Response of Sunflower (Helianthus annuus L.) to Application of Bioactive Humic Substances

Sunflower is the second most cultivated oilseed crop in Slovakia. It remains an attractive crop in primary agricultural production because of the many benefits it provides. The study aimed to assess the impact of biological material (Subaro HTS, Sumiko HTS) and products containing bioactive substances (Humix® Universal, Humix Bór, Energen Fulhum Plus and Energen Stimul Plus) on sunflower production in the 2021–2022 growing seasons. A partial aim was to investigate the possible effect of adaptogens on a plant organism, specifically sunflower. The field trials were designed using the perpendicularly split block method with a randomized block complete design on an experimental basis of SAU in Nitra, located in a warm maize production area. The variability of weather conditions was statistically demonstrated on the achieved production parameters. Weather conditions were more favorable in 2022 regarding seed yield 3.25 ±0.31 tons per hectare (t.ha-1) and oil content 47.14 ±0.90%. Evaluation of biological material confirmed that the hybrid Sumiko HTS achieved significantly higher yields of seeds 3.29 ±0.28 t.ha-1 and oil content 46.66 ±1.32% compared to Subaro HTS. The utilization of bioactive substance combinations exhibited significant impact on sunflower production. Specifically, superior values in the examined parameters, such as seed yield 3.30 ±0.26 t.ha-1 and oil content 46.99 ±1.12%, were observed in instances where Energen Fulhum Plus + Energen Stimul Plus preparations, inclusive of adaptogens, were applied during the growth stage BBCH 18.