The formation of maize grain yield depending on sowing dates in the Northern Steppe of Ukraine

Topicality. The productivity potential of maize determines the prospects of this crop in the grain balance of Ukraine. In the context of the crisis caused by the war and global climate change, which has a significant effect on crop production in the Steppe zone, the productivity of grain crops, including maize, is becoming increasingly unstable over the years, leading to a decline in the gross harvest of the crop. Given the changing weather conditions, in particular climate warming, substantiation, development and implementation of agrotechnical practices to mitigate the negative effects of drought, heat and soil moisture deficit is relevant. In the complex of zonal agrotechnical practices, the sowing dates of crops play an important role. Seed germination, timely emergence of seedlings, and optimal plant density depend on the sowing date. Early sowing in insufficiently warmed soil prolongs the sowing – germination period, or late sowing in excessively dry soil results in sparseness of seedlings and low grain productivity. Therefore, there is a requirement to create the most favourable conditions for the growth of maize plants, considering the biological characteristics and environmental requirements of hybrids, soil, climate and weather conditions. Purpose. Identification of the peculiarities of growth and development of maize plants and formation of maize grain yield depending on the sowing date of biotypes belonging to different maturity groups in the Northern Steppe of Ukraine. Materials and Methods. New maize hybrids of different ripeness groups DN Pulsatsiia, DN Atlant, DN Drah, DN Nazar were sown on the experimental plot of the Laboratory of Agricultural Resources of Maize and Sorghum at the SE Institute of Grain Crops of NAAS in three dates. The following research methods were used: laboratory and field methods for determining plant height, number of leaves per plant, individual plant productivity, grain moisture content; statistical method for performing correlation, analysis of variance and statistical evaluation of research results. Results. It was found that the highest grain yields were formed by the early ripening hybrid DN Pulsatsiia (10.27 t/ha), the mid-early hybrid DN Atlant (10.96 t/ha), the mid-ripening hybrid DN Drah (11.61 t/ha) and the mid-late hybrid DN Nazar (11.49 t/ha) at the early sowing date. Conclusions. In the growing season of 2021–2023, the highest grain yield was formed by maize hybrids of all maturity groups at early sowing date. Sowing corn both at the optimal and late time resulted in a decrease in grain yield in corn hybrids by an average of 4.5 and 13.1%, respectively, compared to the early time. Based on the experimental data, it was found that new maize hybrids DN Pulsatsiia, DN Atlant, DN Drah, DN Nazar form the highest grain yield in the Northern Steppe of Ukraine when they are sown on 14–25 April. Key words: maize, hybrid, sowing date, yield attributes, individual productivity of plants, grain yield