Level 2 Horticulture Science
PLANT PROPAGATION
ASEXUAL PROPAGATION
US 20556
10 Credits – Internal Assessment
Contents
• Asexual vs sexual Propagation
• Asexual propagation (overview)
• Division
• Layering
• Tissue culture
• Cuttings
• Budding and Grafting
• Plant Breeders Rights
Propagation:
DEFN:
Plant propagation is the
process of creating new
plants
Plant propagation can also
refer to the artificial or natural
dispersal of plants.
Types of Propagation:
Things that are not
examples of Propagation
Asexual and Sexual Propagation
• Asexual Propagation - using one parent plant to produce a
new individual that is a clone (genetically identical)
• Key words: offspring, new individuals, parent plant(s),
• Sexual Propagation – recombination of the genes to produce
a new individual that is a genetically different
(also known as sexual reproduction)
In Angiosperms -This always involves flowers and always
results in seed.
In Gymnosperms/ ferns and Moses this results in spores
Question – if a plant self pollinates is it sexual or asexual
propagation?
Examples of Propagation Techniques
Sexual
Seed
Asexual
Layering
Tissue Culture
Grafting
Budding
Stem Cuttings
Leaf cuttings
Root Cuttings
Bulbs
Corms
Runner
Rhizomes
Crown division
Stolons
Asexual Propagation (outline)
We will be investigating 5 methods of asex prop.
1. Cuttings
2. Grafting and Budding
3. Division
4. Layering
5. Tissue Culture
To begin to understand asexual propagation (AsexP) we
need to understand meristematic cells
Parts of a plant
Importance of Meristematic cells
• Meristematic cells – plant cells that are capable of dividing
to create new plant cells that are unspecialised
• Cambium layer – contains the meristematic cells
• Unspeciallised cells are able to turn into any type of plant
cells.... Eg
•
•
•
•
xylem
Phloem
Epidermal
Mesophyll
Location of cambium layer
Division
• Plant structures
Cuttings
4 types of cuttings
• Leaf
• Stem
• Hardwood
• Semi-hardwood
• Softwood
• 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
Importance of Meristematic cells
• Meristematic cells – plant cells that are capable of dividing
to create new plant cells that are unspecialised
• Cambium layer – contains the meristematic cells
• Unspeciallised cells are able to turn into any type of plant
cells.... Eg
•
•
•
•
xylem
Phloem
Epidermal
Mesophyll
Location of cambium layer
How does crown tissue work.
• The crown area of a plant
contains both stem and root
tissue and corresponding
cells such as xylem, phloem
and epidermis
• Theses cells are already
speciallised and will go onto
create more of the same
specialised cells.
Crown of rhubarb
plants
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.
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
• Both air layering and ground layering are
used in commercial horticulture to produce
cloned plants.
• Layering is more difficult than taking cuttings
but has the advantage that the plant is still
attached to the parent plant receiving water
and nutrients.
Air layering
is often
used to fast
track the
creation of
a bonsi
The rooting process in
layering may take form
a few weeks to several
years depending on the
plant being propagated
Air layering
• Air Layering is generally used
when other forms of
propagation are difficult.
• Two techniques are shown –
but both expose the cambium
layer
• You tube – Creating a bonsi
Ground layering
• Ground layering is often used for brambles (cane berries
such as raspberries etc.)
• Also used for apples (although no longer commonly used)
Compound trench layering
Simple ground layering