Faculty of Civil & Environmental Engineering, Israel Institute of Technology (TECHNION), Haifa, Israel; School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, USA.
J Plant Physiol. 2020 Sep;252:153227. doi: 10.1016/j.jplph.2020.153227. Epub 2020 Jul 4.
Changes of chlorophyll (Chl) and carotenoid (Car) contents and their ratio (Car/Chl) represent a sensitive indicator of vegetation photosynthetic activity, developmental changes, and stress responses. The goal of this study was to design methods for estimating Car/Chl in plants across species, seasonal changes and ontogenetic phases requiring no species-specific parameterization. Four tree species (maple, chestnut, beech, and elm), wild vine shrub, and two crops species (maize and soybean) featuring contrasting leaf structure and photosynthetic pathways, a wide variation of pigment content and composition were studied. Two models based on leaf pigment absorption coefficients retrieved from reflectance spectra were proposed and tested. The first model uses the ratio of absorption coefficients at 500 and 700 nm and the second one-the difference between absorption coefficients at 500 and 660 nm. Both models accurately described Car/Chl changes in the range from 0.15 to 0.6 with determination coefficients R of 0.87 for the first model and 0.82 for the second; algorithms for Car/Chl estimation did not require parameterization for each species accurately assessing Car/Chl with normalized root mean square error below 11 % and 14 %, respectively. The findings of a close relationship between leaf absorption coefficients, retrieved from reflectance, and Car/Chl present the first step towards accurate generic quantification of pigment composition and hence the progression of developmental stages, impact of stresses, and potential photosynthetic activity.
叶绿素 (Chl) 和类胡萝卜素 (Car) 含量及其比值 (Car/Chl) 的变化是植被光合作用活性、发育变化和应激反应的敏感指标。本研究旨在设计一种方法，以估算跨物种、季节性变化和个体发育阶段的 Car/Chl，而无需进行物种特异性参数化。研究了四种树种（枫、栗、山毛榉和榆）、野生藤本灌木和两种具有不同叶片结构和光合作用途径、色素含量和组成差异较大的作物（玉米和大豆）。提出并测试了两种基于叶片色素吸收系数的模型，这些吸收系数从反射率光谱中提取。第一种模型使用 500nm 和 700nm 处的吸收系数之比，第二种模型使用 500nm 和 660nm 处的吸收系数之差。这两种模型都能准确描述 0.15 到 0.6 范围内的 Car/Chl 变化，第一个模型的决定系数 R 为 0.87，第二个模型的决定系数 R 为 0.82；Car/Chl 估算算法不需要对每个物种进行参数化，能够准确地评估 Car/Chl，归一化均方根误差分别低于 11%和 14%。叶片反射率中提取的反射率与 Car/Chl 之间的密切关系表明，这是精确量化色素组成以及评估发育阶段、应激影响和潜在光合作用活性的第一步。
