Investigation of Nonlinear Plant Response Determined by Chlorophyll Fluorescence to Periodic Saturating Light Flashes under Photoinhibition Conditions

In this article, we investigate the possibility of using wavelet transform-based bispectral analysis of data obtained by long-term continuous recording of chlorophyll fluorescence in tobacco plant (Nicotiana tabacum L.) leaves to detect signs of photoinhibition in plants. Using PAM fluorometry, continuous four-hour time series were obtained, the data analysis of which using the generally accepted approach confirmed photodamage to the photosynthetic apparatus of plants illuminated with high-intensity light (λ = 625 nm, 900 µmol photons/(s m2)), as well as light-dependent recovery of samples under low-intensity light (λ = 625 nm, 2 µmol photons/(s m2)). The approach proposed in present work made it possible to identify patterns in the appearance of a peak on a bispectral index map to analyze stressful conditions. A change in the degree of nonlinearity of the transmission of an external periodic signal in plant signaling systems was demonstrated during the transition from darkness to high-intensity light, as well as during the transition from high-intensity light to low-intensity light or to darkness.