Seed dormancy and germination stimulation syndromes for Australian temperate species

Understanding seed germination biology and the dynamics of seed dormancy is essential to developing reliable germination techniques. This paper presents some new data and reviews recent findings from germination studies on Australian species, with respect to the role of temperature and moisture in the control of dormancy and germination. A seed-burial experiment was conducted over a 1-year period (January-December) with seeds of Acanthocarpus preissii Lehm., Astroloma xerophyllum (DC.) Sond., Gahnia grandis (Labill.) S.T.Blake, Goodenia scaevolina F.Muell. and Tersonia cyathiflora (Fenzl) J.W.Green to determine the fluctuations in temperature and moisture seeds naturally experience in the buried environment. All seeds became hydrated during autumn (March) while soil temperatures were > 15 degrees C, suggestive of a period of warm stratification before the onset of cooler winter temperatures appropriate for germination. Evidence of rapid wetting and drying of seeds in the soil environment was also present. Laboratory experiments testing stratification as a means for dormancy loss showed that several weeks of warm stratification at 26/13 degrees C or 33/18 degrees C promoted germination of Lomandra preissii (Endl.) Ewart, Marianthus bicolor (Putt.) F.Muell. and Xyris lanata R.Br. seeds. X. lanata seeds also responded to several weeks of cold stratification at 5 degrees C. By integrating this new data with other published data on germination of Australian species, diagrammatic models of germination timing, dormancy syndromes and propagation strategies for temperate Australian species are presented as working hypotheses to help direct future research.