Évaluation d'un modèle dynamique de croissance et de développement de la tomate (Lycopersicon esculentum Mill), TOMGRO, pour différents niveaux d'offre et de demande en assimilats

Abstract

TOMGRO, a tomato growth and development model, has been examined under different levels of assimilate source and sink activities, induced, by CO2 enrichment and truss thinning. The main purpose was the evaluation ot the assumptions on dry matter partitioning and fruit setting. The photosynthesis submodel has been calibrated to fit the daily dry-matter production. The main input parameters to the development and growth submodels have been experimentally measured. The calibrated model provides good simulations of the leaf area expansion, but it takes no account of the variations in the assimilates stored in leaf blades. Total fruit growth is well simulated in spite of a small underestimation for of development and simulations of source/sink balance leads to good simulations of the number of set fruits. This result confirms the hypothesis that fruit set depends on the ratio between assimilate source and sink activities. This calibration with a beef tomato cultivar proves the robustness of the model and permits some improvements to be suggested. The surplus assimilates should be stored in a pool, which could exert a buffer effect during low supply periods. Sink strength of reproductive and vegetative parts should be measured for different cultivars, and under various climatic conditions. Finally, whether the functions of assimilate distribution and fruit set are still valid under very low supply conditions or whether some organs have priority over the others remains to be determined. © 1993.