Formation of productivity of amaranth varieties in the Right Bank Forest Steppe of Ukraine under the influence of MaxiMarin absorbent

Purpose. To carry out an economic evaluation of amaranth varieties ‘Kharkivskyi­1’, ‘Helios’ and ‘Sem’ for the application of MaxiMarin absorbent used to compensate for lack of rainfall and uneven moisture in the forest steppe of Ukraine. Methods. During 2021–2023, three varieties of amaranth and MaxiMarin brand absorbent in the form of granules were studied in the field (Uman, 48°46¢N, 30°14¢E) at an application rate of 25 kg/ha. The varieties were evaluated according to the following parameters: weight of leaves, inflorescence and roots, yield of green mass in the flowering and full maturity phases. Amaranth grain yield, protein, fat and starch content were also determined. The methods of analysis of variance and correlation were used. Results. The absorbent applied had a significant effect on the productivity indicators, which were characterized by a significant difference between varieties. In particular, the average increase in the mass of leaves per plant for the studied varieties of amaranth was 12.2%, the mass of inflorescence – 8.9%, or 3.6 g/plant. The variety ‘Kharkivskyi­1’ responded best to the introduction of an absorbent that improved growth conditions, the weight of its inflorescence increased by 12.6%, or 5.3g/plant. The strengthening of growth processes was made possible by the improved deve­lopment of the root system and an increase in its mass, depending on the variety, of 12.3–24.6% (2.1–3.0 g/plant). At the same time, total plant weight increased by an average of 12.4% (11.2–13.3% in different varieties). Green mass yield increased by 13.6–16.5% (4.75–5.75 t/ha) due to the use of absorbent and was in the range of 33.0–40.0 t/ha. The highest values were characterized by the variety ‘Sem’ – 34.3 t/ha in the control and 40.0 t/ha in the experiments with added absorbent. Its application also caused an increase in the yield of different varieties of amaranth by 0.30–0.38 t/ha or 16.0–18.3% (the most productive was the variety ‘Sem’ – 2.08 and 2.46 t/ha, depending on the variant of the experiment) and a significant decrease in the concentration of protein (by 0.1–10.0%), fats (by 7.4–19.5%) and starch (by 3.2–8.2%). Conclusions. Absorbents are an effective tool for levelling moisture imbalances and ensuring maximum realization of the productive potential of amaranth, but improving the water regime has a negative effect on the accumulation of protein, fats and starch.