Department of Engineering Mathematics, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
J R Soc Interface. 2013 May 29;10(85):20130326. doi: 10.1098/rsif.2013.0326. Print 2013 Aug 6.
Plants display a range of striking architectural adaptations when grown at elevated temperatures. In the model plant Arabidopsis thaliana, these include elongation of petioles, and increased petiole and leaf angles from the soil surface. The potential physiological significance of these architectural changes remains speculative. We address this issue computationally by formulating a mathematical model and performing numerical simulations, testing the hypothesis that elongated and elevated plant configurations may reflect a leaf-cooling strategy. This sets in place a new basic model of plant water use and interaction with the surrounding air, which couples heat and mass transfer within a plant to water vapour diffusion in the air, using a transpiration term that depends on saturation, temperature and vapour concentration. A two-dimensional, multi-petiole shoot geometry is considered, with added leaf-blade shape detail. Our simulations show that increased petiole length and angle generally result in enhanced transpiration rates and reduced leaf temperatures in well-watered conditions. Furthermore, our computations also reveal plant configurations for which elongation may result in decreased transpiration rate owing to decreased leaf liquid saturation. We offer further qualitative and quantitative insights into the role of architectural parameters as key determinants of leaf-cooling capacity.
当植物在高温下生长时，它们会表现出一系列引人注目的结构适应性。在模式植物拟南芥中，这些适应性包括叶柄的伸长，以及叶柄和叶片与土壤表面的夹角增大。这些结构变化的潜在生理意义仍在推测之中。我们通过构建数学模型并进行数值模拟来解决这个问题，检验了这样一个假设，即伸长和升高的植物结构可能反映了一种叶片冷却策略。这为植物水分利用和与周围空气相互作用建立了一个新的基本模型，该模型将植物内部的热和物质传递与空气中的水蒸气扩散耦合起来，使用一个依赖于饱和度、温度和水蒸气浓度的蒸腾项。我们考虑了一个二维、多叶柄的茎干几何形状，并增加了叶片形状的细节。我们的模拟表明，在水分充足的条件下，增加叶柄长度和角度通常会导致蒸腾速率增加和叶片温度降低。此外，我们的计算还揭示了一些植物结构，由于叶片液体饱和度降低，伸长可能会导致蒸腾速率降低。我们进一步提供了定性和定量的见解，了解结构参数作为叶片冷却能力的关键决定因素的作用。
