Продуктивність сорго зернового залежно від агротехнічних заходів в умовах Північного Степу України

Purpose. To determine the impact of the factors of hybrid, plant density, and growth regulator application on the productivity of Sorghum bicolor in the steppe zone of Ukraine. Methods. The study was conducted under the conditions of insufficient moisture in the Northern Steppe of Ukraine from 2022 to 2024. The research methods included: Field observations to monitor phenological stages and assess the impact of studied factors on grain sorghum yield. Tabular method for data systematization, arrangement, and presentation. Graphical method for visualizing research results. The scientific program aimed to study the influence of technological elements on phenological, biometric, structural-morphological indicators, and grain sorghum yield. To achieve the objective, a three-factor experiment was designed: hybrid (different maturity groups of grain sorghum hybrids − ‘Kalatur’, ‘ES Alize’, ‘ES Foehn’, ‘Albanus’, and ‘ES Musson’; plant density (170, 200, and 230 thousand plants per hectare); growth regulator (growth regulator ‘Appetizer’ applied at the 4–5 and 7–8 leaf stages at a rate of 0.5 l/ha with a working solution of 150 l/ha). Results. Over the study years, the highest grain yield was achieved by the medium-early hybrids: ‘ES Foen’ (5.17 t/ha), ‘Kalatur’ (5.13 t/ha), and ‘ES Musson’ (5.11 t/ha) at a plant density of 200 thousand per hectare with ‘Appetizer’ growth regulator application. At 170 thousand plants per hectare, the highest productivity was observed in the early-maturing hybrid ‘Albanus’ (4.02 t/ha) and the medium-early hybrids ‘ES Musson’ (4.01 t/ha) and ‘ES Foen’ (3.79 t/ha). At 230 thousand plants per hectare, high yields were recorded for ‘ES Musson’ (4.60 t/ha), ‘Albanus’ (4.51 t/ha), and ‘ES Foen’ (4.37 t/ha). Conclusions. The study confirmed the significant role of plant density and growth regulator application in optimizing the productive potential of grain sorghum hybrids. Increasing plant density from 170 to 200 thousand plants per hectare ensured high yields ranging between 4.43 and 4.87 t/ha (on average across study years) for hybrids ‘Kalatur’, ‘ES Alize’, ‘ES Foehn’, ‘Albanus’, and ‘ES Musson’. However, further increasing density to 230 thousand plants per hectare led to plant suppression and yield reduction by 4–16%. The ‘Appetizer’ growth regulator proved to be a modern adaptive cultivation technology element, increasing yield by 0.17–0.41 t/ha, demonstrating both economic and technological efficiency. Proper regulation of plant density is crucial, as excessive density may result in competition for nutrients and moisture, reducing productivity. Therefore, combining optimal density with growth regulator application in cultivation technology significantly enhances grain sorghum yield in the steppe zone of Ukraine.