## 3 Results and Discussions
### Growing Environment Measurement by the WSN
#### 3.1.4. Vigor Measurement of Mandarin Orange Leaves by Using Fluorescent Method  
The measurements were made at three areas in each leaf shown in the Figure 5b in order to find the pigment distribution inside the leaf. First, the distribution of pigments inside each leaf was examined for 10 leaves taken from three trees of weak vigor (weak leaf) and for another 10 leaves taken from three trees of strong vigor (strong leaf). Each bar in the chart of Figure 20 shows the difference among the three areas for the good color leaf of strong vigor, bad color leaf of weak vigor and good color of weak vigor. Figure 20a corresponds to the result of chlorophyll (CHL), Figure 20b corresponds to that of flavonoid (FLAV), Figure 20c corresponds to that of anthocyanin (ANTH), and Figure 20d corresponds to that of nitrogen balance index (NBI).  
Figure 19. Comparison of temperature distribution between weak leaf and strong one.  
Figure 17. Mapping of the leaf to the template: (**a**) Sample of the mapping; (**b**) apply this mapping method to real leaf.  
Figure 18. Thermal images of the leaves: (**a**) Strong leaf; (**b**) Weak leaf; (**c**) Temperature difference between strong leaf and weak one.  
As a result, the difference in each value among the three areas was hardly found in the case of the strong leaf. Meanwhile, as is shown in Figure 20, in the case of the weak leaves, it was found that a leaf with a good color has a similar tendency as the strong leaf, and the leaf with bad color has a difference among the three areas inside the leaf for CHL and NBI. Although there is a little problem in the weak leaf, the average value of the three areas was used as a representative value of each leaf in the later discussion. According to the results of the CHL, FLAV, ANTH and NBI for 10 weak leaves and for another 10 strong leaves, the CHL is distributed from 22 to 42 for the weak leaves, while it is distributed from 38 to 52 for the strong leaves. The ANTH is around 0.1 for the weak leaves and the existence of anthocyanin was confirmed while it was almost 0 in the strong leaves and no anthocyanin was found. The FLAV is distributed from 1.4 to 1.8 for the weak leaves while it is distributed from 1.3 to 1.6 for the strong ones. The tendency that the FLAV of the weak leaf is slightly higher than that of the strong leaf was observed. The NBI showed a similar tendency to the CHL. That is, the NBI is distributed from 13 to 30 for the weak leaves while it is distributed from 30 to 42 for the strong ones.  
Figure 21 shows the relationship between ANTH and NBI for strong leaves and weak leaves. As for the strong leaves, a weak negative correlation was found between the ANTH and NBI (Figure 21a). Meanwhile, in the case of the weak leaf, a strong negative correlation was found and the correlation coefficient was 0.95 (Figure 21b).  
Generally, photosynthesis is caused by a light reaction (electron transfer system) that generates biochemical energy such as ATP and NADPH and a dark reaction (Calvin cycle) that immobilizes the carbon dioxide using these biochemical energies. The energy of sunlight is entirely used to immobilize the carbon dioxide when the light reaction is balanced with the dark reaction. However, the surplus energy that is not used for immobilization of the carbon dioxide contributes to active oxygen generation in the plant body and tissue destruction occurs when the solar energy uptake by the light reaction exceeds the carbon dioxide fixation by the dark reaction. As one of the defense mechanisms to this phenomenon, it is known that resolving the chlorophyll that takes part in the light  
Figure 20: Comparison of each index of various leaves: (**a**) The rusult of chlorophyll; (**b**) The result of flavonoid; (**c**) The result of anthocyanin; (**d**) The result of NBI.  
reaction and generating anthocyanins reduces the surplus sunlight, and the light reaction is made to balance with the dark reaction [23]. The negative correlation between the ANTH and CHL obtained in our experiments seems to be consistent with this fact.