Abstract
The photochemical reflectance index (PRI) is a widely used spectral index which can show stress-induced changes in photosynthesis (e.g., increase of the nonphotochemical quenching of chlorophyll fluorescence (NPQ)). The artificial illumination of plants improves the efficiency of estimation of photosynthetic processes on the basis of PRI measurements. However, the simultaneous activity of different light sources with different locations can disturb the measurement of PRI. Using pulses of a green-yellow measuring light can potentially solve this problem. The aim of the present work was to investigate the possibility of using green-yellow light pulses for the investigation of light-induced changes in PRI in higher plants (pea, wheat, and pumpkin) and for the analysis of connection between PRI and the energy-dependent component of NPQ (NPQF). First, we showed that using green-yellow light pulses eliminated shifts of reflected light, which were connected with the application of a red actinic light. Second, analysis of light dependences of NPQF, the absolute value of PRI, and changes in PRI (the difference between the PRI under the actinic light and the initial value of PRI without this light, ΔPRI) showed that the dynamics of the increase of NPQF and the decrease of PRI and ΔPRI were similar. Changes in NPQF and ΔPRI were found to be significant. In contrast, changes in the absolute value of PRI were not significant in most of the variants of the experiments. Third, scatter plots between NPQF and ΔPRI showed similar linear correlations for investigated species; moreover, a total set of experimental points (for pea, wheat, and pumpkin) were also described by the same linear regression. Thus, our results show that (i) pulses of green-yellow measuring light can be used for measurements of PRI, and (ii) ΔPRI is a more effective indicator for the estimation of NPQ than the absolute value of PRI.
Highlights
Terrestrial plants can be affected by numerous environmental stressors
The first question of our work was whether using green-yellow light (GYL) pulses can exclude error which is connected with changes in the AL intensity
The photochemical reflectance index (PRI) is an important spectral index which is widely used for the remote monitoring of photosynthetic processes in plants [2,4,5,7]
Summary
Terrestrial plants can be affected by numerous environmental stressors (excess light, high and low temperatures, drought, salinity, attacks of insects, phytopathogens, etc.). Many stressors can disturb photosynthetic processes [1], and thereby decrease the productivity of plants. The early identification of stressor-induced photosynthetic changes plays an important role in precision agriculture and ecological monitoring, and the development of methods for the remote sensing of photosynthetic processes is a topical practical problem [2]. Measurements of chlorophyll fluorescence and different spectral indices on the basis of reflected light are effective tools for such remote sensing [2,3,4,5,6,7]. One of the key spectral indices is the photochemical reflectance index (PRI), which is connected with photosynthetic parameters and the content of pigments in plant [4,5,6,7,8,9].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
