|Authors: ||K. Takayama, H. Nishina, K. Mizutani, S. Iyoki, S. Arima, K. Hatou, Y. Miyoshi|
|Keywords: ||image sensing, photosynthesis, plant diagnosis, speaking plant approach|
The chlorophyll fluorescence imaging technique is useful to evaluate the photosynthetic functions of living plants.
In our previous study, we developed a chlorophyll fluorescence imaging system for full-size tomato plants in a greenhouse.
This system images the chlorophyll fluorescence induction phenomenon, a dynamic change in chlorophyll fluorescence intensity induced by an excitation light under dark condition and analyzes the shape of the induction curve, i.e., the time course of the chlorophyll fluorescence intensity during this phenomenon.
The shape of the induction curve is characterized with the initial maximum peak (P), the following transient dip (S) and secondary small peak (M). We defined a photosynthetic function index (PFI; the fluorescence intensity of P divided by the average fluorescence intensity from S to M) to evaluate the shape of the induction curve.
In this study, we applied this system to evaluate the photosynthetic functions of tomato plants grown under different night air temperatures during winter and to detect the difference in photosynthetic functions of two tomato cultivars, i.e., ‘Reika’ and ‘Tomimaru’, in a greenhouse.
The PFI of the plants grown under relatively low night air temperature (11°C) was significantly lower than that of the plants grown under normal night air temperature (15°C). The PFI of ‘Tomimaru’ was significantly higher than that of ‘Reika’. The differences in PFIs would be partly due to the differences in the chlorophyll pigments compositions.
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