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SEED ANALYSIS FACT SHEET : GERMINATION AND DORMANCY
THE GERMINATION TEST
Germination is probably the single most convincing and accepted index of
seed quality. The exact procedures and regimes under which different
kinds of seeds are germinated have been developed over 100 years of experience
of experience in germination testing and have been augmented during the last
50 years by a systematic program of referee testing involving interchange
of samples and results among laboratories.
AOSA (Association of Official Seed Analysts) Rules for Testing Seed
covers the following aspects of germination testing:
1. Generally use 400 seeds in four replications
of 100 seeds each. A minimum of 200 seeds can be used when double tests
are done and for mixtures.
2. The pure seed or pure seed unit is used for
the test. The germination is directly affected by what is defined as
pure seed. AOSA rules define pure seed.
3. AOSA rules also provide the following species
a. Substrate: examples are blotters, towels, kimpak,
b. Recommended temperatures in centigrade: frequently
used temperatures are 20/30c alternating, 20c, 15c, constant.
c. Number of days in the test for maximum germination.
d. Additional instructions: KNO3, light (8 hours
minimum), prechilling for certain number of days at 5c or 10c.
4. The interpretation of a normal seedling is
based on written definitions and drawings of normal and abnormal seedlings
for most kinds of seeds tested.
Reasons why seeds do not germinate:
causes: physical, chemical, environmental, insufficient maturation
1. physical restraints
seed coat, fruit coat
layer over radicle
2. chemical restraints
hormones examples: GA, ethylene
nutrients example: KNO3
water and oxygen: too much or too little of either
· some species light inhibited
examples: Nemophila, Phacelia (flower
· some species light promoted
example: red light is needed for germination
of grand rapids lettuce
· alternating temperatures
· constant temperatures too high or too
Some seeds have rudimentary, basal or axile
In families: apiaceae, papaveraceae, ranunculaceae,
liliaceae. (onions, asparagus, carrots, buttercups, poppies, columbine).
Embryos need to grow and develop within the seed before they will germinate.
SEED DETERIORATION, DEATH, OR SEVERE IMMATURITY
1. Seed deterioration or death:
a. pathogens: fungi, bacteria, virus, insects
b. mechanical injury: improper handling, conditioning
c. temperature (improper storage): heat or cold damage
d. age: seed constituents break down, cells stop respiration
2. Severe immaturity: seed harvested too early,
or essential tissues aborted (nutritive tissues or embryo). Insufficient
nutrients or embryo development to support germination.
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