Abstract:

A tomato variety Ligeer87-5 was used to study the effect of photosynthesis characteristic and chlorophyⅡ fluorescence parameters of its seedlings leaves by infliction 0.3,0.6,0.9,1.2 mgSe/kgNa2SeO3 liquor under low temperature stress, day time(12±1)℃ and night time(8±1)℃.The results showed that,with the extended of time of the low temperature stress,the photosynthetic rate（Pn）,stomatal conductance（Gs）, intercellular CO2 concentration（Ci）,and several fluorescence parameters including maximum fluorescence(Fm),photochemical maximum efficiency of PSⅡ(Fv/Fm),potential photoche- mical efficiency(Fv/Fo),photochemical quenching coefficient(qP),were decreased.At the same time,minimal fluorescence(Fo),nonphotochemical quenching coefficient(qN) were increased. Otherwise, tne different Se levels treatment could relieved effects of low temperature stress on chlorophyⅡ fluorescence parameters in tomato seedlings and the optimal treatment concentration of Se was 0.9 mgSe/kgNa2SeO3