Zhang Jiayu, Kaiser Elias, Zhang Hanyi, Marcelis Leo F M, Vialet-Chabrand Silvere
Horticulture and Product Physiology, Department of Plant Sciences, Wageningen University & Research, Wageningen, Netherlands.
Plant Methods. 2025 Jan 24;21(1):6. doi: 10.1186/s13007-025-01326-3.
Quantifying plant transpiration via thermal imaging is desirable for applications in agriculture, plant breeding, and plant science. However, thermal imaging under natural non-steady state conditions is currently limited by the difficulty of quantifying thermal properties of leaves, especially specific heat capacity (C). Existing literature offers only rough estimates of C and lacks simple and accurate methods to determine it.
We developed a non-invasive method to quantify k (the product of leaf thickness (lt), leaf density(ρ), and C), by fitting a leaf energy balance model to a leaf temperature (T) transient during and after a ~ 10 s light pulse. C was then estimated by dividing k by lt*ρ. Using this method, we quantified C for 13 horticultural and tropical plant species, and explored the relationship between C and leaf water content, specific leaf area and T response rate during the light pulse. Values of C ranged between 3200-4000 J kg K, and were positively correlated with leaf water content. In species with very thick leaves, such as Phalaenopsis amabilis, we found leaf thickness to be a major factor in the temperature response to a short light pulse.
Our method allows for easy determination of leaf C of different species, and may help pave the way to apply more accurate thermal imaging under natural non-steady state conditions.
通过热成像对植物蒸腾作用进行量化，在农业、植物育种和植物科学等领域具有应用价值。然而，在自然非稳态条件下进行热成像，目前受到叶片热特性量化困难的限制，尤其是比热容（C）。现有文献仅提供了C的粗略估计，且缺乏简单准确的测定方法。
我们开发了一种非侵入性方法，通过将叶片能量平衡模型拟合到约10秒光脉冲期间及之后的叶片温度（T）瞬变过程，来量化k（叶片厚度（lt）、叶片密度（ρ）和C的乘积）。然后用k除以lt*ρ来估算C。利用该方法，我们对13种园艺和热带植物的C进行了量化，并探讨了C与叶片含水量、比叶面积以及光脉冲期间T响应率之间的关系。C值在3200 - 4000 J kg K之间，且与叶片含水量呈正相关。在叶片非常厚的物种中，如蝴蝶兰，我们发现叶片厚度是对短光脉冲温度响应的主要因素。
我们的方法能够轻松测定不同物种的叶片C，可能有助于为在自然非稳态条件下应用更精确的热成像铺平道路。
