TYPES OF GERMINATION
The nature of germination varies in different seeds. During germination the cotyledons may be brought above the soil surface.This type of germination is called epigeal germination. If during germination the cotyledons remain underground the type of germination is known as hypogeal.
EPIGEAL GERMINATION
During the germination of a bean seed, the radicle grows out through the micropyle. It grows downwards into the soil as a primary root arise. The part root arise. The part of the embryo between the cotyledon and the cotyledon and the radicle is called the hypocotyl. This part curves and pushes upward through the soil protecting the delicate shoot tip. the hypocotyl then straightens and elongates carrying with it two cotyledons which turn green and leafy. They start manufacturing food for the growing seedlings. The plumule which is laying between two cotyledon, begins to grow into first foliage leave manufacturing food.
HYPOGEAL GERMINATION
In maize, the endorsperm provides food to the embryo which begins to grow. The radicle along with a protective covering (coleorhiza) grows out of the seed. The epicotyl is the part of the embryo between the cotyledon and the plumule. The epicotyl elongates and the plumule grows out of the coleoptile and forms the first foliage leaves. The seedling now begins to produce its own food and the endorsperm soon shrivels. This type of germination in which cotyledon remains below the ground is known as hypogeal germination.