Plant simulation models are abstractions of plant physiological processes that are useful for investigating the responses of plants to changes in the environment. Because photosynthesis and transpiration are fundamental processes that drive plant growth and water relations, a leaf gas-exchange model that couples their interdependent relationship through stomatal control is a prerequisite for explanatory plant simulation models. Here, we present a coupled gas-exchange model for $C_4$ leaves incorporating two widely used stomatal conductance submodels: Ball–Berry and Medlyn models. The output variables of the model includes steady-state values of $C{O}_2$ assimilation rate, transpiration rate, stomatal conductance, leaf temperature, internal $C{O}_2$ concentrations, and other leaf gas-exchange attributes in response to light, temperature, $C{O}_2$, humidity, leaf nitrogen, and leaf water status. We test the model behavior and sensitivity, and discuss its applications and limitations. The model was implemented in Julia programming language using a novel modeling framework. Our testing and analyses indicate that the model behavior is reasonably sensitive and reliable in a wide range of environmental conditions. The behavior of the two model variants differing in stomatal conductance submodels deviated substantially from each other in low humidity conditions. The model was capable of replicating the behavior of transgenic $C_4$ leaves under moderate temperatures as found in the literature. The coupled model, however, underestimated stomatal conductance in very high temperatures. This is likely an inherent limitation of the coupling approaches using Ball–Berry type models in which photosynthesis and stomatal conductance are recursively linked as an input of the other.

中文翻译：

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C4叶片的耦合气体交换模型与气孔电导模型的比较

植物模拟模型是植物生理过程的抽象，可用于研究植物对环境变化的响应。因为光合作用和蒸腾作用是驱动植物生长和水关系的基本过程，所以通过气孔控制将它们相互依存的关系耦合起来的叶片气体交换模型是解释性植物模拟模型的先决条件。在这里，我们提出了一个耦合的气体交换模型$C_4$叶子融合了两个广泛使用的气孔电导子模型：Ball-Berry和Medlyn模型。模型的输出变量包括的稳态值$C{Ø}_2$ 同化率，蒸腾速率，气孔导度，叶片温度，内部 $C{Ø}_2$ 浓度和其他叶片气体交换属性，以响应光线，温度， $C{Ø}_2$，湿度，叶氮和叶水状态。我们测试模型的行为和敏感性，并讨论其应用和局限性。该模型是使用新颖的建模框架以Julia编程语言实现的。我们的测试和分析表明，模型行为在广泛的环境条件下相当敏感且可靠。在低湿度条件下，气孔导度子模型不同的两个模型变体的行为基本上彼此偏离。该模型能够复制转基因的行为$C_4$如文献所述，叶片在中等温度下生长。然而，耦合模型低估了高温下的气孔导度。这可能是使用Ball-Berry型模型的耦合方法的固有局限性，在该模型中，光合作用和气孔电导被递归链接为彼此的输入。