SEED GERMINATION: DEFINITION, TYPES, FACTORS

SEED GERMINATION: DEFINITION, TYPES, FACTORS & PROCESS

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.

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 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.

Hyopgeal Germination

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.

Practical Activity

To investigate epigeal and hypogeal germination Requirements

1. Tin or box, soil, water, maize grains and bean seeds. Procedure
2. Place equal amounts of soil into two containers labelled A and B.
3. In A, plant a few maize grains.In B, plant a few bean seeds.
4. Water the seeds and continue watering daily until they germinate.
5. Place your set-ups on the laboratory bench.
6. Observe daily for germination.
7. 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.
8. Observe and draw the seedlings from each set Label the parts and indicate the soil level on your diagram.
9. On the fifth day since emergence, again uproot another seedling.
10. Observe and draw.
11. Indicate the soil level on your diagram..
12. Tabulate the differences between the two types of germination studied.

EVALUATION

1. What are the different types of germination?
2. What are 3 types of seed germination?
3. What is radicle and Plumule?
4. What are the methods of seed germination?
5. What is radical seed?
6. What is the most common method of germinating seeds?
7. What is meant by Hypogeal germination?
8. What is Ragdoll method seed germination?
9. What is the best pH for seed germination?
10. What is the fastest seed to germinate?