PLANT PROPAGATION

ASEXUAL PROPAGATIONUS 20556

10 Credits – Internal Assessment

Level 2 Horticulture Science

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 TechniquesSexual Asexual

Seed LayeringTissue CultureGraftingBuddingStem CuttingsLeaf cuttingsRoot CuttingsBulbsCormsRunnerRhizomesCrown divisionStolons

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 ForsythiaLeaf cuttings of petunias

Hardwood cuttings of grape vinesTip (softwood) cuttings of Hydrangeas

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 structureThree parts to a

seed

• Seed coat• Endosperm• Embryo

‘A seed is a plant in a box with it’s lunch’

Seed Sowing Menu

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. The seed absorbs water until it swells and smoothens its exterior wrinkles.

2. Swelling continues until the coat of the seed bursts open.

3. Food stored in cotyledons or endosperm soaks up water and soluble substances dissolve in it.

4. Respiration begins thus energy and raw materials are supplied by food for cell division and growth.

5. 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 ForsythiaLeaf cuttings of petunias

Hardwood cuttings of grape vinesTip (softwood) cuttings of Hydrangeas

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