Seed Testing: Principles and Practices

Contents

Contents Preface................................................................................................................................................ix Introduction........................................................................................................................................xi Chapter 1. Why Seeds are Tested, and When.........................................................................................................1 Seed Testing Organizations.................................................................................................................3 A Rich Heritage - Classic Contributions and Memorable Milestones ................................................6 Chapter 2. Seeds and Seedlings.............................................................................................................................11 Angiosperm Seed ..............................................................................................................................12 Gymnosperm Seed ............................................................................................................................17 Classification of Embryos (Both Angiosperms and Gymnosperms) ................................................22 Seed Unit Structure ...........................................................................................................................23 Seed Morphology..............................................................................................................................25 Germination - Transition from Seed to Seedling ..............................................................................27 Seedlings ...........................................................................................................................................27 Chapter 3. Sampling and Subsampling..................................................................................................................33 The Sampling Process.......................................................................................................................34 Subsampling in the Laboratory .........................................................................................................38 Chapter 4. Testing for Physical Purity ...................................................................................................................43 Equipment and the Working Environment .......................................................................................44 Subdividing - Obtaining the Sample for Testing...............................................................................48 The Purity Separation .......................................................................................................................48 Noxious Weed Seed Examination and Other Bulk Exams................................................................50 Pure Seed...........................................................................................................................................50 Weed Seed ........................................................................................................................................53 Special Purity Tests and Procedures .................................................................................................54 Uniform Blowing Procedure.............................................................................................................56 Chapter 5. Germination and Viability Testing........................................................................................................59 Seed Selection, Preparation, and Planting.........................................................................................59 Substrata for Germination Tests........................................................................................................60 Germination Chambers .....................................................................................................................68 Duration of Test.................................................................................................................................70 Evaluation of Seedlings.....................................................................................................................71 Dormancy..........................................................................................................................................72 Causes of Loss of Germinability.......................................................................................................76 Tests for Detecting Damage of the Seed Coat...................................................................................78 Chapter 6. Seedling Evaluation...............................................................................................................................83 Overview of Seedling Evaluation .....................................................................................................83 Factors Affecting Seedling Evaluation..............................................................................................89 Seedling Evaluation of Different Representative Families...............................................................92 Chapter 7. Tetrazolium Testing.............................................................................................................................117 Principles.........................................................................................................................................117 Applications ....................................................................................................................................118 Limitations ......................................................................................................................................120 Facilities, Equipment, and Supplies................................................................................................120 General Procedures .........................................................................................................................121 Preparation of Dry Seed Before Moistening...................................................................................121 Moistening.......................................................................................................................................121 Preparation for Staining ..................................................................................................................122 Staining with TZ Solution...............................................................................................................127 Preparation for Evaluation ..............................................................................................................128 Evaluation .......................................................................................................................................129 Tetrazolium Methods for Various Representative Families ............................................................131 The Tetrazolium Test as a Vigor Test ..............................................................................................150 Accuracy of Tetrazolium Test Results.............................................................................................150 Chapter 8. Seed and Seedling Vigor Testing.......................................................................................................155 History of Seed Vigor Testing.........................................................................................................155 Seed Vigor Test Benefits .................................................................................................................160 Standardization of Seed Vigor Tests ...............................................................................................162 Classification of Seed Vigor Tests...................................................................................................165 Vigor Tests - Principles and Procedures..........................................................................................169 Chapter 9. Genetic and Varietal Purity Testing...................................................................................................193 Part 1: DNA and Protein Genetic Purity Tests ................................................................................196 Analytical Methods Analyzing DNA-Marker Techniques ..........................................................197 Protein Electrophoresis................................................................................................................201 Bioassay Tests to Detect Genetic Traits.......................................................................................204 Part 2: Varietal Identification Tests Based on Morphological, Chemical, Growth Habits and Other Characteristics ................................................................................................................208 Seed and Seedling Morphology...................................................................................................208 Chemical (Quick) Tests ...............................................................................................................208 Cytological Tests ........................................................................................................................218 Growth Chamber Testing.............................................................................................................220 Disease Resistance Tests..............................................................................................................231 Chapter 10. Seed Health Testing ..........................................................................................................................237 Seed Health Testing Methods..........................................................................................................239 Serology ..........................................................................................................................................248 DNA Techniques .............................................................................................................................252 Standardization of Seed Health Testing Methods ...........................................................................254 Chapter 11. Seed Moisture Content Testing........................................................................................................257 Oven-Drying Methods ....................................................................................................................259 Distillation Methods........................................................................................................................260 Solvent-Extraction Methods............................................................................................................261 Electronic Moisture Meters.............................................................................................................261 Other Methods.................................................................................................................................262 The Air-Oven Method.....................................................................................................................263 Chapter 12. Seed Laboratory Management, Accreditation, and Quality Assurance.......................................271 Preliminary Considerations.............................................................................................................272 Equipment and Facilities.................................................................................................................276 Types of Tests..................................................................................................................................277 Record-Keeping - State and Federal Regulations ...........................................................................281 Seed Analyst Training .....................................................................................................................281 Certification of Analysts..................................................................................................................282 Proficiency and Referee Programs..................................................................................................283 Research and Development.............................................................................................................283 Financial Support ............................................................................................................................284 Quality Assurance ...........................................................................................................................285 Laboratory Accreditation ................................................................................................................286 Chapter 13. Statistical Applications to Seed Testing .........................................................................................293 Section One - Tolerances.................................................................................................................293 Application of Tolerances in Seed Testing .....................................................................................295 Tolerances for Purity Tests..............................................................................................................298 Tolerances for Incidental Seed Contamination with Noxious Weeds .............................................300 Tolerances for Germination Tests....................................................................................................302 Tolerances for the Tetrazolium Test ................................................................................................304 Tolerances for Electric Conductivity and Accelerated Aging Tests................................................305 Tolerances for Seed Moisture Determination..................................................................................305 AOSA Tolerances for Fluorescence Tests of Lolium and 400 - 1,000-Seed Separations in Purity Analyses ...........................................................................................................................305 Section Two - Seed Lot Heterogeneity............................................................................................307 Appendix: Tolerance Tables............................................................................................................313 Glossary..................................................................................................................................................................339 Index........................................................................................................................................................................351 ...