Solar-induced chlorophyll (chl) fluorescence (SIF) has been shown to be positively correlated with vegetation photosynthesis, suggesting that it is a useful signal for understanding of environmental responses and spatial heterogeneity of photosynthetic activity at various scales from leaf to the globe. Photosynthesis is often inhibited in stressful environments (photoinhibition), but how photoinhibition influences the relationship between photosynthesis and chl fluorescence remains unclear. Here, I studied light energy allocation among photosynthesis, chl fluorescence and heat dissipation in photoinhibited leaves and tested whether photosynthesis in photoinhibited leaves can be evaluated from chl fluorescence and reflectance spectra in remote sensing. Chl fluorescence and reflection spectra were examined with the pulse amplified modulation (PAM) system and spectroradiometer, respectively. Photoinhibited leaves had lower photosynthetic rates and quantum yields of photochemistry (Φ_P) and higher chl fluorescence yields. Consequently, photosynthesis was negatively correlated with chl fluorescence, which contrasts the positive relationships between photosynthesis and SIF observed in past remote sensing studies. This suggests that vegetation photosynthesis evaluated solely from chl fluorescence may be overestimated if the vegetation is dominated by severely photoinhibited leaves. When a model of energy allocation was applied, Φ_P estimated from chl fluorescence and photochemical reflectance index (PRI) significantly correlated with the observed Φ_P, suggesting that the model is useful to evaluate photosynthetic activities of photoinhibited leaves by remote sensing.

太阳诱导的叶绿素（chl）荧光（SIF）已显示与植被的光合作用正相关，这表明它是了解环境响应和从叶到地球各个尺度的光合作用空间异质性的有用信号。光合作用通常在压力环境中被抑制（光抑制），但是光抑制如何影响光合作用和chl荧光之间的关系仍然不清楚。在这里，我研究了光抑制叶片中光合作用，chl荧光和散热之间的光能分配，并测试了是否可以通过遥感中的chl荧光和反射光谱评估光抑制叶片中的光合作用。Chl荧光和反射光谱分别用脉冲放大调制（PAM）系统和分光辐射计检查。受光抑制的叶片的光合作用的光合速率和量子产率较低（Φ_P）和较高的chl荧光产量。因此，光合作用与chl荧光呈负相关，这与过去遥感研究中观察到的光合作用和SIF之间的正相关关系形成了鲜明的对比。这表明，如果植被被严重光抑制的叶子所占主导地位，则仅通过chl荧光评估的植被光合作用可能被高估了。当施加能量分配的模型，Φ _P从叶绿素荧光，并与观察到的Φ显著相关光化学反射指数（PRI）估计_P，表明该模型是通过遥感来评估photoinhibited叶光合活性是有用的。