ISHS Acta Horticulturae 276: II International Symposium on Computer Modelling in Fruit Research and Orchard Management
A MODEL OF THE ANNUAL CYCLE OF DRY MATTER PRODUCTION AND PARTITION IN CITRUS AND OTHER EVERGREEN FRUIT TREES |
| Authors: | A. Harpaz, S. Gal, E.E. Goldschmidt, D. Rabber, E. Gelb |
| Abstract:
Evergreen fruit trees differ in their dry matter economy and developmental traits from decidious fruit trees as well as from annual crop plants. Citrus has been used in the present study as a representative of the evergreen fruit trees. The basic unit simulated is a single tree, which is characterized by a set of state variables. During each time segment (a calendar day) the activity of the tree is described as a sequence of activities and events. First the physiological time accumulated during the current day is calculated. Then, the daily amount of dry matter available for allocation is determined as the amount produced by photosynthesis plus a fraction of the reserves - this constitutes 'the daily supply'. Next, the daily supply is allocated to the tree components according to a novel growth priorities partitioning scheme. Special attention has been paid to the fruit growth demand. Finally, the values of the state variables are updated according to a set of differential equations which describe the growth and mortality of the tree components. The fruits are also updated according to the fruit self-thinning drop mechanism. The computer program (written in Fortran) constitutes a short main module which drives the simulation and a set of special purpose modules, each of which is responsible for a different component of the model (e.g. photosynthesis, partitioning, etc.). The modulation and flexibility of the program make it a powerful tool in the current stage of model development and as a basis for further improvement. | |
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