Facultad de Ciencias Exactas y Naturales, CONICET, Universidad de Buenos Aires, INQUIMAE, Buenos Aires, Argentina.
Facultad de Ciencias Exactas y Naturales, Dpto. de Química Inorgánica, Analítica y Química Física, Universidad de Buenos Aires, Buenos Aires, Argentina.
Photochem Photobiol. 2021 Jan;97(1):110-121. doi: 10.1111/php.13273. Epub 2020 May 22.
Optical properties of plant leaves are relevant to evaluate their physiological state and stress effect. The main objective of this work was to study how variegation, pigment composition or reflective features modifies leaves' photophysical behavior. For this purpose, green leaves (Ficus benjamina), purple leaves (Tradescantia pallida), green leaves covered by white trichomes (Cineraria maritima) and variegated leaves (Codiaeum aucubifolium) were analyzed. Firstly, foliar surface morphology was evaluated by scanning electron microscopy. UV-vis and near-IR reflectance and transmittance spectra were obtained to calculate absorption (k) and scattering (s) coefficients. The theoretical approaches of Pile of Plates and Kubelka-Munk's theory resulted still valid for nonstandard leaves with differing surface conditions. However, frequently used spectral indices were not reliable for predicting water content, when leaves differed from conventional ones. The proportionality between the absorption factor and chromophore/pigment concentration was also lost for hairy leaves. A simplified model to describe these facts was presented here. Fluorescence spectra were recorded and corrected, due to light re-absorption. Water-optical parameter connection and pigment-optical parameter connection were thoroughly discussed. Leaf surface morphology and pigmentation have not only influenced the optical features of leaves but also played a role in the effect that particulate matter could cause on leaf photosynthesis.
植物叶片的光学性质与评估其生理状态和胁迫效应有关。本工作的主要目的是研究杂色、色素组成或反射特征如何改变叶片的光物理行为。为此，分析了绿色叶片（榕属植物）、紫色叶片（紫露草）、被白色绒毛覆盖的绿色叶片（马利筋）和斑驳叶片（变叶木）。首先，通过扫描电子显微镜评估叶片表面形态。获得紫外-可见和近红外反射和透射光谱，以计算吸收（k）和散射（s）系数。对于具有不同表面条件的非标准叶片，堆垛板和 Kubelka-Munk 理论的理论方法仍然有效。然而，当叶片与传统叶片不同时，常用的光谱指数对于预测水分含量并不可靠。多毛叶片的吸收因子与发色团/色素浓度之间的比例关系也丧失了。本文提出了一种简化模型来描述这些事实。记录并校正了荧光光谱，以消除光再吸收。深入讨论了水光学参数关系和色素光学参数关系。叶片表面形态和色素不仅影响叶片的光学特性，而且还影响颗粒物对叶片光合作用的影响。
