Application of the Research on Spatio-Temporal Differentiation of a Vegetation Index in Evaluating Sunflower Hybrid Plasticity and Growth-Regulators in the Steppe Zone of Ukraine

The purpose of the study was to establish dependence of sunflower productivity on hybrid plasticity under the climatic conditions of the Steppe zone and effectiveness of growth-regulators on the basis of the analysis of differentiation of a vegetation index. The research on the development and productivity of different sunflower hybrids under the natural-climatic conditions of the Steppe zone of Ukraine was conducted in the years of 2019 (medium-wet), 2020 (dry) and 2021 (wet). Spatio-temporal differentiation of the vegetation of sunflower hybrids was established on the basis of calculation of a normalized difference vegetation index (NDVI) using the data of the decoded space images of Sentinel 2. Cartographic and grapho-analytical materials reflecting the reaction of plants to natural-climatic conditions and multifunctional growth-regulators were obtained. The dependence of the reaction of sunflower hybrids to multifunctional growth-regulators on their plasticity in response to the natural-climatic conditions of the Steppe zone was established. There was a weak reaction to application of growth-regulators of the sunflower hybrids Oplot and P64HE133 which are characterized by a high level of plasticity in response to the natural-climatic conditions of the Steppe zone. It was proven that the application of the biological preparation Helafit Combi exceeded the level of agrocenoses productivity in comparison with the chemical preparation ArchitectТМ by 1.1-5.4%. It was established that foliar treatment with growth-regulators led to a decline in water uptake by the sunflower hybrids by 1.2–10.0% in the dry year, by 3.8–8.6% in the medium-wet year and by 3.7%–21.9% in the wet year. There was a significant reduction in the level of water uptake by the hybrid Hector – by 7.7–10.0% and the hybrid 8KH477KL – by 1.2–21.9%. The research results are the basis for forecasting the development of sunflower hybrid crops with further measurement of the crop productivity that allows establishing a probable level of efficiency of sunflower hybrid production by agricultural producers under the climatic conditions of the Steppe zone.