Sexual Propagation

1
Sexual Propagation
2
Objectives

• Objective 17.1Define Propagation.
• Objective 17.2List the two types of plant
  propagation.
• Objective 17.3Define germination.
• Objective 17.4Identify the life cycle of plants.
• Objective 17.5Identify the parts of a seed.

3

• Objective 17.6Define seed dormancy.
• Objective 17.7Explain why some seeds will not
  germinate right after ripening.
• Objective 17.8Define scarification.
• Objective 17.9Identify the factors affecting
  germination.

4

• Objective 17.10Identify germination media
  requirements and components.
• Objective 17.11Explain the ideal germination
  environment.
• Objective 17.12Identify the proper steps in
  transplanting a seedling.

5
Define Propagation

• Propagation the increase of a plant species from
  one generation to the next

6
List the two types of plant propagation

• Sexual propagation
• The union of a male and female gamete.
• Produces a genetically unique offspring.
• Asexual propagation
• The clone of a plant that is genetically
  identical to the mother plant.

7
Define germination

• Germination the development of a seed from a
  resting stage to a stage of growth.

8
(No Transcript)
9
Stages of Germination
10
(No Transcript)
11
(No Transcript)
12
Identify the life cycle of plants

• Annuals
• Germinate, grow, flower and die in one growing
  season.

13
Identify the parts of a seed

• Seed Coat
• Hard surface that protects the interior of a
  plant.
• Comprised of two coats
• Testa outer layer
• Endosperm/Cotyledons
• Food storage section of the seed.
• It supplies enough energy for the plant to grow
  until the leaves start to produce energy.

14


15

• Embryo
• The miniature plant that forms from the union of
  the sex gametes.
• Four parts
• Plumule
• 1st terminal bud
• Develops into the first shoot that emerges from
  the seed.

16

• Hypocotyl
• 1st true stem
• Causes the plumule and cotyledons to emerge from
  the seed.
• Radicle
• 1st root of the plant
• 1st to emerge from the seed

17

• Cotyledons
• 1st leaf or leaves that emerge from the seed.
• They fall off after the 1st true leaves form.

18
Define seed dormancy

• Seed Dormancy
• A protective condition that prevents the seed
  from germinating until all of the environmental
  factors required for optimum growth are present.

19
Explain why some seeds will not germinate right
after ripening

• Some seed coats are too thick or extremely hard
  to allow moisture into the embryo.
• Some seed coats contain a chemical inhibitor that
  must be washed away.

20
Define Scarification stratification

• Scarification
• The scratching or removal of the seed coat to
  induce germination.
• Sandpaper
• Removal of an end of the seed
• Create a crack in the seed
• Soak in sulfuric acid
• Must be washed several times after soaking in
  sulfuric acid.
• dried

21
Identify the factors affecting germination

• Water absorption
• The seed does not need to be submerged in water,
  just moist.
• The water softens the seed coat.
• Causes the embryo to release the hormone
  gibberlin.
• Gibberlin activates digestive enzymes that cause
  the release of cytokins auxins.
• Cytokins and auxins induce cell elongation and
  cell division.

22

• Temperature
• Minimum point at which seed will NOT germinate
• 32-39
• Optimum desired level for most species
• 68-86
• Maximum point at which seeds will not germinate
• 113-120

23

• Light
• Affects germination
• 4 types of light
• responsive plants
• Full light
• Half light/ half dark
• Full darkness
• No affect either way

24
Identify germination media requirements and
components

• Requirements
• Not too heavy
• Contain small amount
• of nutrients for plant growth
• Free of all pathogens or weeds
• Holds water, but allows aeration and drainage
  (porosity) components

25

• Vermiculite
• Sterile
• Soft surface
• Light weight
• Holds 500 water by weight (1ft39lbs40 lbs of
  water)

26

• Perlite
• Sterile
• Volcanic rock
• Light weight
• Rough surface holds water because of surface
  tension
• Drains well
• pH 7.0-7.5
• Dusty floats out of the medium

27
Ideal general propagation soil mixture

• Two bushels
• Sphagnum peat moss- 1 bushel
• Horticulture vermiculite 3- 1 bushel
• Ground limestone- 10 tablespoons
• 20 supers phosphate- 5 tablespoons
• Ammonium nitrate- 4 tablespoons
• Chelated iron sequestrene 300- 1 level teaspoon
• marithon systemic insecticide

28
Explain the ideal germination environment

• Aeration
• Must have enough air for respiration
• If the soil is too hard (no pore space), water
  retention will be dramatically reduced

29

• Temperature
• Plants have an optimum temperature for growth
• Bottom heat (5-10 higher than the air
  temperature) helps expedite germination
• Heat should be removed once germination occurs
  because the plants become too succulent (soft)
  and leggy and does not transplant well.

30

• Moisture
• Too much water causes the plant to rot.
• Too light water causes the plant to dry out and
  die.
• Water drives many of the reactions in the plant.
• Photosynthesis, respiration, nutrient uptake and
  nutrient transport

31

• Intermittent Low-Pressure Misting
• Controlled by a
• Time clock
• Solar-activated counter
• Electronic leaf
• Sub irrigation
• Seed flats are soaked with water from the bottom.
• Applied only during daylight hours because of
  disease and lower temperature caused by
  evaporative cooling of the water

32

• Light
• Red wavelengths have the most influence on
  germination
• Far-red light become leggy

33
Identify the proper steps in transplanting a
seedling

• Transplant once the 1st true leaves are fully
  developed
• Only remove plant from the plug-tray that can be
  planted within a few minutes
• Water once transplanted to set the soil and
  prevent drying out