Abstract: The gas exchange and chlorophyll fluorescence parameters in leaves of three broadleaved tree species including Aesculus chinensis, A. octandra, A. hybrida were determined under field conditions. The results showed that light compensation point is different in three speciec, light compensation point in A. chinensis is lower (12.53 μmol·m^-2·s^-1) than other two speciec (respectively 12.53, 36.11, 46.41 μmol·m^-2·s^-1); Light saturation point is different in three speciec, Light saturation point in A. chinensis is highter (1 475 μmol·m^-2·s^-1) than other two speciec (respectively 1 366.67,1 025 μmol·m^-2·s^-1); Maximum net photosynthetic rate is different too, Maximum net photosynthetic rate in A. chinensis is higher (9.47 μmol CO₂·m^-2·s^-1) than other two speciec (respectively 5.91,2.30 μmol CO₂·m^-2·s^-1). indicating that A. chinensis had higher photosynthetic capacity and stronger utilization ability for light energy. The electron transport rate(ETR), PSⅡ efficiency(Yield) and photochemical quenching(qP) in the leaf were much higher in A. chinensis than in A. octandra and A. hybrida. These results indicated that the quantum yield of PSⅡ electron transport and the efficiency of primary conversion of light energy of PSⅡ.

Key words: gas exchange, chlorophyll fluorescence, Aesculus chinensis, A. octandra, A. hybrida