RESUMO
Taking two-year-old Diospyros kaki as test material, this paper studied the effects of high CO2 concentration (700 micromol x mol(-1)), high temperature (5 degrees C higher than the mean daily temperature); and their combination on the net photosynthesis rate (Pn), evapotranspiration (Tr), stomatal conductance (Gs), water use efficiency (WUE), chlorophyll content, Fv/Fm, and Fv/Fo under different soil moisture conditions, with the ambient air temperature and CO2 concentration (380 micromol x mol(-1)) as the control. Under all test soil moisture conditions, the combination of high CO2 concentration and high temperature decreased the Tr and Gs, but increased the WUE. This combination increased the Pn when the soil moisture content was 75%-85% and 55%-65% of field capacity, but decreased the Pn when the soil moisture content was 35%-45%. High CO2 concentration increased the Pn and WUE but decreased the Gs and Tr under all test soil moisture conditions. The effects of high temperature and its combination with high CO2 concentration on the WUE depended on soil moisture condition, with the WUE increased with increasing soil moisture content. Comparing with the control, high CO2 concentration also increased the leaf Chla, Chlb, Chl (a + b), and Car concentrations and the Fv/Fm and Fv/Fo values, relieved the water stress, and increased the stress-resistance of D. kaki.