The physiological and physical changes undergone by a reproductive body, such as a seed, pollen grain, spore, or zygote, immediately prior to and including the first visible indications of growth. The process will not occur unless both internal and external conditions are favourable. In seeds the various factors causing * dormancy must be overcome and dehydrated seeds must have a supply of water. Temperature and light can also affect germination. Following imbibition of water by a dry seed, the respiration rate increases markedly as food reserves are broken down and protein synthesis commences. The radicle is normally the first organ to emerge through the testa, followed by the plumule. See also epigeal , hypogeal. |
