Sex-related growth and secondary compounds in Juniperus oxycedrus macrocarpa

Gender-related differences in growth and concentration of secondary metabolites have been documented in dioecious plants. Males usually grow faster than females, whilst females allocate more resources to reproduction and chemical defences than males, hence their growth is reduced. This hypothesis was tested on prickly juniper (Juniperus oxycedrus macrocarpa), a Mediterranean evergreen tree. The results showed that males grew faster than females but also had higher concentrations of both phenolics and terpenoids. However, neither phenolic nor terpenoid concentrations were correlated with growth in either sex, nor with a “reproductive effort” index in female trees. No browsing occurred on any of the trees sampled. Contrary to predictions, this study suggests that allocation of resources to reproduction in plants may reduce the resources available to both growth and secondary compounds. This might be particularly pronounced in plants with “expensive” fruits, such as prickly juniper, characterised by relatively large, long-lived fruits.