ISHS Acta Horticulturae 313: III International Symposium on Computer Modelling in Fruit Research and Orchard Management
MODELLING THE IMPACT OF LEAF SENESCENCE ON NITROGEN PARTITIONING IN SYCAMORE (ACER PSEUDOPLATANUS L.) SEEDLINGS. |
| Authors: | R. Habib, P. Millard |
| Abstract:
The importance of nitrogen reserves for sustainable growth of trees is well-known. It is recognized that spring leaf growth of deciduous trees depends largely upon the nitrogen (N) supply of the previous year, through the remobilization of N stored during the winter. Modelling the growth, nitrogen uptake by the root system and the N partitioning within the tree, including the withdrawal from senescing leaves, would enable us to translate our mechanistic understanding of the processes into a framework for mature trees and extend the model from one season to several years. The withdrawal of N during leaf senescence has still not been included in a model describing the distribution of nitrogen within a plant during a growing season. This limits the use of modelling to the current year's growth. In a previous study, a model was used to predict N allocation within trees up to the onset of leaf senescence (Habib et al., 1990). A major limitation in extending the model to include leaf N withdrawal during canopy senescence was that sink needs were considered as driving forces in N partitioning. In order to be able to model nitrogen withdrawal from senescing leaves, a negative growth rate (i.e. a decrease in leaf mass) can be used to allocate nitrogen back from leaves to other tissues. This is illustrated here with data from sycamore seedling experiments (Millard and Proe, 1991). | |
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