The seed dormancy is broken by the effect such as:
Some seeds require the chilling treatment for a period of time. That is cold treatment destroys the inhibitors present in the seed coat.
The light has an important role in breaking the seed dormancy and germination. Some of the seeds are sensitive to radiations.
The seed dormancy can be overcome by applying the chemicals. They are the gibberellins, cytokinins, ethylene, chlorohydrins, thiourea, etc.