Anyone know if there is (bro)science out there on whether an autoflower can revert to a photoperiod after switch to 12:12 light sched? My pheno #1 looks like a photo while #2 had no change with the flip.
No, it is either auto flowering or photoperiod.
Light schedules can not change an autoflowers' genetics.
Autos are nowhere near as stable as photoperiod plants as yet and strange plants are far more common in autos as compared to photos with their decades of selective breeding already.
A reduction in light hours may cause an auto that is flowering to experience excessive stretching though, perhaps this is what is confusing you?
To add up, people bump into totally different situation, when shitty breader auto isphoto and never starts to flower under 18/6 20/4 or 24/0, in such cases you have to go to 12 12 to force flower ...
12 12 wont effect auto in any way, just slowing development or flower time.
Autos dont give a fuck how long is night, whenever they feel mature to have next generation aka sex, they will start to bloom.
Autos don't typically change with flipping the lights. They are time based. Most growers recommend 18/6 light cycle all the way to finish to help maximize yield. Sometimes thier internal clock fails and you have to switch to 12/12 for it to change, but most of the time they will change when they are ready. Good luck and Happy growing. I run autos 18/6 all the way through and and super happy with the results. Haven't had one not flip itself yet.