The dissertation presents a theoretical justification and a new solution to the current scientific problem of evaluation and selection of maize hybrids of different ripeness groups for the Western Forest-Steppe zone of Ukraine and development of effective agricultural measures for their cultivation to form consistently high grain yields.
The structure of the dissertation is determined by the logic of the research, the tasks set and consists of an introduction, six chapters, section conclusions, dissertation conclusions, recommendations for agricultural production, a list of sources used and addendum.
The relevance of the topic is highlighted as well as the importance of growing maize in the soil and climatic conditions of the Western Forest-Steppe zone of Ukraine. The scientists working on creation of new competitive hybrids of maize and improvement of technology of cultivation of this crop are pointed out. The connection of work with the corresponding thematic programs, plans, tasks of the Institute of Agriculture of the Carpathian region of NAAS is reflected.
Research goals, main tasks, methods for their implementation are formed and the scientific novelty of the results obtained is reflected. The personal contribution of the applicant, publications and implementation of the best options in the farms of the region on the topic of the dissertation work are determined.
The phylogenetic, morphological and biological features of the culture are given. The increase in the grain yield of this crop, depending on the use of varietal resources and technology elements, is substantiated.
The soil-climatic conditions of the Western Forest-Steppe are analyzed, in particular, the features of the weather conditions of the years of research, the hydrothermal coefficient (HTC) is determined, and the physicochemical and agrochemical characteristics of the soil of the research plots are given. The scheme of studies, techniques and methods are described.
In section 3 «Growth and development of corn plants depending on weather factors» it is determined that the air temperature of the sowing-germination period (first – third decade of May) for 2019–2021 exceeded the long-term average by 0.2–1.2 °C and the amount of precipitation – by 2.3–14.8 mm, which affected the field germination of maize hybrid seeds. During the growing season of maize plants, the sum of active temperatures varied from 2311 oC in 2021 to 2448.5 oC in 2019 with a long-term average of 2372.2 oC. The amount of precipitation was 414.8 mm (2020) – 432.9 mm (2021). Depending on weather conditions and maturity group, the duration of the growing season of hybrids was in the range of 125–127 days. Depending on biological features, hybrids provided different leaf surface area in the phase of flowering – grain formation (36.6–48.2 thousand m2/ha) and net photosynthesis productivity (10.5–14.4 g/m2) per day. The highest percentage of diseases was observed in 2021. Group resistance to the main diseases of maize of early-maturing hybrids was provided by DN Meotyda, of middle-early maturing hybrids – Orzhytsia 237 MV. On gray forestal surface-gleyed soils, on the background of mineral nutrition N120P60K60, the yield of green mass of hybrids of early-maturing group (FAO 100–199) varied from 57.3 to 61.1 t/ha, middle-early (FAO 200–299) – 60.3–64.1 t/ha).
Section 4 «Features of the formation of maize productivity when using microfertilizers» substantiates the effectiveness of the use of microfertilizers in the technology of maize growing. It is established that pre-sowing treatment of seeds with microfertilizers: seed oracle (1.0 l/t), valagro EDTA mix 5 (0.2 kg/t) and brexil Combi (0.5 kg/t) contributes to an increase in field germination by 2.9–3.7 %, weight of 1000 grains – by 28–41 g, provides a significant increase in yield of 0.21–0.43 t/ha.
Section 5 «Productivity of maize hybrids depending on the level of mineral nutrition of plants» presents experimental data on the effect of mineral fertilizers on changes in the structural parameters of plants and corn cobs, and an increase in the growing season of the crop. It was established that by the application rates of fertilizers N120P90K90, the yield of green mass was in the range of 49.7–53,8 t/ha, with higher nitrogen nutrition (N150P90K90) – 57.3–62,7 t/ha.
Section 6 «Economic assessment of agrotechnological methods of growing maize» provides calculations of the economic efficiency of growing maize grain, depending on the ability of the hybrid to respond positively to the soil and climatic conditions of the studied area.
