ISHS Acta Horticulturae 184: I International Symposium on Computer Modelling in Fruit Research and Orchard Management
A CARBON BALANCE MODEL FOR APPLE TREE GROWTH AND PRODUCTION |
| Authors: | R.C. Seem, T.R. Oren, S.P. Eisensmith, D.C. Elfving |
| Abstract:
A model has been developed to quantitatively describe the wholetree physiological process for apple tree growth based on carbon assimilate production, distribution and utilization. Special emphasis was placed on description of growth in terms of dynamic interactions within the tree and between the tree and its environment. Three major tasks were addressed in the modeling effort: 1) tree-environment linkages, which signal the start of growth events in spring and mediate growth rates; 2) canopy structure and photosynthesis, in which an explicit model for leaf distribution allows the simulation of a wide range of canopy sizes and shapes; and 3) assimilate distribution and utilization by the tree organ systems for their maintenance and growth. The tree model consists primarily of organ and physiology submodels. Organ submodels represent six physiologically distinct organ groups: leaf biomass (spur or shoot leaves); current-season extension shoot biomass; stem biomass (aboveground biomass older than one growing season); root biomass; fruit biomass; and stored reserve carbohydrate biomass. Physiology submodels are used to account for features of tree physiology important to the model but not fitting within the organ submodel design. The three physiology submodels include resource production, resource allocation, and tree-environment interactions (a tree phenology model and a mechanism to link the environment to the other submodels). The model can be easily interfaced with disease or insect pest models. The model program, written in FORTRAN V, allows the user to progress through a growing season by use of a set of 16 commands. The command structure permits the user to display and/or alter 83 of the simulation variables at any time during the simulation process. Although the model program was developed on a large computer system it has been modified to run on a microcomputer (IBM-PC). | |
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