Abstract: To better understand the physiological and ecological responses of maize to elevated atmospheric CO₂ concentration and soil cadmium pollution under future climate change, we investigated the interactive effects of different CO₂ concentrations and CdCl₂ stresses on leaf gas exchange, chlorophyll content, plant biomass as well as the MDA content and related antioxidant enzyme activities of the maize cultivar Zhengdan 958 in a split-plot experiment with environmental growth chambers. Elevated atmospheric CO₂ concentration increased net photosynthetic rate (P_n) by 24% (P<0.001) and 6% (P<0.05) under mild and severe CdCl₂ stress, respectively. Elevated atmospheric CO₂ concentration decreased the transpiration rate and stomatal conductance of maize leaves (P<0.001), and thus increased the instantaneous water use efficiency (P<0.001). Mild CdCl₂ stress significantly increased leaf biomass under ambient CO₂ concentration (P<0.001), but elevated CO₂ concentration decreased root biomass (P<0.05) and stem biomass of maize (P<0.001). Mild and moderate CdCl₂ stress increased MDA content and POD activity in maize leaves under different CO₂ concentrations, but elevated CO₂ concentration reduced MDA content and POD activity. There were significantly interactive effects of CO₂ concentration and CdCl₂ stress on the P_n of maize plants (P=0.002). Our results suggested that elevated atmospheric CO₂ concentration could increase net photosynthetic rate and instantaneous water use efficiency of maize under mild and moderate CdCl₂ stress, but reduce the MDA content, thus improving the resistance of maize plants to CdCl₂ stress.

Key words: maize (Zea may L.), CO₂ concentration, Cd stress, gas exchange parameter, physiological process