The effects of rudimentary embryos and elevated oxygen on seed dormancy of Eryngium yuccifolium Michx. (Apiaceae)

Dormant seeds of Eryngium yuccifolium Michx. contain rudimentary embryos embedded in endosperm, testa and pericarp. Hydrated embryo-covering structures can inhibit oxygen from reaching the embryo. The rudimentary embryo was examined as a potential seed dormancy mechanism and the effect of elevated oxygen on seed dormancy loss was determined. Embryo length and dormancy was regularly determined for seeds stratified at 15°C and 3°C. Stratification at effective temperatures was conducted in ambient O₂ (22.3 kPa) and elevated O₂ (>90 kPa). Embryo elongation was a prerequisite for germination. Embryo elongation was restricted to cold temperatures (3°C), whereas seed germination occurred only in warm temperatures (25°C). Stratification in elevated O₂ (>90kPa) did not promote embryo elongation and subsequent seed dormancy loss. Results indicate the rudimentary embryo contributes to E. yuccifolium seed dormancy and elevated O₂ inhibits embryo elongation.