АНАЛИЗ ВЛИЯНИЯ ПРИРОДНОЙ ВЛАГООБЕСПЕЧЕННОСТИ НА УРОЖАЙНОСТЬ ПОДСОЛНЕЧНИКА В ЗАСУШЛИВЫХ УСЛОВИЯХ КРЫМСКОГО ПОЛУОСТРОВА

Abstract

The Crimean Peninsula is located in the dry zone. In the steppe Crimea, which is the driest part of the peninsula, the major limiting factor for crop productivity is the natural moisture supply of plants. The purpose of the research was to establish the relationships between hydrometeorological factors (moisture reserves in the soil before sowing, precipitation amount and Selyaninov hydrothermal coefficient during the growing season) and sunflower yield depending on planting dates (I, II, III decade of April) and plant density (30, 40, 50, 60, 70 thousand units per hectare). The studies were carried out on the trial fields of the Research Institute of Agriculture of Crimea (village of Klepinino) in 2017–2019 using hybrid of ultra-early sunflower ‘Avangard’. The laying of field experiments, accounting, analyzes and statistical processing of data were carried out according to the methods of field research and methodology of field agricultural experiments with oil crops. A strong correlation was observed: 1) between yield and precipitation amount in May (r = 0.977) and moisture reserves before sowing (r = 0.978), planting dates – the first decade of April; 2) between precipitation amount in May (r = 0.932) and moisture reserves before sowing (r = 0.977–0.978), sunflower was sown in the second decade of April; 3) moisture before sowing (r = 0.892), crop planted in the third decade of April. A close positive relationship (r = 0.853–0.972) was observed at the optimal plant density for the region (40 thousand units/ha) between the amount of precipitation in April–May, moisture reserves in the soil before sowing and yield of sunflower. This indicates a high value of moisture availability during this period in the crop yield formation. In denser crops (50–70 thousand units/ha), the closest relationship is observed between the yield and the amount of precipitation in May. This makes the latter primary and decisive in the cultivation of crops with such a density since the competition for moisture increases with an increase in the number of plants per unit area. The closest relationship between the Selyaninov hydrothermal coefficient and sunflower yield was observed in April and May (r = 0.833–0.967) when plants grow more intensively and require sufficient moisture.