Turner Review No. 1 - The process of germination in Australian species

Australian species germinate under the combination of environmental conditi ons where the potential for survival is enhanced. Most species also have do rmancy mechanisms that prevent all seeds from germinating in any particular rainfall event. Immaturity of the embryo prevents some species from germin ating until environmental parameters change to more favourable conditions. Seed-coat inhibitors may also delay germination, with some seed requiring i ngestion and dispersal by animals or a series of rainfall cycles to facilit ate germination. Adaptations to fire include germination mechanisms facilit ated by impervious seed coats, seed-coat inhibitors and biochemical sensing of water-soluble components of smoke and the high soil nitrate levels foun d following the burning of vegetation. Germination is generally limited und er saline soil conditions until rainfall dilutes concentrations to near-zer o water potentials. Australian species tend to germinate under temperatures that approximate the rainfall season in their native habitat. Light sensin g by Australian species ensures germination takes place only near the surfa ce for some species or only under complete burial conditions in others. Mor e recent research has emphasised the interaction of multiple and sequential cues to relieve dormancy and initiate germination. Knowledge of germinatio n mechanisms provides a basis for better land management, enriched conserva tion, improved rehabilitation and advanced horticulture, forestry and farmi ng practices.