Seed testing viability - the germination percentage vigor - the ability to germinate quickly, produce “strong” seedling growth with normal morphology, withstand unfavorable conditions both are measures of “seed quality”

Viability tests direct germ. test (e.g., petri dish test, rolled towel test, soil test) excised embryo test (e.g., for woodies with certain forms of dormancy) tetrazolium (TTC) test (detects dehydrogenases present only in living tissue) x-ray analysis (nondestructive method that detects presence of vital tissues, signs of insect infestation, aging)

Other seed tests verification of species and/or cultivar % weed seeds seed health tests estimating seed vigor

Verification of species and/or cultivar seed size, shape, surface features (useful for species ID) isozyme (protein) markers (different forms of the same enzyme) RFLPs (specific nucleotide sequences, cut by specific restriction enzymes) RAPDs (random DNA segments amplified by PCR)

Seed health tests visual evaluation (e.g., spores or fungal sclerotia, insect presence) incubation on agar medium virus testing (e.g., ELISA)

Estimating seed vigor seedling growth rate (avg. no. of days to germination, morphological appearance) germination under stressful conditions (e.g., cold tests) others (accelerated aging, electrolyte leakage, etc.)

Seedling growth rate Average no. of days to germinate E.g., 49% germ. at day 7, 43% germination at day 14; so (49)(7) + (43)(14) ÷ 92 (total germ. %) = 10.3 days