Influence of selected environmental variables on the germination of Eucalyptus costata

Eucalyptus costata is a widespread eucalypt species used in restoration works. It is common to the Mallee, a vegetation type in the semiarid temperate region of southern Australia, characterised by hot summers and mild winters, generally reliable but highly variable rainfall, and nutrient poor soils composed primarily of sands. An understanding of the germination biology of Eucalyptus costata may assist in its successful establishment. We studied the impacts of light, temperature, salinity, moisture and sowing depth on the germination of E. costata in the laboratory and considered the results in a restoration context. Germination was lowest under the highest temperature regime (35°C/25°C), high salt concentrations (>100 mM) and low water potentials (taking 14 MPa of humidity per day to germinate). Sowing depths greater than 2 cm reduced seedling emergence. These results suggest that E. costata’s germination requirements are shallow sowing in low salinity soils during periods of cool or mild wet weather, consistent with winter and spring planting.