Chlorophyll fluorescence parameters of Sabina przewalskii Kom. and Sabina chinensis(Lin.) Ant. that distributed in different altitude regions were tested for evaluating their differences and seasonal variation patterns at the same growing circumstance. The results indicated, there were similar patterns of seasonal variation in chlorophyll fluorescence parameters between two Sabina trees, the low temperature in winter resulted in a significant decreases in the maximum efficiency of PSⅡ photochemistry (Fv/Fm), the efficiency of excitation capture by open reaction centers (Fv′/Fm′), photochemical quenching coefficient(qP), non-photochemical quenching coefficient (qN), effective quantum yield(Yield) and photosynthetically active radiation(PAR) in both S.przewalskii and S.chinensis, however, these parameters all increased and returned to normal levels as air temperature rose. Compared with those in S.chinensis, there were significantly higher Fv/Fm, Fv′/Fm′, qP, qN and Yield in S.przewalskii. These results suggested a better capacity for PSⅡ photochemistry in S.przewalskii. might account for its greater regulation capacity for low temperature than S.chinensis, and at the same time it implied that the cold-resistance ability and seasonal variation of photosynthetic characteristics can effectively be estimated by chlorophyll fluorescence technology.
