How can i find out, Auto Hulkberry is "compatible" with topping?
I wouldn't worry about it. If you're interested in information about autos, you might want to log on to the cannabis site dedicated to auto flowers.
Note — I'm not saying leave RIU, just check out that site and go to the "auto flower myths" section where you'll find that auto growers routinely top their plants.
The wound that's created when a plant is topped it minuscule - it heals over in a few hours. Once that vegetation is removed, the growth hormones can't go to the apical stem so they go to the other stems. Life goes on.
I'm in day 52 of my first photo grow, having done five auto grows. I top my plants so as to remove the apical stem and have never seen any evidence that topping causes a problem.
My experience with autos has been that they fill and then grow out of my 2' x 4' tent. That's happened with Gorilla Glue, Gelato, and Strawberry Pie autos, all from different vendors. The fact that they grow so much has been such a PITA that I'm doing a photo grow so that I can
control influence plant height.
The biggest issue that is see - across all four cannabis sites that I read — is that growers spend a lot of time adding "just the right touch" of supplements and very little time actually feeding their plants, by that I mean giving them enough light to get to the light saturation point (800-1000µmols).
My approach to growing autos — get an RO unit, switch to Jacks 3-2-1 for RO, top the plant (to even out the canopy), put a big honking light in the tent, get the PPFD as close to 1000µmols as the plants can handle, and watch your tent fill up. My topped autos are routinely >=50" tall and yield is at least 500 gm/square meter.