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Tetrazolium Testing of Shrubs

Tetrazolium Testing of Shrubs. Victor Vankus USDA Forest Service National Seed Laboratory www.nsl.fs.fed.us. Topics. Describe the tz test and general procedures Special considerations for shrubs Germination, Viability and the Tz test Benefits of using Tz/Problems associated with the test

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Tetrazolium Testing of Shrubs

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  1. TetrazoliumTesting of Shrubs Victor Vankus USDA Forest Service National Seed Laboratory www.nsl.fs.fed.us

  2. Topics • Describe the tz test and general procedures • Special considerations for shrubs • Germination, Viability and the Tz test • Benefits of using Tz/Problems associated with the test • Wrap-up

  3. What is a TZ test? • Index or measure of the respiration process inside living cells, tissue and seed. • An estimate of viability at one point in time. • An estimate of what may or may not happen in the future.

  4. Method Overview and Considerations • Pure Seed • Preconditioning • Preparation for Staining • Staining • Preparation for Evaluation • Evaluation • Reporting

  5. Pure Seed • What is the pure seed unit?

  6. Preconditioning • Water Content

  7. Preparation for Staining • Expose the Tissue

  8. Stain • 38° C., hours or days? • Surface area exposed • Degree of dormancy

  9. Preparation for Evaluation • Expose the Embryo

  10. Evaluation • Staining patterns • Turgidity

  11. Report • Report tz test result as a range or as a single number? • Tz test alone or with a germination test result? • What does an estimated viability test result mean? • Is the tz test result used as part of a Pure Live Seed calculation?

  12. Considerations for Shrubs • Seed anatomy • Maturity • Dormancy

  13. Cornus embryo • Endocarp • Seed coat • Cotyledons • Endosperm • Hypocotyl • Radicle

  14. Viburnum embryo • Endocarp • Seed coat • Endosperm • Embryo

  15. Acer embryo • Pericarp • Seed coat • Cotyledons • Hypocotyl • Radicle

  16. Cephalanthus embryo • Pericarp • Seed coat • Endosperm • Cotyledons • Hypocotyl • Radicle

  17. Ilex embryo • Endosperm • Embryo

  18. Parthenocissus embryo • Endosperm • Cotyledons • Hypocotyl • Radicle

  19. Prunus embryo • Endocarp • Seed coat • Cotyledons • Epicotyl • Hypocotyl • Radicle

  20. Rhus embryo • Endocarp • Seed coat • Cotyledons • Radicle • Hypocotyl

  21. Ribes embryo • Seed coat • Endosperm • Cotyledons • Hypocotyl • Radicle

  22. Serenoa embryo • Endocarp • Seed coat • Endosperm • Embryo

  23. Celtis embryo • Endocarp • Seed coat • Cotyledons • Hypocotyl • Radicle

  24. Considerations for Shrubs • Seed anatomy • Maturity • Dormancy

  25. Considerations for Shrubs • Seed anatomy • Maturity • Dormancy Influence of Seed Health and Genetics on germination. Stress factors Environmental conditions present as seed develops Maturity at harvest/dispersal Storage conditions, length in storage Processing Age Genetic factors Ecology/plant evolution dormancy conditions required for germination

  26. Relationship between age, seed health, range of conditions required for germination Seed mature at dispersal Age Expiration High vigor Seed health vigor Medium vigor Low vigor none

  27. Relationship between age, seed health, range of conditions required for germination Seed mature at dispersal Age Expiration Degree of dormancy and conditions required for germ.

  28. Relationship between age, seed health, range of conditions required for germination Seed mature at dispersal Age Expiration Degree of dormancy and conditions required for germ.

  29. Relationship between age, seed health, range of conditions required for germination Seed mature at dispersal Age Expiration High vigor Seed health vigor Medium vigor low degree of dormancy, broad range of germ. conditions Low vigor none little variation between tz and germination

  30. Relationship between age, seed health, range of conditions required for germination Seed mature at dispersal Age Expiration High vigor Seed health vigor Medium vigor little or no dormancy, secondary dormancy, with initial broad range of conditions for germination, narrow range over time Low vigor none potential for variation between tz and germination

  31. Relationship between age, seed health, range of conditions required for germination Seed mature at dispersal Age Expiration High vigor Seed health vigor Medium vigor physiological dormancy, initial narrow range of conditions for germination, broader range over time Low vigor none potential variation between tz and germination.

  32. Relationship between age, seed health, range of conditions required for germination Seed mature at dispersal Age Expiration High vigor Seed health vigor Medium vigor physiological dormancy and embryo immaturity, narrow range of conditions for germination Low vigor none potential for significant variation between tz and germination

  33. Germination is the transformation of the embryo into a seedling. Seed viability is a term used to describe the potential of a seed to germinate under certain conditions. Tz is a measure of seed viability, an estimate of the total germination potential. Germination, viability and the tz test

  34. Benefits of using Tz • Useful during collection, processing, storage, with a germination test to determine plant production value of a seed lot. • Advantages: • Ability to test dormant seed • When used to supplement germination test results to further explain or determine dormancy, rating for vigor, diagnosing causes of seed deterioration.

  35. Problems associated with Tz test • Disadvantages: • Requires experience • Cost • State seed laws • Uniformity between analysts and testing laboratories • Inability to provide useful information with regard to dormant seed

  36. Wrap-up • Understand the tool, what a tz test is. • Benefits, limitations, when to use tz test. • Tz is a science and an art, many shades of gray.

  37. This presentation and a list of references can be found on the National Seed Laboratory website at: www.nsl.fs.fed.us

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