Analysis of growth, water balance and respiration of tomato fruits under water deficit by using a multiple chamber system

A multiple chamber system was developed for on-line measurements of gas (CO₂ and H₂O) fluxes in intact fruits and leaflets of tomato plants, where fruit growth rate and pedicel sap flux can be also measured. By using the system for the simultaneous measurements with six plants, effect of water deficit on fruit growth was analyzed in relation to water balance and respiration in the fruits and to photosynthesis and transpiration in the leaflets. The water deficit caused drastic depression in fruit growth in the daytime, which was considered to be associated with depressions in pedicel sap flux, fruit respiration and leaf photosynthesis. Furthermore, sap backflow and fruit shrinkage corresponding to about 2% of the fruit volume were induced by rise in evaporative demand under the water deficit. These results suggest that the multiple chamber system developed can be applied to quantitative analyses of environmental effects on fruit growth, translocation and sink-source relationship in tomato plants.