Foliar chemistry of juvenile Eucalyptus grandis clones does not predict chemical defence in maturing ramets

The tendency for managers of eucalypt plantations to plant large, homogeneous (i.e. clonal) stands presents a new suite of problems. Perhaps foremost among them is the elevated risk of disease or predation. One way to counter this risk is to select material with high natal resistance, such as material with high concentrations of plant secondary metabolites. This would be much simpler if we could predict future defences from the chemistry of juvenile plants. The present study aimed to determine the relationship between the concentrations of formylated phloroglucinol compounds (FPCs) in the leaves of newly established Eucalyptus grandis (Hill ex Maiden) clones in the nursery and those in the same genetic material in experimental plantations. There was almost no relationship between the concentrations of defensive chemicals in the leaves of newly established E. grandis clones growing in pots in the nursery and of those in the same genetic material growing in plantations. This implies that age effects and probable gene × environment interactions prevent evaluating the defensive qualities of clones until they are several years old and even then the results are site-specific.