Seed dormancy is due to:

Abscisic acid induces dormancy of buds towards the approach of winter. Abscisic acid accumulates in many seeds during maturation and apparently contributes to seed dormancy. Because ABA triggers dormancy, this hormone is also known as dormin. The buds and seeds sprout only when the effect of ABA is overcome by gibberellins. Related Theory $A B A$ acts as a general inducer of senescence. The onset of senescence is correlated with stomatal closure and destruction of chlorophyll. This hormone inhibits the protein and RNA synthesis. The ABA content of aging leaves increases markedly as senescence is initiated.