Zasukha A. Substantiation of technology elements for the cultivation of corn for grain and production of fuel pellets

The dissertation presents a theoretical generalisation and a practical solution to the scientific problem of the growth, development, and patterns of yield and quality formation in both primary and secondary corn products, as well as the economic and energy efficiency of cultivation technology elements under the conditions of the Right-Bank Forest-Steppe of Ukraine. The relevance of the research topic, its connection with scientific programmes, plans, and priorities is substantiated, and the aim and objectives are outlined. These were achieved by determining the peculiarities of corn productivity formation depending on the application of macro- and microfertilizer and desiccants, as well as assessing the feasibility of producing fuel pellets from corn by-products. The study refined elements of the technology for cultivating corn as both a grain and an energy crop. Further developments were made regarding the specificities of corn plant growth and development, as well as the formation of yield and quality in primary and secondary products under varying applications of macro- and microfertilizer and desiccants. The practical significance of the findings lies in the development of scientific and practical recommendations aimed at increasing corn grain yield and optimising the utilisation of by-products for fuel pellet production. It was established that a linear increase in corn plant height continues until the BBCH 85 growth stage, with the highest plant and ear attachment heights recorded in the variant with the application of mineral fertilisers N90Р70K70 (a.i. per ha) combined with foliar application of the microfertilizer Ikar Bigo Roots (0.5 l/ha), Ikar Fosto (0.5 l/ha), and Ikar Zinto (0.5 l/ha), reaching 225.9 cm and 91.3 cm, respectively. The best parameters for the leaf surface area of corn crops were recorded at the BBCH 65 growth stage with the application of mineral fertilisers N90Р70K70 and foliar spraying of Ikar Bigo Roots (0.5 l/ha) + Ikar Fosto (0.5 l/ha) + Ikar Zinto (0.5 l/ha), reaching 50.3 thousand m²/ha. The use of mineral fertilisers increased the leaf area of corn by 4.3–15.8%, the photosynthetic potential of crops by 4.2–12.6%, and the net photosynthetic productivity by 3.0–14.3%, while microfertilizer contributed increases of 1.3–4.3%, 1.1–3.8%, and 1.1–6.9%, respectively, compared to the control. It was established that the application of mineral fertilisers reduced the dry matter content in corn plants and individual organs. However, microfertilizer had no significant effect on the dry matter content of corn plants or its structural components (stems, leaves, cob wrappers and cores, and grain). The dry matter content ranged from 62.0% to 64.0% in grain, 35.9% to 38.0% in leaves, 32.1% to 35.4% in cob wrappers and cores, and 25.0% to 28.0% in stems. The study confirmed that, within the overall plant structure, the stem accounted for 40.4%, grain for 36.5%, leaves for 14.6%, cob wrappers and stalk for 4.8%, and the panicle for 3.7%. The most favourable conditions for grain formation were observed in the variant with the application of N90Р70K70 before sowing, followed by foliar feeding with Ikar Bigo Roots (0.5 l/ha) + Ikar Fosto (0.5 l/ha) + Ikar Zinto (0.5 l/ha), which resulted in the highest values for cob length (17.7 cm), cob diameter (4.6 cm), number of kernels per cob (489.3), grain weight per cob (141.2 g), weight of 1,000 kernels (287.2 g), total plant weight (512.2 g), cob with grain (169.1 g), stem (231.5 g), leaves (89.5 g), and panicle (22.1 g). The highest grain and by-product yields of corn were obtained in the variant with the application of mineral fertilisers N90Р70K70 in combination with foliar spraying of Ikar Bigo Roots (0.5 l/ha) + Ikar Fosto (0.5 l/ha) + Ikar Zinto (0.5 l/ha), reaching 9.41 t/ha and 13.72 t/ha, respectively. The use of mineral fertilisers increased grain yield by 11.3–18.8% and by-product yield by 15.2–22.1%, while microfertilizer contributed increases of 3.5–6.5% and 5.8–9.8%, respectively, compared to the control variants. No significant differences were found between the various desiccants in terms of moisture content and yield of grain and by-products; however, the timing of desiccation had a more pronounced effect. When desiccants were applied at the first stage (40% grain moisture content), grain and by-product moisture content decreased by 8.9–9.0% and 12.1–12.3%, respectively. At the second stage (30% grain moisture content), reductions of 6.9% and 5.7–5.9% were observed, while at the third stage (20% grain moisture content), the decreases were 3.1–3.3% and 1.7–1.9% compared to the control. The highest corn grain yield (8.69–8.80 t/ha) was recorded at the third stage of desiccant application, while the highest by-product yield (17.41–18.47 t/ha) was obtained at the first stage. Grain yield was primarily influenced by the timing of desiccation (60.5%) and the type of desiccant used (22.4 %).