Fundamental study on environment control for high quality fruit production based on dynamics of mass accumulation into fruits

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Dynamics of mass fluxes in a growing fruit of tomato )Lycopersicon esculentum Mill.) as affected by environmental conditions were analyzed with special reference to fruit water balance and phloem and xylem transport into the fruit. Many kinds of plant instrumentations for measuring mass fluxes in the fruits were newly developed as follow : 1. Multiple chamber system for on-line measurements of transpiration, respiration and photosynthesis in intact fruits and leaves on six plants ; 2. System for online measurements of fruit expansive growth and sap flux through the pedicel ; 3. Method for individual evaluation of phloem sap and xylem sap fluxes through the pedicel ; 4. EDTA method for evaluation relative intensity of fluxes of photoassimilates through the pedicel ; 5. Method for tracing sap backflow from the fruit ; 6. Method for individual evaluation of fluxes of chemical elements accumulated into the fruits through phloem and xylem. By using these methods newly developed, effects of light, day-night temperature, water stress and salt stress on dynamics on mass fluxes into the fruits were elucidated quantitatively. In particular, the importance of phloem transport into the fruits was clearly suggested. For example, phloem transport into the fruits was enhanced by light and temperature increase in the daytime depending on fruit respiration as well as leaf photosynthesis, and higher contribution of phloem sap was found (90 % under the stress conditions and 70 % under the non-stress). Furthermore, it was suggested that the production of high quality tomato fruits with higher concentrations of sugars, acids and chemical elements can be enabled by the short-term salt stress treatment with the salt refined from deep-sea water.