The photochemical reflectance index: an optical indicator of photosynthetic radiation use efficiency across species, functional types, and nutrient levels
The photochemical reflectance index: an optical indicator of photosynthetic radiation use efficiency across species, functional types, and nutrient levels
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DOI：
10.1007/s004420050337
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发表时间：
1997-12-01
期刊：
影响因子：
2.7
通讯作者：
Surfus, JS
中科院分区：
文献类型：
--
作者：
Gamon, JA;Serrano, L;Surfus, JS
光化学反射指数（PRI）源自 531 和 570 nm 的窄带反射率，被探索作为代表三种功能类型（一年生、落叶多年生和常绿多年生）的 20 个物种的光合辐射利用效率的指标。在各个物种中，中午全日照下的冠层顶部叶子表现出 PRI 和 Delta F/Fm' 之间的强相关性，Delta F/Fm' 是一种基于荧光的光系统 II (PSII) 光化学效率指数。 PRI 还与二氧化碳净吸收量和通过气体交换测量的辐射利用效率显着相关。当按功能类型检查物种时，常绿植物相对于一年生植物和落叶植物表现出显着降低的中午光合速率。中午的减少与辐射利用效率的降低有关，令人高兴的是净二氧化碳吸收量、PRI 和 Delta F/Fm' 值的降低，以及光保护性叶黄素循环色素玉米黄质水平的增加。对于每种功能类型，营养缺乏导致 PRI 和 Delta F/Fm' 相对于受精对照均降低。将叶子暴露在日间辐射过程中并模拟中午气孔关闭的实验室实验表明，PRI 随辐照度和叶子生理状况的变化而迅速变化。在这些研究中，PRI 与 Delta F/Fm' 和辐射利用效率密切相关，这些效率是通过除最低光水平之外的气体交换确定的。在暴露于增加的光水平时检查差异光谱表明，531 nm Delta 反射信号由两个光谱分量组成。在低辐照度下，该信号以 545 nm 分量为主，与辐射利用效率没有密切关系。在超过 100 μmol m(-2)s(-1) 的逐渐升高的光水平下，531 nm 信号越来越多地以 526 nm 成分为主，这与光利用效率以及叶黄素色素紫黄质向炭疽黄质和玉米黄质的转化相关。进一步考虑构成 531 nm 信号的两个分量可能会得出适用于广泛照明范围的光合功能指数。本研究的结果支持使用 PRI 作为全日照下叶片和冠层光合辐射利用效率的种间指数，但不适用于从深荫到全日照的大范围光照。不同物种、功能类型和营养处理的冠层顶部叶片的 PRI 和光合辐射利用效率之间存在一致的关系，这表明如果冠层和林分结构的问题能够得到解决，则可以通过远程反射测量提供的“俯视图”得出相对光合速率。
The photochemical reflectance index (PRI), derived from narrow-band reflectance at 531 and 570 nm, was explored as an indicator of photosynthetic radiation use efficiency for 20 species representing three functional types: annual, deciduous perennial, and evergreen perennial. Across species, top-canopy leaves in full sun at midday exhibited a strong correlation between PRI and Delta F/Fm', a fluorescence-based index of photosystem II (PSII) photochemical efficiency. PRI was also significantly correlated with both net CO2 uptake and radiation use efficiency measured by gas exchange. When species were examined by functional type, evergreens exhibited significantly reduced midday photosynthetic rates relative to annual and deciduous species. This midday reduction was associated with reduced radiation use efficiency, delectable as reduced net CO2 uptake, PRI, and Delta F/Fm' values, and increased levels of the photoprotective xanthophyll cycle pigment zeaxanthin. For each functional type, nutrient deficiency led to reductions in both PRI and Delta F/Fm' relative to fertilized controls. Laboratory experiments exposing leaves to diurnal courses of radiation and simulated midday stomatal closure demonstrated that PRI changed rapidly with both irradiance and leaf physiological slate. In these studies, PRI was closely correlated with both Delta F/Fm' and radiation use efficiency determined from gas exchange at all but the lowest light levels, Examination of the difference spectra upon exposure to increasing light levels revealed that the 531 nm Delta reflectance signal was composed of two spectral components. At low irradiance, this signal was dominated by a 545-nm component, which was not closely related to radiation use efficiency. At progressively higher light levels above 100 mu mol m(-2)s(-1), the 531-nm signal was increasingly dominated by a 526-nm component, which was correlated with light use efficiency and with the conversion of the xanthophyll pigment violaxanthin to antheraxanthin and zeaxanthin. Further consideration of the two components composing the 531-nm signal could lead to an index of photosynthetic function applicable over a wide range of illumination. The results of this study support the use of PRI as an interspecific index of photosynthetic radiation use efficiency for leaves and canopies in full sun,but not across wide ranges in illumination from deep shade to full sun. The discovery of a consistent relationship between PRI and photosynthetic radiation use efficiency for top-canopy leaves across species, functional types, and nutrient treatments suggests that relative photosynthetic rates could be derived with the ''view from above'' provided by remote reflectance measurements if issues of canopy and stand structure can be resolved.