Viable seeds of numerous plant species are not capable of germinating immediately after harvest under conditions suitable for the germination process. Such seeds are termed primarily dormant. Primary dormancy is established during seed development and maturation on the mother plant. This type of dormancy is particularly common in wild plants. Dormancy is a very important phenomenon which prevents germination on mother plants, facilitates seed dispersal, ensures plant survival of natural catastrophes, and reduces intra-specifc competition (Bewley et al. 2013). The phenomenon has turned out to be non-obligatory, its expression depending on environmental factors, e.g., temperature. Seeds can be fully dormant; such seeds are not able to germinate at any temperature (Hilhorst 2007). There are also seeds which are not capable of germination only within a certain temperature range, whereas they germinate at temperatures outside that range. Thus, the expression of dormancy in such seeds depends on temperature, and dormancy release is associated with widening the range of germination temperature. Under natural conditions, primarily dormant seeds are exposed to fuctuating environmental conditions, e.g., light, temperature, moisture, and the presence of gases, which leads to dormancy state cyclicity (Finkelstein et al. 2008). Primary dormancy can be removed also by cold stratifcation, dry storage, light, or chemicals (Bewley et al. 2013). It is commonly accepted that the balance between abscisic acid (ABA) and gibberellins (GAs) and/or sensitivity to these hormones are responsible for regulation of the dormancy state and germination of seeds in response to environmental signals (Finkelstein et al. 2008; Rodríguez-Gacio et al. 2009). ABA is considered as the most important hormone responsible for the establishment of dormancy during seed development and for maintenance of dormancy during seed imbibition. In turn, GAs have been cited as factors involved in dormancy release and/or germination. Dormancy release has been shown as involving a decline in the ABA content and an increase of the GAs level (Bewley et al. 2013).