1. Seed germination

2. activity
In your groups list the requirements needed for seed to germinate
2mins

3. Learning outcomes
Identify the process involved in pollination and distinguish the stages of seed germination
Compare the seed types epigeal and hypogeal
Explain the requirements for successful germination

4. Seed germination requirements
Water
Temperature
Oxygen
Food
Light
time

5. water
Seeds hold very little water. It is one of the reasons that seeds can stay dormant for a long time

6. temperature
The requirements of individual seeds vary within an overall range of 5-35ºC. In our climate 10-20º C is typical
Heat will speed up the process which is why we use greenhouses and propagators to assist germination

7. Oxygen
A supply of oxygen is necessary for respiration

8. food
A supply of food is necessary to fuel the process until the plant is able to photosynthesise. The food is stored in the seed in the cotyledons of the endosperm.
If seeds are planted too deep they can die by exhausting their food supply before reaching the point at which they can photosynthesise

9. light
Some seeds require light to germinate

10. time
Some seeds have a chemical inhibitors which needs to diminish before germination is possible

11. Stages in germination Imbibition:
The initial step in the development of seed germination is to absorb water or imbibition The seed absorbs water and as a  result it swells. The swelling of seed causes the seed coat to rupture and allows the radicles to move downward  forming the  root.
Respiration:
When the seed absorbs water, it also respires. While in the beginning the respiration is anaerobic and later it becomes aerobic.

13. Inducing germination
Some seeds are difficult to germinate either because of their tough coat, or because of chemical inhibitors, or because they must be exposed to certain temperatures before germination will occur.

14. Seed stratification
The purpose of this is to expose the seed to a period of cold such as it would encounter under natural conditions.
Placing the seed in a refrigerator for a period of time as indicated on the seed packet
Some seeds may require periods of high heat to germinate

15. Seed scarification
The purpose of this is to weaken the seed coat and allow water to enter.
Large seeds such as those of peas and beans may be nicked with a knife. smaller seeds can be rubbed with an abrasive substance such as sandpaper.

16. activity
In your group using the learner resource centre research the following to produce a hand out including diagrams:
Seed stratification
Seed scarification
20mins

17. epigeal
In this type of germination the seed/cotyledons remain inside the soil
The cotyledons play the role in photosynthesis
There is a greater elongation of the epicotyl
The terminal part of the plant of the epicotyl is curved to protect the plumule from friction
Example bean

19. hypogeal
In this type of germination the seed/cotyledons emerges out of the soil
The cotyledons turn green and act as the first true leaves of the plant
There is a great elongation of the hypocotyl
The terminal part of the hypocotyl is curved to protect the plumule from the friction of the soil
Example pea