Abstract:

In order to discuss the physiological mechanism of effect of sub-low night temperature on photosynthesis in tomato leaves, the change of net photosynthetic rate（Pn）and chlorophyⅡfluorescence paramerers of tomato leaves under the condition of sub-low night temperature at 9 ℃for 3 to 9 days and then recover for 9 days at optional temperature were studied. Treated with sub-low night temperature at 9 ℃ for more than 3 days, it was shown that the net photosynthetic rate (Pn), the maximum photochemical efficiency(Fv/Fm), potential activities of PSII(Fv/Fo), the actual photochemical efficiency of PSⅡreaction center (ΦPSⅡ), rate of electronic transmission of photosynthesis (ETR), photochemical quenching coefficient (qP) of leaves deceased, while intrisic fluorescenc of (Fo), the relative reduction state of PSⅡ(1-qP) and the non-photochemical quenching coefficient (NpQ) increased. But when tomato leaves were treated with sub-low nigth temperature for less than 9 days and then recovered for 9 days,most chlorophyll fluorescence parameters could come back to CK, except NpQ. These results showed that the phenomenon of photoinhibition of photosynthesis in tomato mature leaves has been induced obviously after treated with sub-low night temperature at 9 ℃ for 3 days, and that it was reversible that the effect of treatment of sub-low night temperature at 9 ℃for less than 9 days on PSⅡ. Namely, the phenomenon of photoinhibition of photosynthesis in tomato leaves induced by short-term 9 ℃ sub-low night temperature could recover.

Key words: tomato, low temperature, recovery, photosynthesis, photoinhibition