Light, nitrogenous compounds, smoke and GA(3) break dormancy and enhance germination in the Australian everlasting daisy, Shoenia filifolia subsp subulifolia

Shoenia filifolia subsp. subulifolia (F.Muell.) Wilson has an innate dorman cy period that prevents germination during summer thundershower events. Hig h-temperature dry storage or applications of nitrate or gibberellic acid (G A(3)) shortened the required after-ripening period. Combinations of KNO3 an d GA(3) had an additive effect on germination. In addition to KNO3, Ca(NO3) (2) and K-3 [Fe(CN)(6)] also increased germination percentages. However, NH 4Cl, KNO2, NaN3 and a 1 % concentration of smoke water (Kings Park and Bota nic Garden Smoky Seed Starter) showed no stimulatory effect on germination in this arid-zone ephemeral. The solution of combustion products did not af fect 27 week-old seeds when grown in the light, but the light requirement t ended to be overcome by gradually increasing concentrations of smoke water. The after-ripening requirement, nitrate, GA and the P-tr form of phytochro me may be linked in Shoenia filifolia subsp. subulifolia via their associat ion with cellular membranes. The capacity of smoke water to also stimulate germination in the dark may indicate that the active ingredient in smoke co uld be a nitrous oxide-generating compound. Seeds with sufficient levels of GA to sense light and/or increased levels of water-soluble nitrogenous com pounds can germinate with the first winter rains in open-soil sites of this Mediterranean-climate region of Western Australia.