Temperature dependence of postphloem transport regulated by respiration in tomato fruits

Temperature effect on postphloem transport in tomato fruits was analyzed by measuring fruit growth rate, pedicel sugar flux and fruit respiratory CO₂ efflux under changes in air temperature around fruits. Dynamic responses of fruit growth rate and pedicel sugar flux to temperature change around fruits were clearly found to be associated with change in fruit respiration. Fruit growth rate and pedicel sugar flux were remarkably enhanced with fruit respiration by temperature rise around fruits, where those Q₁₀ values between 20°C and 30°C distributed around 2.3. These enhancements in fruit growth and sugar translocation by the temperature rise were not found in the truss with the respiration-inhibited fruits. From these results, it can be suggested that respiration in tomato fruits contributes to the temperature effects on the expansive growth and the sugar accumulation through regulation of the energy-dependent process of the postphloem sugar transport in the fruits.