Abstract: Taking two-year-old Diospyros kaki as test material, this paper studied the effects of high CO2 concentration (700 μmol·mol-1), high temperature (5 ℃ higher than the mean daily temperature), and their combination on the net photosynthesis rate (Pn), evapotranspiration (Tr), stomatal conductance (Gs), water use efficiency (WUE), chlorophyll content, Fv/Fm, and Fv/Fo under different soil moisture conditions, with the ambient air temperature and CO2 concentration (380 μmol·mol-1) as the control. Under all test soil moisture conditions, the combination of high CO2 concentration and high temperature decreased the Tr and Gs, but increased the WUE. This combination increased the Pn when the soil moisture content was 75%〖KG-*2〗-〖KG-*7〗85% and 55%〖KG-*2〗-〖KG-*7〗65% of field capacity, but decreased the Pn when the soil moisture content was 35%〖KG-*2〗-〖KG-*7〗45%. High CO2 concentration increased the Pn and WUE but decreased the Gs and Tr under all test soil moisture conditions. The effects of high temperature and its combination with high CO2 concentration on the WUE depended on soil moisture condition, with the WUE increased with increasing soil moisture content. Comparing with the control, high CO2 concentration also increased the leaf Chla, Chlb, Chl(a+b), and Car concentrations and the Fv/Fm and Fv/Fo values, relieved the water stress, and increased the stress-resistance of D. kaki.

Key words: climate change, Diospyros kaki, photosynthesis, antibiotic, antibiotic resistance gene, horizontal gene transfer, multiple antibiotic resistance.