Tomato fruit quality in relation to water and carbon fluxes

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 (CO2 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.