SUNFLOWER HYBRIDS PRODUCTIVITY DEPENDING ON SOIL TILLAGE SYSTEMS

Abstract

The study was conducted under the conditions of the southern Steppe in the Rozdilna District of Odesa Region on the fields of Kolos LLC during 2023–2025. Four soil tillage systems were compared: 1. Stubble cultivator Horsch Tiger 6MT. 2. Verti-till tillage using a Salford implement. 3. Qualidisc disc harrow as the control. 4. Direct seeding with the Mzuri Pro-Til seeding complex with Strip-till tillage. All systems were evaluated under both Classic technology (hybrid NK Kondi) and Clearfield technology (hybrid P64LP130). The aim was a detailed investigation of the formation of sunflower generative organs and assessment of individual and population productivity. The main methods included dynamic counting of bracts, tubular flowers, and fully developed seeds, as well as calculation of biological yield and its comparison with actual (harvested) yield. Generative organ initiation begins in the phase of 4–6 true leaf pairs. An optimal head has a diameter of 20–25 cm and contains approximately 1500 seeds. The inflorescence consists of ligulate (ray) flowers and tubular (disc) flowers (fertile), with protandry preventing self-pollination. Flowering lasts 20–30 days. The number of bracts ranged from 21.7 to 22.2 per plant, with an advantage for Clearfield technology and the Verti-till and Strip-till systems. The number of tubular flowers was 1464–1594, fully developed seeds – 941–1157, and potential realization – 62.7–71.5 %. Classic technology outperformed in the number of tubular flowers (+13.6 %) and seeds (+7.3 %). Strip-till and Verti-till systems provided the highest realization level (+7.4–8.2 % over control) and the lowest percentage of empty seeds (28.6–30.3 %). Biological yield ranged from 2.29 to 2.95 t/ha, with Classic technology showing a 6.0 % advantage. Actual yield (at seed moisture 7–10 % and impurity content 3–5 %) varied from 1.39 to 3.30 t/ha. In favorable years (2023–2024), Classic technology gave a 10.8 % advantage (2.94 vs 2.65 t/ha). In the droughty year 2025, Clearfield outperformed by 17.3 %. The highest yield in all years was formed under Strip-till, with yield increases of 10.2–27.0 % depending on weather conditions and technology. Real sunflower productivity reaches only 65–70 % of its potential. The degree of potential realization depends on annual weather conditions and technological measures. Innovative tillage systems optimize plant growth and development, promote the formation of a powerful head, and enhance drought tolerance. Bract number can serve as an early marker of productivity. The results support recommending Classic technology on highly fertile fields and Clearfield technology under high weed pressure and moisture deficit. For both technologies, Strip-till and Verti-till systems provide the best performance, especially under the dry conditions of southern Ukraine. Prospects for further research include: evaluation of the technologies’ impact on seed oil content, economic efficiency, and ecological sustainability; comparison with other hybrids; and analysis of long-term effects on soil properties.