Growth stress in Eucalyptus dunnii

Growth stress in 9-y-old plantation-grown Eucalyptus dunnii was assessed by measuring longitudinal growth strain. Strain varied considerably (370–1560 ìm–1) and was sufficiently heritable (h2 =0.3–0.5) that tree breeding may be an effective way to reduce the incidence of growth stress in this species. Although the formation of longitudinal growth strain appears to be under strong genetic control (P = 0.0015), there was a tendency for tall thin trees to exhibit higher stress than short thick trees (P = 0.025 for height:diameter ratio). Two provenances and three families identified in this study show potential as superior material for further tree breeding.