Effect of Increased Amount of Carbon Dioxide on Soluble Sugar Concentration and Activity of Related Enzymes during Tomato Fruit Development.

The effect of increased amount of CO2 on the sugar concentration, sucrose synthase (E.C. 2.4.1.13) and sucrose phosphate synthase (E.C. 2.4.1.14) activities in developing tomato (Lycopersicon esculentum Mill. cv. Lady First) fruits was studied. The CO2-enriched tomatoes had significantly higher fruit weight, higher total and reducing sugars during development compared to the control. The sucrose synthase activity was sig-nificantly higher in enriched fruits up to 50 days after anthesis and after that decreased drastically, while it was decreased gradually in the controls. The decrease in sucrose synthase activity was accompanied by decreasing sucrose concentration. There were no significant differences in sucrose concentration and sucrose phosphate synthase activity between the treatments. The sucrose phosphate synthase activity showed relatively constant throughout the fruit development.