Department of Electrical & Computer Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece.
Institute of Agri-Food and Life Sciences, University Research Center, Hellenic Mediterranean University, 71410 Heraklion, Greece.
Sensors (Basel). 2023 Mar 1;23(5):2699. doi: 10.3390/s23052699.
Chlorophyll meters are portable devices used to assess and improve plants' nitrogen management and to help farmers in the determination of the health condition of plants through leaf greenness measurements. These optical electronic instruments can provide an assessment of chlorophyll content by measuring the light passing through a leaf or by measuring the light radiation reflected from its surface. However, independently of the main principle of operation and use (e.g., absorbance vs. reflectance measurements), commercial chlorophyll meters usually cost hundreds or even thousands of euros, making them inaccessible to growers and ordinary citizens who are interested in self-cultivation, farmers, crop researchers, and communities lacking resources in general. A low-cost chlorophyll meter based on light-to-voltage measurements of the remaining light after two LED light emissions through a leaf is designed, constructed, evaluated, and compared against two well-known commercial chlorophyll meters, the SPAD-502 and the atLeaf CHL Plus. Initial tests of the proposed device on lemon tree leaves and on young Brussels sprouts plant leaves revealed promising results compared to the commercial instruments. The coefficient of determination, R2, was estimated to be 0.9767 for the SPAD-502 and 0.9898 for the atLeaf-meter in lemon tree leaves samples compared to the proposed device, while for the Brussels sprouts plant, R2 was estimated to be 0.9506 and 0.9624, respectively. Further tests conducted as a preliminary evaluation of the proposed device are also presented.
叶绿素仪是一种便携式设备，用于评估和改善植物的氮素管理，并通过叶片绿色度测量帮助农民确定植物的健康状况。这些光学电子仪器可以通过测量透过叶片的光或测量其表面反射的光辐射来评估叶绿素含量。然而，无论主要操作和使用原理（例如，吸收度与反射率测量）如何，商业叶绿素仪的价格通常在数百甚至数千欧元之间，这使得对自我种植感兴趣的种植者和普通市民、农民、作物研究人员以及一般资源匮乏的社区无法承受。本设计、构建、评估了一种基于叶片两次 LED 光发射后剩余光的电压测量的低成本叶绿素仪，并与两款知名的商业叶绿素仪（SPAD-502 和 atLeaf CHL Plus）进行了比较。与商用仪器相比，该设备在柠檬树叶片和年轻抱子甘蓝植物叶片上的初步测试显示出了有前景的结果。与商用仪器相比，在柠檬树叶片样本中，SPAD-502 和 atLeaf 叶绿素仪的决定系数 R2 分别估计为 0.9767 和 0.9898，而在抱子甘蓝植物中，R2 分别估计为 0.9506 和 0.9624。还介绍了作为对所提出的设备的初步评估而进行的进一步测试。
