Relationships between fruit cracking and changes of fruit diameter associated with solute flow to fruit in cherry tomatoes.

摘要

The occurrence of cracking in cherry tomatoes grown in water culture in a glasshouse was investigated in relation to diurnal changes in fruit size and rate of solute uptake. When cracking in 250 fully ripe tagged cv. Sun Cherry fruits was checked hourly during 10 days in July, about 83% of the cracking occurred between 4.00 and 10.00 h. Diurnal changes in diameters of fully ripe fruits measured by a laser beam sensor system starting at 0.00 h during summer and autumn revealed that in summer, cv. Sun Cherry Extra fruit diameters increased from 3.00 to 6.00 h, then decreased from 8.00 to 14.00 h, after which they again increased, gradually during the day but sharply after sunset. A similar trend was observed in the autumn with cv. Sun Cherry, but toa lesser extent. A rapid increase in fruit diameter coincided with the time of fruit cracking. When the diurnal change in solute flow rates through Sun Cherry Extra plants was investigated using a sap flow system, the flow in the stem and petioles was always directed distally throughout the diurnal cycle, but the flow rates in both tissues were much faster during the day than at night. In contrast, the solute in peduncles flowed proximally during the late morning to evening and distally during the darkperiod, indicating that solute flow to fruits occurs during the evening and early morning hours. The results suggest that rapid fruit expansion was induced by solute inflow into the fruits during the night/early morning and that the fruit skin's inability to endure the internal pressure led to fruit cracking.