For germination, dry mature seeds need to be hydrated under optimal temperature in the presence of oxygen. This water uptake is triphasic, including an initial rapid imbibition (phase I), followed by a lag phase with little change in water content (phase II), and a further increase in water content coincident with radical emergence (phase III) [8], [9] and [10]. Upon imbibition, embryonic cells switch from quiescence to highly active metabolism. Although seed germination is a major subject in plant physiological research, there is still a long way to go to elucidate the mechanism of seed dormancy and germination.