Comparison of the photosynthetic characteristics of four species with leaf appearing in autumn under field conditions.

The diurnal trends of gas exchange and chlorophyll fluorescence parameters in four species ( var. and ) were determined and compared with a portable photosynthesis analysis system. Our study revealed that had the lowest light compensation point (LCP), while the other three species had higher LCP (12.37-14.99 μmol m s); had the highest light saturation point (LSP) (1,189 μmol m s), and and had lower LSP with the values being 322 and 345 μmol m s, respectively, and var. showed the intermediate LSP. Both the species and exhibited a typical and obvious decline in net photosynthetic rate ( ) during midday, which was not observed in . This indicated a possible photoinhibition in and as the ratio of variable to maximum fluorescence (Fv/Fm) values were higher in these two species. The minimal fluorescence (F) values were lower in and var. . The diurnal changes of transpiration rate () in all four species presented only one peak, appearing between 11:00 h or 13:00 h. By using simple correlation analyses, it was observed that the environmental factors affecting were different among four species and the main factors were photosynthetic photon flux density (PPFD) and relative humidity especially for and . The results of studying indicated that the four species could be divided into two groups. The species var. and were more adapted to a relatively high irradiance, and and could be grown in moderate-shade environment in order to scale up their growth and productivity.