葉の分光反射率・分光透過率を用いた葉内クロロフィル量測定装置の試作研究

本文基于Kubelka-Munk理论，建立了植物叶片的反射率和透射率与叶绿素含量的数学模型，提出了一种无损测量叶片叶绿素含量的光学方法。在此基础上，假设Kubelka-Munk理论中的散射系数和吸收系数都可以表示为植物叶片色素含量的线性函数，利用中心波长为880 nm的三个波段的反射率和透射率计算叶绿素含量，通过实验验证了模型和方法的适用性。用该模型计算的反射率和透射率与实测值吻合得很好。此外，还用最小二乘法确定了计算中所需的几个不可测常数。我们还证实了这些结果与植物学领域的几个众所周知的事实是一致的。本文提出的方法在0 ~ 80 μ g/cm ~ 2的范围内，对所有植物叶绿素含量的估算误差为6.6 μ g/cm ~ 2。实验还证实，该仪器在叶绿素含量0 ~ 100 μ g/cm ^2范围内的估算误差为7.8 μ g/cm ^2。

In this investigation, we propose a nondestructive or optical method of measuring the chlorophyll content in a leaf after constructing a mathematical model of reflectance and transmittance of plant leaves as a function of their chlorophyll pigment content.The model is based on the Kubelka-Munk theory, and involves the modeling of the multiple reflection of light in a leaf which is assumed to be composed of a stack of four layers. It also includes the assumption that the scattering coefficient and the absorption coefficient of the Kubelka-Munk theory can be expressed as a linear function of the pigment content of a plant leaf.In the proposed method, the chlorophyll content is calculated from reflectances and transmittances at three bands whose center wavelengths are 880nm, 720nm and 700nm.Experiments were performed in order to confirm the applicability of the model and the method. Reflectance and transmittance calculated with the model showed very good agreement with measured values. Furthermore, several unmeasurable constants necessary in the calculation were determined by a least squares method. We also confirmed that these results were consistent with several well known facts in the botanical field. The method proposed here showed a very small estimation error of 6.6mu g/cm^2 over the chlorophyll content range from 0 to 80mu g/cm^2 for all kinds of plants tested.After the applicability was confirmed, we developed a hand-held instrument to measure the chlorophyll pigment content in a leaf in accordance with the proposed method. It was also confirmed by an experiment that this instrument showed a small estimation error of 7.8mu g/cm^2 over the chlorophyll content range from 0 to lOOmu g/cm^2.