Photosynthetic Activity of Spring Barley Crops Depending on Nutrient Optimization and Varietal Characteristics under the Conditions of the Southern Steppe of Ukraine

Abstract

Objective. To determine the effect of varietal characteristics, pre-sowing seed inoculation, and foliar fertilization during the growing season on the photosynthetic activity of spring barley crops under the conditions of the Southern Steppe of Ukraine. Methods. Field studies were conducted in 2023–2025 at the Educational, Scientific and Practical Center of Mykolaiv National Agrarian University. Results. The patterns of leaf area formation, photosynthetic potential, and net photosynthetic productivity during different interphase periods of spring barley plant growth and development were established. It was determined that the Tamango cultivar was characterized by higher indicators of crop photosynthetic activity compared with the Nadiinyi cultivar. Regardless of the biopreparation treatment, plants of the Tamango cultivar formed a slightly larger leaf area at all growth and development stages, reaching 12.6 thousand m²/ha at tillering, 30.7 thousand m²/ha at stem elongation, and 35.0 thousand m²/ha at heading. These values exceeded those of the Nadiinyi cultivar by 0.8–1.4 thousand m²/ha, or by 2.6–11.1%. The most effective treatment for improving the photosynthetic activity of spring barley crops was the combination of pre-sowing seed treatment with the biopreparation MycoFriend and two foliar applications of HELPROST® Universal. Under this treatment, the leaf area at heading reached 39.2–40.1 thousand m²/ha, the photosynthetic potential during the tillering– stem elongation period reached 0.48–0.50 million m²/ ha × days, while net photosynthetic productivity during the stem elongation–heading period was 14.69–15.30 g/m² per day. The results obtained confirm the effectiveness of combining pre-sowing seed treatment with the biopreparation MycoFriend and foliar application of HELPROST® Universal for improving the photosynthetic activity of spring barley crops, particularly in the Tamango cultivar. Conclusions. The most effective element of the spring barley cultivation technology under the conditions of the Southern Steppe of Ukraine is the integrated application of MycoFriend for pre-sowing seed inoculation and HELPROST® Universal for foliar fertilization of crops during the growing season. This agronomic practice ensures the maximum realization of the photosynthetic activity of spring barley crops throughout the growing season.