TYPES OF GERMINATION
What are the 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.
- During the germination of a bean seed, the radicle grows out through the micropyle.
- It grows downwards into the soil as a primary root from which other roots arise.
- The part of the embryo between the cotyledon and the radicle is called the hypocotyl.
- This part curves and pushes upwards through the soil protecting the delicate shoot tip.
- The hypocotyls then straightens and elongates carrying with it the two cotyledons which turn green and leafy.
- They start manufacturing food for the growing seedling.
- The plumule which is lying between two cotyledons, begins to grow into first foliage leaves which start manufacturing food.
- In maize, the endosperm provides food to the embryo which begins to grow.
- The radicle along with a protective covering(c(?/eorfci2a) 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 endosperm soon shrivels.
- This type of germination in which the cotyledon remains below the ground is known as hypogeal germination.
To investigate epigeal and hypogeal germination Requirements
- Tin or box, soil, water, maize grains and bean seeds. Procedure
- Place equal amounts of soil into two containers labelled A and B.
- In A, plant a few maize grains.In B, plant a few bean seeds.
- Water the seeds and continue watering daily until they germinate.
- Place your set-ups on the laboratory bench.
- Observe daily for germination.
- On the first day the seedlings emerge from the soil, observe them carefully with regard to the soil level. Carefully uproot one or two seedlings from each set.
- Observe and draw the seedlings from each set Label the parts and indicate the soil level on your diagram.
- On the fifth day since emergence, again uproot another seedling.
- Observe and draw.
- Indicate the soil level on your diagram..
- Tabulate the differences between the two types of germination studied.