Plant Sciences Unit, Institute of Agricultural, Fisheries and Food Research (ILVO), Melle, Belgium.
Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium.
Ann Bot. 2018 Sep 24;122(4):669-676. doi: 10.1093/aob/mcy105.
Currently, functional-structural plant models (FSPMs) mostly resort to static descriptions of leaf spectral characteristics, which disregard the influence of leaf physiological changes over time. In many crop species, including soybean, these time-dependent physiological changes are of particular importance as leaf chlorophyll content changes with leaf age and vegetative nitrogen is remobilized to the developing fruit during pod filling.
PROSPECT, a model developed to estimate leaf biochemical composition from remote sensing data, is well suited to allow a dynamic approximation of leaf spectral characteristics in terms of leaf composition. In this study, measurements of the chlorophyll content index (CCI) were linked to leaf spectral characteristics within the 400-800 nm range by integrating the PROSPECT model into a soybean FSPM alongside a wavelength-specific light model.
Straightforward links between the CCI and the parameters of the PROSPECT model allowed us to estimate leaf spectral characteristics with high accuracy using only the CCI as an input. After integration with an FSPM, this allowed digital reconstruction of leaf spectral characteristics on the scale of both individual leaves and the whole canopy. As a result, accurate simulations of light conditions within the canopy were obtained.
The proposed approach resulted in a very accurate representation of leaf spectral properties, based on fast and simple measurements of the CCI. Integration of accurate leaf spectral characteristics into a soybean FSPM leads to a better, dynamic understanding of the actual perceived light within the canopy in terms of both light quantity and quality.
目前，功能结构植物模型（FSPM）大多依赖于对叶片光谱特征的静态描述，而忽略了叶片随时间发生的生理变化的影响。在包括大豆在内的许多作物物种中，这些随时间变化的生理变化非常重要，因为叶片叶绿素含量会随叶片年龄而变化，而在荚果形成期间，营养氮会从营养器官转移到发育中的果实。
PROSPECT 是一个从遥感数据估算叶片生化组成的模型，非常适合通过将 PROSPECT 模型与特定波长的光模型相结合，对叶片组成的叶片光谱特征进行动态近似。在这项研究中，将 PROSPECT 模型集成到大豆 FSPM 中，通过将叶绿素含量指数（CCI）的测量值与 400-800nm 范围内的叶片光谱特征联系起来，同时建立了一个特定波长的光模型。
CCI 与 PROSPECT 模型参数之间的直接联系使得我们仅使用 CCI 作为输入，就能非常准确地估算叶片光谱特征。与 FSPM 集成后，可以在单个叶片和整个冠层尺度上对叶片光谱特征进行数字重建。因此，获得了冠层内光照条件的精确模拟。
该方法基于 CCI 的快速简单测量，实现了叶片光谱特性的非常准确表示。将准确的叶片光谱特征集成到大豆 FSPM 中，可以更好地动态了解冠层内实际感知到的光量和光质。
