Ryzhenko A. Productivity of sunflower hybrids depending on the sowing rate in the conditions of the left-bank forest steppe of Ukraine

The research was conducted in the Left-Bank Forest-Steppe of Ukraine on podzolic light loam chernozems. The reaction of sunflower hybrids to growing conditions was studied by establishing the stability and plasticity of hybrids in relation to the yield formation due to changes in morphological characteristics of plants. Criteria assessment of weather conditions allows us to establish that the Left Bank Forest-Steppe of Ukraine is an area suitable for growing sunflower hybrids and realizing the yield potential at a high level, provided by the stable required amounts of positive, active, effective temperatures and heat units, sufficient rainfall. To go through the full cycle of sunflower plant development, the required amount of active temperatures for hybrid ‘Ukrainskyi F1’ - 2354.6℃; ‘P63LL06’ - 2306.4; ‘NK Brio’ - 2401.3; ‘NK Ferti’ - 2379.7℃; sum of effective temperatures,℃: ‘Ukrainskyi F1’ - 1081.5; ‘P63LL06’ - 1056.9; ‘NK Brio’ - 1104.9; ‘NK Ferti’ - 1109.1℃. The sum of temperatures, both at a biological minimum temperature of 10℃ and 5℃, corresponds to the biological needs of sunflower plants and is not a limiting factor for cultivation. It is established that the assignment of hybrids to different maturity groups according to the originators is conditional and varies depending on the geographical location of the growing area. The longevity of sunflower seeds is determined by the properties of hybrids, growing and storage conditions, and is an extremely important property for crops with a high content of fat, which should be constantly monitored. The economic longevity of sunflower seeds for storage without regulation of temperature and humidity ("ex situ") is maintained for 8 months, biological - 23 months; at a temperature of + 10 - 11 and 32 months, respectively; at a temperature of + 5℃ - economic longevity was 27 months, and after 36 months the germination remained at 70%. With storing at a stable low temperature - 0℃ and - 5℃ seed germination is not lost and does not fall below the regulatory requirements. The total technological costs for sunflower growing are 17.6 - 19.8 thousand UAH/ha. Profit for growing of traditional hybrids is: ‘Ukrainskyi F1’- 8.44 - 12.4; ‘P63LL06’- 12.6 - 15.2; ‘NK Brio’ - 16.8 - 19.8 thousand UAH/ha, of high-oleic sunflower ‘NK Ferti’ - 32.1 - 37.1 thousand UAH/ha. The cost of sunflower seeds is 5308 - 7303 UAH/ton. The highest profitability for growing of high-oleic sunflower hybrid ‘NK Ferti’ is 169.8 - 209.6%. Profitability for growing of traditional hybrids is: ‘Ukrainskyi F1’- 47.7 - 68.9; ‘P63LL06’ - 67.0 - 87.6; ‘NK Brio’ - 88.0 - 114.1%. The energy efficiency ratio for growing sunflower hybrids varies from 3.77 to 4.87. The highest energy efficiency ratio was for the cultivation of hybrid ‘NK Brio’ - 4.50 - 4.87. The variation of the coefficient was much higher for the cultivation of different hybrids than for changes in the seeding rate.