Abstract: In the crop growth simulation models,the Leaf Initial Quantum Yield(α) and the Maximum Net Photosynthetic Rate(Pmax) are two sensitive parameters in calculating the photosynthesis,which have always being the nodus in the research of the crop growth simulation models.Based on seven years field observations in the experiment base of Shandong Agricultural University,where the data were measured by Li-6400.The light response curves of photosynthesis were fitted and values of the two parameters of winter wheat were settled.The rsults showed that values of the α and Pmax,changed with the different varieties of the winter wheat,which indicated large instability,but when seven years experimental data of the total winter wheat variety were fitted,the results showed a relatively steady range of α and Pmax with 0.053-0.107mol·mol-1 and 10.1-49.2μmol·m-2·s-1 respectively.The range of the two key parameters for the crop growth simulation model in this study could provide references for the calibration and validation of the key parameters in crop growth simulation models.

Key words: Huang-Huai-Hai areas, Huang-Huai-Hai areas, Winter wheat, Crop model, Photosynthesis, Initial quantum yield(α), Maximum photosynthetic rate(Pmax)