Abstract: The differences of photosynthetic physiological adaptabilities in two different plants, Cardiandra moellendorffii and Hydrangea macrophylla, were described in the present study. Photosynthetic rates and chlorophyll fluorescence parameters were measured with GFS3000 gas exchange systems (Walz, Germany) and MiniPAM fluorometer (Walz, Germany) in leaves of two different plants under different light, CO2 and temperature environment. Results showed that Hydrangea macrophylla possessed higher levels in LSP, LCP and Pnmax, higher values for Yield and qP in comparison to that of Cardiandra moellendorffii under the increasing light environment. With the increasing of CO2 concentrations, the higher photosynthetic rates Pn were found in Hydrangea macrophylla. The photosynthetic rates Pn increased with the increasing leaf temperature, until the temperature of leaves respectively reached 28℃ in Cardiandra moellendorffii and 36℃ in Hydrangea macrophylla. Moreover, in both species the changes of the stomatal conductance Gs and transpiration rate E were significantly different under different light intensities, CO2 concentrations and leaves temperature. The results indicated that the photosynthetic physiological adaptabilities of different species had a closely relation with their different ecotypes．

Key words: Cardiandra moellendorffii, Hydrangea macrophylla, photosynthesis, chlorophyll fluorescence, heat dissipation