Herbicide influence on the agrocenose of soy and its photosynthetic activity in the western Forest Steppe of Ukraine

The use of herbicides can significantly affect the processes of plant photosynthesis, as it leads to inhibition of pigment production, impairs the transport of electrons in the respiratory chain and carbon fixation. The purpose of the study is to determine the effect of herbicide application on weediness and photosynthetic activity of soybeans. On the basis of a field study in the conditions of the Educational and Scientific Center of the Lviv National University of Nature Management, the dependence of soybean yield on the level of weediness of the culture was established. The highest yield of soybeans - 29.0 t/ha was obtained in the application of the herbicide Primekstra TZ Gold 500 SC c.s. (4.5 l/ha), the smallest – 27.3 t/ha among the experimental variants was obtained with the post-emergence application of the herbicide Pulsar s.c. (1 l/ha). Application of herbicide Primekstra TZ Gold 500 SC c.s. did not affect the intensity of photosynthesis, and the number of pigments in soybean leaves was not significantly different from the indicator in the control. The use of drugs Kommand k.e. and Pulsar s.c. led to a slight decrease in the number of pigments in the first days after application and their gradual stabilization. Use of the herbicide Concur c.s. had the effect of weakening photosynthetic activity and reducing the number of pigments. This indicates that the active substance metribuzin is not absolutely selective with regard to the effect on soybean plants, that is, in the case of its use, there is a probability of suppressing the culture. The practical significance of the obtained results lies in revealing the possibilities for choosing effective herbicides with increased selective phytotoxicity, which provide effective control of the number of weeds with a minimal probability of a negative impact of herbicides on the soybean agrocenosis