[Analysis of Chlorophyll Fluorescence Transient by Spectral Multi-exponential Approximation].

The method for analysis of chlorophyll fluorescence transient using approximation of measured signal by multi-exponential series is described. Visualization of partial sums of this series allows us to find amplitudes and characteristic times of individual phases of fluorescence induction curve. This method gives more rigid criteria of phase identification instead of semi-empirical approach currently used. Applied to Chlamidomonas reinhardtii sulfur deprivation case, it shows efficiency in finding visually undistinguishable phases of fluorescence transient for early detection of stress.

Machine learning methods for assessing photosynthetic activity: environmental monitoring applications.

Monitoring of the photosynthetic activity of natural and artificial biocenoses is of crucial importance. Photosynthesis is the basis for the existence of life on Earth, and a decrease in primary photosynthetic production due to anthropogenic influences can have catastrophic consequences. Currently, great efforts are being made to create technologies that allow continuous monitoring of the state of the photosynthetic apparatus of terrestrial plants and microalgae. There are several sources of information suitable for assessing photosynthetic activity, including gas exchange and optical (reflectance and fluorescence) measurements. The advent of inexpensive optical sensors makes it possible to collect data locally (manually or using autonomous sea and land stations) and globally (using aircraft and satellite imaging). In this review, we consider machine learning methods proposed for determining the functional parameters of photosynthesis based on local and remote optical measurements (hyperspectral imaging, solar-induced chlorophyll fluorescence, local chlorophyll fluorescence imaging, and various techniques of fast and delayed chlorophyll fluorescence induction). These include classical and novel (such as Partial Least Squares) regression methods, unsupervised cluster analysis techniques, various classification methods (support vector machine, random forest, etc.) and artificial neural networks (multilayer perceptron, long short-term memory, etc.). Special aspects of time-series analysis are considered. Applicability of particular information sources and mathematical methods for assessment of water quality and prediction of algal blooms, for estimation of primary productivity of biocenoses, stress tolerance of agricultural plants, etc. is discussed.