SULFUR-CONTAINING FERTILIZERS IN SUNFLOWER CULTIVATION TECHNOLOGY: PRODUCTIVITY AND SEED QUALITY OF ANTEMIS AND TERRAMIS HYBRIDS

Abstract

Field studies were conducted in 2023-2025 on gray forest soils of the Republic of Tatarstan in order to assess the effect of sulfur sources in the mineral nutrition system on the yield and oil content of sunflower hybrids Antemis and Terramis. The experiment was performed according to a two–factor scheme: factor A - hybrid; factor B – food options. The control without fertilizers, the background of nitrogen-phosphorus-potassium fertilizers (nitrogen, phosphorus, potassium) for a planned yield of 2.5 t/ha (N111P12K121), the background with ammonium sulfate of 100 kg/ha and the background with sulfur bentonite of 50, 100 and 150 kg/ha were compared. Biological and actual yields, oil content, and gross oil yield were taken into account; differences were checked by variance analysis. The years of research varied in moisture availability during the growing season, which made it possible to assess the stability of the hybrids' response to nutrition in different conditions. The background of nitrogen-phosphorus-potash fertilizers increased productivity compared with the control: the actual yield increased for Anthemis from 1.25 to 2.30 t/ha, for Terramis from 0.93 to 2.12 t/ha, and the oil harvest increased to 1065 and 968 kg/ha. The inclusion of sulfur enhanced the background effect. The maximum biological yields were obtained with the addition of ammonium sulfate (3.46 t/ha for Anthemis and 3.27 t/ha for Terramis) and were accompanied by the largest oil harvest (1502 and 1340 kg/ha). Sulfur bentonite showed a dose-dependent effect; at a dose of 150 kg/ha, maximum oil content values were noted (51.5% for Anthemis and 50.1% for Terramis) with high oil harvest (1442 and 1327 kg/ha), however, the increases at a high dose decreased relative to the transition of 50→100 kg/ha. Antemis was characterized by a higher absolute level of performance, Terramis – by greater relative responsiveness. To maximize oil yield, it is advisable to combine the background with ammonium sulfate; with the priority of oil content, sulfur bentonite of 100-150 kg/ha is used, taking into account economic efficiency.