RU2810590C1 - Method for environmental monitoring of plant stress conditions - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: crop production and experimental biology. In the method, the leaf and standards are illuminated with a directed light flux from the source, and the intensity of the reflected mixed flux and its diffuse component are measured. The leaf is placed on a cylindrical surface so that the central vein of the leaf is located along the axis of the cylinder. A digital camera located opposite the center of the leaf is used as a receiver of reflected light. Two digital images are obtained with symmetrical positions of the light source at an angle of 20 degrees on one side and the other from the camera’s line of sight to the center of the leaf. The images are calibrated using images of the reference surfaces in the images. Based on the known values of their reflection coefficients, the reflection coefficients of sections of the leaf surface are determined. The reflection coefficients of sections of the leaf surface are measured by the brightness of the corresponding pixels in the images along lines perpendicular to the axis of the cylindrical surface. Areas of the image of the leaf surface on lines parallel to the cylinder axis are used to obtain repeat measurements; the area of mixed reflection is identified on the indicatrix of reflection coefficients based on the maximum value of the reflection coefficient. A section of the leaf surface located symmetrically to the selected area of mixed reflection relative to the main vein of the leaf is taken as a diffuse reflection region. As a bilateral feature, the ratio of the mixed and diffuse reflection coefficients of the selected symmetrical areas is used. The functional state of the plant is judged by the average value of the found bilateral trait, expressed in relative units, with differences in coefficients of less than 5% - an insignificant effect on the functional state of the plant. The stability of plant development is judged by the fluctuating asymmetry of a bilateral trait, an increase of which by 30% indicates the influence of the spectrum on the stability of plant development.

EFFECT: implementation of environmental monitoring of plant stress conditions, expanding functionality, increasing the efficiency, reliability and accuracy of measurements, and reducing their labor intensity.

1 cl, 6 dwg, 2 ex

Description

The invention relates to experimental biology and is intended for use in environmental monitoring, in determining the state of plants by the optical properties of their leaves, as well as in agricultural sectors (open ground crop production and light culture) when optimizing environmental parameters.

Measuring plant stress means quantifying the impact of the environment on plant health. The plant, as an element of the ecological system, interacts with the environment through the perception of incoming signals about the values of factors characterizing the environment. The generated signals correct vital processes in plants, set by genetic development programs, depending on environmental conditions. Stressful influences caused by external factors are varied in direction, degree and time of exposure, but all of them, to one degree or another, disrupt the normal state of the body, affecting metabolism, plant productivity, their functional state and stability of development in general.

A feature of environmental monitoring, in contrast to selective methods aimed at determining the influence of individual factors on various individual plant indicators, is the complexity and integrity of the assessment of the effect of a set of environmental factors on the general condition of plants.

One of the criteria for assessing the general condition of plants is their functional state, i.e. a physiological state that reflects the level of functioning of the plant as a whole or its individual systems, and also shows the plant’s adaptability to the conditions of its existence. The functional state of plants is largely influenced by natural or controlled environmental factors. The content of functional diagnostics is an objective assessment, detection of deviations and establishment of the degree of dysfunction of various organs and physiological systems of a living organism based on measuring physical, chemical or other objective indicators of their activity using instrumental or laboratory research methods. The existing methods of functional diagnostics of plants are based on physiological ideas about the activity of the organs under study or the entire plant as a whole [Bondareva L.A., Sukhanova M.V. Assessment of the possibility of using methods of functional diagnostics of plants to solve problems of environmental monitoring. Biotechnosphere. 2015. No. 6 (42). pp. 11-15].

Currently, optical methods have become widespread in environmental monitoring, allowing one to assess the stress state of plants non-invasively, without damaging plant tissue. Among them, the most convenient are methods that determine the reflective properties of leaves (their coefficients of diffuse and/or directional reflection). Various technical solutions are known for determining the reflective properties of plant leaves.

There is a known method for determining the reflectivity (gloss) of a surface, implemented in a gloss meter of the FB-2 type. The method is based on measuring the amount of photocurrent excited in a photocell under the action of a beam of light reflected from the surface being measured. A photocell is placed in the side tube to measure gloss (the specular component of the light flux) and in the middle tube to measure scattered light. To adjust the gloss meter, working standard samples (standards) are used [Livshits M.L. Technical analysis and control of varnish and paint production. M.: 1973. - p.182.]

The disadvantage of this technical solution is that the need to change the position of the photocell reduces the efficiency of measurements and increases their complexity.

There is a known method for determining the reflectivity of an object, in which a flat sample and a standard are illuminated with a beam of light directed along the normal, and the diffuse reflection coefficient of the sample is judged by the ratio of the intensities of light reflected at a certain angle [Zege E.P., Katsev I.L. Method for determining diffuse reflectance coefficient. A.S. USSR No. 750288. Application: 2581746, 1978.02.20. Date of application: 1978.02.20. Publ.: 1980.07.23].

The method has insufficient functionality, since it does not provide for the determination of the specular component characteristic of plant leaves.

There is a known method for determining spectral directional hemispherical reflection coefficients, according to which a sample and a standard are illuminated with a directed beam of light, the intensity of the reflected light is measured, and the sample is rotated to determine the reflection indicatrix [Aksyutov L.N., Kholopov G.K. Method for determining spectral directional hemispherical reflection coefficients. A.S. USSR No. 543855. Application: 2085011, 1974.12.17. Date of application: 12/1974/17. Publ.: 1977.01.25].

The method is quite labor-intensive due to the need to construct a backscattering indicatrix.

There is a known method in which a sample is placed on a spherical substrate, its image is obtained in the camera plane, the image brightness field is photometric element by element, and the angles of incidence and reflection of light are determined from the linear coordinates of the image elements for real points on the surface of the sample, for which brightness indicatrices are constructed [Tantashev M. V., Kholopov G.K. A method for measuring the brightness indicatrices of light-scattering coatings. A.S. USSR No. 1651168. Application 4689397/25. 05/11/89. Publ. 05.23.91. Bull. No. 19].

The implementation of this method for determining the reflective properties of a plant leaf is difficult due to the impossibility of placing a flat leaf on a spherical substrate without damaging it.

A technical solution is known when various methods of environmental monitoring for determining the functional state of plants are implemented in one device: measuring fluorescence induction and its spectral analysis, determining the content of photosynthetic pigments based on the reflection and transmission spectrum of a plant leaf [Smirnov A.A. etc. Portable device for monitoring plant stress conditions. RF Patent No. 2775493. Application: 2021130759, 10/21/2021. Application submission date: 10/21/2021. Published: 07/01/2022. Bull. No. 19].

At the same time, the determination of the stress state of plants is not reliable enough, since there is no provision for determining the components of the reflected flow, which are characteristic signs of the state of the plant.

Another approach to assessing the general condition of plants is the morphogenetic one, in which changes in plants due to disturbances in homeostasis are judged by the stability of their individual development. A numerical indicator and criterion for assessing developmental stability is the fluctuating asymmetry ( FA ) of bilateral (normally mirror) features. The latter is defined as a consequence of the failure of ontogenetic processes in a living organism under the influence of environmental factors that disrupt the interconnection of plant parts, which prevents the preservation of their symmetry. Such changes in a living organism occur long before the action of environmental factors affects the functional state of the plant. Morphological characteristics (leaf width, distances between characteristic points of the leaf surface, angles between veins) are most often used as bilateral ones when calculating the FA value, since these structures are easily perceived by the human eye or simple measuring instruments (ruler, protractor, etc.). However, their measurement is quite labor-intensive, and ensuring measurement accuracy is a serious problem. Currently, due to the development of measurement technologies and procedures, non-morphological characteristics (properties) of plants, in particular physiological or biochemical ones, are also used. The latter are determined by the quantitative and qualitative content of various substances, primarily pigments, in plant tissues and are directly related to the physiological processes occurring in them.

Scientific studies have shown that higher levels of FA of bilateral plant traits indicate a greater degree of deviation of environmental parameters from optimal ones. This phenomenon is used in environmental monitoring [Mendes G., Boaventura MG, Cornelissen T. Fluctuating Asymmetry as a Bioindicator of Environmental Stress Caused by Pollution in a Pioneer Plant Species. Environmental Entomology, 47(6), 2018, 1479-1484. doi:10.1093/ee/nvy147].

There is a known method according to which, using a hyperspectral digital camera, an image of a plant leaf is obtained, the reflectivity of the leaf surface is found in certain spectral ranges, the values of vegetation indices are determined, and the stability of plant development is judged by the FA value of the found indices. [Rakutko S.A., Rakutko E.N. Method for determining the stability of plant development. Pat. RF. No. 2 752 953. Application: 2020123106, 07/13/2020. Application submission date: 07/13/2020. Published: 08/11/2021 Bulletin. No. 23].

The disadvantage of this known method is that the bilateral characteristics in the method are vegetation indices, which mainly depend on the parameters of the light environment, which affects the concentration of pigments in the leaf tissue. The influence of other environmental factors in the method is not disclosed. This reduces the reliability of the measurements.

The closest to the stated one is the technical solution, according to which the leaf of the plant is illuminated, the intensity of the reflected mixed flow and its diffuse component are measured, and their ratio is used to judge the functional state of the plants [Bondareva L.A., Sukhanova M.V. A method for assessing the functional state of plants to determine their water needs. Pat. RF No. 2719788. Application: 2019115574, 05/21/2019. Application submission date: 05/21/2019. 04/23/2020 Bulletin. No. 12]

The disadvantage of this known method is that at low levels of exposure to environmental factors on plants, their response to the functional state, due to the high adaptability of plants, may be insufficient for assessing stress. This reduces the accuracy and reliability of environmental monitoring.

The technical task is to ensure the possibility of non-invasive environmental monitoring of the functional state of plants and the stability of their development.

The technical result is the implementation of the purpose of the invention, expanding its functionality, increasing the efficiency, reliability and accuracy of measurements, reducing their labor intensity.

The technical result is achieved by the fact that in the method of environmental monitoring of stress conditions of plants, which consists in illuminating the leaf and standards with a directed flow of light from the source, measuring the intensity of the reflected mixed flow and its diffuse component, according to the invention, the leaf is placed on a cylindrical surface so that the central vein of the sheet was located along the axis of the cylinder, a digital camera located opposite the center of the sheet is used as a receiver of reflected light, two digital photographs are taken with symmetrical positions of the light source at an angle of 20 degrees on one side and the other from the camera’s line of sight to the center of the sheet, calibration is performed images based on images of standard surfaces in the images, measure the reflection coefficients of sections of the sheet surface by the brightness of the corresponding pixels in the photographs along lines perpendicular to the axis of the cylindrical surface, sections of the image of the sheet surface on lines parallel to the cylinder axis are used to obtain repeatability of measurements, highlight the area of mixed reflection on the indicatrix of the coefficients reflections according to the maximum value of the reflection coefficient; the area of the leaf surface located symmetrically to the selected area of mixed reflection relative to the main vein of the leaf is taken as the area of diffuse reflection; the ratio of the coefficients of mixed and diffuse reflection of the selected symmetrical areas is used as a bilateral feature; the functional state of the plant is judged by the average value of the found bilateral trait, the stability of plant development is judged by the fluctuating asymmetry of the bilateral trait.

The technical result is ensured by the fact that:

- the presented set of essential features provides a quantitative assessment of the impact of the environment on plant health, i.e., the implementation of the purpose of the invention;

- giving the sample the shape of a cylindrical surface creates different lighting and observation conditions for different points on the surface, which allows one to obtain a large amount of information about the reflective properties of the sheet in one image, thereby increasing the efficiency of measurements;

- obtaining data using a digital camera reduces the complexity of measurements;

- obtaining two digital images of a sample illuminated from two symmetrical source locations makes it possible to assess the stress state of plants both in terms of its functional state and development stability, which expands the functionality of the environmental monitoring method and increases the reliability of the assessment;

- the use of several standards allows for more accurate calibration of determining the reflection coefficients of a sample based on the brightness of the pixels in the image; the use of software algorithms for obtaining information from digital images increases the accuracy of the results obtained.

The claimed technical solution relates to a method, i.e. it is a process of performing actions on a material object using material means. The object is the leaves of plants, based on the reflective properties of which a conclusion is made about the degree of stress of the plants. The activities are procedures for measuring the reflective properties of leaves. Material means are laboratory equipment and data acquisition tools.

The invention is illustrated by drawings.

In fig. Figure 1 shows the formation of an indicatrix of the reflection coefficient from a sample (plant leaf) placed on a cylindrical substrate; in fig. 2 - formation of a brightness field in the plane of the camera’s sensitive matrix; in fig. 3 - indicatrix of the reflection coefficient in a rectangular coordinate system; in fig. 4 - illustration of the method implementation; in fig. 5 - example of a table of reflection coefficients measured during implementation of the method; in fig. 6 - calculation of the average value and FA of the bilateral sign.

The invention is based on the following provisions . The mixed light flux reflected from a plant leaf contains two components: diffuse, more or less corresponding to Lambert’s law, and specular, the flux of which is concentrated in a fairly narrow solid angle [Okayama H. 1996. How different are the indicatrixes of the leaves of various woody plant species? Applied Optics. Vol. 35, No. 18. 3250-3254]. The diffuse component is formed due to the presence of various types of roughness and irregularities on the surface of the plant leaf. The reason for their appearance is reduced turgor, deficiency of nutrients, surface damage under the influence of unfavorable environmental factors. On the contrary, a larger share of the mirror component in the mixed flow indicates a better ecological state of the plant, and the absence of the need for external intervention (watering, fertilizing or other forms of plant care).

Let the leaf of a plant 1 be placed on a semi-cylindrical substrate 2 , and the corner between the directions to the light source 3 and the camera 4 , measured in a plane perpendicular to the cylinder axis is fixed. For the positive direction of the angle ( ) the direction taken is counterclockwise from the camera's line of sight to the light direction line. Let the distances from the light source and camera to the sheet significantly exceed its dimensions, and the light source is collimated, i.e. emits a parallel beam (Fig. 1). The analysis shows that different sections of the curved surface adopted by the sheet are in different conditions of illumination from the source and observation by the camera. Let us consider the characteristic points of the sheet surface. With positive the extreme point recorded by the camera is the far left point. A is the first characteristic point. In it, the camera's sighting ray is tangent to the semi-cylindrical surface, which means the viewing angle is zero. For any sheet reflectivity, the reflectance coefficient of a given area is also zero. When moving to the other edge along the semi-cylindrical surface, sections of the sheet are characterized by different combinations of incidence and observation angles. To point B (second characteristic point), located on the bisector of the angle , diffuse reflection is observed. The vicinity of point B is an area of mixed reflection, since, along with the diffuse component, a specular component appears here, because The angle of incidence of the flow at this point is equal to the angle of reflection. The reflection coefficient values here take on significantly larger values. With further movement along the semi-cylindrical surface, a second zone of diffuse reflection is observed. When reaching the third characteristic point C, the tangent is equal to the angle , the incident ray is tangent to the semi-cylindrical surface. Further, for any reflectivity of the sample, the reflectance coefficient of a given area is zero, since illumination does not fall on this area. The fourth characteristic point is point D - the other edge of the semi-cylindrical surface. The real points of its surface A , B , C and D marked on the surface of the sheet in the image are projected respectively into the points , , And .

The camera creates an image of the leaf within the points - in a plane perpendicular to its optical axis. Brightness of each pixel in the image is proportional to the reflectance of the sheet surface area , corresponding to a given pixel (Fig. 2). For a grayscale photo, the pixels in the photo are characterized by a certain level of gray. The mixed reflection region, due to the presence of a specular component, has the appearance of a light stripe parallel to the cylinder axis. When saving an image in 8-bit format, the maximum intensity value (white level) of a pixel in the image is 255 units. A value of zero corresponds to black level. Pixels lying on a line perpendicular to the axis of the generating cylinder ( , where M is the number of pixels in the image corresponding to the width of the sample) is used to determine the reflectance of various points on the sheet surface. Pixels on lines parallel to the axis ( , where K is the number of pixels in the image corresponding to the length of the sample) are used as repeat measurements to improve the accuracy of measurements.

To move from the gray level (brightness) of a pixel measured from a digital photograph to the reflectance of the corresponding section of the sample surface apply the linear interpolation formula

,

Where And - reflection coefficients of standards

(close to 0 and 100%, respectively);

And - the brightness of the pixels of their images,

measured from a digital photograph.

Well-known software tools, for example, the ImageJ program, allow you to visualize the distribution of brightness fields in an image in the form of a curve in rectangular coordinates (Fig. 3). In such a graph, the specular reflection region appears as a peak on a fairly smooth curve corresponding to diffuse reflection. The shape of the reflection indicatrix integrally characterizes the state of the plant.

The considered provisions reveal the physical basis of the proposed technical solution (Fig. 4). The plant leaf is placed symmetrically on a cylindrical surface. Measurements are taken for areas of the leaf surface on the left ( L ) and right ( R ) that are symmetrical relative to the central vein.

The tissues of plant leaves have a cellular structure, in which multiple reflections and refractions of incident light occur, forming the reflective properties of its surface. They, in turn, depend on the size, shape and number of cells in the tissue, its pigment composition, moisture supply, nutrient content, that is, on the parameters by which one can judge the condition of the plant as a whole.

In position I , when the light source is on one side (conditionally to the left) of the camera, the reflection coefficients are determined: mixed flow for the left section and diffuse component for the right section . By moving the light source to position II , on the other side (conditionally to the right) of the camera, the reflection coefficients are determined: the mixed flow for the right section and diffuse component for the left section . These four parameters obtained using hardware are the initial ones for the processing algorithm, which makes it possible to numerically assess the stress state of plants by its 1) functional state (by the average value ratio of the reflection coefficients of the mixed flow and its diffuse component) left and right areas of the leaf surface and 2) stability of development (according to FA of the bilateral trait ).

Calculation formulas: ; ; ; .

At high levels of stress caused by a significant deviation from normal environmental conditions, a convenient tool for environmental monitoring is to assess the functional state of plants based on a selected trait . The morphogenetic approach in this case can give indistinguishable values of this sign for bilateral structures. With short-term stress and/or low levels, on the contrary, its influence may not significantly affect the functional state of plants (value ), however, will manifest itself in the instability of their development, characterized by significant differences bilateral signs. Since it is impossible to predict in advance the strength of the influence of external factors on the state of a plant, a universal approach is to simultaneously determine both the functional state of plants and the stability of their development during environmental monitoring.

The method is carried out as follows .

A plant leaf whose stress state needs to be assessed is placed on a cylindrical surface. In this case, it is enough that the sheet, with its tight fit, covers half of the cylinder. The central vein (axis of symmetry of the leaf) should be located along the axis of the cylinder, in the center of its half.

The digital camera is placed opposite the center of the sheet, on a line perpendicular to the cylinder axis. Standards with known reflection coefficients are placed in the camera's field of view. The light source creating a parallel flow is placed on a line deflected at an angle of 20° to one side from the camera’s line of sight (the point of intersection of the lines lies on the axis of the cylinder). At this angle, the position of surface areas with diffuse and mixed reflection is maximally spaced within the boundaries of the digital image, since the distance is one third of .

Take the first picture with the camera. Change the position of the light source to be symmetrical relative to the camera’s line of sight. A second photo is taken. The brightness of the reference images in the photographs is determined, and the reflectance coefficients of sections of the sheet surface are determined from the known values of their reflection coefficients. In this case, the reflectance coefficients of sections of the sheet surface are determined by the brightness of the corresponding pixels in the images along lines perpendicular to the axis of the cylindrical surface; sections of the image of the sheet surface on lines parallel to the cylinder axis are used to obtain repeated measurements.

The distribution of the brightness field in a digital image is visualized in the form of a curve (indicatrix) of the dependence of the reflectance coefficient on the linear coordinate measured along a straight line perpendicular to the camera’s line of sight. On the resulting mixed reflection curve, a sharp burst area is identified, corresponding to the appearance of the specular component of the reflection, and the position of this area relative to the edge of the image and its size are determined. At the same distance from the other edge of the image (symmetrically with respect to the projection of the central vein to the specified linear coordinate), a section of the diffuse reflection component of the same size is identified.

Another equivalent option for selecting areas is directly from the table of initial data of reflection coefficients.

Find the reflection coefficients for each selected area for the mixed flow and its diffuse component at the first And and second And position of the light source.

Find the values of the bilateral characteristic for the selected areas of the leaf And . To increase accuracy, repeat measurements are taken on photographs along lines parallel to the cylinder axis.

Find the average value of the bilateral sign , by which the functional state of the plant is judged.

Find the FA value of the bilateral sign , by which the stability of plant development is judged.

To improve the accuracy of determination And find their average values based on repeated measurements.

Example 1. In the laboratory of energy ecology of light culture of the Institute of Atomic Energy in the spring of 2023, cucumber seedlings (Cucumis Sativus) were grown under artificial conditions. The influence of the radiation spectrum on the state of plants was studied. Some plants were grown under fluorescent lamps (FL), and some under LED sources (LED) with a red-blue spectrum, all other environmental conditions being equal.

The leaves under study were about 10 cm wide. A cylinder was used around which the leaf was wrapped. To place the sheet in its entire width on half of the cylindrical surface, its diameter was taken to be 3 cm. By alternately changing the position of the light source, two digital photographs were taken. Calibration was carried out using two standards.

The resolution of the digital image was 640 pixels across the width of the projected surface of the sheet. In fig. Figure 5 shows the reflectance coefficients of areas of the surface of a plant leaf grown under LL. The data is presented in the table for each pixel at both positions of the light source.

Analysis of the tabular data shows that a sharp increase in the reflection coefficient (the appearance of a specular component in the mixed reflection for the conditionally left section L) is observed from 211 to 215 pixels. Here is the data block . Data for the same pixels, but with a different position of the light source, form a block (diffuse reflection for the conditionally left section L). The center of symmetry of the image, corresponding to the middle of the sheet, is pixels 320 and 321. At the same distance of 210 pixels, but from the other edge of the image, starting from 430 pixels and towards the center of symmetry, up to pixel 426, there is a zone of diffuse reflection for the conditionally right section R at position I of the light source and the mixed reflection zone of this section at position II of the light source.

In fig. Figure 6 shows the definition of the final indicators and their average values. In plants grown under LL, the average value of the bilateral trait =3.662 rel. units Magnitude =0.0187 rel. units

Similar measurements were carried out for plants grown under SD. They have an average value of the bilateral trait =3.837 relative units, i.e. the differences are insignificant (less than 5%). This means that the radiation spectrum had a weak effect on the change in the reflectivity of leaves and had little effect on the functional state of plants.

However, the magnitude =0.0241 rel. units, which is 30% more than the same indicator for LL. This means that the radiation spectrum affected the stability of plant development and the subtle mechanisms of homeostasis control, which has not yet manifested itself in physiological processes. An increase in PA indicates a less favorable spectrum of DM compared to LL.

Example 2 . Similar measurements were carried out when studying the influence of water regime on the reflective properties of leaves of pepper plants (Capsicum Annuum L.) .

The control and experimental plants were provided with normal watering throughout the entire growing period, but the experimental plants were limited in watering several days before measurements.

The following data was obtained:

In control =3.317 relative units, =0.0582 rel. units

In experience =2.620 relative units, =0.0576 rel. units

In experimental plants, the proportion of the specular component in the mixed reflection decreased, which was reflected in a decrease in the indicator by 20% compared to the control due to a drop in leaf turgor due to insufficient watering of plants. The differences in FA values are insignificant, since the plants were formed under the same normal conditions; a decrease in the level of watering in the time preceding the experiment did not lead to a decrease in the stability of their development.

If, based on the results of environmental monitoring, the corresponding dependencies of plant parameters on the level of existing environmental factors are found, optimization of environmental parameters is possible.

Claims (1)

A method for environmental monitoring of stress conditions of plants, which consists in illuminating the leaf and standards with a directed flow of light from a source, measuring the intensity of the reflected mixed flow and its diffuse component, characterized in that the sheet is placed on a cylindrical surface so that the central vein of the sheet is located along the axis of the cylinder, a digital camera located opposite the center of the sheet is used as a receiver of reflected light, two digital photographs are obtained at symmetrical positions of the light source at an angle of 20 degrees with one and on the other side of the camera's line of sight to the center of the sheet, the images are calibrated using images of the standard surfaces in the images, the reflectance coefficients of sections of the sheet surface are determined from the known values of their reflection coefficients, the reflection coefficients of sections of the sheet surface are measured by the brightness of the corresponding pixels in the images along lines perpendicular to the axis cylindrical surface, areas of the image of the sheet surface on lines parallel to the cylinder axis are used to obtain measurement repetitions, a mixed reflection region is selected on the indicatrix of reflection coefficients based on the maximum value of the reflection coefficient, a section of the sheet surface located symmetrically to the selected mixed reflection region relative to the main one is taken as a diffuse reflection region leaf veins, the ratio of the coefficients of mixed and diffuse reflection in the selected symmetrical areas is used as a bilateral feature; the functional state of the plant is judged by the average value of the value of the found bilateral feature, expressed in relative units; if the coefficients differ by less than 5%, the effect on the functional state of the plant is insignificant , the stability of plant development is judged by the fluctuating asymmetry of a bilateral trait, an increase in which by 30% indicates the influence of the spectrum on the stability of plant development.