An Apparent Induction of Secondary Dormancy in Eucalyptus globulus Labill Seeds

Eucalyptus globulus is a major plantation forestry species in southern Australia. Commercial E. globulus seedlots have high viability (95%) and uniform germination, which is completed within 5-6 days. However commercial nurseries have reported delays in germination with seedling emergence spread over five to ten weeks. According to growers and seed suppliers the problem is not restricted to particular seedlots and occurs in most nurseries. Observations have suggested that a brief period of desiccation or high temperature between sowing and germination may lead to the delays, but no clear cause has been established. Further, there is nothing in the literature to indicate either cause or possible management strategies. According to the ISTA guidelines the germination period of E. globulus is 5-14 days under laboratory conditions and in the field, germination should occur before 26 days. The aim of the present project was to establish the factors responsible for this apparent induction of previously unreported secondary dormancy in E. globulus seed and to provide a basis for commercial management of the problem.