Abstract: Chilling-sensitive tomato（Solanum lycopersicon）‘Money Maker’and chilling-tolerant wild tomato（S. habrochaites）‘LA1777’were cultivated in phytotron，and effects of low night temperature of 15 ℃（control），9 ℃ and 6 ℃ and recovery on carbohydrate content and sucrose-metabolizing enzymes activities in tomato fruits were investigated. The results showed that fructose and glucose levels increased in chilling-tolerant wild tomato（‘LA1777’）fruits after 0.5 d treatment at 6 ℃，while with no significant change in chilling-sensitive tomato（‘Money Maker’）fruits. The sucrose and starch levels in‘Money Maker’fruits decreased significantly at 6 ℃，but increased in‘LA1777’. During the recovery period，the sucrose levels in two types tomato fruits both recovered to control level. The fructose and glucose contents in fruits after low night temperature-treatment could not recovered to the control level，except for 9 ℃. The invertase and sucrose synthase（SS hydrolysis direction）activities decreased in two types of tomatoes at 6 ℃，and could not recovery to the control level；However，the sucrose synthase synthesis direction and sucrose phosphate synthase（SPS）activities increased in chilling-sensitive tomato（‘Money Maker’）fruits while with no significant change in chilling-tolerant wild tomato（‘LA1777’）. These results demonstrate that the chilling-tolerant tomato（‘LA1777’）enhances higher level of total carbohydrate content to acclimate chilling stress under short-time low night temperature，while chilling-sensitive tomato responses to low temperature by decreasing it.

Key words: tomato, low night temperature, carbohydrate, sucrose-metabolizing enzymes