**2.1 Definitions of seed dormancy**

Seed dormancy is an internal condition of a viable seed which constraint its germination despite enable growing conditions of suitable temperature and moisture availability [4]. Therefore, seed dormancy can be simply described as a resting state of a viable seed that must be broken either by time or deliberate conditions before the seed germinates at temperature and moisture levels suitable for required growth. In operational term, dormancy is a block to the completion of germination of an intact viable seed with suitable growth conditions. The block evolves based on the species of the seeds and climatic conditions in the prevailing environment [5–8]. Also, seed dormancy is a state in which seeds do not germinate despite the presence of all of the necessary conditions (temperature, humidity, oxygen, and light). It is caused by hard seed coat impermeability or a lack of supply and activity of the enzymes required for germination. Dormancy is a significant limiting factor in the production of many field crops. To overcome dormancy, organic material is subjected to a variety of physical and chemical pretreatments. Some plant species have both physical and internal dormancy, making it difficult to produce high-frequency healthy seedling growth, despite the fact that seed sprouting and the generation of healthy seedlings is a requirement for plant output. However, the constraint in definitions of the seed dormancy is inability to observe it in no other measure than the absence of germination [9, 10]. This is because a state of dormancy can take a value between maximum dormancy and non-dormancy. Therefore, dormancy is not typically associated with the absence of germination in seed rather it is a characteristic of the seed that determines the conditions essential for germination.
