Results of agronomic research on sunflower in Crimea

The research was aimed at developing a scientifically justified cultivation technology for sunflower hybrids of domestic breeding, ensuring their high productivity and seed quality in the arid conditions of the Crimean Peninsula. In the contrasting weather conditions of the research years (2017-2021), the hybrids Signal (1.22 t/ha), Garant, and Sprint (1.18 t/ha) were notable in terms of yield. Hybrids Komandor, Garant, Sprint, and Gorstar (coefficient of ecological plastici-ty bi > 1) were distinguished as demanding to the agronomy level. The hybrid Kometa should be cultivated on an extensive background (coefficient of ecological plasticity bi < 1) to unlock its potential at minimum cost, and it was the most stable in terms of yield (stability index Ϭd2 = 0.48). The most unstable hybrid was Kommandor (stability coefficient Ϭd2 = 2.19). We formed the optimal parameters of the sunflower hybrid model for the conditions of the steppe zone of the peninsula. We established the influence pattern of water reserves in the soil before sowing, HTC and precipitation during the growing season, as well as the natural water availability of the cultivation zone on the sunflower yield depending on the plant density at different sowing dates. The sunflower hybrid Avangard should be sown in the beginning or end of April at a given density of 40-50 thousand plants/ha to guarantee a high yield (1.19-1.32 t/ha). We noted that the seed oil content did not depend on the plant density but decreased if the hybrid was sown late (from 45.2 to 41.6%). Due to the uncertain-ty of water availability during the growing season, it is advisable to sow the sunflower hybrid Fakel in April on two dates – one part in the beginning, and one part at the end of the month with a density of 40 thousand plants at harvesting time (1.35-1.39 t/ha). We noted that the oil content of sunflower seeds decreased at late sowing (from 45.2 to 40.8%) and did not depend on the plant density.