Profiles of light absorption and chlorophyll within spinach leaves from chlorophyll fluorescence
Profiles of light absorption and chlorophyll within spinach leaves from chlorophyll fluorescence
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DOI：
10.1046/j.1365-3040.2002.00910.x
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发表时间：
2002-10-01
影响因子：
7.3
通讯作者：
Evans, JR
中科院分区：
文献类型：
--
作者：
Vogelmann, TC;Evans, JR
叶绿素荧光用于估计叶绿素溶液和叶片内吸收光的分布。对于叶绿素溶液，发射的荧光强度随距离照射表面的距离呈对数线性下降，这与比尔定律预测的结果一致。在显微镜载玻片上进行外延光照时，叶绿素溶液的荧光量与叶绿素浓度成正比。这些关系似乎适用于光学更复杂的菠菜叶子。在外延光照下，叶片横切面发出的叶绿素荧光曲线与叶片横切面提取物的叶绿素含量相对应。因此，利用表观荧光测定叶片组织的相对叶绿素含量。叶片间的荧光分布与波长和取向有关，在50 ~ 70 μ m深度处达到峰值。通过水分渗透叶片，计算了在空域和细胞壁界面处散射引起的路径延长。令人惊讶的是，栅栏状叶肉和海绵状叶肉的路径延长值相似，绿光下的路径延长值最大（550 > 650 > 450 nm）。结合叶绿素在叶片上的分布，计算了表观消光系数的分布。菠菜叶片内的光分布可以用表观消光系数和Beer-Lambert/ bouger定律很好地近似。光的吸收深度比光纤测量预测的要大，其中50%的蓝光和绿光分别达到125微米和240微米深。
Chlorophyll fluorescence was used to estimate profiles of absorbed light within chlorophyll solutions and leaves. For chlorophyll solutions, the intensity of the emitted fluorescence declined in a log-linear manner with the distance from the irradiated surface as predicted by Beer's law. The amount of fluorescence was proportional to chlorophyll concentration for chlorophyll solutions given epi-illumination on a microscope slide. These relationships appeared to hold for more optically complex spinach leaves. The profile of chlorophyll fluorescence emitted by leaf cross sections given epi-illumination corresponded to chlorophyll content measured in extracts of leaf paradermal sections. Thus epifluorescence was used to estimate relative chlorophyll content through leaf tissues. Fluorescence profiles across leaves depended on wavelength and orientation, reaching a peak at 50-70 mum depth. By infiltrating leaves with water, the pathlengthening due to scattering at the airspace : cell wall interfaces was calculated. Surprisingly, the palisade and spongy mesophyll had similar values for pathlengthening with the value being greatest for green light (550 > 650 > 450 nm). By combining fluorescence profiles with chlorophyll distribution across the leaf, the profile of the apparent extinction coefficient was calculated. The light profiles within spinach leaves could be well approximated by an apparent extinction coefficient and the Beer-Lambert/Bouguer laws. Light was absorbed at greater depths than predicted from fibre optic measurements, with 50% of blue and green light reaching 125 and 240 mum deep, respectively.