Seed testing viability the germination percentage vigor the
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
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