© 2001 Heron Publishing—Victoria, Canada
Photosynthetic light acclimation in peach leaves: importance of changes in mass:area ratio, nitrogen concentration, and leaf
nitrogen partitioning
X. Le Roux (1), A. S. Walcroft (1), F. A. Daudet (1), H. Sinoquet (1), M. M. Chaves (2), A. Rodrigues (2) and L. Osorio (2)
1. U.M.R. PIAF (INRA-Université Blaise Pascal), Domaine de Crouelle, 234 Avenue du Brezet, 63039 Clermont-Ferrand Cedex 02, France / 2. Dept. Botânica e Engenharia Biológica, Instituto Superior de Agronomia, Tapada da Ajuda, 1399 Lisboa codex, Portugal / Received December 23, 1999
Summary
Photosynthetic light acclimation of leaves can result from (i) changes in mass-based leaf nitrogen concentration, Nm, (ii) changes in leaf mass:area ratio, Ma, and (iii) partitioning of total leaf nitrogen among different pools of the photosynthetic machinery. We studied variations
in Nm and Ma within the crowns of two peach (Prunus persica L. Batsch) trees grown in an orchard in Portugal, and one peach tree grown in an orchard in France. Each crown was digitized
and a 3-D radiation transfer model was used to quantify the intra-crown variations in time-integrated leaf irradiance, <PARi>. Nitrogen concentration, leaf mass:area ratio, chlorophyll concentration, and photosynthetic capacity were also measured
on leaves sampled on five additional peach trees in the orchard in Portugal. The data were used to compute the coefficients
of leaf nitrogen partitioning among carboxylation, bioenergetics, and light harvesting pools. Leaf mass:area ratio and area-based
leaf nitrogen concentration, Na, were nonlinearly related to <PARi>, and photosynthetic capacity was linearly related to Na. Photosynthetic light acclimation resulted mainly from changes in Ma and leaf nitrogen partitioning, and to a lesser extent from changes in Nm. This behavior contrasts with photosynthetic light acclimation observed in other tree species like walnut (Juglans regia L.) in which acclimation results primarily from changes in Ma.
Keywords:
chlorophyll, intra-crown variability, Juglans regia, leaf irradiance, photosynthesis, Prunus persica, radiation transfer model, specific leaf area, walnut.
