The influence of polyguanidin on the direction of biochemical processes in wheat (Triti- cum L.) plants.
Authors: Levishko A. , Gumeniuk I. , Tsvigun V. , Mazur S. , Botsula O. 
Published: May 2023

Modern crop production requires a balance of high and sustainable productivity with maximum safety for the environment, consumers and agricultural workers. The well-known chemical compound polyguanidine, which was previously used as a disinfectant, surfactant and complexing agent, has recently become widely used as a plant growth and development stimulant. Despite the increasing use of polyguanidine preparations as a growth stimulant, there is no data in the literature on its mechanism of action on plants. There are many studies that try to determine whether the effect of biostimulants on plant productivity is a direct or indirect response, for example, through the soil or microbiome. In many cases, biostimulants are considered in terms of their effects on various plant regulatory and functional systems (signaling, metabolic, uptake and transport mechanisms, etc.). But, in general, these modes of action are very diverse and may include activation of nitrogen metabolism or release of phosphorus from soils, general stimulation of soil microbial activity, or stimulation of root growth and increased plant nutrition. The effect of polyguanidin on the physiological parameters of wheat plants was studied under vegetation and laboratory conditions. Seeds of winter wheat variety Bogdana were used for the study. For the determination of flavonoids, a spectrophotometric method based on the measurement of their absorption with aluminum chloride complex was used. It was proved that the treatment of wheat in the tillering and earing phases with polyguanidin had the greatest effect on the protein content in winter wheat grain, which ensured the formation of this indicator at the level of 11.0–13.4% compared to the control. The treatment of wheat seeds with a preparation based on polyguanidine increased the amount of chlorophyll a by almost two times, while the content of chlorophyll b and carotene increased somewhat less. Thus, the use of polyguanidine contributes to the efficient functioning of the photosynthetic apparatus of plants, which will increase their productivity. Since the energy basis of photosynthesis is the absorption of solar radiation by photosynthetic pigments, which are used to form organic matter, there is a direct link between chlorophyll content and plant productivity. Therefore, we decided to check the content of the main photosynthetic pigments in plants after treatment with polyguanidine. At the first stage of our research, plants at the early stages of ontogenesis were analyzed. Thus, we have shown that the treatment of wheat seeds with a polyguanidine-based preparation increases the amount of chlorophyll a almost twice. Evaluation of flavonoid content in wheat plants showed a decrease in their amount after treatment with polyguanidin. That is, after the treatment, the plants, on the contrary, reduced their adaptive potential, because at the biochemical stage it was believed that there were no unfavorable factors in the environment. The analysis of the free proline content showed an increase in its concentration after treatment with the test substance almost doubled both after the first and after the second treatment. Also, it should be noted that reducing the concentration of the drug to 0.15 liters per 200 liters of the working solution increases the level of proline after the first treatment. The increase in proline, in this case, can lead to an increase in stress resistance, which is provided by metabolic and physiological changes. Consequently, its accumulation and conversion into other amino acids due to changes in the activity of proline oxidase contributes to an increase in the protein content in the grain.