Responses of wheat photosynthetic characteristics to the increase of CO_2 concentration

Using portable photosynthesis measuring system,the influence of atmospheric CO2 concentration increase on wheat photosynthetic characteristics including net photosynthetic rate(Pn),stomatal conductance(Cs),transpiration rate(Tr) and intercellular CO2 concentration(Ci)was analyzed in flowering stage and filling stage when the wheat has a comparatively strong field and the changing of water use efficiency under future conditions of high CO2 concentration was predicted.The results indicated that in different growth stages(flowering stage and filling stage),the net photosynthetic rate(Pn),intercellular CO2 concentration(Ci)and water use efficiency increased gradually with the increase of CO2 concentration,which is exactly contrary to the stomatal limitation value(Ls),the stomatal conductance(Cs) and transpiration rate(Tr) decreased first and then increased and decreased again at last;CO2 concentration had highly significant positive correlation with the net photosynthetic rate(Pn),water use efficiency and intercellular CO2 concentration(Ci),of which the correlation coefficient with CO2 concentration(Ci) is the highest;CO2 concentration had significant positive correlation with stomatal conductance(Cs) and transpiration rate(Tr) at flowering stage,exactly on contrary to the filling stage,and meanwhile,the stomata limitation value(Ls)had highly significant negative correlation with CO2 concentration at both two stages.The research can provide scientific basis for high quality and yield wheat cultivation realized by the fully utilizing light and water resources in flowering stage and filling stage under the environmental background with gradually increased atmospheric CO2 concentration.