Productivity of amaranth under the combination of seed pre-treatment and optimized mineral nutrition

Abstract

The aim of the research was to determine the effect of different rates of mineral fertilizer, foliar feeding with the biopreparation Azotofit, and seed pre-treatment on the formation of amaranth yield under the conditions of the Southern Steppe of Ukraine. Methods. The study was conducted from 2023 to 2025 on southern chernozem at the Educational, Scientific, and Practical Center of Mykolaiv National Agrarian University. The amaranth variety Lera was sown. The experiment was two-factor. Nutrient regime (factor A): Control (without fertilizers or preparations); N15P15K15; N15P15K15 + foliar application of Azotofit at the 4–6 leaf stage; N15P15K15 + foliar Azotofit at the 4–6 leaf stage and at early budding; N30P30K30; N30P30K30 + foliar Azotofit at the 4–6 leaf stage; N30P30K30 + foliar Azotofit at the 4–6 leaf stage and at early budding; No fertilizers + foliar Azotofit at both stages. Azotofit was applied as a water solution at a rate of 1.0 L/ha with a working fluid rate of 300 L/ha. Seed treatment (factor B): 1. Water treatment; 2. Seed treatment with Azotofit (1 L/t). Foliar applications were performed at the 4–to 6–leaf stage and at the beginning of bud break. Crop management practices were common for the Southern Steppe region. Results. It was established that amaranth yield significantly depended on nutrition intensification and seed pre-treatment. The application of mineral ferti-lizers increased crop productivity compared to the control. Under N15P15K15, yield gain averaged 0.60–0.87 t/ha, while under N30P30K30, it ranged from 0.90 to 1.18 t/ha depending on seed treatment. Maximum yields were achieved when the higher fertilizer rate was combined with two foliar applications and seed treatment with Azotofit, resulting in mean yields of 2.09–2.45 t/ha, which exceeded the control by 1.09–1.27 t/ha. Yield increases due to seed treatment ranged from 0.18 t/ha in the control to 0.30–0.32 t/ha under mineral nutrition, averaging 19–20%. Two foliar applications of Azotofit provided an additional 0.18–0.24 t/ha, which in some years increased productivity by 15–25%. Optimized fertilization systems reduced yield losses under drought-stress conditions in 2025, indicating enhanced adaptive potential of the crop. Conclusions. It was determined that the combination of mineral fertilization with seed pre-treatment and foliar applications of Azotofit is an effective component of amaranth cultivation technology in the Southern Steppe of Ukraine. The use of the biopreparation ensured a stable yield increase (18–20%), with maximum efficiency under N30P30K30 combined with two foliar applications. The findings substantiate the feasibility of including biopreparations in adaptive cultivation technologies.