Level 1 Horticulture Science
AS 90923
PLANT PROPAGATION
PLANT PROPAGATION
The following PowerPoint notes are to support students towards the
assessment for:
AS 90923 Demonstrate knowledge of basic plant propagation techniques
Level 1
4 credits
Internal Assessment
Achievement
Achievement with Merit


Demonstrate
knowledge of basic
plant propagation
techniques.
Demonstrate in-depth
knowledge of basic
plant propagation
techniques.
Achievement with
Excellence
 Demonstrate
comprehensive
knowledge of basic
plant propagation
techniques.
CONTENTS
The difference between asexual and sexual
 Types of sexual propagation
 Types of asexual propagation
 Seed Sowing
 Cuttings
 Division
 Ground Layering

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
EXAMPLES OF PROPAGATION
Asexual

Cuttings


Grafting


Whip and tounge / cleft /
budding etc
Division


Hardwood /SemiHardwood/ Soft-wood
Tubers/ runners/
rhizomes/ crown/
stolons/ bulbs/ corms
Layering

Ground/ air
Sexual
Propagation using Seed
Note:
• Always involves
flowers
except in
gymnosperms (pine
trees) ferns and
mosses
• Sexual propagation
always results in a
seed
SEED SOWING
To understand seed sowing technique we will be
looking at:
 Seed structure
 Germination
 Respiration
 Seed requirements
 Seed Dormancy
Seed Sowing
Menu
SEED SOWING – SEED STRUCTURE
Three parts to
a seed
Seed coat
 Endosperm
 Embryo

Seed Sowing
Menu
‘A seed is a plant in a box with it’s lunch’
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
Two different
situations:
 Cotyledon(s)
appear above
ground as first
leaves (seed
leaves)
 Cotyledon(s)
remain below
the ground
SEED SOWING – SEED STRUCTURE

There are two types of plants that produce
seeds:
Monocotyledons
and Dicotyledons
Seed Sowing
Menu
SEED STRUCTURE
Seed Sowing
Menu
GERMINATION

Starts when the seed begins to absorb water

Ends when the new plant is able to get all its’
energy from photosynthesis.
GERMINATION – THE PROCESS
1.
2.
3.
4.
5.
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.
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.
RESPIRATION IN SEEDS

INPUTS
OUTPUTS
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

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.
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?
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.

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.
END – SEED SOWING

Back to Main menu
CUTTINGS

Stem cuttings are the
second most widely
used form of
propagation in
horticulture.
(Number one is seed)
Semi- hardwood cuttings of Forsythia
Tip (softwood) cuttings of Hydrangeas
Leaf cuttings of petunias
Hardwood cuttings of grape vines
DIVISION
Examples of
Asexual
Examples of
Sexual
GRAFTING
Examples of
Asexual
Examples of
Sexual
LAYERING
Examples of
Asexual
Examples of
Sexual