Might as well cover IR here too. I have stared at these simple charts for a good while before it began to sink in
Again thanks to TL
only the 'crazy ones' (like us) who'd 'need to' (read: 'like playing around with cool stuff') - let's say - have a bunch of IR LEDs on a separate channel, throw 'em on after lights out to 'encourage' the Pr-->Pfr equilibrium during dark reversion back over to the left side of that equation, and shorten the dark cycle duration required for certain short-day plants as a result:
and validated on SkunkSkool
The first and last hour of a day's sunlight is mostly red light because of the scattering effect on blue light. "So at the onset of the dark period much of the phytochrome is in the Pfr form. However, Pfr is unstable and returns to phytochrome Pr in the dark." The red light in sunrise returns the Pr to the Pfr form. "Phytochrome Pfr is the active form and controls flowering and germination. It inhibits flowering of short-day plants (the long night period is required for the conversion of Pfr to Pr) and promotes flowering of long day plants."