This work proposed a model of tomato growth adapted from the Fishman and Génard model developed to predict carbon and water accumulation in peach fruit. The main adaptations relied on the literature on tomato and mainly concerned: (i) the decrease in cell wall extensibility coefficient during fruit development; (ii) the increase in the membrane reflection coefficient to solute from 0 to 1, which accounted for the switch from symplasmic to apoplasmic phloem unloading, and (iii) the negative influence of the initial fruit weight on the maximum rate of active carbon uptake based on the assumption of higher competition for carbon among cells in large fruits containing more cells. A sensitivity analysis was performed and the model was calibrated and evaluated with satisfaction on 17 experimental datasets obtained under contrasting environmental (temperature, air vapour pressure deficit) and plant (plant fruit load and fruit position) conditions. Then the model was used to analyse the variations in the main fluxes involved in tomato fruit growth and accumulation of carbon in response to virtual carbon and water stresses. The conclusions are that this model, integrating simple biophysical laws, was able to simulate the complex fruit behaviour in response to external or internal factors and thus it may be a powerful tool for managing fruit growth and quality.

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This review is about the involvement of the water and carbon fluxes in the formation of tomato fruit quality. This approach has provided new insights that help in understanding and controlling some of the major variables of fruit quality. Variations in the concentration of dry matter and sugars have been coupled with the conditions of climate and root medium: these concentrations increase under high radiation, high vapour pressure deficit (VPD) or high nutrient concentration. Dry matter and sugar concentrations would not be affected by the availability of assimilates (CO 2 concentration or fruit load). Such increases in dry matter or sugar concentration could be associated with variations in the balance between water and assimilate influx to the fruit i.e. between the fluxes of the phloem and xylem saps and of fruit transpiration. Similarly, the observed relation between the occurrence of blossom-end rot (BER) and conditions of osmotic or water stress can be explained by variations of Ca transport to the fruit by the xylem influx. Fruit cracking could be related to high variations in fruit growth and water influx under changing conditions of temperature or VPD. In contrast, acids and products of the secondary metabolism that are synthesised during the maturation stages could not be linked to the water and carbon fluxes between the plant and the fruit. Lycopersicon esculentum Mill. / xylem / phloem / fruit quality / sugar concentration / acid concentration / BER / water status / fruit cracking Résumé-Qualité du fruit de tomate en relation avec les flux d'eau et de carbone. Cette synthèse s'intéresse aux rôles des flux d'eau et de carbone dans la formation de la qualité du fruit de tomate. L'approche considérée a donné de nouveaux aperçus qui permettent de mieux comprendre et contrôler des variables majeures de la qualité du fruit. Les variations de concentration en matière sèche et en sucres ont été mises en relation avec les conditions climatiques et le milieu racinaire : ces concentrations augmentent sous fort rayonnement, fort déficit de pression de vapeur (DPV) ou en présence de fortes concentrations en minéraux. Les concentrations en matière sèche et en sucres ne seraient pas affectées par la disponibilité en assimilats (liée par exemple à la concentration en CO 2 ou la charge en fruits). De telles augmentations des concentrations en matière sèche et en sucres ont pu être associées à des variations de l'équilibre entre les entrées d'eau et d'assimilats dans le fruit, c'est-à-dire entre les flux de sève phloémienne et xylémienne et la transpiration. De la même manière, la relation observée entre l'apparition de la nécrose apicale ou blossom-end rot (BER) et les conditions de stress osmotique ou hydrique peut être expliquée par des variations de l'apport de calcium dans le fruit par le flux xylémien. Les craquelures du fruit seraient liées à des variations importantes de la croissance du fruit et de l'entrée d'eau sous des conditions variables de température et de DPV. Par contre, les acides et les produits du ...

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Summary 1.Biological invasions have an anthropogenic origin, and although many species are able to spread on their own within the newly invaded area, long-distance dispersal events shown to accelerate rates of spread are frequently associated with human activities. In a previous study, the performances of several invasion models of the spread of the horse chestnut leafminer Cameraria ohridella in Germany were compared, demonstrating that the best model in qualitative and quantitative terms was a stratified dispersal model taking into account the effect of human population density on the probability of long-distance dispersal events. 2. Similar data were collected in France over 4 years (2000 -2004, 5274 observation points). These data were used to assess the performance of the best-fit models from Germany using the original parameters and to model the spread of the leafminer in France. 3. The stratified dispersal model accounting for variations in human population density developed in Germany, predicted the invasion of France with a similar level of predictive power as in the area where it was developed. This suggests that an equivalent level of predictability can be expected in a newly invaded country with similar environmental conditions. 4. We applied the model to forecast the future invasion dynamics in the UK from 2005 to 2008, based on the first observations of Cameraria in the country in [2002][2003][2004]. Predictions are discussed in the light of different prevailing environmental conditions. 5. Synthesis and application . The model and predictions developed in this study provide one of the few examples of an a priori model of invasion in a newly invaded country, and provide a simple modelling framework that can be used to explore the spread of other invading organisms. In the case of Cameraria , little can be done to prevent or slow its spread but our model, by predicting changes in distribution and rates of spread, provides fore-warning of where and when damaging pest populations are likely to appear.