Influence of growth stimulants on the elements of sunflower hybrids productivity in the conditions of the Southern Steppe of Ukraine

Received: 03-Jul-2025, Manuscript No. mp-24-140576; Accepted: 23-Oct-2025, Pre QC No. mp-24-140576 (PQ); Editor assigned: 06-Jul-2025, Pre QC No. mp-24-140576 (PQ); Reviewed: 09-Oct-2025, QC No. mp-24-140576; Revised: 16-Oct-2025, Manuscript No. mp-24-140576 (R); Published: 30-Oct-2025, DOI: 10.5281/zenodo.17722671

Introduction

Sunflower (Helianthus annuus L.) is among the most widely cultivated crops in Ukraine and many other countries due to its high economic efficiency, stable market demand, and relatively low production costs compared to other oilseed crops. Its cultivation is favored by simplified agronomic practices and favorable agroclimatic conditions in regions such as the Ukrainian Steppe. The sunflower seed is highly valued for its oil, which contains 47-52% oil content, and is rich in essential fatty acids, fat-soluble vitamins (A, D, E, K), phosphatides, and stearins-components that contribute to the high nutritional and culinary qualities of sunflower oil (Kalenska, et al. 2017, Kalenska, et al. 2020, Yevchuk, 2022, Grechka and Kulinych, 2023, Yurkevich, et al. 2022, Fedoryaka, et al. 2021, Yeremenko, et al. 2017). The oil’s oxidative stability ensures a long shelf life, making it a key export product. Notably, sunflower oil accounts for approximately 98% of Ukraine’s total vegetable oil production.

The Steppe zone of Ukraine provides favorable conditions for sunflower cultivation, except for the frequent limitation of soil moisture. Despite this constraint, the region consistently achieves high sunflower yields, supporting the crop’s dominant role in local agriculture.

In 2022-2023, an increase in the population dynamics of cotton bollworms in sunflower crops was observed. The highest yield of the sunflower hybrid P64LC108 (Pioneer company) was obtained at 3.81 t/ha in the treatment variant with the application of the drug Radiant, KS, at a consumption rate of 0.5 l/ha (Diedukh, et al. 2020).

Materials and Methods

The research was conducted in the experimental field of the Institute of Irrigated Agriculture of the National Academy of Agrarian Sciences (NAAS), located in the Kherson region of Ukraine. Field trials were carried out following standard agricultural practices and methodological guidelines (Ushkarenko, et al. 2019).

A two-factor field experiment was designed as follows:

Factor A-Sunflower hybrids:

Yason: Early-maturing hybrid (originator: V.Ya. Yuriev Institute of Plant Breeding, NAAS)

Zlatson: Mid-early hybrid (originator: V.Ya. Yuriev Institute of Plant Breeding, NAAS)

Charodiy: Mid-early hybrid (originators: V.Ya. Yuriev Institute of Plant Breeding, NAAS and the Selection and Genetic Institute)

Factor B-Plant growth stimulants:

STIMPO (Manufacturer: Agrobiotech, Ukraine)

Vympel (Manufacturer: Dolina, Ukraine)

The experimental design followed a randomized complete block layout (RCBD) with appropriate replications (Note: specify the number of replications and plot size, if available). Plant growth stimulants were applied according to manufacturer recommendations at the designated growth stages.

Results and Discussion

The study revealed significant differences in sunflower plant height depending on both the hybrid genotype and the application of plant growth stimulants. The most intensive increase in plant height occurred during the interphase period from head formation to flowering, indicating a critical stage in plant morphogenesis.

During the earlier interphase period, from emergence to head formation, the average plant height across all experimental treatments was 67 cm, with a mean daily growth rate of 1.5 cm. However, during the head formation to flowering phase, plant height increased by a factor of 2.3. The average daily growth rate during this period rose sharply, ranging from 2.7 to 3.8 times higher than in the initial stage (Tab. 1). This accelerated growth reflects the genotypic potential of the hybrids under favorable environmental conditions and the physiological effects of biostimulant application.

Table 1. Plant height and average daily growth rate of sunflower plants depending on hybrid composition and plant growth stimulants, cm (average for 2017-2019).

These findings align with previous studies indicating that the flowering stage in sunflower is accompanied by rapid biomass accumulation and elongation, particularly when growth stimulants are applied during vegetative transitions (Kalenska, et al. 2020, Yeremenko, et al. 2017). The enhanced growth rate observed during this stage suggests that plant height can serve as an early morphological indicator of hybrid response to biostimulants.

The genotype of the sunflower hybrid significantly influenced plant height and daily growth rate. The highest values were observed during the flowering phase in the Charodiy hybrid, with a plant height of 175 cm and a daily growth rate of 5.3 cm/day. Conversely, the Yason hybrid exhibited the lowest values, with a height of 138 cm and a growth rate of 3.8 cm/day, representing reductions of 26.8% and 39.5%, respectively, compared to the Charodiy hybrid.

Seed treatment with plant growth stimulants had a positive effect on plant height across all hybrids. During the head formation phase, plant height increased by 9.7-14.9%, while the average daily growth rate improved by 16.7-18.9% relative to untreated controls. These differences decreased during the flowering phase, with height increases ranging from 4.3% to 9.5%, and daily growth rate improvements between 2.3% and 14.5%.

In addition to enhancing plant height, the application of growth stimulants significantly increased dry matter accumulation per unit area in all hybrid plots (Tab. 2).

Table 2. Dynamics of dry matter accumulation by sunflower hybrids depending on stimulants, t/ha (average for 2017-2019).

The greatest increase in dry matter accumulation was observed from the head formation phase to the flowering phase, with an average 2.6-fold increase across all treatments. From the flowering phase to full seed maturity, the accumulation rate slowed but remained substantial, with a 2.4-fold increase. The lowest dry matter accumulation values, ranging from 0.44 to 0.49 t/ha, were consistently recorded during the head formation phase in the Yason hybrid plots, regardless of plant growth stimulant treatment.

Throughout all developmental stages, the Charodiy hybrid exhibited the highest dry matter accumulation, particularly when treated with the Vympel biostimulant. On average, Charodiy outperformed Zlatson by 3.5-8.4% and Yason by 28.3-52.9%, demonstrating its superior biomass production capacity under the tested conditions.

Application of growth stimulants positively influenced dry matter accumulation at all growth stages. Specifically, treatment with Vympel increased dry matter by 8.9-21.2% at head formation, 9.5-18.3% at flowering, and 8.7-17.9% at full seed maturity compared to untreated controls. Notably, the highest dry matter yield was recorded in the Charodiy hybrid treated with Vympel, reaching 4.24 t/ha.

Analysis of experimental data confirmed that both hybrid genotype and growth stimulant application significantly affected sunflower seed yield (Tab. 3). The yield difference among hybrids (Factor A) ranged from 0.47 to 0.86 t/ha, corresponding to 17.2-36.8%. The highest average yield was observed in the Charodiy hybrid (3.20 t/ha), while the Yason hybrid recorded the lowest average yield (2.34 t/ha).

Table 3. Sunflower hybrid yield depending on growth stimulants, t/ha.

Growth stimulant application (Factor B) also significantly increased seed yield across all hybrids. For Yason, the untreated control yield averaged 2.10 t/ha, increasing by 7.1-26.7% following treatment with STIMPO and Vympel. The Zlatson hybrid exhibited yield increases of 16.9-37.2%, while Charodiy yields improved by 19.1-33.5%, demonstrating the stimulants’ broad efficacy across genotypes.

The influence of the studied factors on sunflower seed yield formation varied considerably (Fig. 1). Hybrid composition contributed the most, accounting for 68.2% of the variation in seed productivity. Plant growth stimulants had a significant but smaller effect, contributing 20.5%. The interaction between hybrid genotype and growth stimulant treatment (Factor AB) accounted for 4.9%, highlighting the importance of selecting appropriate growth stimulants based on the genetic potential of each hybrid. The residual variation, representing the impact of uncontrolled factors, was 6.4%, primarily attributed to variations in weather conditions across the study years.

Figure 1: Variability of sunflower hybrid seed yield traits (Factor A) depending on the influence of plant growth stimulants (Factor B), % (average for 2017-2019).

Conclusion

The highest seed yield of 3.82 t/ha was recorded for the Charodiy hybrid treated with the Vympel growth stimulant. On average, seed productivity differences among hybrids ranged from 0.47 to 0.86 t/ha (17.2-36.8%) in favor of the Charodiy hybrid. Application of the STIMPO and Vympel biostimulants significantly increased yields across all hybrids, with improvements ranging from 7.9% to 37.2%. The hybrid genotype was the predominant factor influencing seed yield, contributing 68.2%, while growth stimulants accounted for 20.5% of the yield variation.

References

1. Kalenska SM, Yeremenko OA, Taran VG, Krestyaninov EV, Ryzhenko AS. (2017). Adaptability of field crops under variable growing conditions. Sci works Inst Bioenergy Crops Sugar Beet. 25:48-57.

   [Google Scholar]

2. Kalenska S, Ryzhenko A, Novytska N, Garbar L, Stolyarchuk T, Kalenskyi V, Shytiy O. (2020). Morphological features of plants and yield of sunflower hybrids cultivated in the Northern part of the Forest-Steppe of Ukraine. Am J Plant Sci. 11:1331-1344.

   [Crossref] [Google Scholar]

3. Yevchuk LA. (2022). Prospects for the use of sunflower seeds. Agro perspective. 3:18.
4. Grechka G, Kulinych I. (2023). Sunflower-a universal crop in modern agricultural production of Ukraine. Beekeep Ukr. 11:23-30.
5. Yurkevich EO, Valentyuk NO, Kohut IM, Yevych VS. (2022). High-oleic sunflower is an innovative way for further sustainable development of organic agriculture of the southern region and preserving soil fertility. Taurida Scientific Herald. 125:104-110.
6. Fedoryaka VP, Bakhchivanzhi LA, Pochkolina SV. (2021). Efficiency of sunflower production and sale in Ukraine. Her Socio-Econ Res. 41:139-144.
7. Yeremenko OA, Kalenska SM, Kalytka VV, Malkina VM. (2017). Sunflower yield depending on agrometeorological conditions of the southern Steppe of Ukraine. Agrobiology. 2:123-130.
8. Diedukh  IV,  Marchenko  TYu,  Lavrynenko  YuO, Svitlakova AS, Mishchenko SV, Marchenko VD. (2025). The effectiveness of modern insecticides in the system of protection  of  sunflower  crops  from  cotton  bollworm (Helicoverpa  armigera Hb)  in  the  conditions  of  the Rooster of Ukraine. Agricultural Innovations. 30:62-68.
9. Ushkarenko VO, Vozhehova RA, Holoborodko SP, Kokovikhin SV. (2014). Methodology of field experiment (Irrigated agriculture). Kherson: Hrin DS. 448.