中文摘要：

以15℃夜温为对照，研究了12℃、9℃、6℃夜间低温对番茄（Lycopersicon esculentum Mill．）光合作用和叶绿素荧光参数的影响。结果表明：夜间低温抑制了植株总干物质的积累；总叶绿素含量、净光合速率下降；光合作用相关因素中气孔导度（Gs）、胞间CO2浓度（Ci）、蒸腾速率（Tr）下降，气孔限制值（Ls）增大。12℃、9℃夜低温处理10d净光合速率及相关因素可恢复到正常水平；6℃低温处理10d对番茄净光合速率的影响则不可恢复，而对光合作用相关因素的影响是可恢复的，说明在恢复期间6℃夜低温处理净光合速率的降低与Gs、Ci、Tr、Ls无关。所有夜间低温处理对Fv／Fm、ΦPSⅡ、ETR影响较小，低温胁迫解除后很快得到恢复，说明试验所设定的夜间低温及其处理时间未对PSⅡ系统造成伤害。

英文摘要：

Effects of different low night temperature （12℃, 9℃, 6℃, and 15℃ as control） on photosynthesis and chlorophyll fluorescence characteristics were investigated in tomato seedlings . Results showed that the dry matter accumulation of plants was restrained under low night temperature. Total chlorophyll content and net photosynthetic rate decreased. The stomatal conductance （Gs） , intercellular CO2 concentration （Ci） , transpiration rate （Tr） decreased but the stomatal limitation （Ls） increased in comparison with the control. The photosynthetic rate and related factors could be resumed to normal standard after 10 days treatment of 12℃ and 9℃ . Photosynthetic related factors could be recovered, but the net photosynthetic rate could not resumed at 6℃. This indicated that the low photosynthetic rate was not related to Gs, Ci, Tr and Ls during the recovery period after 6℃ treatment. Fv/Fm, ΦPSⅡ , ETR were not significantly affected under low night temperature, because all of them could be recovered soon after released from low night temperature stress. The results indicated that PS Ⅱ of tomato seedlings was not damaged under the low night temperature and the period of treatment within the designed experiments.