光响应曲线的参数是研究植物生理状态的重要指标, 常用的光响应曲线模型无法准确地计算出光饱和点和最大净光合速率。该文利用光响应曲线新模型——指数改进模型、直角双曲线模型、直角双曲线修正模型、非直角双曲线模型和指数模型, 拟合高粱(Sorghum bicolor)、苋(Amaranthus tricolor)、大麦(Hordeum vulgare)和半夏(Pinellia ternata)的光响应曲线, 并随机选取部分数据进行检验, 得到了各模型计算出的主要生理参数, 并对这些数据进行了比较分析, 讨论了各模型之间的优缺点和准确性, 描述了C₃、C₄植物光响应的适宜性。结果表明, 基于C₃植物得到的指数改进模型和直角双曲线修正模型能较准确地计算出C₃、C₄植物饱和光强和最大净光合速率, 并在描述光响应曲线时比另外3个模型具有更高的精确性和适宜性。实验结果可为光响应曲线模型在C₃和C₄光合途径植物中的应用提供参考。

Aims Our primary aim was to compare the differences and accuracies of light-response curves between C₃ and C₄ plants as described by five light-response curve models: modified exponential (a new model), rectangular hyperbola, modified rectangular hyperbola , non-rectangular hyperbola and exponential. Methods Light-response curves of Xizang hulless barley (Hordeum vulgare), grain sorghum (Sorghum bicolor), amaranth (Amarantus mangestbus) and Pinellia ternate were measured by a portable photosynthetic gas analysis system with a LED radiation source (LI-6400). The collected data were used to fit and test the five light-response curve models, and photosynthetic parameters, such as light saturation point and maximum net photosynthetic rate, were compared with the measured values. Important findings The results show that the light-response curves of the four plants described by the modified exponential and modified rectangular hyperbola models are better than the rectangular hyperbola, non-rectangular hyperbola and exponential models, especially when light intensity is beyond the light saturation point. The results also indicate that the modified exponential and modified rectangular hyperbola models also describe the light-response curves characteristics of C₄ plants, although the two models were established based on C₃ plants. Therefore, these two models provide a reference for the application of light-response curve models in plants with different photosynthetic pathways including C₃ and C₄.