On-line measurements of CO₂ and H₂O gas fluxes, sap flux and expansive growth in an intact tomato fruit

A system for on-line measurements of CO₂ and H₂O gas fluxes, pedicel sap flux and expansive growth in an intact tomato fruit was newly developed, where the gas fluxes in leaflets also can be measured. The system was composed of a fruit chamber,a leaf chamber, CO₂ and H₂0 gas analyzing unit and an on-line computer. Furthermore a laser displacement sensors system was equipped in the fruit chamber for evaluating fruit expansive growth, and the pedicel sap flux was evaluated as sum of the H₂O gas flux and the growth rate in the fruit. Diurnal dynamics as affected by light condition were observed in respiration, transpiration, pedicel sap flux and expansive growth in the immature intact fruit, which were clearly enhanced in the light. In fruit water balance, about 30% of the sap flux imported through the pedicel was lost by transpiration from the calyx and the berry, and the residual 70% contributed to fruit expansive growth. These results suggest that the on-line system developed is applicable to quantitative analyses of respiration, sap flux and water balance of an intact tomato fruit in environmental studies on fruit expansive growth and photoassimilate translocation.