1. Level 1 Horticulture Science
AS 90923
Plant Propagation

2. Plant Propagation
The following PowerPoint notes are to support students towards the assessment for:
AS Demonstrate knowledge of basic plant propagation techniques
Level credits Internal Assessment
Achievement
Achievement with Merit
Achievement with Excellence
Demonstrate knowledge of basic plant propagation techniques.
Demonstrate in-depth knowledge of basic plant propagation techniques.
Demonstrate comprehensive knowledge of basic plant propagation techniques.

3. Contents The difference between asexual and sexual
Types of sexual propagation
Types of asexual propagation
Seed Sowing
Cuttings
Division
Ground Layering

4. The difference between asexual and sexual
Definitions
Asexual Involves only one parent to make a new individual that is a clone of the parent (genetically identical). In plants there are heaps of ways of doing this.
Sexual Involves 2 (or 1) parent plants mixing their genes to produce offspring. In plants the parents have ‘sex’ using flowers and the offspring are seeds

5. Examples of Propagation
Asexual
Sexual
Cuttings
Hardwood /Semi-Hardwood/ Soft-wood
Grafting
Whip and tounge / cleft / budding etc
Division
Tubers/ runners/ rhizomes/ crown/ stolons/ bulbs/ corms
Layering
Ground/ air
Propagation using Seed
Note:
Always involves flowers
except in gymnosperms (pine trees) ferns and mosses
Sexual propagation always results in a seed

6. Seed sowing To understand seed sowing technique we will be looking at:
Seed structure
Germination
Respiration
Seed requirements
Seed Dormancy
Seed Sowing Menu

7. Seed sowing – seed structure
Three parts to a seed
Seed coat
Endosperm
Embryo
‘A seed is a plant in a box with it’s lunch’
Seed Sowing Menu

8. Seed sowing – seed structure
Seed coat -the outer covering of a seed helps protect the embryo from injury and drying out. Seed coats can be thin and soft as in beans or thick and hard as in walnuts or coconut seeds.
Endosperm, a temporary food supply, is packed around the embryo in the form of special leaves called cotyledons or seed leaves. These are often the first parts visible when the seed germinates.
Embryo – the ‘baby’ plant.
Seed Sowing Menu

9. Two different situations:
Cotyledon(s) appear above ground as first leaves (seed leaves)
Cotyledon(s) remain below the ground

10. Seed sowing – Seed Structure
There are two types of plants that produce seeds:
Monocotyledons
and Dicotyledons
Seed Sowing Menu

11. Seed Structure
Seed Sowing Menu

12. Germination Starts when the seed begins to absorb water
Ends when the new plant is able to get all its’ energy from photosynthesis.

13. Germination – the process
The seed absorbs water until it swells and smoothens its exterior wrinkles.
Swelling continues until the coat of the seed bursts open.
Food stored in cotyledons or endosperm soaks up water and soluble substances dissolve in it.
Respiration begins thus energy and raw materials are supplied by food for cell division and growth.
A radical appears first and then a pumule.

14. Respiration
During respiration (in plants and animals) energy is released from sugar (glucose) by a series of chemical reactions. The sugar is broken down into carbon dioxide and water in a process which uses oxygen.

15. Respiration in seeds
INPUTS OUTPUTS

16. Seed requirements List the inputs all seed require to germinate
Match your list to the following.
Allows seed to swell and break seed coat
Required for respiration
Speeds up the various chemical processes

17. Seed dormancy
Dormant seeds are seeds that are still alive but when the seed is supplied all that it needs to germinate, - it doesn't.
The seed is asleep, waiting for the proper time to awaken.
Seed dormancy aids a species' survival by delaying germination so that 'overall germination' is dispersed over time.

18. Seed Storage Germination needs water. warmth and oxygen
Seed storage needs (the opposite)
Cool and dry!
Why can we not store seeds in a oxygen free environment?

19. Seed Sowing Summary
Seeds don’t get re-assessment opportunities. Once they begin to germinate they either survive or die.
Seeds need the WOW factor to survive (water oxygen, warmth). Soil, light, CO2 are only for ‘grown-up’ seeds
A seed is a plant in a box with it’s lunch – but no dinner – if a seed is in the packet too long it will run out of lunch and die.

20. Sexual Propagation – Exercise
Which of the following statements are true T/F
If we collected 1000 seeds from one kowhai tree, it is unlikely that any one seed will have the same genetic material
A sunflower produces 800 seeds. The genetic material in each seed has come form two parents
Seed is made after a pollen grain and an egg (ovum) have joined together in a flower
Seed is spread by bees and other insects in a process known as pollination
A Flower contains both the male and female sexual organs of a plant.

21. End – Seed Sowing
Back to Main menu

22. cuttings
Stem cuttings are the second most widely used form of propagation in horticulture.
(Number one is seed)

23. Semi- hardwood cuttings of Forsythia
Leaf cuttings of petunias
Hardwood cuttings of grape vines
Tip (softwood) cuttings of Hydrangeas

25. Division
Examples of Asexual
Examples of Sexual

27. Grafting
Examples of Asexual
Examples of Sexual

28. Layering
Examples of Asexual
Examples of Sexual