几种光合作用光响应典型模型的比较研究

光响应曲线是判定植物光合效率的重要方法，通过曲线可以获得植物光合特性的相关生理参数，但不同模型提取的光响应参数和指标存在差异。本文选择直角双曲线、非直角双曲线和两种指数曲线模型，分别对3个品系常绿杨光响应数据进行拟合，提取了各光响应曲线模型的主要特征参数，对比分析了各模型参数问的差异，并对光饱和点（LSP）的不同计算方法进行了讨论。最后用巨尾桉光响应数据对分析结果作了进一步验证。结果表明，直角和非直角双曲线模型拟合的最大净光合速率（P＇max）、表观量子效率（a）及暗呼吸速率（Rd）值高于指数模型拟合值，且直角双曲线拟合的各参数均比非直角双曲线拟合的各参数的值大，而两指数模型各参数拟合值基本一致；在LSP计算方法中，用光通量200μmol·m^-2·s^-1以下的点拟合的Pn-I直线与其它模型相结合得到光饱和点的方法不可靠，会使计算结果明显偏小，用接近最大总光合速率Pmax一定比例的方法估计LSP也存在较大偏差，而P＇max由于消除了Rd的影响，计算光饱和点时各模型的估计比例相对固定，是一个比较理想的LSP估计方法，初步得出直角、非直角及指数模型用P＇max来估计光饱和点时应选取的比例分别为（78±1）％、（82±1）％及（96±1）％。

Comparison of Different Light Response Models for Photosynthesis

Parameters and indexes derived from different models of photosynthesis-light response showed distant values, but these models were still the major methods to judge the feature of plant photosynthesis so far. In this paper, four light response models including the rectangle hyperbola, the non-rectangle hyperbola and two kinds of index curves were used to fit the light response data of evergreen poplar clone. Parameters and indexes from different models were compared. Methods of calculating light saturation point （LSP） were also studied in this paper. Results showed that the main characteristic parameters, including maximum net photosynthetic rate （ P＇max ）, apparent quantum efficiency （ a ）, clark respiration rate （ Rd ）, which were obtained from the models of hyperbola ,were higher than those from two index curve models. And parameters estimated from rectangle hyperbola were higher than those of the non-rectangle hyperbola. While the parameters derived from two kinds of index models appeared no difference. As for calculation methods of LSP, the LSP obtained from the straight line fitted by photosynthetic photon flux density under 200μmol, m^-2.s^-1 combined with other models was underestimated and this method seems unreliable. It is also unreasonable that LSP was estimated through the maximum gross photosynthesis rate （Pmax）. However, LSP could be effectively estimated through P＇max by eliminating the influence of Rd, and the estimation percentage of each models was basically fixed. The percentages for calculating LSP through P＇max in rectangle hyperbola, non-rectangle hyperbola and index curves were suggested to be （78 ± 1 ）%, （ 82 ± 1 ） % and （96 ± 1 ） %, respectively. Beside, light response data of Eucalyptus grandis × E. urophylla were used to validate those conclusions.