ABA is the hormone that keeps it dormant, gibberellin is hormone that promotes seed germination. Gibberellin application can  break the dormancy of old dud seeds.
Needs to be mixed with few drops of 90+% alcohol and mixed to specific concentration. I'm not sure what the ppm is for seeds but to induce plant response roughly 2-300ppm.
I'll say no more as there are people in the community who get animated whenever PGRS are mentioned as if it's an illegal drug trade. Plant Growth Regulators (PGRs) are a broad category that includes both naturally occurring compounds (phytohormones) and artificially manufactured, synthetic substances. Stick to phytohormones and you are fine. But there needs to be a clear distinction.
All naturally occuring plant hormones are phytohormones. So for anyone to say you should not use them, tis funny. As every living plant consists of naturally occuring phytohormones. The specific spectral ratio you apply will dictate the hormonal balance of a plant.
Synthetic pgrs are what you stay away from and are mostly illegal in alot of places.