Abstract: Two simplified leaf photosynthesis models of winter wheat including the impact of CO2were established, based on the observed data which obtained with LI-6200 portable photosynthesis system in the experimental fields in Shandong Agricultural University. 50 group data were used in simulation to determine the parameters of models. The coefficients of correlation were 0.796 and 0.793. The validation of models using observed 77 group data showed that the simulation powers were almost the same as each other. The coefficients of correlation were 0.9613 and 0.9609 at 0.01% error possibility level. Therefore, the two models all possessed the trait of practicability. The model of hyperbolic form was simpler and easier to use than that of exponential form. So it could be used in the crop models as the sub-model of leaf photosynthesis, and was helpful theoretically to assess the impact of the variation of CO2concentration and temperature on the trend of production of winter wheat.

Key words: CO_2, CO_2, Winter wheat, Leaf photosynthesis, Simplified model