Dieback of rural eucalypts: the effect of stress on the nutritional quality of foliage [Eucalyptus blakelyi]

In a series of glasshouse experiments, with seedlings and grafted plants derived from dieback and healthy populations of trees, the influence was tested of deprivation of nutrients, drought, waterlogging, saline waterlogging and addition of excess phosphate, on the nutritional quality of foliage. Differences in the foliar properties of plants from different genetic sources were not consistent with the differences between the source populations. Most of the environmental stresses applied caused a reduction in foliar quality. It is hypothesized that the enhanced nutritional quality of the foliage of dieback trees is more likely to be a consequence of benign growing conditions than of environmental stress. Field data for soil properties and the effect of drought on mature trees are consistent with this view.