The sunflower seed dormancy is due to

Solution(By Examveda Team)

The sunflower seed dormancy is due to Ethrel.
Ethrel is a versatile plant growth regulator which improves colouration and accelerates uniform ripening of fruits.
Freshly harvested sunflower seeds are considered to be dormant because they fail to germinate at relatively low temperatures (10°C). This dormancy results mainly from embryo dormancy and disappears during dry storage.
Sunflower seed dormancy begins around the third week after pollination and is overcome during storage. It is induced by abscisic acid and broken by ethylene. The dormancy period depends on the genotype and the environmental conditions during maturation and storage.