LEPSE, Univ Montpellier, INRAE, Institut Agro Montpellier, Montpellier, France.
CAPTE-EMMAH, Université d'Avignon et des Pays de Vaucluse, INRAE, Avignon, France.
Plant Physiol. 2021 Jun 11;186(2):977-997. doi: 10.1093/plphys/kiab113.
Canopy light interception determines the amount of energy captured by a crop, and is thus critical to modeling crop growth and yield, and may substantially contribute to the prediction uncertainty of crop growth models (CGMs). We thus analyzed the canopy light interception models of the 26 wheat (Triticum aestivum) CGMs used by the Agricultural Model Intercomparison and Improvement Project (AgMIP). Twenty-one CGMs assume that the light extinction coefficient (K) is constant, varying from 0.37 to 0.80 depending on the model. The other models take into account the illumination conditions and assume either that all green surfaces in the canopy have the same inclination angle (θ) or that θ distribution follows a spherical distribution. These assumptions have not yet been evaluated due to a lack of experimental data. Therefore, we conducted a field experiment with five cultivars with contrasting leaf stature sown at normal and double row spacing, and analyzed θ distribution in the canopies from three-dimensional canopy reconstructions. In all the canopies, θ distribution was well represented by an ellipsoidal distribution. We thus carried out an intercomparison between the light interception models of the AgMIP-Wheat CGMs ensemble and a physically based K model with ellipsoidal leaf angle distribution and canopy clumping (KellC). Results showed that the KellC model outperformed current approaches under most illumination conditions and that the uncertainty in simulated wheat growth and final grain yield due to light models could be as high as 45%. Therefore, our results call for an overhaul of light interception models in CGMs.
冠层光截获决定了作物捕获的能量数量，因此对作物生长和产量的建模至关重要，并且可能对作物生长模型（CGM）的预测不确定性有很大贡献。因此，我们分析了农业模型互比较和改进项目（AgMIP）使用的 26 个小麦（Triticum aestivum）CGM 的冠层光截获模型。21 个 CGM 假设光衰减系数（K）是常数，根据模型的不同，其取值范围从 0.37 到 0.80。其他模型考虑了光照条件，并假设冠层中的所有绿色表面具有相同的倾斜角（θ），或者 θ 分布遵循球形分布。由于缺乏实验数据，这些假设尚未得到评估。因此，我们进行了一项田间实验，用五个叶型不同的品种在正常和双行间距下播种，并从三维冠层重建中分析了冠层中 θ 的分布。在所有的冠层中，θ 的分布都很好地用椭球分布来表示。因此，我们对 AgMIP-Wheat CGM 集合的光截获模型与具有椭球叶角分布和冠层聚集（KellC）的基于物理的 K 模型进行了比较。结果表明，在大多数光照条件下，KellC 模型的表现优于当前方法，并且由于光模型导致的模拟小麦生长和最终籽粒产量的不确定性可能高达 45%。因此，我们的结果呼吁对 CGM 中的光截获模型进行全面审查。
