PLANT GROWTH REGULATORS IN SUNFLOWER CROPS OF NORTHERN STEPPES OF UKRAINE

Abstract

Relevance. To offset negative influences such as increased technological load, deterioration of water and nutrient regimes, as well as soil humus degradation in sunflower nutrition systems, it is advisable to utilize a broader range of elements, including micro-fertilizers and plant growth regulators, in addition to conventional mineral and organic fertilizers. The regulatory mechanisms of stimulants contribute to strengthening the development of leaf surfaces, activating key functions essential for the sunflower’s vital processes, such as membrane processes, cell division, respiration, nutrition, enzymatic system functioning, and photosynthesis. The result of such influence is the formation of a branched root system with enhanced absorptive capacity. Primary Objective. The main objective of this research was to study the impact of various growth regulators on morphogenesis, growth, development, and productivity of different maturity group sunflower hybrids in the conditions of the Northern Steppe of Ukraine. Additionally, our goal was to identify the most optimal growth stimulants in sunflower crops, promoting resilience to diseases and environmental adversities, ensuring optimal plant growth and development, and contributing to obtaining high and consistent oilseed yields. Methods. The conduct and organization of field studies were in accordance with widely accepted scientific methodologies. The experimental phase of the research took place from 2018 to 2020 at the scientific research field of the National Scientific Center of DniprovskAgrariannd Economic University. The experiments were conducted within the framework of a stationary rotation of crops, including fallow – winter wheat – maize – barley – sunflower. The main objective was to study the effectiveness of modern technologies in cultivating cereals, legumes, and oil crops. Results and findings. Based on the conducted scientific research, it was determined that the use of the growth stimulator Ceron (0.5 l/ha) ensured the formation of the maximum leaf area for sunflowers, amounting to 70,900–78,100 thousand m²/ha, or more by 5.5–10.2% compared to the control. Sunflower plants in this case also exhibited the largest head diameter (23–26 cm), surpassing the control by 11.5–30.4%, and the maximum number of seeds per head (863.0–925.3 units), which was higher by 3.4–5.6%. The weight of 1000 seeds varied, being the highest for the medium-early hybrid Sumico HTS (54.0–60.0 g) and the lowest for the medium-late hybrid Subaro HTS (51.0–55.0 g). The use of growth stimulators also positively influenced the level of sunflower yield, providing an increase of up to 1.7 times. The Ceron preparation (0.5 l/ha) proved to be the most effective, ensuring an additional grain yield from 0.160 to 0.750 t/ha, corresponding to 8.2–43.3%. The use of regulatory preparations such as Ceron (0.5 l/ha) and Architect (0.5 l/ha) also contributed to an increase in oil content, respectively, by 3–8 percentage points.