Patterns of productivity formation in early-maturing sunflower hybrids in the Western Forest-Steppe

Purpose. To determine the impact of seeding rates and foliar application of plant growth regulators on the formation of yield and seed quality in early-maturing sunflower hybrids. Methods. The research was conducted in 2022–2024 at the experimental fields of the Podillia Research Center of Podillia State University. A three-factor experimental design was used, which included: sunflower hybrids (‘P62LL109’, ‘MAS 81K’, ‘YeS Monaliza’), two seeding rates (60,000 and 65,000 plants/ha), and foliar application of growth regulators at the four to six leaf stage [control, Deimos (1.5 l/ha), Mars ELBi (0.75 l/ha), Treptolem (15 ml/ha)]. The study evaluated seed yield, 1000-kernel weight, seed oil content, and oil yield. Results. On average, over the years of research, the highest yield was observed in hybrids ‘P62LL109’ (4.03 t/ha) and ‘MAS 81K’ (3.92 t/ha) at a seeding rate of 65,000 plants/ha and treatment with the growth regulator Deimos. The optimal growing conditions for ‘YeS Monaliza’ were at seeding rates of 60,000 plants/ha with Deimos application, resulting in a yield of 3.81 t/ha. Growth regulators contributed to an increase in 1000-kernel weight across all hybrids and study years. Specifically, Deimos increased this parameter compared to the untreated control by an average of 3.58, 3.07, and 2.51 g; Mars ELBi by 0.80, 1.33, and 0.84 g; and Treptolem by 2.05, 1.67, and 1.75 g over the study years, respectively. Conclusions. For the ‘P62LL109’ hybrid, the highest seed oil content was achieved at a seeding rate of 60,000 plants/ha with Treptolem (53.6%) and Deimos (52.7%) treatments, with Deimos being equally effective at both seeding rates. For ‘MAS 81K’, the optimal combination was at a seeding density of 60,000 plants/ha with Deimos application, resulting in an oil content of 47.3%. The second most effective treatment under this seeding rate was Treptolem. At a seeding rate of 65,000 plants/ha, Mars ELBi was the most effective, followed by Treptolem. For the ‘YeS Monaliza’ hybrid, the best condition for increasing seed oil content was ensured by a seeding rate of 60,000 plants/ha with Deimos treatment (51.8%), followed by Mars ELBi. The highest oil yield across all hybrids was recorded with growth regulator treatments. The maximum values for ‘P62LL109’ and ‘MAS 81K’ were achieved at 65,000 plants/ha, while for ‘YeS Monaliza’, while the best results were at 60,000 plants/ha.