Influence of the sowing time and the density of the sunflower’s standing on the water regime of soil in the Right-bank Steppe of Ukraine

The article presents the results of scientific research on the influence of sowing terms and the density of sunflower standing on the water regime of the soil in the Right-bank Steppe of Ukraine. The research was carried out at the Kirovohrad DHSGDS NAAS of Ukraine, which is located in the chernozem zone of the Right Bank Steppe of Ukraine. Climatic conditions are typical for a given region. Research has established that the amount of available moisture in the soil layer 0-10 cm in the third term of sowing was lower than in the first and second, there was a gradual decrease in the number of available moistures in topsoil. The reserves of available moisture in the meter layer of soil before sowing, in the phase of flowering and before harvesting differed from year to year and depended on the time of sowing and the density of plants standing. Of importance for sunflower plants is the content of available moisture in the 0-100 cm layer of soil after the flowerbud stage. During this period sunflower intensively consumes available moisture from deeper layers of soil. After flowering, growth processes in sunflower plants are suspended, and the use of moisture from the soil is slowed down. At this time enhanced the formation and maturation of seeds and the accumulation of oil in achenes. Plants do not require such amount of moisture, as in the initial periods of growth and development. It has been established that the level of sunflower productivity is largely determined by the conditions of the water regime of the soil. The water regime is formed by weather conditions, the amount of moisture reserves in the soil, the amount and intensity of precipitation per year, incl. and for the vegetative period. To a large extent, the water regime of the soil depends on the morphological characteristics of the hybrids, the density of plant standing, the timing of sowing, and the technology of cultivation. Under these conditions, the density of plants at 60 thousand / ha contributed to the economic consumption of moisture to form a unit of yield per hectare. The highest yield was provided by the hybrid LG 55.82 for the first sowing term – 3.85 t / ha. Given the annual variation of weather conditions, spring, sowing should be made with regard to water and thermal regimes. High moisture reserves in the soil during vegetation are a prerequisite for high yields of sunflower seeds.