Effect of primary tillage on soil fertility indicators and productivity of sunflower hybrids under insufficient moisture conditions in the Lower Don region

Abstract

Sunflower is the main oilseed crop in the Rostov Region. Since the sown area under this crop is limited to no more than 15% of arable land, the study of primary tillage methods is of particular relevance. The aim of this research was to evaluate the effect of primary tillage on soil condition, yield structure components, and final yield of sunflower hybrids. The study was conducted from 2021 to 2023 under conditions of unstable moisture supply in the Lower Don region (Azov zone of the Rostov Region). The experiment was a two-factor design: Factor A (primary tillage method) included two treatments – control: minimum tillage to a depth of 10-12 cm; and moldboard plowing to a depth of 23-25 cm. Factor B comprised sunflower hybrids Tristan, Samurai KL, and Immi. Sowing, observations, recordings, and data analysis were performed according to standard agronomic methodologies. Compared to minimum tillage, moldboard plowing provided an increase in the main yield structure components of sunflower: head diameter by 8.9%, number of achenes per head by 3.5%, 1000-achene weight by 3.9%, and achene weight per head by 5.29%, which consistently resulted in a yield increase of 0.19 t/ha (+8.0%). The hybrid Immi showed the highest responsiveness to tillage method, whereas the hybrid Samurai KL exhibited high plasticity and stability of productivity components. The obtained data can be used to improve sunflower cultivation technology. When growing sunflower hybrids in the zone of unstable moisture in the Lower Don region, in order to increase yield, moldboard plowing to a depth of 23–25 cm should be carried out after winter wheat.