/m2 of philips Son-T = ~1000umol
so 270w/m2 should be around 500umol
Plus a DLI / PPFD calculator says they’re between 20-45DLI. Even at the lower light intensity they’d probably be better off adding a lil co2 rather than more light. ~45DLI is 500umol@24/0 and 700umol@18/6. Granted we’re talking veg schedules, not flower, it applies to autoflowers.
(Addendum: Based on this photosynthetic efficiency chart 1200umol at ambient co2 will be, more or less, equivalent to 400umol at 1400ppm co2. That seems too simplistic for reality, so I would love if someone would prove me wrong.)
(These two graphs are part of this article.)
Need the carbon for carbon fixation, most of the mass of the plant is from carbon. Otherwise, plant protective mechanisms turn on if it receives more light than it can utilize and fix at any one time. And, then there is the Pr and Pfr conversion to consider.
If we are talking ADD, there are some measurement tools available to measure the PS efficiency, as well; and you can see the efficiency change as the intensity increases. This thing for instance:
Yeah, that’s the intensity for each of the weeks from the people in that last article. It’s a weird chart tho, and the weeks are listed at the top but the words at the bottom look like they’re every 5 days or so, instead of weekly
2 weeks to clone, 3 more weeks for veg, and then 9 weeks of flower
Closer to 16/8 for me, but use whatever photoperiod appropriate for your setup.
By this, I mean if you have strong lighting in veg, go closer to 16 on. If your veg lighting is on the weaker side, go closer to 24. By hour 14, my plants start drooping, which means they’ve about had their fill for a day and need to rest.
I’ve used 24/0 before with good results if the light is weaker.
