A model and measurement comparison of diurnal cycles of sun-induced chlorophyll fluorescence of crops
A model and measurement comparison of diurnal cycles of sun-induced chlorophyll fluorescence of crops
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DOI：
10.1016/j.rse.2016.09.021
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发表时间：
2016-12
影响因子：
13.5
通讯作者：
C. Tol;M. Rossini;S. Cogliati;W. Verhoef;R. Colombo;U. Rascher;G. Mohammed
中科院分区：
文献类型：
--
作者：
C. Tol;M. Rossini;S. Cogliati;W. Verhoef;R. Colombo;U. Rascher;G. Mohammed
在这项研究中，太阳能诱导叶绿素荧光（SIF）在760 nm（F760）的测量相结合的高光谱反射率（R）的测量收集在田间的农作物，以更好地了解荧光（ChlF）信号的植被。“土壤冠层观测光合作用和能量通量”（SCOPE）模型，它结合了辐射传输和光合作用的酶动力学与湍流热交换的植被冠层，部分反演获得模型参数从R采取健康（无压力）作物在生长季节。400和900 nm之间的反射光谱在中午在不同的日子在生长季节获得的色素浓度，叶面积指数和叶片倾角。然后，这些参数被用来模拟昼夜循环的半小时叶绿素谱，使用测量的天气变量作为输入。模拟了三种情况：（i）ChlF的恒定发射效率（在光系统水平），（ii）用光系统的电子传递、光合作用和ChlF模型每半小时计算的可变发射效率，和（iii）恒定发射效率，其被设定为光系统II的完全阻断的光化学电子传递和最小的非光化学猝灭的理论最大值。前两种情况下的模拟进行了比较，在O2-A波段的光谱拟合方法在非胁迫水稻和苜蓿的叶绿素从现场测量检索。这种比较和敏感性分析表明，SCOPE再现了大部分的季节性变化的SIF调整到R后，即使ChlF的排放效率保持不变，和F760值主要是由叶绿素含量，干物质，衰老材料和叶面积和叶倾角，而叶水分和类胡萝卜素含量有很小的影响。在这些作物的光合系统水平的叶绿素排放效率的日变化很小。第三种情况的模拟进行了比较，以测量的草，经过化学处理，以阻止电子传输，并挑起最大叶绿素。这一比较表明，所观察到的增加inF 760确实可以解释在光系统水平上的ChlF发射效率的变化。可以得出结论，高光谱反射率和叶绿素信号一起可以揭示植被结构和功能的动态。
In this study, measurements of solar induced chlorophyll fluorescence (SIF) at 760 nm (F760) are combined with hyperspectral reflectance (R) measurements collected in the field over agricultural crops in order to better understand the fluorescence (ChlF) signal of the vegetation. The ‘Soil-Canopy Observation Photosynthesis and Energy fluxes' (SCOPE) model, which combines radiative transfer and enzyme kinetics of photosynthesis with turbulent heat exchange in vegetation canopies, was partly inverted to obtain model parameters fromRtaken over healthy (unstressed) crops during the growing season. Reflectance spectra between 400 and 900 nm obtained at midday on different days in the growing season were used to obtain pigment concentrations, leaf area index and leaf inclination. These parameters were then used to simulate diurnal cycles of half-hourly ChlF spectra, using measured weather variables as input. Three scenarios were simulated: (i) a constant emission efficiency of ChlF (at the photosystem level), (ii) a variable emission efficiency calculated per half hour with an electron transport, photosynthesis and ChlF model for the photosystem, and (iii) a constant emission efficiency that was set to a theoretical maximum value for fully blocked photochemical electron transport of photosystem II and minimal non-photochemical quenching. The simulations of the first two scenarios were compared to ChlF retrieved from field measurements in the O2-A band with the spectral fitting method in unstressed rice and alfalfa. This comparison and a sensitivity analysis showed that SCOPE reproduces most of the seasonal variability of SIF after tuning toReven if the ChlF emission efficiency is kept constant, andF760values are mostly determined by chlorophyll content, dry matter, senescent material and leaf area and leaf inclination, whereas leaf water and carotenoid content had small effects. Diurnal variations in the ChlF emission efficiency at photosystem level were small in these crops. The simulations of the third scenario were compared to measurements of grass that was treated chemically to block electron transport and to provoke maximum ChlF. This comparison showed that the observed increase inF760can indeed be explained by a change in the ChlF emission efficiency at the photosystem level. It is concluded that hyperspectral reflectance and the ChlF signal together can reveal both the dynamics of vegetation structure and functioning.