© 2000 Heron Publishing—Victoria, Canada
Distribution of leaf mass per unit area and leaf nitrogen concentration determine partitioning of leaf nitrogen within tree
canopies
A. Rosati (1), K. R. Day (2) and T. M. DeJong (3, 4)
1. Istituto Sperimentale per l'Orticoltura, Via dei Cavalleggeri 25, 84098 Pontecagnano (SA), Italy / 2. Tulare County UCCE, Agriculture Building, 2500 W. Burrell Avenue, Visalia, CA 93291-4584, USA / 3. Department of Pomology, University of California, Davis, CA 95616, USA / 4. Author to whom correspondence should be addressed (tmdejong@ucdavis.edu) / Received April 14, 1999
Summary
Distribution of leaf nitrogen with respect to leaf mass per unit area (Ma), nitrogen per unit mass (Nm) and nitrogen per unit area (Na) within peach (Prunus persica L.) tree canopies was studied in two field experiments. In one experiment, leaf light exposure and Ma were measured on leaves from different canopy positions of peach trees subjected to five nitrogen (N) fertilization treatments.
Leaf light exposure and Ma were linearly related and the relationship was independent of N fertilization. In a subsequent experiment, N fertilizer was
applied to previously unfertilized trees in midsummer, after shoot growth had terminated. Application of N fertilizer did
not affect mean canopy Ma. Fertilization increased Nm of all leaves throughout the canopy compared with non-fertilized trees. No significant relationship between Nm and Ma was found in either fertilized or control trees. There was a linear relationship between Na and Ma and the slope of the relationship was increased by N fertilizer application. We conclude that distribution of Na in peach tree canopies is primarily a function of Ma partitioning with light and Nm, which is related to soil N availability.
Keywords:
modeling, nitrogen allocation, nitrogen fertilization, photosynthesis, Prunus persica.
