Seed Storage - University of Georgia

Producing Plants From Seed Paul A. Thomas and Bodie. V. Pennisi The University of Georgia

2005 Plant Propagation Workshop Southeast Greenhouse Conference

No Two Seeds Are Alike

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

Seed Collecting Seeds collected from hybrids rarely look like the parent plant due to the random reassortment of genetic material, and the random sources of pollen. Native species tend to be more stable, but also have variation between generations. To get a clone, try vegetative propagation!

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

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

Terms To Know Inbred Lines – Progeny from identical lines that are homozygous. These are then used to make hybrids Hybrid Lines – The progeny of two or more inbred lines

Seed Cleaning / Separation Cleaning seed reduces disease and weed seed from growing along with your selection

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

Fleshy Berry Seed

Extraction Methods • Fermentation

• Flotation • Blender Separation • Screen-Press Separation • Gravity Separators • Hand Separation • Sifting • Drying (Heating Pine Cones)

Seed Deterioration Seeds lose half their storage life for every 1% increase in seed moisture between 5 and 14%. Seeds lose half their storage life for every 5 degrees C increase in storage o o temperature between 0 and 50 C.

Seed Storage o

Moist Storage @35 to 50 F o

Dry Storage @ 35 to 50 F* o

o

Cold Storage @ 0 F, –18 C * o

Cryopreservation @ -196 C * *** at 3 – 8% Moisture

Terms To Know Recalcitrant Seed – These seeds are able to germinate without dessicating. These seeds lose viability after drying and must be planted quickly. Oak, Maple, Coffee Orthodox Seed – The seeds dessicate after reaching full development to allow the seed to be quiescent or dormant until conditions are right to germinate. Beans

SEED STORAGE Recalcitrant Seed – Short-term Viability Tropical – Store warm and moist (ASAP) Coffee, Cocoa, Mango, Macadamia, Avocado, Tea Subtropical – Store cool and moist (ASAP) Maple, Oak, Elm, Poplar, Salix,

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

Medium - Lived - Store dry and cold ( 2-5 years) Marigold, Petunia, Coleus Long - Lived – Store dry and cold ( 5-200 years) Morning Glory, Zinnia, Hollyhock

Life Expectancy Of Selected Seeds Sugar Maple English Elm Cocklebur White Clover Sensitive Plant Indian Lotus Artic Lupine

2 weeks 26 weeks 16 years 90 years 200 years 1,040 years 10,000 years

Testing Viability - Simplified

Handling Tiny Seeds

Mix Seed with Sand

Seed Coatings

•Fungicides/Rhyzobia •Polycoating •Pre-germinated

Important Information Directions

Planting Depth

Expiration Date Source

More Information

Lot Number

Germination Percentage

Scientific Name

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

Advantages of Seed Dormancy • Favors seedling survival

• Creates a seed bank • Seed dispersal (birds)

• Synchronizes germination with seasons

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

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

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

Types of Dormancy in Seed

Exogenous Dormancy - Imposed by factors outside the embryo. Seed coat. Endogenous Dormancy – Imposed by factors within the embryo. Underdeveloped embryo.

Types of Dormancy in Seed Double Dormancy - Any combination of endogenous and exogenous factors Secondary Dormancy - Factors outside the seed induce dormancy after the seed was previously non-dormant. High Soil Temperatures (Thermo-dormancy)

Exogenous Dormancy

• Physical – Impermeable seed coat : Scarification • Mechanical – Seed covering restricts radical : Removal • Chemical – Inhibitors in seed coat : Removal / Leaching

Endogenous 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

Double 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

Secondary 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

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

Lettuce, Butterflyweed, Tobacco

Germination Of Lettuce

Preconditioning Seeds (for more uniform germination)

Methods: Mechanical scarification Soaking In Water Acid Scarification Moist Chilling / Freezing Double Dormancy

Mechanical Scarification

Acid Scarification An alternative to scraping the seed coat is to use acid to etch through the coat. There are many reference books that advise which acid and how long to treat.

Hot Water Scarification Water temperature should be over 110OF Let soak for a few hours. Stir often. Do not re-heat the water. Plant ASAP.

Moist Stratification Cold or Warm

Seed Soaking / Leaching Seed soaking optimizes the amount of imbibed seeds and evens out the stage of imbibition by insuring 100% moisture availability Soaking too long can cause anoxia and reduced germination. 12-36 hours is a very common soaking period.

Clean & Organized Environment

Window-Box Propagation Two clear halves of sweater/storage boxes taped together with duct tape as a hinge make ideal propagation boxes! Place the box in a sunny window, and open it up for an hour at night to replace air and dry off leaves. Works for almost all tropical plants.

Root Zone Heating Rooting medium temperature, given control, may be applied to speed up growth. A good example is using heating pads under planted seed flats to speed up germination or rooting. The right temperature can take a week or month off of rooting schedule and can take a few days to a few weeks off of germination. Time is money.

Electric Heating Tapes

Mist Benches

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

Fungicides BanRot!

Follow The Label Directions!

Seedling Production Options Community Pot Seeding Box Plug Tray Fabric Matt Hydroseeding Direct Broadcast

Sowing Success •Proper seed bed •Proper planting season •Proper pretreatment •Proper seed handling •Proper sowing depth •Proper sowing rate •Proper post-sowing care

Transplanting Seedlings • • • • •

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

Growing Out 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!

Gardener by Ann North

Some of the seeds of hope Planted tentatively in the fall Have not come up They lie stillborn and unrealized Somewhere in the spring soil Decaying The Strongest and best ones Pushed up though the leaves And layers of cold, hard resistance Right into clear blue air And stand there nakedly green Breathing It's always that way with growing things Never knowing at the start Which will make it and which will fail But the thing to hold fast to Never to lose faith in, is simply, Sowing