A simulation model of growth at the shoot-bearing fruit level: I. Description and parameterization for peach

Abstract

A simulation model of daily C assimilation and allocation in an isolated shoot-bearing fruit is presented. The system is divided into three compartments: fruits, one-year-old stem, and leafy shoots. The pool of C assimilates available daily for distribution is the daily assimilation of C, plus that mobilized from reserves if the demand of sink organs exceeds the product of photosynthesis. Equations of leaf photosynthesis incorporate a feedback inhibition through the leaf storage reserves, and the effect of light extinction caused by foliage. Carbon assimilation of fruits is considered. The mobilization of reserves first concerns the leafy shoot, and then the one-year-old stem to a lesser extent. The model simulates carbon partitioning based on organ demands and priority rules. Maintenance respiration costs, which are calculated on the basis of the Q 10 concept, have first priority. Vegetative and reproductive growth are given second and third priority. Daily carbon demands for the vegetative and reproductive organs are based on an analytical formulation of the potential growth rate at any time. The accumulation or replenishing of reserves, first in the leafy shoot compartment and then, in the case of saturation, in the one-year-old stem compartment, is given last priority. A parameterization of the model is presented for peach, with several values for cultivar-dependent and location-dependent parameters (two cultivars and locations considered). The input data required by the model are described. Finally, some simulations concerning a sensitivity analysis are presented to illustrate the model behaviour.