| dc.description.abstract | Chlorophyll fluorescence has been proved by many theses to be effective as an application for observing the growth state of plants. The advantage is that it can be measured without destroying the structure of the leaf, and it has a faster measurement time. However, most of the current studies measure the fluorescent signal of the leaf as a whole, and lack the analysis from the perspective of each fluorescent component in the fluorescent signal of the leaf. Therefore, the purpose of this thesis is to set up a frequency domain fluorescence lifetime measurement system, and combine multiple fluorescence analysis technology to measure the changes of the fluorescence signals of various components in the leaves of different plants under photosynthesis.In this thesis, using correction plane to solve the nonlinear effects of voltage and phase caused by the photodetector PMT used in the experiment. It also proves the correctness and accuracy of the system in measuring the fluorescence lifetime through fluorescent standards sample. When measuring the R6G fluorescent standard sample, its ideal fluorescence lifetime is 3.9 ns, and the error rate of modulation and phase is about 0.5%. When measuring Eosin Y fluorescence standard sample, its ideal fluorescence lifetime is 1.08 ns, and the error rate of modulation is about 12%, and phase is about 7.5%. It is inferred that the modulation frequency used in the measurement is too low, which makes the system have a large error when measuring samples with a short fluorescence lifetime.In the measurement of the leaf fluorescence signal, it was found that the change of the fluorescence lifetime of the leaf can be divided into the reaction zone and the steady zone. In the experiment also tried to analyze the changes of the fluorescence lifetime of leaves through polar coordinates. It was found that the distribution of the fluorescence lifetime on the polar coordinates can be represented by a straight line by fitting, and the change of the fluorescence lifetime is the same as that. Also, there is a relationship between leaf fluorescence intensity and the distribution of the fluorescence lifetime on the polar coordinates. In the final experiment, the multiple fluorescence analysis technology was used to analyze and observe the changes of the intensity and weight of each fluorescent component in the leaves under photosynthesis. At the same time, combined with the measurement of the fluorescence spectrum, two characteristic peaks (F685 and F730) in the fluorescence spectrum of the leaves were found. The response time of fluorescence spectral intensity is very close to the response time of the fluorescence lifetime. If the system can improve the accuracy of the multiple fluorescence lifetime analysis in the future, the correlation between the two can be more clearly observed. | en_US |