Hort 4040 - 2011

Paul A. Thomas

The University of Georgia

Producing Plants From Seed

No Two Seeds Are Alike

Expiration DateExpiration Date

Planting DepthPlanting Depth

DirectionsDirections

Important Information

SourceSource

Germination Germination PercentagePercentage

Lot NumberLot Number

Scientific NameScientific Name

More Information

•Fungicides/RhyzobiaFungicides/Rhyzobia

•PolycoatingPolycoating

•Pre-germinatedPre-germinated

Seed Coatings

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!

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.

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

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

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..

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

• Physical – Impermeable seed coat : Scarification

• Chemical – Inhibitors in seed coat : Removal / Leaching

Exogenous 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

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

Testing Viability - Simplified

• 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 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

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:

Hot Water Scarification

Water temperature should be over 110OF

Let soak for a fewhours. Stir often.

Do not re-heatthe water.

Plant ASAP.

Mechanical Scarification

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.

Germination Of Lettuce

Handling Tiny Seeds

Mix Seed with Sand

Electric Heating Tapes