Seed germination enhancement through breaking seed dormancy: A review in tropical and temperate tree species

The most important factor for the success of plantation is readily availability of quality seeds. In favorable climatic conditions with optimum moisture and temperature most of the tree species germinate quickly and in unfavorable conditions some degree of seed dormancy occurs. There are various kinds of dormancy occur in trees species such as; exogenous dormancy due to hard seed coat, seed coat impermeable to water, presences of chemical; endogenous dormancy due to immaturity of embryo, oxidation and presence of inhibitors; and double dormancy which include both seed coat and embryo dormancy. In most of tropical tree seeds, physical dormancy occurred because of hard seed coat whereas temperate trees seeds mainly have physiological dormancy.