Chlorophyll Fluorescence Induction Research Articles

ASSESSMENT OF CRITICAL PERIODS OF GROWTH AND DEVELOPMENT OF OILSEED RADISH PLANTS (RAPHANUS SATIVUS L. VAR. OLEIFORMIS PERS.) ON THE BASIS OF CHLOROPHYLL FLUORESCENCE INDUCTION METHOD

The article highlights the results of studying critical periods in the phenological development of oilseed radish varieties based on the use of basic indicators of the chlorophyll fluorescence induction curve (initial fluorescence (F0), plateau zone fluorescence (Fpl), maximum fluorescence (Fm), and stationary fluorescence (Fst). This complex was applied to oilseed radish plants of three varieties – ‘Rayduga’, ‘Zhuravka’ and ‘Lybid’ with the presentation of results for the variety ‘Zhuravka’ due to the similarity of the obtained data. phases of growth and development of oilseed radish: cotyledon phase, budding phase, flowering phase, green pod phase and yellow-green pod phase. Based on the use of a single-beam porous fluorimeter ‘Floratest’, developed by the Research and Engineering Center of Microelectronics of the Institute of Cybernetics named after V.M. Glushkova (Ukraine) formed curves of chlorophyll fluorescence induction (CFI) in the mode of 90-second fixation of parameters for each phenological phase of oilseed radish plants.The system of graphical display of regularity of formation of basic indicators of CFI curve within the main phenological phases is analyzed and generalizations and conclusions concerning dynamics of course of photochemical physiological processes of photosystem II of plants are made. in the process of phenological stage changes and the corresponding processes of morphogenesis of oilseed radish plants. The dynamics of exogenous and endogenous factors on the formation of indicators of assimilative activity of oilseed radish plant photosystems is analyzed on the basis of analysis of position and changes in time of main points of CFI schedule and substantiated obtained indicators with predicted physiological state of plants and possible assimilation activity. The values of baseline and indication indicators of CFI curve are compared to the main phenological phase of flowering, which is defined as the baseline in ensuring the realization of the productive potential of oilseed radish plants.

Methodological Fundamentals of Information System Design in Crop Production

Introduction. The creation of new technologies for precision agriculture is intended to increase productivity, labor efficiency and improve production processes. According to the World Food Program (WFP), 811 million people are chronically hungry, 283 million are in a state of starvation or close to starvation. An estimated 45 million more in 43 countries around the world are on the brink of starvation. Today's conditions require agriculture to feed a planet with an ever-growing population, minimize costs, and develop technologies that do not pollute the planet. Therefore, modeling of biological objects, research and design of intelligent systems for agriculture are of great interest to scientists around the world today. The purpose of the paper is development of the main approaches to building a full-scale experiment from the point of view of planning methodology, data processing, and model selection. The methodical basics, principles and practical component of planning an experiment in crop production are disclosed. The results of the development of the automatic decision-making system and the basic mathematical models for the construction of the information system are presented. Results. The basis of the study of the plant organism is a natural experiment. Field experiments in crop production are difficult to reproduce and face a number of difficulties related to the accuracy of the research methods used, which consist in the reliability and accuracy of the measurement results. For the first time, a multi-level information system for monitoring the condition and needs of plants, which contains a wireless sensor network, an ontologically controlled node, a global database, a knowledge base, an explanatory module, a control module, a computer, and a human-machine interface, which allows taking management decisions, was used for the research. decision. Our algorithm system is able to take into account the variability of changes in a multivariate environment. An information system where the chlorophyll fluorescence induction parameter, induction, measured in real time, acts as a control module. This is a promising way of adjusting irrigation regimes, monitoring the condition of plants and caring for perennial plantations. Conclusions. An important part of this work is the study of the effect of induction of chlorophyll fluorescence and the study of the methodology of research on photosynthesis. This effect is very sensitive to many changes in the plant. This is an advantage of the method and is a requirement for the research methodology or the specifics of its conduct. The study of plant objects faces a number of difficulties. Of special interest is the composition of the soil and the influence of soil characteristics on the growth and development of plants, for the creation of profile soil maps. Due to the fact that the plant object is not only a collection of individual systems inside the organism, but is also exposed to the constant influence of external factors of the environment, climate and soil, which must be taken into account when creating new information systems, the purpose of which is to increase productivity. Keywords: wireless sensor network, methodology, biosensors, information system, mathematical model, agriculture, plant physiology.

Prolonged Use of Insecticide Dimethoate Inhibits Growth and Photosynthetic Activity of Wheat Seedlings: A Study by Laser-Induced Chlorophyll Fluorescence Spectroscopy.

This paper is an extension of the work published in Journal of Fluorescence (2011) 21: 785-791. In the previous work, we studied the effect of dimethoate (50, 100 and 200ppm) on growth and photosynthetic activity of wheat seedlings after 10days of dimethoate treatment. In the present study, new measurement conditions (dimethoate concentration: 25ppm, treatment period: 20days and 30days) were used in addition to those used in the past work. Various plant growth parameters, photosynthetic pigment content, laser-induced chlorophyll fluorescence (LICF) spectra and fluorescence induction kinetics (FIK) curves were recorded after 10, 20 and 30days of dimethoate treatments. LICF spectra were recorded in the region of 650-780nm using violet diode laser (405nm). FIK curves were recorded at 685nm using red diode laser (635nm). Fluorescence intensity ratio (FIR) of two fluorescence peaks around 685 and 730nm, and variable chlorophyll fluorescence decrease ratio (Rfd) were determined from LICF spectra and FIK curves respectively. Curve-fitted parameters of LICF spectra were used for determination of FIR (F685/F730). The effect of treatment of the insecticide dimethoate on growth and photosynthetic activity of wheat seedlings was examined by using these parametersas well as the past work. In 10-days treatment, 25 and 50ppm dimethoate showed stimulatory effect with better stimulation being observed at 25ppm. All studied concentrations higher than 50ppm exhibited inhibitory effect on wheat seedlings. In case of dimethoate treatment studied for longer durations (more than 10days), all concentrations showed inhibitory effect. Lower doses which showed some positive response for short time duration become toxic with the extension of treatment periods. Thus, this study clearly confirms the toxic effect of dimethoate on wheat plants.

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.

The Impact of Cameraria ohridella (Lepidoptera, Gracillariidae) on the State of Aesculus hippocastanum Photosynthetic Apparatus in the Urban Environment

The paper presents the results on resistance of Aesculus hippocastanum Linnaeus, 1753 trees to Cameraria ohridella Deschka & Dimić, 1986 (Lepidoptera, Gracillariidae) impact under conditions of a modern urban environment on the example of Dnipro city as the largest industrial city in Ukraine. Field experiments were conducted in all park areas of the city, which allowed covering the full gradient of the existing urban environment and considered the different degrees of the tree settlement by the invasive insect species. The research of the impact of C. ohridella caterpillars’ vital activity on the photosynthetic apparatus state was carried out by applying a chlorophyll fluorescence induction technique. Diagnosis of photosynthetic dysfunction of fresh Ae. hippocastanum leaves was conducted using a portable “Floratest” fluorometer manufactured in Ukraine. Interpretation of the obtained Kautsky curves showed that significant changes in their critical parameters associated with the degree of leaf damage by C. ohridella caterpillars were not detected. The influence of tree growth site conditions on the following 4 main indicators of chlorophyll fluorescence induction was established: the initial value of fluorescence induction after irradiation; the value of “plateau” fluorescence induction; the maximum value of fluorescence induction; the stationary value of fluorescence induction after light adaptation of the plant leaf. It was found that the efficiency coefficients of photochemical processes in Ae. hippocastanum trees growing in low terrain levels differed significantly, which can probably be interpreted as their response to the specific characteristics of the urban environment.

ФОТОХІМІЧНА АКТИВНІСТЬ ЛИСТКІВ СОЇ ЗА ДІЇ ФІТОПАТОГЕННИХ БАКТЕРІЙ РІЗНОЇ ВІРУЛЕНТНОСТІ

Soybean plants were grown in a greenhouse. In the phase of 4-6 leaves soybeans were artificially infected with strains of pathogens: Xanthomonas axonopodis pv. glycines 9284 and Xanthomonas axonopodis pv. phaseoli 8843. These strains were obtained from the Ukrainian collection of microorganisms of the Zabolotny institute of Microbiology and Virology of National Academy of Sciences of Ukraine. The photochemical activity of soybean leaves was determined by the biophysical method of chlorophyll fluorescence induction in 13 days after plant inoculation with bacterial strains. A portable Florotest fluorometer was use for measurements. A degree of chlorophyll degradation and suppression of photosynthetic activity in soybean leaves at artificial infection with bacterial strains isolated from different plant species of the Fabaceaeae family dependent from its virulence have been shown. The strain X. axonopodis pv. glycines 9284, isolated from soybean plants, have been highly virulent and acted more negatively than the low virulent to soybean strain X. axonopodis pv. phaseoli 8843. In particular, the value of the minimum fluorescence F0 decreased by 37.0 and 15.4 % for inoculation by strains with different virulence degree: X. axonopodis pv. glycines 9284 (from soybeans) and X. axonopodis pv. phaseoli 8843 (from beans) respectively. There was also a significant decrease in the value of Fm in these variants – by 54.9 % (X. axonopodis pv. glycines 9284) and 19.3 % (X. axonopodis pv. phaseoli 8843). At the same time, the value of maximum quantum yield of PSII (Fv / Fm) was decreased by 11.8 % in the variant with inoculation of soybean plants with the highly virulent strain X. axonopodis pv. glycines 9284, that indicates photoinhibition or damage of antenna complexes of the PSII photosynthetic apparatus of soybean plants. At the same time, only the tendency to reduce the maximum quantum yield of PSII was determined under action infection plants with X. axonopodis pv. phaseoli 8843. A parameter chlorophyll fluorescence decrease ratio Rfd, which shows the activity of CO2 assimilation in the Calvin cycle, was inhibition more at the action of artificial infection with a highly virulent strain – X. axonopodis pv. glycines 9284 – 54.5 and less – at infection with a low virulence strain – X. axonopodis pv. phaseoli 8843 – by 10.8 %. With prolonged action of the pathogenic bacterial strains X.axonopodis pv. glycines 9284 and the X. axonopodis pv. phaseoli 8843 (fortnight) showed significant inhibition of the catalase and peroxidase activity of leaf tissues, which is evidence of an increase in the formation of ROS. It was demonstrated that the highly virulent strain X.axonopodis pv. glycines 9284 most of all suppressed the catalase activity of soybean leaf tissues.

Impact of invasive species Parectopa robiniella (Gracillariidae) on fluorescence parameters of Robinia pseudoacacia in the conditions of the steppe zone of Ukraine

Robinia pseudoacacia L. is one of the most common and environmentally adaptable introduced tree species which has become an important element of artificial afforestation and landscaping in Ukraine over the past 150 years. Throughout the history of its introduction on the territory of Ukraine, this species was considered resistant because of the absence of dangerous phytophages. At the beginning of the XXI century, the phytosanitary situation changed as the result of the penetration and rapid spread of a number of North American invasive phytophages. The appearance and distribution of the miner Parectopa robiniella (Clemens, 1863) (Lepidoptera, Gracillariidae) feeding on R. pseudoacacia was recognized as the largest invasion in Ukraine. This paper considers the issues of studying the effect of P. robiniella caterpillars feeding on R. pseudoacacia in various forest-growing conditions in the steppe zone of Ukraine. The process of photosynthesis, as the most important physiological parameter, was chosen as indicator of condition. The study was conducted using biosensor technology which made it possible to measure the effect of caterpillar feeding on critical parameters of chlorophyll fluorescence (the Kautsky curve). The research has shown that the initial value of fluorescence induction was within the range of 196–284 RFU, and the maximum value of the background fluorescence parameter was recorded in undamaged leaves and under shading conditions. Both the effect of phytophages and the shading factor caused a significant decrease in the values of fluorescence induction of the “plateau” both in the conditions of an artificially washed sandbar, on the watershed area of a watershed-gully landscape, as well as on natural sandy-loam soil. The maximum values of photosynthetic fluorescence induction under the simultaneous influence of the studied factors had rather high variability. In contrast to the fluorescence induction parameter, the “plateau” of the highest maximum fluorescence induction was reached in the absence of pest damage under conditions of total shading. As revealed by dispersion and regression analyses, the maximum fluorescence index was most dependent on the amount of solar radiation and on the degree of the leaf surface damage by phytophages. Significantly higher values of the steady-state fluorescence induction parameter were determined in the absence of insect damage in both shading and lighting conditions. A statistically significant combined influence of abiotic and biotic factors on the “plateau” fluorescence induction parameter was determined in comparison with the mono-influence of individual factors. A highly significant dependence of the maximum efficiency indicator of primary photosynthesis processes on individual factors of exogenous influence was established, while the combined effect of these factors did not affect this parameter. The obtained data allow one to apply in practice the methods of analyzing chlorophyll fluorescence induction to establish the physiological state of tree flora in forest and garden farms.

Intelligent Processing of Data From Chlorophyll Fluorometric Sensors

Introduction. Chlorophyll fluorescence induction (CFI) is a monitoring method of plant objects. CFI is a radiation of chlorophyll in red spectrum during a chlorophyll lighting of alive plant in blue spectrum. Chlorophyll fluorometers – the special devices that are used for measurement of CFI. Series of such devices were developed in V.M. Glushkov Institute of Cybernetics of the NAS of Ukraine. In particular, fluorometer «Floratest» and a network of wireless sensors were developed for CFI measurement. An accumulation of massive amount of measurements resulted into possibility to use intellectual methods like neural networks. The purpose of the paper is to research the possibilities of machine learning methods (neural networks, support vector machine (SVM), XGBoost algorithm) for analysis of CFI curves that were measured by means of sensors developed in V.M. Glushkov Institute of Cybernetics of the NAS of Ukraine. Results. Neural networks, SVM, XGboost ensure early detection of influence of stress factors on state of plants before appearance of external symptoms on plants that was showed on basis of data received during experiments with treatment of plants by herbicide. Analogically there was showed the possibility of using the machine learning methods for determination of soil humidity. The better methods for given tasks were determined. The study of possibilities to enhance the results of mentioned methods by means of normalization was conducted. The best results were demonstrated by z-score normalization and by minimax normalization to the range [-1;1]. Conclusions. The application of different machine learning algorithm for processing CFI curves demonstrated that SVM and XGBoost better suit for task of classification plants treated by means of herbicide. Neural network demonstrated worst results. The application mentioned methods for task of determination of artificial watering necessity demonstrated that neural network shows better result, SVM shows worse result and XGBoost shows worst result. Keywords: Chlorophyll fluorescence induction, neural network, support vector machine, algorithm XGBoost.

Application the Wireless Sensory Network Cluster in Digital Agriculture

The authors made a review of "Information technology of express-estimation of plant state in large territories in stressful environment." The essence of digital agriculture and its main components are briefly described. The main part of the article describes the cluster of Wireless Sensor Network. The main components of the cluster and the principle of the cluster are given. The work of the cluster is based on the "Information technology of express-estimation of plant state in large territories in stressful environment." This technology is based on the method of chlorophyll fluorescence induction. The introduction of new information technology into industrial digital agriculture will make it possible to determine in real time the condition of plants suffering from the influence of one or another stress factor and develop an appropriate managerial decision to compensate the influence of a certain factor. The main technical requirements for the wireless node of the cluster are the ability to work in the field conditions; easy location on the plant; low cost; lightweight up to 25 g, small size, etc. The WSN cluster is intended for use in the agricultural sector and for environmental monitoring. Using the data collected by the cluster and an express analysis of the state of plants is carried out, which allows making the necessary managerial decision on the use of fertilizers, fungicides, pesticides, herbicides and the need for irrigation. The authors took into account that the cultivation of corn for grain occupies a large sector in the agrarian sector of Ukraine and is an urgent task. The authors analyzed the industrial technology of growing of crop for grain and it was adapted for the information technology for measuring the CFI. The main points of the technological process for the use of the WSN cluster in industrial agriculture on the example of corn are determined, and on their basis, a scheme for measuring the CFI of plants by the WSN cluster was developed. A brief step-by-step methodology has been developed for using the WSN cluster in measuring the CFI of corn. The authors also presented an analysis of energy consumption in the WSN and proposed the ways to improve the energy efficiency of the WSN nodes. Keywords: sensors, wireless sensor network, express diagnostics of plant, smart agriculture.

Biphasic effects of typical chlorinated organophosphorus flame retardants on Microcystis aeruginosa

The potential accumulation of chlorinated organophosphorus flame retardants (Cl-OPFRs) in aquatic environments sparked interest in studying the effects of Cl-OPFRs on cyanobacterial blooms. In this work, two common Cl-OPFRs, tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and tris(2-chloroethyl) phosphate (TCEP), induced dose-dependent biphasic effect on bloom-forming M. aeruginosa. The hormetic response to low-dose Cl-OPFRs was associated with the upregulation of the type I NADH dehydrogenase (NDH-1) complex and its mediated cyclic electron transfer (CET) pathway, as reflected by a transient post-illumination increase in chlorophyll fluorescence, the dark reduction of P700+ and the change of NDH-1-related gene expression. The increased CET activity and carotenoid content jointly reduced the intracellular ROS production, facilitating cyanobacterial growth. Conversely, a higher concentration of both Cl-OPFRs induced severe inhibition of growth and photosynthetic oxygen-evolving activity through an imbalance between PSII and PSI. Toxic-dose Cl-OPFRs inhibited state transition and fixed cells into the State I with a higher PSII/PSI ratio, as indicated by chlorophyll fluorescence induction, 77 K fluorescence emission spectra and photosystem stoichiometry. The elevated PSII/PSI ratio created an imbalance between the two photosystems and eventually lead to ROS overproduction, which generate adverse effects on cell growth. This work provides important insights into the hormetic mechanism of Cl-OPFRs on Microcystis aeruginosa and their potential roles in harmful cyanobacteria blooms.

An empirical model for estimating daily atmospheric column-averaged CO2 concentration above São Paulo state, Brazil

BackgroundThe recent studies of the variations in the atmospheric column-averaged CO2 concentration ({text{X}}_{{{text{CO}}_{{2}} }}) above croplands and forests show a negative correlation between {text{X}}_{{{text{CO}}_{{2}} }}and Sun Induced Chlorophyll Fluorescence (SIF) and confirmed that photosynthesis is the main regulator of the terrestrial uptake for atmospheric CO2. The remote sensing techniques in this context are very important to observe this relation, however, there is still a time gap in orbital data, since the observation is not daily. Here we analyzed the effects of several variables related to the photosynthetic capacity of vegetation on {text{X}}_{{{text{CO}}_{{2}} }} above São Paulo state during the period from 2015 to 2019 and propose a daily model to estimate the natural changes in atmospheric CO2.ResultsThe data retrieved from the Orbiting Carbon Observatory-2 (OCO-2), NASA-POWER and Application for Extracting and Exploring Analysis Ready Samples (AppEEARS) show that Global Radiation (Qg), Sun Induced Chlorophyll Fluorescence (SIF) and, Relative Humidity (RH) are the most significant factors for predicting the annual {text{X}}_{{{text{CO}}_{{2}} }} cycle. The daily model of {text{X}}_{{{text{CO}}_{{2}} }} estimated from Qg and RH predicts daily {text{X}}_{{{text{CO}}_{{2}} }} with root mean squared error of 0.47 ppm (the coefficient of determination is equal to 0.44, p < 0.01).ConclusionThe obtained results imply that a significant part of daily {text{X}}_{{{text{CO}}_{{2}} }} variations could be explained by meteorological factors and that further research should be done to quantify the effects of the atmospheric transport and anthropogenic emissions.

Effects of supplemental light on tomato growth and the mechanism of the photosystem II apparatus.

The addition of supplemental light (SL) is an effective way to offset insufficient lighting. Although it is commonly believed that SL increases leaf photosynthesis and therefore improves yield and fruit flavor, the mechanism underlying the effects of SL on the photosystem II (PSII) apparatus remains unclear, and SL leads to high energy consumption. In order to save energy, we investigated the physiological status of the PSII apparatus, plant growth parameters and fruit parameters under two types of overhead SL with a low daily energy consumption of 0.0918 kWh m-2. The results showed that SL significantly increased the leaf chlorophyll content from full unfolding to yellowing. However, a remarkable increase in the absorption flux per cross-section (ABS/CS), the quantum yield of electron transport (φEo) and the performance index (PIabs) was observed only in a relatively short period of the leaf life cycle. SL also enhanced the fruit yield and quality. The obviously increased ΔVK and ΔVJ components of the chlorophyll fluorescence induction kinetic (OJIP) curve, along with the significantly decreased PIabs from days 40–60 after unfolding in the SL-treated groups, resulted in more rapid leaf aging and earlier fruit ripening compared with the control plants (CK). Therefore, an energy-friendly SL strategy can alter the physiological status of the PSII apparatus, affecting yield and fruit quality and maturity.

Interactions Between Carbon Metabolism and Photosynthetic Electron Transport in a Chlamydomonas reinhardtii Mutant Without CO2 Fixation by RuBisCO.

A Chlamydomonas reinhardtii RuBisCO-less mutant, ΔrbcL, was used to study carbohydrate metabolism without fixation of atmospheric carbon. The regulatory mechanism(s) that control linear electron flow, known as “photosynthetic control,” are amplified in ΔrbcL at the onset of illumination. With the aim to understand the metabolites that control this regulatory response, we have correlated the kinetics of primary carbon metabolites to chlorophyll fluorescence induction curves. We identify that ΔrbcL in the absence of acetate generates adenosine triphosphate (ATP) via photosynthetic electron transfer reactions. Also, metabolites of the Calvin Benson Bassham (CBB) cycle are responsive to the light. Indeed, ribulose 1,5-bisphosphate (RuBP), the last intermediate before carboxylation by Ribulose-1,5-bisphosphate carboxylase-oxygenase, accumulates significantly with time, and CBB cycle intermediates for RuBP regeneration, dihydroxyacetone phosphate (DHAP), pentose phosphates and ribose-5-phosphate (R5P) are rapidly accumulated in the first seconds of illumination, then consumed, showing that although the CBB is blocked, these enzymes are still transiently active. In opposition, in the presence of acetate, consumption of CBB cycle intermediates is strongly diminished, suggesting that the link between light and primary carbon metabolism is almost lost. Phosphorylated hexoses and starch accumulate significantly. We show that acetate uptake results in heterotrophic metabolism dominating phototrophic metabolism, with glyoxylate and tricarboxylic acid (TCA) cycle intermediates being the most highly represented metabolites, specifically succinate and malate. These findings allow us to hypothesize which metabolites and metabolic pathways are relevant to the upregulation of processes like cyclic electron flow that are implicated in photosynthetic control mechanisms.

Assessment of drought tolerance in some peach cultivars by chlorophyll fluorescence induction method

ISHS IX International Scientific and Practical Conference on Biotechnology as an Instrument for Plant Biodiversity Conservation (physiological, biochemical, embryological, genetic and legal aspects) Assessment of drought tolerance in some peach cultivars by chlorophyll fluorescence induction method

The role of photosynthetic activity in the regulation of flg22-induced local and systemic defence reaction in tomato

Flagellin (flg22) induces rapid and long-lasting defence responses. It may also affect the photosynthetic activity depending on several internal and external factors, such as the phytohormone ethylene or the day/night time. Based on the results, flg22 treatment, neither in the light phase nor in the evening, caused any significant change in chlorophyll fluorescence induction parameters in the leaves of wild-type and ethylene-receptor mutant Never ripe tomato plants measured the next morning. However, flg22 in the light phase decreased the effective quantum yield and the photochemical quenching both locally and systemically in guard cells. In parallel, the production of reactive oxygen species and nitric oxide increased, which contributed to the stomatal closure and a decrease in CO2 assimilation the next day. A decrease in sugar content and elevated hexokinase activity measured after flg22 exposure can also contribute to local defence responses in intact tomato plants.

Вплив фітопатогенних бактерій на активність фотосинтетичного апарату сої

Goal. To determine the differences in the impact of artificial infection with different in spread and harmfulness strains of bacterial pathogens — Pseudomonas savastanoi pv. glycinea (angular spot) and Hanthomonas fuscans pv. fuscans (small black spot) on the parameters of photochemical activity of the photosynthetic apparatus of soybean (Glycine max). Methods. Classical microbiological, biophysical, statistical. The biophysical method of induction of chlorophyll fluorescence was used to assess the condition and activity of the photosynthetic apparatus of soybean plants under artificial infection with bacterial strains. Results. The tendency was fixed to increase the minimum fluorescence (F0) of soybean leaves infected with P. savastanoi pv. glycinea B9190, as well as its reduction by lesions of X. fuscans pv. fuscans B9283. In the leaves of the affected plants, the suppression of the fluorescence maximum (Fm) by 16.2% was detected at infection with P. savastanoi pv. glycinea B9190 and its increase by 14.1% under the influence of X. fuscans pv. fuscans B9283. Quantum efficiency of photosystem II (FSII) — Fv/Fm parameter — decreased by 11.5% in leaves affected by P. savastanoi pv. glycinea B9190, while infection with X. fuscans pv. fuscans B9283 — increased that parameter by 7.1%. Indicator “decrease in chlorophyll fluorescence” (Rfd value), which is closely correlated with photosynthetic activity by inoculation of soybean plants with strains of P. savastanoi pv. glycinea B9190 and X. fuscans pv. fuscans B9283, was suppressed almost equally — by 6.7 and 6.1%, respectively. Conclusions. Artificial infection with the most common and harmful pathogen P. savastanoi pv. glycinea B9190 significantly adversely affected the fast “light” and slow “dark” reactions of photosynthesis by reducing the content of active chlorophyll, inhibiting its resynthesis, deteriorating the maximum quantum efficiency of FSII, and reducing carbon assimilation. The photosynthetic apparatus of soybeans proved to be more resistant to X. fuscans pv. fuscans B9283. The pathogen suppressed only the “dark” processes of photosynthesis, which can affect plant productivity. The potential efficiency of carbon assimilation (Rfd value) was suppressed almost equally — by 6.7 and 6.1% in the case of artificial infection of soybean plants with phytopathogenic strains — P. savastanoi pv. glycine B9190 and X. fuscans pv. fuscans B9283, respectively. Thus, the ability of the bacterial pathogen to have a more destructive and rapid effect on the plant organism gives it advantages to spread, scale and capture certain ecological niches and increase the manifestation of harmfulness.

Modeling solar-induced fluorescence of forest with heterogeneous distribution of damaged foliage by extending the stochastic radiative transfer theory

Solar Induced chlorophyll Fluorescence (SIF) has been used as a novel proxy of photosynthetic activity, which carries information about plant physiological state from the remote sensing observations. It is of great interest and potential to use SIF to detect forest stresses, but the approach requires accurate modeling of the SIF emission within stressed forests. However, the existing radiative transfer approaches of SIF generally ignore the within-crown heterogeneity caused by pests. To account for within-canopy scattering with both high accuracy and efficiency, FluorESRT was proposed as a new model for simulating the SIF of forests with heterogeneous distribution of damaged foliage, which was the synergy of the SIF radiative transfer and the Stochastic Radiative Transfer (SRT) model for forest with vertical distribution of damage. The performance of FluorESRT for both homogeneous and heterogeneous cases were well validated not only by the one-dimensional (1D) model SCOPE but also by the three-dimensional (3D) model DART. As an analytically simple approach, FluorESRT can evaluate the sensitivity of canopy SIF and apparent reflectance to the level of pest damage. The impact of structural properties of damaged foliage on canopy fluorescence, as well as the response of hyperspectral signals on the pest damage was analyzed. According to our study, hyperspectral vegetation indices with the consideration of SIF showed higher sensitivity to pest damage in the early stage when the response of broad band vegetation indices was hardly detectable. The results indicated that the potential of FluorESRT to simulate SIF and hyperspectral apparent reflectance should play a critical role in early monitoring of pest damage.

EVALUATION OF THE INFLUENCE OF RAILWAY TRANSPORT ON THE PROCESS OF INDUCTION OF CHLOROPHYL FLUORESCENCE IN THE LINDEN TREES LEAVES

The paper presents the results of the study of the influence of railway transport on the passing the fluorescence induction of chlorophyll in the leaves of broad-leaved linden (Tilia platyphyllos). The relevance of research is due to the increase in the intensity of the negative impact of transport on the environment, directly on phytocenoses, which causes a violation of physiological processes and leads to the failure of photosynthesis, which is very important for the vital activity of plants. Thus, the aim of the work was to study the influence of railway transport on the induction of chlorophyll fluorescence in the leaves of broad-leaved linden trees, as one link in the overall monitoring of the impact of railway transport on the environment. The passage of IFH in tree leaves was evaluated using the portable device "Floratest". Trees grown on the territory of the Holosiiv Park were used as controls, and trees growing on the territory of the locomotive depot "Ukrzaliznytsia" served as experimental samples. Measurements of chlorophyll fluorescence induction were carried out on leaves growing on the lower tiers of trees. Assessment of the physiological state of linden leaves under the influence of railway transport was carried out according to the main parameters of the Kautsky induction curve. It was established that the IFH indicators, such as F0, Fpl, F st, Fv, F max, in the trees growing on the territory of the locomotive depot exceeded the IFH indicators of the trees from the Holosiiv park, which is explained by the failure of the dynamic balance between the IFH processes and the violation of photosynthetic processes in the trees . According to the comparative analysis of IFH parameters in control and experimental samples of linden tree leaves, it can be concluded that the trees growing on the territory of the locomotive depot "Ukrzaliznytsia" were slightly stressed by possible noise, vibration and chemical pollution caused by the operation of the railway.

Diagnosis of the functional state of the photosynthetic apparatus Taraxacum officinale (L.) Weber ex F. H. Wigg. by the method of chlorophyll fluorescence induction

The informativeness is established of the method of induction of chlorophyll fluorescence for bioindication in the conditions of anthropogenic influence on the example of T. officinale plants, by the parameters: F0, Fm, Fst, Fv, Fv/Fm та k1, k2. The main parameters of the induction curve can be used as test indicators to determine the resistance of plants to adverse factors. Changes in these indicators characterize the processes associated with the influence of the environment on the course of both light and dark phases of photosynthetic processes in chloroplasts. The photosensitivity of T. offic- inale leaves, which indicates the physiological state of plants, decreases with increasing adverse external influences. It is established that the plants of T. officinale have the maximum intensity of photosynthesis, which grow in more favorable ecological conditions control. Therefore, the use of the device «Floratest» to determine the condition of plants at different levels of anthropogenic load is promising and requires further research.

Field Study of the Effects of Two Different Environmental Conditions on Wheat Productivity and Chlorophyll Fluorescence Induction (OJIP) Parameters

Wheat is one of the main cereal crops for ensuring food supply. Thus, increasing grain yield is a major target for plant breeders, where insights into wheat productivity can be gained by studying the activity of the components of photosynthetic apparatus. The objectives of this study were to evaluate the agronomical performance of three winter wheat varieties and test photosynthetic efficiency over two different locations. Chlorophyll fluorescence was used to evaluate the maximum quantum yield of photosystem II (PSII) (TR0/ABS) and performance index on absorption basis (PIabs) of flag leaves and glumes of heads at the flowering stage until the mid-senescence stage. The grain yield of all varieties on average was significantly higher at Osijek compared to Tovarnik. Variety Tika Taka exhibited the highest yield reduction (27.1%) at Tovarnik compared to Osijek, followed by El Nino (20.5%) and Vulkan (18.7%), respectively. A higher amount of precipitation in June at Tovarnik provoked higher Fusarium head blight disease intensity, which could be seen as the bleaching of plant heads at the plots and resulted in an earlier decrease in photosynthetic activity. Therefore, earlier senescence and contracted grain fill duration could occur.