In order to improve temperature and water management in the greenhouse cultivation of Satsuma mandarins, short-term water and carbon balance in intact Satsuma mandarin fruits was studied by measuring fruit expansive growth, CO 2 and H 2O gas exchange, sap flux into the fruit through the phloem and xylem, and 13C partitioning. Seventy-one days after full bloom, with day/night temperature set at 28°C/23°C and under fine weather conditions, sap flux through the xylem into the fruit showed a dynamic diurnal change which was related to changes of fruit volume. In leaves, 13C partitioning decreased from 11:00 until 23:00, remaining constant thereafter, whereas in fruits, 13C partitioning increased from 11:00 until 23:00, and then remained contrast. Investigating the cumulative water balance, 19% of water output was lost by fruit transpiration, whereas 81% contributed to fruit growth. In cumulative carbon balance, 39% of carbon output was lost by fruit respiration, whereas 61% contributed to fruit growth. Quantitative analyses of physiological responses to environmental conditions, as measured in this study, are essential for establishing energy-saving temperature management strategies.
