1. Germination

2. Learning objectives(3/4)
Define the term: Germination.
Explain the factors necessary for and role of digestion and respiration in germination.
Outline the stages of seed development

3. What are the 3 factors needed for germination
What is germination 3.

4. Germination
Growth of seed or embryo into a plant

5. Germination – Factors necessary
Water
Oxygen
Suitable temperature or Warmth
Mnemonic: WOW
Dormancy must be complete

6. Germination – Factors necessary
Water
Activates enzymes which break down food reserves in endosperm/cotyledon
Medium for germination reactions e.g. digestion
Transport medium for digested products

7. Germination – Factors necessary
Oxygen
Needed for cellular respiration
Suitable temperature
Allows maximum enzyme activity

8. Events in Germination (detail) http://www. youtube. com/watch
Water is absorbed
Food reserves are digested in the endosperm and cotyledon to allow the food to change
Digested food is moved to the embryo for respiration
New cells are produced using amino acids
Glucose is turned into ATP to drive cell division
Radicle breaks through the testa
Plumule emerges above ground
New leaves begin to photosynthesise
Events in germination cease when the plants leaves have developed and the plant has started to photosynthesise

9. Events in Germination
Plumule
Radicle
Cotyledon

10. Events in Germination
Plumule
Radicle

11. Changes in dry weight of seeds during germination
Mass drops initially due to respiration, but then begins to increase due to photosynthesis

12. Changes in dry weight of seeds during germination
Food reserves in endosperm are transferred to the growing embryo

13. Germination of broad bean (hypogeal)

14. Germination of broad bean (hypogeal)

15. Germination of broad bean
Ground
Seed – water is absorbed through the micropyle

16. Germination of broad bean
The testa splits
Radicle emerges

17. Germination of broad bean
Plumule emerges
Radicle continues to grow

18. Germination of broad bean
The plumule is hooked to protect the leaves at the tip
Epicotyl

19. Germination of broad bean
The plumule grows above the surface of the soil
Lateral roots develop

20. Germination of broad bean
Plumule straightens and the leaves open out
Throughout Hypogeal germination the cotyledons remain below the ground

21. Germination of sunflower (Epigael)
Seed – water is absorbed through the micropyle

22. Germination of sunflower
Radicle emerges

23. Germination of sunflower
Hypocotyl Hook

24. Germination of sunflower
Seed coat discarded
Germination of sunflower
Cotyledons
Radicle grows downwards

25. Germination of sunflower
Leaves emerge
Cotyledons wither
In Epigeal germination the cotyledons rise above the ground

26. Review the plant life cycle2
pollen is transferred 3
After fertilization flower withers 1
seeds develop in ovary 4
seeds disperse and germinate into new plant 4

27. Learning Check Define germination List the conditions of germination
Briefly describe the events in germination
When does germination stop
What is the difference in hypogeal and epigeal germination

28. Can you…… Define the term: Germination.
Explain the factors necessary for and role of digestion and respiration in germination.
Outline the stages of seed development