A Non-invasive and Real-time Monitoring of the Regulation of Photosynthetic Metabolism Biosensor Based on Measurement of Delayed Fluorescence in Vivo

In this paper, a new principle biosensor for non-invasive monitoring of the regulation of photosynthetic metabolism based on quantitative measurement of delayed fluorescence (DF) is developed. The biosensor, which uses light-emitting diode lattice as excitation light source and a compact Single Photon Counting Module to collect DF signal, is portable and can evaluate plant photosynthesis capacity in vivo. Compared with its primary version in our previous report, the biosensor can better control environmental factors. Moreover, the improved biosensor can automatically complete the measurements of light and CO2 response curves of DF intensity. In the experimental study, the testing of the improved biosensor has been made in soybean (Glycine max Zaoshu No. 18) seedlings treated with NaHSO3 to induce changes in seedlings growth and photosynthetic metabolism. Contrast evaluations of seedlings photosynthesis were made from measurements of net photosynthesis rate (Pn) based on consumption of CO2 in tested plants. Current testing results have demonstrated that the improved biosensor can accurately determine the regulatory effects of NaHSO3 on photosynthetic metabolism. Therefore, the biosensor presented here could be potential useful for real-time monitoring the regulatory effects of plant growth regulators (PGRs) and other exogenous chemical factors on plant growth and photosynthetic metabolism.