ISHS Acta Horticulturae 495: WCHR - World Conference on Horticultural Research
MODELING AND ARCHITECTURAL ANALYSIS AS BASES FOR FRUIT CROPS MANAGEMENT |
| Author: | E. Costes |
| Abstract:
In the current economic context, fruit crops are submitted to competitiveness and to consumer's demand which dictate an improvement of product quality and a reduction of inputs. This context defines new objectives for researchers and needs to develop new approaches among which modeling is a major research tool to improve orchard management. A review of models for horticulture has recently be made by Gary et al. (1998). The present paper briefly reviews the main models developed in the last years for fruit crops management. Models are classified according to their objectives : knowledge conceptualization, education or decision support. A particular emphasis will be put on models accounting for plant architecture and on the different plant scales considered. Since most of fruit species are perennials, their aerial structure is complex and changes with time. Until now only few species and a limited number of growth processes and development have been modeled. A first class of models focuses on a particular physiologic process and a particular organ in the plant. This is the case of models for bud dormancy (Erez et al., 1990), and for leaf photosynthesis (Buwalda, 1991; Grossman and Dejong, 1994). Obviously, many models deal with fruit development including different processes such as water import (Bussières, 1994) or sugar content (Génard and Souty, 1996). Only a few models deal with the heterogeneity within the plant using stochastic methods (Agostini and Habib, 1996, for flowering and pollination on kiwifruit; Hall and Gandar, 1996, for fruit growth). A second class of models accounts for several organs simultaneously. A first example is related to the tree structure edification where the distribution of axillary branches along one-year-old shoots is modeled using stochastical processes (Costes and Guédon, 1997). This approach aims at evaluating, in the nursery, the ability of young apple trees to be conducted in the most current training systems used in intensive orchards, such as "vertical axis" or "solaxe" (Lespinasse, 1980; Lespinasse and Lauri, 1997). A similar approach has been applied to the distribution of axillary flowers in Prunus species, considering the vegetative growth associated to fruit development (Fournier et al., 1997; Costes and Guédon, 1996). Models dealing with interactions between fruits and close associated vegetative shoots have been proposed by Bruchou and Génard (1996). In this case, the bearing shoot is represented by different compartments, one being the source (leafy shoot) the other one being sinks (fruits). Different attempts have been carried out to built models at whole plant scale. Most of these modeling approaches need strong simplifications on the tree structure representation. Compartment representations are used for models of carbon and nitrogen partitioning either in aerial part of the trees or in the whole plant, including the root system (Dejong and Grossman, 1992; Habib et al, 1989). When focus is on ligth interception or interaction with climatic environement, tree structure is assimilate to set of randomly distributed leaves, or to geometrical forms such as ellipsoids (Norman and Welles, 1983). Buwalda and Piller (1996) | |
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