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 f ruit quality. Variations in the concentration of dry matter and sugars have been coupled with the conditions of climate and root medium: these concent rations increase under high radiation, high vapour pressure deficit (VPD) o r high nutrient concentration. Dry matter and sugar concentrations would no t be affected by the availability of assimilates (CO2 concentration or frui t load). Such increases in dry matter or sugar concentration could be assoc iated 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 frui t transpiration. Similarly, the observed relation between the occurrence of blossom-end rot (BER) and conditions of osmotic or water stress can be exp lained by variations of Ca transport to the fruit by the xylem influx. Frui t cracking could be related to high variations in fruit growth and water in flux under changing conditions of temperature or VPD. In contrast, acids an d products of the secondary metabolism that are synthesised during the matu ration stages could not be linked to the water and carbon fluxes between th e plant and the fruit.