The development of an optimal sowing model to ensure maximum productivity of high-oleic sunflower hybrids under the conditions of the Southern Steppe of Ukraine

Abstract

High-oleic sunflower hybrids are of strategic importance for ensuring both high yield and superior oil quality, particularly under the increasingly arid conditions of the Southern Steppe of Ukraine. The optimization of sowing parameters – especially row spacing and plant density – plays a key role in improving productivity, resource-use efficiency and crop adaptability. However, the interaction between genotype and spatial sowing configuration remains insufficiently studied under variable climatic conditions. This study aimed to determine an optimal sowing model for high-oleic sunflower hybrids by integrating yield performance, seed quality indicators and environmental adaptability. Field experi-ments were conducted in 2019 ÷ 2021 on southern chernozem soils using a multifactorial design that included seven hybrids, four row spacing options (15 ÷ 70 cm) and six plant density choices (35,000 ÷ 60,000 plants/ha). Results and conclusions. The results demonstrated that yield formation was significantly influenced by the interaction between hybrid genotype and sowing parameters. Average yields ranged from 2.36 to 2.85 t/ha, with the highest productivity achieved at the row spacing of 30 ÷ 45 cm and the plant density of 45,000 ÷ 50,000 plants/ha. Narrowing row spacing from 70 to 45 ÷ 30 cm increased yield by 12 ÷ 18 %, while excessive density (55,000 ÷ 60,000 plants/ha) reduced individual plant productivity. Oil content varied between 48.9 % and 51.6 %, whereas oleic acid content remained stable (74.4 ÷ 90.8 %), indicating strong genetic control of this characteristic. Optimal configurations improved soil moisture retention and reduced drought stress, allowing for stable crop performance in diversified weather conditions. The integrated sowing model – combining specific hybrids with 30 ÷ 45 cm row spacing and 45,000 ÷ 50,000 plants/ha – provides a practical, resource-efficient solution for maximizing yield and maintaining high seed quality in the Southern Steppe of Ukraine.