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Résumé :
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A dynamic simulation model for tomato crop growth and development, TOMSIM, is evaluated. Potential crop growth and daily crop gross assimilation rate (P-ge,P- d) is computed by integration of leaf assimilation rates over total crop leaf area throughout the day. Crop growth results from P-ge,P- d minus maintenance respiration rate (R-m), multiplied by the conversion efficiency. Dry matter distribution is simulated, based on the sink strength of the plant organs, which is quantified by their potential growth rate. Within the plant, individual fruit trusses and vegetative units (three leaves and stem internodes between two trusses) are distinguished. Sink strength of a truss or a vegetative unit is described as a function of its developmental stage. In this paper, emphasis is on the interactions between the two submodels of, respectively, dry matter production and dry matter distribution. Sensitivity analysis showed that global radiation, CO2 concentration, specific leaf area (SLA) and the developmental stage of a vegetative unit at leaf pruning had a large influence on crop growth rate, whereas temperature, number of fruits per truss, sink strength of a vegetative unit and plant density were less important. Leaf area index (LAI) was very sensitive to SLA and the developmental stage of a vegetative unit at leaf pruning. Temperature did not influence the simulated R-m as increased respiration rate per unit of biomass at higher temperatures was compensated by a decrease in biomass. The model was validated for four glasshouse experiments with plant density and fruit pruning treatments, and on data from two commercially grown crops. In general, measured and simulated crop growth rates from 1 month after planting onwards agreed reasonably well, average overestimation being 12%. However, crop growth rates in the first month after planting were overestimated by 52% on average. Final crop dry mass was overestimated by 0-31%, due to inaccurate simulation of LAI, resulting partly from inaccurate SLA prediction, which is especially important at low plant density and in a young crop. (C) 1999 Annals of Botany Company.
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