Water fulfils key roles in maintaining a plant's biological activity. Water shortage induces stomatal closure, causing a reduction in photosynthesis and transpiration rates. Sun-induced chlorophyll fluorescence (SIF) emission is sensitive to subtle, stress-induced variations in non-photochemical quenching and in photosynthetic electron transport, caused by e.g., a fluctuation in the water availability. Based on this sensitivity, a framework for calibrating a water stress function in a crop growth model using ground-based SIF observations is proposed. SIF time series are simulated by coupling the AgroC crop growth model to the Soil Canopy Observations Photosynthesis Energy (SCOPE) model. This allowed parametrizing the water stress function in the AgroC crop growth model, resulting in improved estimates of actual evapotranspiration and net ecosystem exchange over a sugar beet stand during stressed periods. The improvement in the estimation of the water and carbon fluxes by AgroC during the summer months highlights the ability of canopyscale SIF observations to serve as a remote sensing metric to indicate the intensity of a stress condition. We argue that our framework, linking SIF emission to stress functions, can be used to extract information concerning drought stress from the Fluorescence Explorer (FLEX) satellite, scheduled for launch in 2024.

水在维持植物的生物活性方面起着关键作用。缺水会导致气孔关闭，导致光合作用和蒸腾速率降低。太阳诱导的叶绿素荧光 (SIF) 发射对非光化学猝灭和光合电子传递中微妙的、应力诱导的变化很敏感，这些变化是由例如水可用性的波动引起的。基于这种敏感性，提出了一种使用地面 SIF 观测校准作物生长模型中水分胁迫函数的框架。通过将 AgroC 作物生长模型与土壤冠层观测光合作用能量 (SCOPE) 模型耦合来模拟 SIF 时间序列。这允许参数化 AgroC 作物生长模型中的水分胁迫函数，从而提高了对压力时期甜菜林实际蒸散量和净生态系统交换的估计。夏季月份 AgroC 对水和碳通量估计的改进突出了冠层 SIF 观测作为遥感指标指示压力条件强度的能力。我们认为，我们的框架将 SIF 发射与压力函数联系起来，可用于从计划于 2024 年发射的荧光探索者 (FLEX) 卫星中提取有关干旱压力的信息。夏季月份 AgroC 对水和碳通量估计的改进突出了冠层 SIF 观测作为遥感指标来指示压力条件强度的能力。我们认为，我们的框架将 SIF 发射与压力函数联系起来，可用于从计划于 2024 年发射的荧光探索者 (FLEX) 卫星中提取有关干旱压力的信息。夏季月份 AgroC 对水和碳通量估计的改进突出了冠层 SIF 观测作为遥感指标来指示压力条件强度的能力。我们认为，我们的框架将 SIF 发射与压力函数联系起来，可用于从计划于 2024 年发射的荧光探索者 (FLEX) 卫星中提取有关干旱压力的信息。