Increased temperature produces changes in the bioactive composition of tomato, depending on its developmental stage.

The present study examines the effect of an increased day temperature on vitamin C and carotenoid concentrations in tomato, depending on the developmental stage of fruits when the stress is imposed. Plants were cultivated in a growth chamber initially at 24 °C, and the day temperature was increased to 32 °C when fruits belonging to six different fruit development stages could be differentiated. Vitamin C, phytoene, phytofluene, lycopene, γ-carotene, and violaxantin concentrations were significantly lower when a temperature of 32 °C was imposed during the advanced stages of fruit development compared to the levels observed in the control treatment. However, no effect or increased concentrations were observed when the temperature was increased in earlier stages, indicating the adaptation of the plant metabolism to high temperature. Finally, no effect on β-carotene concentration was observed, regardless of the fruit developmental stage when the temperature increase was applied.