Abstract: The photosynthetic light-response curve and CO2-response curve characters of two main tobacco cultivars(Nicotiana tabacum L.var.K326 and NC297)of Yuxi Yunnan province were compared depending on field experiment data.The results showed that two cultivars had different photosynthetic characteristics.The maximum photosynthetic net rate(Amax),light compensation point(LCP),light saturation point(LSP),apparent quantum yield(AQY),apparent carboxylation efficiency(ACE) and stomata conductance(Cs) in NC297 were higher than that in K326.The water use efficiency(WUE) of NC297 was higher than K326 because of greater net photosynthetic rate(Pn) in NC297 than in K326.Furthermore,the photosynthetic pigments(including chlorophyll a,b and caroteniod)and soluble protein contents were higher in NC297 than in K326.The results indicated that NC297 had greater carboxylation rate,light use efficiency and adaptation to strong light,higher photosynthetic capacity and WUE,so it had higher potential manufacturability in the experiment region.

Key words: Tobacco, Tobacco, Photosynthetic characteristics, Light-response curve, CO2-response curve