Assessment of agrometeorological conditions for growing sunflower hybrids

The aim of the study was to analyse the weather conditions during the vegetation period, their correspondence to the morphobiological characteristics of the hybrids, and to identify sunflower hybrids that are better adapted to the region where the research was conducted. The studies were carried out during 2022-2024 under the conditions of Ternopil region. An analysis of the agrometeorological indicators over the research years revealed considerable differences in the vegetation periods, both in terms of temperature indicators and the total monthly precipitation. According to the temperature data, values exceeded the long-term average. The analysis of weather conditions in the study region indicates that the conditions are suitable for cultivating sunflower hybrids of all maturity groups examined, in terms of both heat resources and moisture availability. The sum of active temperatures for the period from April to September was 3,162.1°C (biological minimum 5°C), and the sum of effective temperatures was 2,263.2°C. At a biological minimum of 10°C, the respective figures were 2,977.1°C and 1,409.1°C. During this period, the highest total of heat units was recorded at 3,642.4°C. The total heat units for the May-September period amounted to 3,433.4°C. Soil moisture reserves within the one-metre layer depended on the year’s weather conditions and varied accordingly. The water consumption coefficient for early-maturing hybrids, under the influence of fertilisers, ranged from 1,173 to 1,012 m³/t per tonne of seed; for mid-early hybrids – from 1,171 to 1,017 m³/t; and for mid-season hybrids – from 1,100 to 989 m³/t per tonne of seed. A correlation analysis between sunflower yield indicators and soil moisture reserves showed a direct correlation, with a correlation coefficient of 0.8456. The results of this research can be used to optimise the timing of sowing and harvesting in accordance with forecasted agrometeorological conditions