sexual propagation

Sexual Sexual PropagationPropagation

ObjectivesObjectives

Objective 17.1Objective 17.1Define Propagation.Define Propagation.

Objective 17.2Objective 17.2List the two types of plant propagation.List the two types of plant propagation.

Objective 17.3Objective 17.3Define germination.Define germination.

Objective 17.4Objective 17.4Identify the life cycle of plants.Identify the life cycle of plants.

Objective 17.5Objective 17.5Identify the parts of a seed.Identify the parts of a seed.

Objective 17.6Objective 17.6Define seed dormancy.Define seed dormancy.

Objective 17.7Objective 17.7Explain why some seeds will not Explain why some seeds will not germinate right after ripening.germinate right after ripening.

Objective 17.8Objective 17.8Define scarification.Define scarification.

Objective 17.9Objective 17.9Identify the factors affecting germination.Identify the factors affecting germination.

Objective 17.10Objective 17.10Identify germination media Identify germination media requirements and components.requirements and components.

Objective 17.11Objective 17.11Explain the ideal germination Explain the ideal germination environment.environment.

Objective 17.12Objective 17.12Identify the proper steps in Identify the proper steps in transplanting a seedling.transplanting a seedling.

Define PropagationDefine Propagation

Propagation: the Propagation: the increase of a plant increase of a plant species from one species from one generation to the generation to the nextnext

List the two types of plant List the two types of plant propagationpropagation

Sexual propagation:Sexual propagation:– The union of a male The union of a male

and female gamete.and female gamete.– Produces a Produces a

genetically unique genetically unique offspring.offspring.

Asexual propagation:Asexual propagation:– The “clone” of a plant The “clone” of a plant

that is genetically that is genetically identical to the identical to the “mother plant.”“mother plant.”

Define germinationDefine germination

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

Stages of GerminationStages of Germination

Identify the life cycle of plantsIdentify the life cycle of plantsAnnuals:Annuals:

–Germinate, grow, flower and die in Germinate, grow, flower and die in one growing season.one growing season.

Identify the parts of a seedIdentify the parts of a seed Seed Coat:Seed Coat:– Hard surface that protects Hard surface that protects

the interior of a plant.the interior of a plant.Comprised of two coatsComprised of two coats

– Testa: outer layerTesta: outer layer Endosperm/Cotyledons:Endosperm/Cotyledons:

– Food storage section of the Food storage section of the seed.seed.It supplies enough energy It supplies enough energy

for the plant to grow until for the plant to grow until the leaves start to produce the leaves start to produce energy.energy.

Embryo:Embryo:– The miniature plant that forms from the The miniature plant that forms from the

union of the sex gametes.union of the sex gametes.Four partsFour parts

– Plumule: Plumule: 11stst terminal bud terminal budDevelops into the first shoot that Develops into the first shoot that

emerges from the seed.emerges from the seed.

– Hypocotyl:Hypocotyl:11stst true stem true stem

– Causes the Causes the plumule and plumule and cotyledons to cotyledons to emerge from emerge from the seed.the seed.

– Radicle:Radicle:11stst root of the root of the

plantplant11stst to emerge to emerge

from the seedfrom the seed

–Cotyledons:Cotyledons:11stst leaf or leaves leaf or leaves that emerge that emerge from the seed.from the seed.

They fall off after They fall off after the 1the 1stst true true leaves form.leaves form.

Define seed dormancyDefine seed dormancy Seed Dormancy:Seed Dormancy:

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

Explain why some seeds will not Explain why some seeds will not germinate right after ripeninggerminate right after ripening

Some seed coats are too thick or Some seed coats are too thick or extremely hard to allow moisture extremely hard to allow moisture into the embryo.into the embryo.

Some seed coats contain a Some seed coats contain a chemical inhibitor that must be chemical inhibitor that must be washed away.washed away.

Define Scarification & stratificationDefine Scarification & stratification

Scarification: Scarification: – The scratching or removal of the seed The scratching or removal of the seed

coat to induce germination.coat to induce germination.SandpaperSandpaperRemoval of an end of the seedRemoval of an end of the seedCreate a crack in the seedCreate a crack in the seedSoak in sulfuric acidSoak in sulfuric acid

– Must be washed several times after soaking in Must be washed several times after soaking in sulfuric acid.sulfuric acid.

– drieddried

Identify the factors affecting Identify the factors affecting germinationgermination

Water absorptionWater absorption– The seed does not need to be submerged The seed does not need to be submerged

in water, just moist.in water, just moist.– The water softens the seed coat.The water softens the seed coat.– Causes the embryo to release the Causes the embryo to release the

hormone gibberlin.hormone gibberlin.– Gibberlin activates digestive enzymes Gibberlin activates digestive enzymes

that cause the release of cytokins & that cause the release of cytokins & auxins.auxins.

– Cytokins and auxins induce cell Cytokins and auxins induce cell elongation and cell division.elongation and cell division.

TemperatureTemperature– Minimum: point at which seed will Minimum: point at which seed will NOTNOT

germinategerminate32-3932-39

– Optimum: desired level for most speciesOptimum: desired level for most species68-8668-86

– Maximum: point at which seeds will not Maximum: point at which seeds will not germinategerminate113-120113-120

LightLight– Affects germinationAffects germination– 4 types of light 4 types of light

responsive plantsresponsive plantsFull lightFull lightHalf light/ half darkHalf light/ half darkFull darknessFull darknessNo affect either wayNo affect either way

Identify germination media Identify germination media requirements and componentsrequirements and components

RequirementsRequirements– Not too heavyNot too heavy– Contain small amount Contain small amount

of nutrients for plant growthof nutrients for plant growth– Free of all pathogens or weedsFree of all pathogens or weeds– Holds water, but allows aeration and Holds water, but allows aeration and

drainage (porosity) componentsdrainage (porosity) components

VermiculiteVermiculite– SterileSterile– Soft surfaceSoft surface– Light weightLight weight– Holds 500 % water by weight Holds 500 % water by weight

(1ft3=9lbs=40 lbs of water)(1ft3=9lbs=40 lbs of water)

PerlitePerlite– SterileSterile– Volcanic rockVolcanic rock– Light weightLight weight– Rough surface holds water because of Rough surface holds water because of

surface tensionsurface tension– Drains wellDrains well– pH 7.0-7.5pH 7.0-7.5– Dusty & floats out of the mediumDusty & floats out of the medium

Ideal general propagation soil Ideal general propagation soil mixturemixture

Two bushelsTwo bushels– Sphagnum peat moss- 1 bushelSphagnum peat moss- 1 bushel– Horticulture vermiculite 3- 1 bushelHorticulture vermiculite 3- 1 bushel– Ground limestone- 10 tablespoonsGround limestone- 10 tablespoons– 20% supers phosphate- 5 tablespoons20% supers phosphate- 5 tablespoons– Ammonium nitrate- 4 tablespoonsAmmonium nitrate- 4 tablespoons– Chelated iron sequestrene 300- 1 level Chelated iron sequestrene 300- 1 level

teaspoonteaspoon

* marithon= systemic insecticide* marithon= systemic insecticide

Explain the ideal germination Explain the ideal germination environmentenvironment

AerationAeration– Must have enough air for respirationMust have enough air for respiration– If the soil is too hard (no pore space), If the soil is too hard (no pore space),

water retention will be dramatically water retention will be dramatically reducedreduced

TemperatureTemperature– Plants have an optimum Plants have an optimum

temperature for growthtemperature for growth– Bottom heat (5-10 higher than the Bottom heat (5-10 higher than the

air temperature) helps expedite air temperature) helps expedite germinationgermination

– Heat should be removed once Heat should be removed once germination occurs because the germination occurs because the plants become too succulent (soft) plants become too succulent (soft) and “leggy” and does not and “leggy” and does not transplant well.transplant well.

MoistureMoisture– Too much water causes the plant to Too much water causes the plant to

rot.rot.– Too light water causes the plant to dry Too light water causes the plant to dry

out and die.out and die.Water drives many of the reactions Water drives many of the reactions in the plant.in the plant.–Photosynthesis, respiration, Photosynthesis, respiration, nutrient uptake and nutrient nutrient uptake and nutrient transporttransport

Intermittent Low-Pressure MistingIntermittent Low-Pressure Misting– Controlled by a Controlled by a

Time clockTime clockSolar-activated counterSolar-activated counterElectronic leafElectronic leaf

Sub irrigationSub irrigation– Seed flats are soaked with water from the Seed flats are soaked with water from the

bottom.bottom.

** Applied only during daylight hours because of Applied only during daylight hours because of disease and lower temperature caused by disease and lower temperature caused by evaporative cooling of the waterevaporative cooling of the water

LightLight– Red wavelengths have the most Red wavelengths have the most

influence on germinationinfluence on germination– Far-red light become “leggy”Far-red light become “leggy”

Identify the proper steps in Identify the proper steps in transplanting a seedlingtransplanting a seedling

Transplant once the 1Transplant once the 1stst true leaves are fully true leaves are fully developeddeveloped

Only remove plant Only remove plant from the plug-tray that from the plug-tray that can be planted within can be planted within a few minutesa few minutes

Water once Water once transplanted to set the transplanted to set the soil and prevent soil and prevent drying outdrying out