-Germination rate and germination capacity of Eucalyptus globulus Labill. increased significantly with increasing temperature (13º to 33 ºC) for all seed sizes to an optimum at 28 ºC, then decreased. Biggest seeds generally germinated best at all temperatures. Germination was also very sensitive to water potential (0 to -0.75 MPa), with no germination occuring at potentials below -0.25 MPa. Eucalyptus globulus / germination / dimension de la semence / température / potentiel hydrique Eucalyptus globulus