Experimental study on using unsaturated light-induced delayed fluorescence to represent plant photosynthetic capacity

Delayed fluorescence (OF) is the phenomenon of long-lived photon emission by plant after being illuminated with light and put into darkness. In field study, the intensity of DF is reported to be a measure of photosynthetic capacity (marked as PhC). In this research, a new method was developed, which used unsaturated light-induced OF intensity (in this research, marked as I-DF) to represent plant PhC. The proposed method prolonged the sustainable working hours of OF detection system. Hence, it was more appropriate than saturated light condition for field study. In order to examine the new method, four different species were chosen as samples to compare I-DF with net photosynthetic rate (Pn) under different intensities of excitation light. The results showed that there is an excellent linear correlation between them (R >= 0.947). The experimental results testified that unsaturated light-induced I-DF can represent the plant PhC.