**2.2 Seed dormancy and germination**

A dormant seed has no capacity to germinate even in the presence of favorable environmental factors and habitable conditions due to either non-viable, empty of embryo or dormancy [4, 5]. Many types of seeds, even when they appear to be ripe,

#### *Factors That Cause Seed Dormancy DOI: http://dx.doi.org/10.5772/intechopen.107004*

fail to germinate even when all environmental parameters are favorable. The embryo's resumption of growth in such seeds is halted by the circumstances within the seeds. The state of slowed growth of seeds or other plant organs caused by internal factors is known as dormancy, but it is also known as the rest period. Seed dormancy is of considerable advantage to the plant. It enables the embryo to safely pass the unfavorable part of the year and germinate when the conditions are suitable for the establishment of the seedlings [3, 5]. In nature, dormancy period coincides with the unfavorable period for the seedling of the species. In other words, a completely non-dormant seed has the capacity to germinate over the widest range of normal physical environmental factors possible for the genotype. Therefore, a suspected case of seed dormancy arises when fresh un-germinated seeds remain at the end of a germination trial period that required some particular conditions of either endogenous, exogenous or combination of both factors to be satisfied. For seed to germination there are needs for basic requirements of water, oxygen and appropriate temperature, in consideration of other factors such as light and hormones. However, seed germinations are generally in three phases, starting with the uptake of water by imbibition of the dry seed which leads to embryo expansion [11–14].
