Leaf gas exchange and chlorophyll fluorescence parameters in three species of Ilex.

The gas exchange and chlorophyll fluorescence parameters in leaves of three broadleaf tree species: Ilex viridis,I.zhejiangensis,and I.cornuta,were determined under field conditions.Results showed that there were no significant differences(P0.05) for light compensation point:(20.94 μmol.m-2.s-1 in I.viridis,29.91 μmol.m-2.s-1 in I.zhejiangensis,and 24.02 μmol.m-2.s-1 in I.cornuta).The light satu-ration point of I.cornuta was significantly greater(P0.05)(1 516.67 μmol.m-2.s-1) than I.viridis(1 204.29 μmol.m-2.s-1) and I.zhejiangensis(1 305.10 μmol.m-2.s-1).Also,the maximum net photosynthetic rate in I.cornuta was significantly greater(P0.05) for CO2(8.43 μmol.m-2.s-1)than I.viridis(3.33 μmol.m-2.s-1) and I.zhejiangensis(5.53 μmol.m-2.s-1).Finally,electron transport rate(ETR),photosystem(PS) Ⅱ effi-ciency(Yield),and non-photochemical quenching(qN) in the leaf were much higher(P0.05) in I.cornu-ta than in I.zhejiangensis and I.viridis.Thus,I.cornuta had a higher photosynthetic capacity and stronger utilization ability for light energy,and its quantum yield of PS II electron transport and the potential capac-ity of heat dissipation were greater(P0.05).