© 2000 Heron Publishing—Victoria, Canada
Foliar nutrient retranslocation in Eucalyptus globulus
E. Saur (1, 2, 3), E. K. S. Nambiar (1, 4) and D. N. Fife (1)
1. CSIRO, Forestry and Forest Products, Plantation Forest Research Centre, P.O. Box 946, Mount Gambier, SA 5290, Australia / 2. INRA, Station de Recherches Forestière de Bordeaux-Cestas, BP45, 33611 Gazinet CEDEX, France / 3. Université des Antilles et de la Guyane, Laboratoire de Biologie et Physiologie Végétales, 97159 Pointe-a-Pitre CEDEX, Guadeloupe,
France / 4. Author to whom correspondence should be addressed (sadanandan.nambiar@ffp.csiro.au) / Received September 29, 1999
Summary
We measured patterns of change in concentrations and contents of nitrogen, phosphorus, potassium, magnesium and calcium in
fully expanded leaves of young Eucalyptus globulus (Labill.) trees growing in a plantation in southeastern Australia, over a 12-month period beginning at the onset of spring.
There was significant net retranslocation of mobile nutrients on a seasonal basis from green leaves, coinciding with continued
growth and production of foliage. There was a close positive relationship between initial nutrient content (N, P and K) of
the leaf and amount retranslocated, and a tight coupling between N and P retranslocated from leaves. Net retranslocation was
significantly correlated with basal area growth increments.
Artificial shading of leaves resulted in senescence and reduction in leaf mass. It also induced retranslocation of N, P and
K from leaves of different ages and from different positions in the canopy. Although the mechanisms underlying the effects
of shading intensity on these changes were not elucidated, shading provided an experimental tool for studying retranslocation.
Comparison of the results with published data for Pinus radiata (D. Don) grown in the same environment indicated a similarity between the species in patterns of change in foliar nutrient
contents and in factors governing foliar nutrient retranslocation, giving rise to unifying principles.
Keywords:
artificial shading, magnesium, nitrogen, phosphorus, Pinus radiata, potassium, senescence, Tasmanian blue gum.
