2005 Plant Propagation Workshop

Paul A. Thomas and Bodie. V. Pennisi

The University of Georgia

Southeast Greenhouse Conference

Producing Plants From Seed

No Two Seeds Are Alike

Provenance : A seed’s origin, in A seed’s origin, in terms of climate and geographical terms of climate and geographical location. This canlocation. This canHave profound effects on seed Have profound effects on seed germination and the plant’s germination and the plant’s survival. Example: Hemlocks survival. Example: Hemlocks grown from southern North grown from southern North Carolina seed sources are more Carolina seed sources are more heat tolerant than Hemlocks grown heat tolerant than Hemlocks grown

from Pennsylvania seed sources.from Pennsylvania seed sources.

Seed Collecting

Seed Collecting

Seeds collected from hybrids rarely look Seeds collected from hybrids rarely look like the parent plant due to the random like the parent plant due to the random reassortment of genetic material, and reassortment of genetic material, and the random sources of pollen. Native the random sources of pollen. Native species tend to be more stable, but also species tend to be more stable, but also have variation between generations.have variation between generations.

To get a clone, try vegetative propagation!To get a clone, try vegetative propagation!

Landraces – Populations of plants – Populations of plants maintained over hundreds of years by maintained over hundreds of years by farmers by holding over some of the farmers by holding over some of the seed crop. This seed crop. This allowed for local allowed for local specialization and specialization and great differences great differences in genetic makeupin genetic makeup

Terms To Know

Heritage Varieties

Vegetables and Vegetables and flowers that were flowers that were grown and passed grown and passed on through many on through many generations by generations by families.families.

Inbred Lines – Progeny from identical – Progeny from identicallines that are homozygous. These are lines that are homozygous. These are then used to make hybridsthen used to make hybrids

Hybrid Lines – The progeny of two – The progeny of two or more inbred linesor more inbred lines

Terms To Know

Seed Cleaning / Separation

For many dry seed, simply For many dry seed, simply crush dried material and crush dried material and blow gently, transferring blow gently, transferring the seed from hand to hand.the seed from hand to hand.

Cleaning seed reduces Cleaning seed reduces disease and weed seed disease and weed seed from growing along with from growing along with your selectionyour selection

Fleshy Berry Seed

• FermentationFermentation

• FlotationFlotation

• Blender SeparationBlender Separation

• Screen-Press SeparationScreen-Press Separation

• Gravity SeparatorsGravity Separators

• Hand SeparationHand Separation

• SiftingSifting

• Drying (Heating Pine Cones) Drying (Heating Pine Cones)

Extraction Methods

Seed Deterioration

Seeds lose half their storage life for Seeds lose half their storage life for every 1% increase in seed moisture every 1% increase in seed moisture between 5 and 14%.between 5 and 14%.

Seeds lose half their storage life for Seeds lose half their storage life for every 5 degrees C increase in storage every 5 degrees C increase in storage temperature between 0temperature between 0ooand 50and 50ooC.C.

Seed Storage

Moist Storage @35 to 50Moist Storage @35 to 50ooFF

Dry Storage @ 35 to 50Dry Storage @ 35 to 50ooFF**

Cold Storage @ 0Cold Storage @ 0ooF, –18F, –18ooC C **

Cryopreservation @ -196Cryopreservation @ -196ooC C **

*** *** at 3 – 8% Moistureat 3 – 8% Moisture

Recalcitrant Seed – These seeds are able – These seeds are able to germinate without dessicating. These to germinate without dessicating. These seeds lose viability after drying and must seeds lose viability after drying and must be planted quickly. be planted quickly. Oak, Maple, Coffee

Orthodox Seed – The seeds dessicate – The seeds dessicate after reaching full development to allow after reaching full development to allow the seed to be quiescent or dormant until the seed to be quiescent or dormant until conditions are right to germinate. conditions are right to germinate. Beans

Terms To Know

SEED STORAGE

Recalcitrant Seed – Short-term Viability

Tropical – Store warm and moist (ASAP) – Store warm and moist (ASAP)Coffee, Cocoa, Mango, Macadamia, Avocado, Tea

Subtropical – Store cool and moist (ASAP) – Store cool and moist (ASAP)Maple, Oak, Elm, Poplar, Salix,

Orthodox Seed

Short-Lived – Store dry and cold (Under 1 yr) – Store dry and cold (Under 1 yr)Vinca, Pansy, Begonia

Medium - Lived - Store dry and cold ( 2-5 years) - Store dry and cold ( 2-5 years)Marigold, Petunia, Coleus

Long - Lived – Store dry and cold ( 5-200 years) – Store dry and cold ( 5-200 years)Morning Glory, Zinnia, Hollyhock

Life Expectancy Of Selected Seeds

Sugar MapleSugar Maple 2 weeks 2 weeksEnglish ElmEnglish Elm 26 weeks 26 weeksCockleburCocklebur 16 years 16 yearsWhite CloverWhite Clover 90 years 90 yearsSensitive PlantSensitive Plant 200 years 200 yearsIndian LotusIndian Lotus 1,040 years 1,040 yearsArtic Lupine 10,000 yearsArtic Lupine 10,000 years

Testing Viability - Simplified

Handling Tiny Seeds

Mix Seed with Sand

•Fungicides/RhyzobiaFungicides/Rhyzobia

•PolycoatingPolycoating

•Pre-germinatedPre-germinated

Seed Coatings

Expiration DateExpiration Date

Planting DepthPlanting Depth

DirectionsDirections

Important Information

SourceSource

Germination Germination PercentagePercentage

Lot NumberLot Number

Scientific NameScientific Name

More Information

The Cycle of Life

1. Imbibed water stimulates Gibberellin synthesis.

2-3. Gibberellins diffuse to the aleurone layer and stimulate the synthesis of enzymes.

4-5. Enzymes break down the starch and the sugars are transported to the developing embryo..

Seed and Plant Dormancy

Dormancy is the condition Dormancy is the condition In which seeds will not In which seeds will not Germinate… even when Germinate… even when most of the environmental most of the environmental conditions are permissive conditions are permissive for germination. There are for germination. There are many types of dormancy!many types of dormancy!

Advantages of Seed Dormancy

• Favors seedling survivalFavors seedling survival

• Creates a seed bankCreates a seed bank

• Seed dispersal (birds)Seed dispersal (birds)

• Synchronizes germination with seasonsSynchronizes germination with seasons

Types of Dormancy in Seed

Quiescent – The seeds are able to Germinate upon – The seeds are able to Germinate upon imbibition of water at permissive temperatures. imbibition of water at permissive temperatures.

Primary Dormancy – Seeds cannot germinate – Seeds cannot germinateeven if immediate conditions are right. This form of even if immediate conditions are right. This form of dormancy delays germination until season, or otherdormancy delays germination until season, or othermacro-environmental issues are right for survival.macro-environmental issues are right for survival.

Secondary Dormancy – An additional level of – An additional level of Protection to prevent germination. Can be induced under Protection to prevent germination. Can be induced under very unfavorable conditions such as drought or cold, etc. very unfavorable conditions such as drought or cold, etc.

Exogenous Dormancy - Imposed by - Imposed by factors outside the embryo. factors outside the embryo. Seed coat.

Endogenous Dormancy – Imposed by – Imposed by factors within the embryo. factors within the embryo. Underdeveloped embryo.

Types of Dormancy in Seed

Secondary Dormancy - Factors outside - Factors outsidethe seed induce dormancy after the the seed induce dormancy after the seed was previously non-dormant. seed was previously non-dormant. High Soil Temperatures (Thermo-dormancy) (Thermo-dormancy)

Types of Dormancy in Seed

Double Dormancy - Any combination - Any combination of endogenous and exogenous factorsof endogenous and exogenous factors

• Physical – Impermeable seed coat : Scarification

• Mechanical – Seed covering restricts radical : Removal

• Chemical – Inhibitors in seed coat : Removal / Leaching

Exogenous Dormancy

Morphological - Underdeveloped embryo : Warm Stratification

Physiological

• Non-Deep – After Ripening : Dry storage

Photo-dormant : Exposure to red light.

• Intermediate – Embryo/coat separation : Cold Stratification

• Epicotyl – Epicotyl dormant : Warm - Cold Stratification

Endogenous Dormancy

Morpho-physiological – Some combination of underdeveloped embryo and physiological dormancy:

Cycles of warm and cold stratification.

Exo-Endodormancy – Combination of exogenous and endogenous dormancy conditions

Sequential combinations of dormancy releasing treatments, Eg. Scarification followed by cold stratification

Double Dormancy

• Thermo-dormancy - High temperatures induce dormancy

Growth regulators or Cold stratification

• Conditional – Change in ability to germinate is related to time of year.

Chilling or Warm stratification

Secondary Dormancy

Photodormancy

Photodormancy : A type of dormancy : A type of dormancy where the ability of the seed to germinate where the ability of the seed to germinate is controlled by the wavelengths and is controlled by the wavelengths and durations of light received by the embryo.durations of light received by the embryo.

Lettuce, Butterflyweed, Tobacco

Germination Of Lettuce

Preconditioning Seeds(for more uniform germination)(for more uniform germination)

Mechanical scarificationMechanical scarificationSoaking In WaterSoaking In WaterAcid ScarificationAcid ScarificationMoist Chilling / FreezingMoist Chilling / FreezingDouble Dormancy

Methods:

Mechanical Scarification

Acid Scarification

An alternative toAn alternative toscraping the seed scraping the seed coat is to use acid coat is to use acid to etch through to etch through the coat. Therethe coat. Thereare many referenceare many referencebooks that advisebooks that advisewhich acid andwhich acid andhow long to treat.how long to treat.

Hot Water Scarification

Water temperature should be over 110OF

Let soak for a fewhours. Stir often.

Do not re-heatthe water.

Plant ASAP.

Moist Stratification Cold or Warm

Seed Soaking / Leaching

Seed soaking optimizes the amount of imbibed Seed soaking optimizes the amount of imbibed seeds and evens out the stage of imbibition by seeds and evens out the stage of imbibition by insuring 100% moisture availabilityinsuring 100% moisture availability

Soaking too long Soaking too long can cause anoxia can cause anoxia and reduced and reduced germination. 12-36germination. 12-36hours is a very hours is a very common soakingcommon soakingperiod.period.

Clean & Organized Environment

Window-Box Propagation

Two clear halves of sweater/storage boxes taped Two clear halves of sweater/storage boxes taped together with duct tape as a hinge make ideal together with duct tape as a hinge make ideal propagation boxes!propagation boxes!

Place the box in a Place the box in a sunny window, and sunny window, and open it up for an hour open it up for an hour at night to replace airat night to replace airand dry off leaves.and dry off leaves.

Works for almost allWorks for almost alltropical plants.tropical plants.

Root Zone HeatingRooting medium temperature, given control, may beRooting medium temperature, given control, may be

applied to speed up growth. A good example is usingapplied to speed up growth. A good example is using

heating pads under planted seed flats to speed heating pads under planted seed flats to speed

up germination or rooting. The right temperatureup germination or rooting. The right temperature

can take a can take a

week or month week or month

off of rooting off of rooting

schedule and schedule and

can take a few can take a few

days to a few weeks days to a few weeks

off of germination. off of germination.

Time is moneyTime is money..

Electric Heating Tapes

We need to provide seedlings a film of water to We need to provide seedlings a film of water to reduce evaporation, and the loss of water. Tooreduce evaporation, and the loss of water. Toomuch water is as bad as too little water!much water is as bad as too little water!

Mist Benches

Fungicides

BanRot!BanRot!

Follow The Label Directions!

Seedling Production Options

Community PotCommunity PotSeeding BoxSeeding BoxPlug TrayPlug TrayFabric MattFabric MattHydroseedingHydroseedingDirect BroadcastDirect Broadcast

•Proper seed bedProper seed bed•Proper planting seasonProper planting season•Proper pretreatmentProper pretreatment•Proper seed handlingProper seed handling•Proper sowing depthProper sowing depth•Proper sowing rateProper sowing rate•Proper post-sowing careProper post-sowing care

Sowing Success

• Minimize root disruption!

• Never press on roots or handle roots!

• Never compact soil around roots

• Work quickly and gently

• Re - water in transplants in minutes

Transplanting SeedlingsTransplanting Seedlings

• Use low levels of fertilizer 50 ppm!

• Do not allow to become dry.

• Do not allow to stay saturated!

• Modify light levels according to species.

• Scout seedling several times a day!

Growing Out SeedlingsGrowing Out Seedlings

Some of the seeds of hopeSome of the seeds of hope

Planted tentatively in the fallPlanted tentatively in the fallHave not come upHave not come up

They lie stillborn and unrealizedThey lie stillborn and unrealizedSomewhere in the spring soilSomewhere in the spring soil

DecayingDecayingThe Strongest and best onesThe Strongest and best onesPushed up though the leavesPushed up though the leaves

And layers of cold, hard resistanceAnd layers of cold, hard resistanceRight into clear blue airRight into clear blue air

And stand there nakedly greenAnd stand there nakedly greenBreathingBreathing

It's always that way with growing thingsIt's always that way with growing thingsNever knowing at the startNever knowing at the start

Which will make it and which will failWhich will make it and which will failBut the thing to hold fast toBut the thing to hold fast to

Never to lose faith in, is simply,Never to lose faith in, is simply, SowingSowing

Gardener by Ann North