Effects of Low Night Temperature on Sucrose Metabolism in Seeding Tomato Leaves

[Objective] To explore the effects of low night temperature on sucrose metabolism in tomato leaves. [Methods] Treatment was set up: 6 ℃ treatment over night(18:00-6:00)for 7 days, using 15 ℃ as control to determine the content of sucrose and starch in tomato leaves and the relative enzyme activity of sucrose metabolism. [Results] Contents of fructose, glucose, sucrose, total sugar and starch were increased in tomato leaves under low night temperature. Contents of fructose and glucose were no obvious difference compared with control, contents of sucrose, total sugar and starch were very significantly different between control. The activities of acid invertase (AI) and neutral invertase (NI) in leaves were increased under low night temperature. And the activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS) in leaves were decreased.[Conclusion]Lead to carbohydrate accumulation in leaves under low night temperature, the photosynthesis feedback inhibition effect has been apparent.