What is Germination? – Definition
Germination is the resumption of growth of the embryo plant inside the seed.
In other words it is the beginning of growth of a seed.
Types of Germination
- Hypogeal germination
- Epigeal germination
- Vivipary
- Pre-harvest Sprouting
- Hypo-epigeal Germination
Hypogeal Germination
When cotyledons remain below soil surface due to rapid elongation of epicotyl then it is called as hypogeal germination.
Occurrence – Majority of monocotyledons, some trees like mango, coconut, areca nut and some large seeded legumes
Epigeal Germination
When cotyledons pushed above soil surface due to rapid elongation of hypocotyls then it is called as epigeal germination.
Occurrence – Mostly in horticultural and woody plant species e.g. cotton, cucumber, guar, gourds, tamarind, castor, sunflower, groundnut
Vivipary
Germination of seed inside the fruit which is still attached to the mother plant and which also nourishes the seedling at initial stages just after germination is termed as vivipary.
When radicle of such seedling elongates, swells in lower part and get stouter, it separates from parent plant. Also due to increase in weight falls on ground vertically in such a way that the radicle goes into soft mud and plumule remains above the soil level. From plumule shoot arises.
Occurrence – Many plants growing along sea coasts e.g. mangroves.
Pre-harvest Sprouting
Sprouting of seeds of standing crop, due to high moisture is known as pre-harvest sprouting.
Occurrence – Groundnut, bajara
Hypo-epigeal Germination
In the dicot species, one cotyledon shows hypogeal germination by remaining beneath the soil as in hypogeal germination while the other cotyledon comes out above soil as epigeal germination.
Occurrence – Paperomia peruviana
Now, which are the factors who affect germination of seed, what are key factors for germination? To get aquainted visit Requirements for Seed Germination.