Photosynthetic Responses of Populus alba×glandulosa to Elevated CO2 Concentration and Air Temperature

This study was conducted to investigate the photosynthetic characters of Populus alba×glandulosa cuttings in response to elevated CO2 concentration and air temperature for selecting tree species adaptive to climate change. The cuttings were grown in environment controlled growth chambers with two combinations of CO2 concentration and air temperature conditions: (i) 22 oC + CO2 380 µmol mol−1 (control) and (ii) 27oC + CO2 770 µmol mol −1 (elevated) for almost three months. The cuttings under the elevated treatment showed reduced tree height and photosynthetic pigment contents such as chlorophyll and carotenoid. In particular, the elevated treatment resulted in a marked reduction in the chlorophyll a closely associated with CO2 fixative reaction system. Different levels of reduction in photosynthetic characters were found under the elevated treatment. A decrease was noted in photochemical reaction system parameters: net apparent quantum yield (7%) and photosynthetic electron transport rate (14%). Moreover, a significant reduction was obvious in CO2 fixative reaction system parameters: carboxylation efficiency (52%) and ribulose-1,5-bisphosphate(RuBP) regeneratio