Climate of the Steppe zone of Ukraine is recently characterized by substantial temperature increase, decrease of rainfalls, and their irregularity. This led to the decrease of the stock of productive moisture in the arable and meter layers of the soil, occurrence of prolonged hydrothermal stresses during critical phases of plant development, especially of the late spring crops including sunflower.
Field studies were carried out over the period 2013 2015 in the scientific-production centre of Tavria State Agrotechnological University (Melitopol district, Zaporizhzhia region, Ukraine), and laboratory studies – in the Laboratory for the Soil and Crop Production Quality (Scientific Research Institute of Agrotechnology and Ecology at TSAU). Field and mathematical-statistical methods were used.The soil of study plots was represented by chernozem containing 3.5 % of humus. Soil moisture conditions in the research years differed, both by the rainfall amount, and its uniformity.
Modern varieties and hybrids of sunflower show a pronounced response to changes in agrometeorological conditions of their growing. In recent years, significant fluctuations of hydrothermal indices between years have occurred even in the same soil and climatic locations thereby providing a significant effect on the exhibition of individual characteristics and properties of agricultural crops and, as a result, of their macrocharacteristics, including yield. This introduces the issue of increasing requirements to adaptive capacities of created varieties and hybrids of sunflower. Highly adapted varieties and hybrids are the key to a stable yield in varying agrometeorological conditions and different eco-geographical zones. The assessment of adaptive and stability capacities of seed material is a prerequisite for the selection of highly adaptive forms.
The highest crop of the studied hybrids was observed in 2015 when, in spite of the unfavourable hydrothermal index of the year, the minimum relative air humidity during the flowering period was optimal (45.8%).
Growing hybrids of different levels of intensity, genetically and biologically diverse, allows the effective exploitation of agroecological potential of different zones.
Keyword: sunflower, yield, seed volume-weight, seed emptiness, weight of 1000 seeds, the ranged row.