Identifying check-prone trees of Eucalyptus globulus Labill. using collapse and shrinkage measurements

Summary Fifty-nine trees were sampled from three provenances of 10-y- old Eucalyptus globulus Labill. plantations grown at two sites in South Australia. The butt logs were backsawn and 176 boards (40 mm × 100 mm × 3600 mm) from the centre cant (two to four boards per cant) were dried. A 10-mm-thick cross-section was removed 400 mm from the end of each board (corresponding to the smaller end of the log) and inspected for the presence of internal checks. The samples were ranked using the mean values of several wood properties, including tangential collapse, total tangential shrinkage, density, growth strain, microfibril angle (MFA) and cellulose crystallite width (Wcryst). The rank positions of the check-prone trees were inspected in each ranking. Tangential collapse showed good potential for identifying the check-prone trees, while total tangential shrinkage and total cross-sectional shrinkage were slightly less sensitive. Density, growth strain, MFA, Wcryst and other shrinkage properties were not as useful. It is recommended that tree breeders should use total tangential shrinkage as an indicator to identify check-prone trees, because this property is not only reliable but can be easily measured on trimmed increment cores at low cost.