EVALUATION OF CLIMATIC PLASTICITY OF SUNFLOWER HYBRIDS AND THE EFFECTIVENESS OF GROWTH-REGULATORY PREPARATIONS BASED ON THE NDVI INDEX

Abstract

Research on the development and productivity of various sunflower hybrids in the natural-climatic conditions of the Steppe zone of Ukraine was conducted during the period 2019–2021. The climatic plasticity of five sunflower hybrids (Ukrainian selection – Hektor and Oplot, foreign selection – DSL403, P64GE133, 8Х477KL) and the effectiveness of the use of multifunctional growth-regulatory preparations ArchitektTM and Helafit Kombi were studied. Spatio-temporal differentiation of the vegetation of sunflower hybrids was determined based on the calculation of the normalized difference vegetation index (NDVI) based on the data deciphered of the Sentinel 2 space images. The obtained cartographic and grapho-analytical materials reflect the reaction of plants on the natural-climatic conditions and multifunctional growth-regulatory preparations, this provided an opportunity to objectively verify vegetation curves under three natural-climatic scenarios of growing sunflower hybrids in the Steppe zone. It was proved that in a dry year (2020) there was a reduction in the duration of the flowering phase of sunflower hybrids, a low level of the NDVI vegetation index was recorded during the phase of head formation (0.22–0.40) and the phase of maturation (0.30–0.40). In the moderately wet year (2019), favorable conditions for plant development and a positive reaction to the introduction of multifunctional growth-regulatory preparations were recorded in the first half of the vegetation, while the second half of the vegetation was characterized by a decrease in soil moisture and a shortening of the flowering phase of sunflower hybrids. In the wet year (2021), a prolongation of the flowering phase, high values of the vegetation index during all phenological phases of plant development, and a positive reaction on the multifunctional growth-regulatory preparations were recorded. The effectiveness of the use of multifunctional growth-regulatory preparations has been proven. Their application contributed the increase in the crop yield of sunflower hybrids: in a dry year – 1.5–11.7%, in a moderately wet year – 4.5–11.5%, in a wet year – 4.5–28.2%. A decrease in moisture consumption by plants was observed in a dry year – in the range of 1.2–10.0%, in a moderately wet year – 3.8–8.6%, in a wet year – 3.7–21.9%.