中文摘要：

以西藏主栽春青稞品种喜马拉雅22为试验材料，于开花期，利用LI-6400XT光合仪分别测定了倒1叶、倒2叶、倒3叶的光合光响应曲线，应用直角双曲线模型（RH）、非直角双曲线模型（NRH）、直角双曲线修正模型（MRH）、指数模型（EM）、修正指数模型（MEM）拟合青稞不同叶位的光响应曲线，比较和分析各模型的拟合参数。结果表明：模型RH、NRH拟合的青稞倒1、倒2、倒3叶最大净光合速率（Pmax）均高于实测值，而模型EM拟合值均小于实测值；模型RH、NRH拟合的青稞倒1、倒2、倒3叶光饱和点（f）远小于实测值，而模型EM拟合值略小于实测值；模型MRH拟合的Pmax,Is均与青稞不同叶位叶片实测值接近。模型MEM由于光抑制项为负值，导致Pmax和Is无法计算。在高光合有效辐射条件下[PAR〉1200μmol photons／（m2·s）]，只有MRH拟合的青稞倒1、倒2、倒3叶光合光响应曲线与实测光响应曲线最为接近，且拟合优度最佳。5种模型的拟合效果为MRH〉MEM〉EM〉RH、NRH。

英文摘要：

The mostly planted hulless barley species ＂Himalaya 22＂ in Tibet was used as the test material, and LI- 6400XT photosynthetic apparatus was used to measure the photosynthetic light response curves of barley leaves in the 1 st, 2nd and 3rd leaf at the flowering stage, and the rectangle hyperbola curve model （RH）, modified rectangle hyperbolic curve model （MRH）, exponential model （EM） and modified exponential model （MEM） were used to portray the light response curves of barley leaves at different positions. The fitting parameters of each model were compared and analyzed. The results showed that the maximum net photosynthetic rate （Priam） of barley leaves in the 1 st, 2nd and 3rd leaf fitted by RH and NRH model was higher than the measured values, while the EM model fitting values were less than the measured value. The light saturation points （Is） of barley leaves in the 1st, 2nd and 3rd leaf fitted by RH and NRH were far less than the measured values, while the EM model fitting values were slightly less than the measured value; the Pnmax and Is of MRH were close to the measured values of the highland barley leaves at different position. Due to light suppression, the phase of the MRH model was negative, leading to that the P and Is could not be calculated. Under the condition of strong photosynthetically active radiation light （PAR〉I 200μmol photon/m2·s）, only the photosynthetic light response curve of barley leaves in the 1st, 2nd and 3rd leaf fitted by the model MRH was the closest to the measured photosynthetic curve with the best goodness of fit. The model fittng ranking was as follow： MRH model〉 MEM model〉 EM〉 RH, NRH model, therefore, the model MRH was the best fitting model of hulless barley.