Florida Orchid Conservation Conference 2011
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Orchid Seed Germination
Dr. Philip Kauth
Post-doc Research Associate
Environmental Horticulture Department
University of Florida
What Will We Learn?
Basic orchid seed biology
How orchid seeds germinate
Techniques to germinate orchid seeds
How to actually sow orchid seeds
Florida Orchid Conservation Conference 2011
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Let’s Talk Seeds
Dicot
Monocot
Orchid Seeds are Different
No or limited nutrient reserves
Dust-like
Wind dispersal
Tiny embryo inside the seed coat
Mass of cells
Undifferentiated
Require a fungus to support germination
and development
Tim Johnson
Florida Orchid Conservation Conference 2011
3
Orchid Seed Germination
Orchid seeds consume mycorrhizal fungi
Water, carbohydrates, minerals, vitamins
Germination in nature:
Very low
Lengthy process
Scott Stewart Scott Stewart
Orchid Seed Germination
Most reliable germination technique
In vitro seed germination
Seeds are germinated under sterile conditions
Surface sterilize seeds
Germinate seeds on nutrient medium
Germination is often higher than in nature
Florida Orchid Conservation Conference 2011
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How Do Orchid Seeds Germinate?
Johnson, 2007 Stewart and Zettler, 2002
*Remember this is in vitro germination*
Germination Techniques
2 techniques exist:
Symbiotic germination
Germination with mycorrhizal fungi
First discovered and practiced in late 1890s
Asymbiotic germination
Germination without the mycorrhizal fungus
First discovered in 1920s
Scott Stewart
Florida Orchid Conservation Conference 2011
5
Symbiotic Germination
Isolate fungi from roots or developing seeds
Culture and maintain fungi
Germinate seeds in vitro with fungi
Culture medium is low nutrient source
Oats, cornmeal, potato
Johnson et al 2007 S. Stewart
Asymbiotic Germination
Seeds germinated in vitro without fungi
Must provide nutrients
Germination media contain
Carbohydrates: sucrose, glucose, fructose
Minerals: nitrogen, potassium, phosphorus,
calcium, iron, etc.
Organic supplements: banana, potato,
coconut water
D. Dutra
Florida Orchid Conservation Conference 2011
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Technique Comparison
Symbiotic Best technique for plant reintroduction
Often higher germination rates depending on species
Perceived as difficult/extra steps and techniques
Use appropriate fungus
Asymbiotic Environmental seed germination conditions
If a fungus can’t be isolated
Long-term plant survival is low in nature
Preferred for production
Johnson et al 2007
Asymbiotic Germination
2 asymbiotic techniques Mature or dry seed
Use mature, loose seed
Individual seeds are surface sterilized
Seeds can be stored until use
Greater chance of contamination
Immature seed or green capsule Use immature seed inside seed capsule
Whole capsule is surface sterilized
Seeds are sterile inside capsule
Reduced contamination
Seeds can’t be stored
Florida Orchid Conservation Conference 2011
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Let’s Begin!
a: laminar flow hood
b: various culture vessels
c: containers
d: ethanol and bleach
e & f: tools
At Home
Substitutions
Pressure cooker for autoclave
Tupperware container for flow hood
Wipe inside with bleach
Clean surface areas with bleach
Florida Orchid Conservation Conference 2011
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Dry Seed Method
Dilute bleach solution Sterilize seeds Replace bleach
with water
Sterilized seeds Dip and plate
method
Inoculate seeds
