INFLUENCE OF TIMES AND RATE OF APPLICATION OF BIOSTIMULATORS-ANTI-STRESSANTS ON PHOTOSYNTHETIC ACTIVITY OF SOYBEAN IN THE CONDITIONS OF THE WESTERN FOREST-STEPPE

Abstract

In modern grain production, soybean occupies a significant place in the structure of sown areas among leguminous crops, which determines the level of vegetable protein production in Ukraine. Currently, soybean is considered one of the most demanded strategic crops, which satisfies the needs of humanity in vegetable protein and oil. The article highlights the results of research that established the main aspects that influence the formation of photosynthetic activity of agrophytocenoses of soybean varieties depending on the use of biostimulants-anti-stressants under climate change conditions. It was noted that the highest rates of photosynthetic activity were formed in soybeans of the Mentor variety under the condition of double treatment with the biostimulant Vuxal BIO Askofol (WUXAL) and ALHUM PLUS (Smart Grow) during the research period of 2023–2025. The highest rates in the “budding-flowering” period were observed in the variant with the application of the biostimulant Vuxal BIO Askofol in the period of 2 internodes (ВВСН 14) and budding (ВВСН 55) with a rate of 1,0 l/ha – 51,1 thousand m2/ha, which exceeded the indicator in the variant without the application of biostimulants by 4,9 thousand m2/ha. The application of lower rates of the drug reduced the leaf surface area: with a rate of 0,5 l/ha by 1,4 thousand m2/ha, with a rate of 0,7 l/ha – by 0,5 thousand m2/ha. The application of the biostimulant Algum plus provided the leaf surface area at the level of 49,2 thousand m2/ha in the variant with a rate of 1,0 l/ha, which was 3,0 thousand m2/ha higher than the variant without the biostimulant. The difference between the use of the drug Vuksal BIO Askofol was 1,9 thousand m2/ha compared to Algum plus. The highest indicator on the variants of the Sirelia variety was 48,4 thousand m2/ha from the application of Vuksal BIO Askofol, which was 4,8 thousand m2/ha higher than the variant without the use of biological products and only 0.3 thousand m2/ha higher than the variant without the use of biological products and only 0,3 thousand m2/ha higher than the application of Algum plus. The photosynthetic potential of soybean varieties differed from the application of biostimulants at the application rate of 1,0 l/ha by 0,27 million m2/ha × day more on the variant of applying Vuksal BIO Askofol and 0,16 million m2/ha × day on the variant of applying Algum plus of the Mentor variety. The highest photosynthesis productivity was in the period of “flowering-grain filling”, the net photosynthesis productivity was within: in the Mentor variety 1,91–2,23 g/m2, in the Sirelia variety 1,83–2,16 g/m2, depending on the experiment variant. The use of the biostimulant Vuksal BIO Askofol on the Mentor variety provided the greatest increase in dry matter when applied to 2 internodes (ВВСН 14) + budding (ВВСН 55), and according to the application rate, this indicator was: 0,5 l/ha – 16,34 g/plant; 0,7 l/ha – 16,52 g/plant; 1,0 l/ha – 16,83 g/plant, which was 1,66, 1,84 and 2,15 g/plant higher than the option without the application of biostimulants.