A distinctive feature of legumes is the ability to combine two most important processes: photosynthesis and nitrogen fixation. However, the course of those processes, and therefore seed potential of those crops depend on a number of biotic and abiotic factors, the commonest being drought. Therefore, interest in physical-biochemical resistance of the plant organism to abiotic stress factors is increasing, as well as search for optimum ways to increase its adaptability. Success of adaptation of a plant’s organism to unfavourable environmental factors is known to largely depend on optimal functioning of assimilative apparatus. Some indicators of the condition of the apparatus are the content and ratio of photosynthesis pigments. Therefore, we aimed at determining the reaction of the pigment complex of Glycine max (L.) Merr. plants, grown against the background of optimal and insufficient watering, to inoculation of seeds with rhizobia bacteria Bradyrhizobium japonicum, cultivated using nanocarboxylates of chromium, cobalt, iron, copper and germanium. Research has shown that utilization of germanium nanocarboxylate as a component of inoculative suspension led to the highest content of chlorophylls in leaves of soybean of the studied variants in the blossoming phase during optimal watering, as well as significant increase in the content of carotenoids compared with the control plants regardless of the level of watering. At the same time, this element caused no significant effect on the chlorophyll content in plants grown in drought. It was confirmed that among soybean plants that were in stress conditions (blossoming phase) for two weeks, the highest content of chlorophylls was in leaves of plants grown from seeds inoculated with rhizobial suspension with addition of chromium and copper nanocarboxylates, which caused 25.3% and 22.8% increase in chlorophyll а, 29.4% and 32.3% in chlorophyll b and 26.4%% and 23.8% in them respectively, compared with the control. Furthermore, chromium and copper nanocarboxylates stimulated the content of carotenoids in the same plants, though it was less expressed than after adding germanium nanocarboxylate. The highest content of photosynthetic pigments in plants after the watering was resumed (phase of bean formation) was in cases of applying chromium and germanium nanocarboxylates. It was confirmed that the most efficient way to protect the pigment complex of soybean plants during drought was using chromium and germanium nanocarboxylates as components of inoculation suspension. The results we obtained indicate the possibility of applying chromium nanocarboxylate in the technology of cultivating soybean in the conditions of water deficiency as an effective way to improve biosynthesis of chlorophylls, as well as using germanium nanocarboxyllate as a component that provides a high level of activity of protective mechanisms of the pigment system of soybean, associated with resisting stress caused by water deficiency.

Plant organisms are constantly affected by external factors of a diverse nature, which can change the course of a number of physiological and biochemical processes, and as a result, be reflected in the growth and development of plants, as well as the realization of their genetic potential. The study of the metabolomic profile of soybean plants against the background 514

The idea of the study was to use soybean lectin as a biologically active compound with a broad spectrum of action to spray soybean plants for stabilization of the formation and functioning of the soybean-rhizobium symbiosis as well as the nitrogen-fixing activity of rhizosphere microbiota against the background of seed treatment with chemical plant protection product Standak Top — an innovative pesticide with fungicidal and insecticidal activity for the control of major diseases and pests of soybean plants. Aim. To study the peculiarities of formation and functioning of soybean-rhizobium symbiosis as well as the nitrogen-fixing activity of rhizosphere microbiota under spraying plants with specific soybean seed lectin on the background of seed treatment with Standak Top and inoculation with nodule bacteria Bradyrhizobium japonicum 634b on the sowing day in the conditions of pot experiments with soil as a substrate. Methods. Physiological, microbiological, gas chromatography, and statistical methods were used. Results. It was shown that after seed treatment with Standak Top (1.5 L/ton of seeds) on the sowing day, there was observed suppression of the process of nodule formation on the roots in the period of soybean vegetative growth. The nitrogen-fixing activity of the symbiotic system was at the control level, while the functional activity of soil diazotrophs was suppressed (by 1.2—2.2 times). Spraying plants in the phase of two trifoliate leaves (V2) with soybean seed lectin (without pesticide) led to an increase in the total mass of nodules on the plant (by 1.5 and 1.9 times as well as by 2.3 and 2.0 times compared to the control of inoculation in the phase of three trifoliate leaves (V3) and beginning of pod formation (R3), respectively). The increase in the total mass of the symbiotic apparatus on soybean roots in the phases V3 and R3 respectively was by 1.4 and 1.5 times in comparison with seed treatment with Standak Top, and the mass of one nodule was higher by 1.3 and 1.6 times, respectively. Soybean seed lectin led to a signifi cant increase in the actual nitrogenase activity of the soybean-rhizobium symbiosis. It was 2.9 and 1.9 times higher compared to control of inoculation and 2.1 and 1.8 times compared to the variant of inoculation + pesticide in the V3 and R3 phases, respectively. The functional activity of soil nitrogen-fixing microorganisms did not change significantly. The use of soybean seed lectin against the background of the seed treatment with Standak Top and inoculation contributed to the stabilization and increase in the rhizobia nodulation ability, the suppression of which was due to the infl uence of such an anthropogenic factor as pesticides. Th ere was observed an increase in the number (by 1.6 and 1.2 times) and mass of root nodules (by 2.2 and 1.5 times and 1.4 and 1.2 times, respectively, compared to the controls of inoculation and inoculation + pesticide). Soybean seed lectin significantly increased the nitrogenase activity of the symbiosis against the background of Standak Top (by 1.9 and 1.6 times and 1.4 and 1.5 times, respectively, in the V3 and R3 phases of soybean ontogenesis) compared to the control of inoculation and inoculation + Standak Top. Conclusions. The obtained results suggest the possibility of using the method of spraying plants with specific lectin as a means of leveling (or mitigating) the negative effect of pesticides used for the seed treatment on the formation and functioning of the symbiosis and rhizosphere diazotrophic microbiota. This indicates the prospects of studying the biological activity of phytolectins in spraying plants in order to regulate the formation and functioning of phytobacterial systems, as well as their responses to various environmental or anthropogenic stress factors, in particular, to the effect of chemical plant-protecting products used for the seed treatment.

Preparations for protecting plants, particularly those with fungicidal activity, continue to be relevant in agricultural production. They are used to effectively combat phytopathogens and ensure high yield of cultivated plants. However, they are among the anthropogenic factors which impose a heavy chemical load on ecosystems. Data about the effects of pesticides on physiological parameters of plants are essential for understanding the main regulatory mechanisms as preconditions to the phytotoxic state of compounds, as well as greater substantial understanding of the functional condition and implementation of adaptive potential of plants during and post stress. An important and relevant task – both practically and theoretically in the conditions of action of fungicide on seeds - is studying the possibilities of application of phytolectines as biologically active compounds with broad spectrum of action, including fungicidal effect, for spraying legumes in order to stabilize their development, ensure effective functioning of legume-rhizobial symbioses and cause fuller realization of productive potential against the background of decrease in chemical pressure on agrocenoses. Therefore, we aimed to evaluate the biological activity of soybean seed lectin (according to the parameters of productivity and functional activity of soybean-rhizobial symbiosis) at the spraying of Glycine max (L.) Merr. plants against the background of seed treatment of pesticide, Standak Top with fungicidal and insecticidal actions on the day of sowing and inoculation with Bradyrhizobium japonicum 634b. We used physiological, biochemical, microbiological and statistical methods of studies. We determined that Standak Top, applied on soybeans that were afterwards inoculated with rhizobia, exerted negative tendency on formation of vegetative mass by plants at the beginning of vegetation, though in the following phases of ontogenesis, their development and productivity reached the level of the control. Nitrogenase activity of symbiosis and the condition of photosynthetic pigment complex (content of chlorophyll and carotenoids and their ratio) were at the level or significantly lower than in the control plants. After spraying soybeans with lectin (without use of the fungicide) in the phase of development of two true leaves, there occurred significant increase in functional activity of the symbiotic system (according to total nitrogenase activity of symbiosis, higher by 1.91 and 1.79 times compared with the controls with inoculation and inoculation + fungicide) and the content of photosynthetic pigments (chlorophylls were higher by 1.12–1.45 times, carotenoids by 1.14–1.39 times) and development of strong leaf apparatus (by 1.33–1.42 times). This caused highest level of realization (by 13.9% and 10.1% higher compared with the controls with inoculation and inoculation + fungicide) of productive potential of cultivated plants. After spraying plants with soybean lectin against the background of use of fungicide, notable and reliable increases occurred in the level of absorption of molecular nitrogen (by 1.72 and 1.52 times according to total activity of symbiosis, compared with the controls with inoculation and inoculation + fungicide), content of chlorophyll (1.25–1.64 times) and carotenoids (1.12–1.42 times) in leaves of soybean, and also plants were actively developing during vegetation (1.12–1.40 times), producing yield that exceeded by 12.8% and 9.1% the controls with inoculation and inoculation + fungicide. Therefore, use of soybean seed lectin for spraying plants against the background of seed treatment of pesticide Standak Top on day of sowing can stabilize and even increase the level of realization of symbiotic and productive potential of soybean-rhizobial symbiosis compared both with the control (inoculation with rhizobia) and the variant with treatment of seeds (rhizobia + fungicide). This indicates on the perspectives of further studies of biological activity of phytolectins aiming at decreasing chemical pressure on ecosystems by leveling out or decreasing the negative impact of chemical means of protection on the plants and symbiosis.