Li Ji, Zhang Yongguang, Gu Lianhong, Li Zhaohui, Li Jing, Zhang Qian, Zhang Zhaoying, Song Lian
International Institute for Earth System Sciences, Nanjing University, Nanjing, Jiangsu, China.
Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
J Exp Bot. 2020 Dec 31;71(22):7179-7197. doi: 10.1093/jxb/eraa408.
Photosynthetic capacity (leaf maximum carboxylation rate, Vcmax) is a critical parameter for accurately assessing carbon assimilation by plant canopies. Recent studies of sun-induced chlorophyll fluorescence (SIF) have shown potential for estimating Vcmax at the ecosystem level. However, the relationship between SIF and Vcmax at the leaf and canopy levels is still poorly understood. In this study, we investigated the dynamic relationship between SIF and Vcmax and its controlling factors using SIF and CO2 response measurements in a rice paddy. We found that SIF and its yield (SIFy) were strongly correlated with Vcmax during the growing season, although the relationship varied with plant growth stages. After flowering, SIFy showed a stronger relationship with Vcmax than SIF flux at both the leaf and canopy levels. Further analysis suggested that the divergence of the link between SIF and Vcmax from leaf to canopy are the result of changes in canopy structure and leaf physiology, highlighting that these need to be considered when interpreting the SIF signal across spatial scales. Our results provide evidence that remotely sensed SIF observations can be used to track seasonal variations in Vcmax at the leaf and canopy levels.
光合能力（叶片最大羧化速率，Vcmax）是准确评估植物冠层碳同化的关键参数。近期对太阳诱导叶绿素荧光（SIF）的研究显示了在生态系统水平上估算Vcmax的潜力。然而，叶片和冠层水平上SIF与Vcmax之间的关系仍知之甚少。在本研究中，我们利用稻田中的SIF和CO₂响应测量，研究了SIF与Vcmax之间的动态关系及其控制因素。我们发现，在生长季节，SIF及其产量（SIFy）与Vcmax密切相关，尽管这种关系随植物生长阶段而变化。开花后，在叶片和冠层水平上，SIFy与Vcmax的关系比SIF通量更强。进一步分析表明，SIF与Vcmax之间从叶片到冠层的联系差异是冠层结构和叶片生理变化的结果，这突出表明在跨空间尺度解释SIF信号时需要考虑这些因素。我们的结果提供了证据，证明遥感SIF观测可用于跟踪叶片和冠层水平上Vcmax的季节变化。
