Elevated levels of ethylene during germination reduces the time to emergence in impatiens

Impatiens seeds treated with the ethylene biosynthetic precursor 1-aminocyclopropane- 1-carboxylic acid (ACC) had reduced times to radicle protrusion and seedling emergence. Sixty hours after imbibition, 68% more seeds showed radicle protrusion on media containing 0.1 or 1.0 mM ACC compared to seeds germinated on water alone. Subsequently, ACC was effectively 'loaded' into impatiens seeds using an aqueous soak prior to being dried back to their original fresh weight. Seeds treated with 15 mM ACC for 24 hours showed a 10-fold increase in ethylene production following imbibition as well as a reduced time for initiation of germination. Similarly, seedling emergence in plug flats began sooner in the 24 hour, 15 mM ACCtreated seeds and required 24 hours less time to emerge compared to untreated seeds.