Germination is a biological process induced by activating the
residual enzymes. Therefore, most studies regarding cereal germination
have focused on the changes in enzyme activity and subsequent
changes in composition. In order to control or optimize the
compositional changes during germination, the metabolic pathway
of germination should be understood. Germination is usually initiated
by water uptake by dry seeds, which encounters the physical
conditions desirable for sprouting. In BR, germination commonly
refers to the process up to the point where the rice kernel has a
radicle of 2–5 mm, and pre-germination is the stage with an
expanded a radicle exposed approximately 0.5–1 mm (Watanabe,
Maeda, Tsukahara, Kayahara, & Morita, 2004). Although variations
in water uptake and enzymatic responses occur across plant
species, germination may be divided into three phases as shown
in Fig. 1.