Lecture 5.1 Flashcards
SEED TESTING
SEED TESTING PURPOSE Before collection
Assess crop
Test maturity
SEED TESTING PURPOSE During processing
Determine the need of after-ripening
Determine the need of drying
Determine the need of cleaning
SEED TESTING PURPOSE After processing
Determine if seed is suitable for plant production
Determine the potential for production of viable plants from the seedlot
Determine if dormancy releasing treatment is needed
Determine the appropriate sowing density
Determine if seed suitable for storage
Determine the price of the seed – seed trade
SAMPLING Purpose:
to obtain a sample of a size suitable for tests,
in which the probability of a constituent being
present is determined only by its level of
occurrence in the seedlot
to obtain a sample of a size suitable for tests,
in which the probability of a constituent being
present is determined only by its level of
occurrence in the seedlot
SAMPLING Purpose:
Sampling Intensity and Size:
Up to 5 containers
Sample each container. Always take at least 5
primary samples
Sample each container. Always take at least 5
primary samples
Sampling Intensity and Size:
Up to 5 containers
Sampling Intensity and Size:
6-30 containers
Sample 5 containers or at least 1 in every 3
containers, whichever is greater
Sample 5 containers or at least 1 in every 3
containers, whichever is greater
Sampling Intensity and Size:
6-30 containers
Sampling Intensity and Size:
31-400 containers
Sample 10 containers or at least 1 in every 5
containers, whichever is greater.
Sample 10 containers or at least 1 in every 5
containers, whichever is greater.
Sampling Intensity and Size:
31-400 containers
Sampling Intensity and Size:
401 or more containers
Sample 80 containers or at least 1 in every 7
containers, whichever is greater.
Sample 80 containers or at least 1 in every 7
containers, whichever is greater.
Sampling Intensity and Size:
401 or more containers
rectangular ports are held in a frame, the ports alternately opening to the left and right.
Soil or Rifle Divider
rectangular ports are held in a frame, the ports alternately opening to the left and right.
Soil or Rifle Divider
Soil or Rifle Divider
rectangular ports are held in a frame, the ports alternately opening to the left and right.
is a probe, long enough to reach all areas of the container and designed to remove an equal volume of seed from each area through which it travels (also named stick sampler).
Seed Trier
Seed Trier
is a probe, long enough to reach all areas of the container and designed to remove an equal volume of seed from each area through which it travels (also named stick sampler).
Sampling Instruments (4)
Soil or Rifle Divider
Seed Trier
Inverted cone divider
Seed dividers
Purpose: To determine the composition by weight of the sample being tested.
Purity Analysis
Purity Analysis purpose
To determine the composition by weight of the sample being tested.
Procedure:
Working sample should contain at least 2,500 seeds. Separate working sample into pure seed, other seed and inert matter.
Purity Analysis
Purity Analysis Procedure
Working sample should contain at least 2,500 seeds. Separate working sample into pure seed, other seed and inert matter.
Purity Analysis:
includes undersized, shriveled, immature and germinated seed, provided they can be definitively identified as the species under consideration. It also includes seed pieces resulting from breakage that are more than half their original size.
Pure seed
Pure seed
includes undersized, shriveled, immature and germinated seed, provided they can be definitively identified as the species under consideration. It also includes seed pieces resulting from breakage that are more than half their original size.
pure seed of other species.
Other seed
Other seed
pure seed of other species.
comprises seed-derived structures like seed-wings as well as other matter not defined as pure seed.
Inert matter
Inert matter
comprises seed-derived structures like seed-wings as well as other matter not defined as pure seed.
Number of seed per unit weight test PURPOSE
Allows calculation of weight of seed to be sown
Seed weight is positively related to seed quality
Allows calculation of weight of seed to be sown
Seed weight is positively related to seed quality
Number of seed per unit weight test PURPOSE
Number of seed per unit weight test Procedure:
1.Eight (8) random replicates of 100 pure seeds.
2.The 8 reps are weighed individually.
3.Calculate the number of seed per kilogram as follows:
4. Compute for the coefficient of variation as:
5.
Crucial during seed storage and handling
Determines the biochemical and physiological
activity of the seed
Moisture Content
Moisture Content
Crucial during seed storage and handling
Determines the biochemical and physiological
activity of the seed
Establish the maximum number of seeds which can germinate under optimum conditions in terms of light, moisture and temperature.
Germination Test
Germination Test purpose
Establish the maximum number of seeds which can germinate under optimum conditions in terms of light, moisture and temperature.
Germination Test
Why use standardized ideal conditions?
- Difference between results can be ascribed to true difference between seed
samples and not to different test methods. - Results obtained for a given seedlot in one laboratory should be identical to
results obtained in any other laboratory, i.e. results are reproducible.
The germination capacity is not equal to the field nursery germination but
in most cases the two figures are strongly related.
Germination Test
General Principles
Consists of 4 reps at 100 seeds per rep
* Uniformly spread the seed, 1.5-5 X the seed width
* Very small seed like Eucalyptus is tested by weight 4 replicates of 0.1 to 1.0 g. Germination is expressed as number of germinants per gram.
Germination
emergence and development of
the seedling to a stage where the
aspect of its essential structures
indicates whether or not it is able
to develop further into a
satisfactory plant under favorable
conditions in the soil
emergence and development of
the seedling to a stage where the
aspect of its essential structures
indicates whether or not it is able
to develop further into a
satisfactory plant under favorable
conditions in the soil
Germination
– intact seedlings with all essential structures (i.e. root, shoot axis, cotyledons, terminal bud), complete healthy and well-developed. Included also are seedlings with slight defects but capable of developing into satisfactory plants, and seedlings which have been infected secondarily.
Normal Germinants
Normal Germinants
– intact seedlings with all essential structures (i.e. root, shoot axis, cotyledons, terminal bud), complete healthy and well-developed. Included also are seedlings with slight defects but capable of developing into satisfactory plants, and seedlings which have been infected secondarily.
Abnormal seedlings
seedlings which are discolored, glassy,
split, broken, stunted, twisted, missing parts, etc.
seedlings which are discolored, glassy,
split, broken, stunted, twisted, missing parts, etc.
Abnormal seedlings
which did not absorb water due to impermeable seedcoat
Hard seeds
Hard seeds
which did not absorb water due to impermeable seedcoat
other than hard seeds which failed to germinate but
remain clean and firm and probably have the potential to germinate
Fresh seeds
Fresh seeds
other than hard seeds which failed to germinate but
remain clean and firm and probably have the potential to germinate
seedlings which at the end of the test have failed to germinate and are neither hard nor fresh
Dead seeds
Dead seeds
seedlings which at the end of the test have failed to germinate and are neither hard nor fresh
Classification of Germinants
Hard seeds
Fresh seeds
Dead seeds
Empty seeds
Insect-damaged seeds
Measure of how fast, uniform and energetic their germination is.
Germinative Energy
Germinative Energy (#1)
Measure of how fast, uniform and energetic their germination
is.
Percentage of seeds that have germinated within a given period,
e.g. day 7 or day 10 after sowing.
Germinative Energy
Germinative Energy (#2)
Percentage of seeds that have germinated within a given period,
e.g. day 7 or day 10 after sowing.
Percentage of seed that has germinated up to the time of peak germination, i.e. the time when the highest number of seed per time unit has germinated.
Germinative Energy
Germinative Energy (#3)
Percentage of seed that has germinated up to the time of peak germination, i.e. the time when the highest number of seed per time unit has germinated.
endosperm is of normal color and texture with well-developed embryo
Good seed
Good seed
endosperm is of normal color and texture with well-developed embryo
Distinguishes between living and dead tissues
Indirect Tests of Viability…
Topographical tetrazolium test
Indirect Tests of Viability…
Topographical tetrazolium test
Distinguishes between living and dead tissues
Simple and economical
Indirect Tests of Viability…
Hydrogen Peroxide Method
Indirect Tests of Viability…
Hydrogen Peroxide Method
Simple and economical
- Used for slow-germinating or dormant seeds
- Performed on 400 seeds, some seeds used as replacement for damaged seeds
- Seed is imbibed followed by embryo excision
- Moderately aseptic working conditions, use 70% alcohol solution
Indirect Tests of Viability…
Excised embryo test
Indirect Tests of Viability…
Excised embryo test
- Used for slow-germinating or dormant seeds
- Performed on 400 seeds, some seeds used as replacement for damaged seeds
- Seed is imbibed followed by embryo excision
- Moderately aseptic working conditions, use 70% alcohol solution
Indirect Tests of Viability…
X-ray Test
Indirect Tests of Viability…
X-ray Test
- X-ray radiography is a quick and non destructive test to determine or distinguish: filled, empty, insect- and physically-damaged seed, degree of seed development, number of seeds in a fruit and viability
- Contrast agents could be used like: BaCl or chloroform
Purpose: determine the health status of a seedlot
Seed health test
Seed health test
Purpose: determine the health status of a seedlot
Seed health test Importance: (3)
1.Seed-borne inoculum may give rise to progressive disease development in the nursery/field and reduce the commercial value of the crop
2.Imported seedlots may introduce diseases into new regions; tests to meet quarantine requirements may therefore be necessary.
3.Seed health testing may explain seedling evaluation and causes of poor germination or field establishment and thus supplement germination testing.
The results of the seed testing is useful not only in determining the planting value of a seed lot but also in calculating the amount of seed to be sown in the nursery.
Calculating amount of seed needed
Calculating amount of seed needed
The results of the seed testing is useful not only in determining the planting value of a seed lot but also in calculating the amount of seed to be sown in the nursery.
