Optimization of nutrient supply and plant density as a factor in improving maize grain quality

Abstract

Purpose. To determine the specific features of the formation of the chemical composition of maize grain in hybrids of different maturity groups under optimized plant density and the combined application of mineral fertilizers and the biological preparation Blue N under the agro-climatic conditions of the Central Forest-Steppe of Ukraine. Methods. The research was conducted during 2024–2026 at the «Lyubaretske» LLC on maize hybrids P9255 and P8436. The area of the accounting plot was 33 m²; the experiment was established with four replications and a sequential multi- tier arrangement of treatments. The experimental design included the application of different rates of mineral fertilizers N60P45K45, N90P60K60, N120P90K90 and N150P120K120 in combination with foliar application of the biological preparation based on the nitrogen-fixing bacterium Methylobacterium symbioticum at the 5–6 leaf stage under different plant densities (60, 70 and 80 thousand plants per hectare). Results. A dependence of starch and crude protein contents in maize grain on the genotypic characteristics of the hybrids, plant density, and fertilization system was established. In hybrid P8436, starch content ranged from 70.90 to 73.30 %, while starch yield ranged from 7.05 to 10.19 t/ha; in hybrid P9255, the corresponding values were 70.15–72.50 % and 7.56–10.18 t/ha, respectively. It was revealed that increasing plant density from 60 to 70 thousand plants/ha contributed to an increase in starch content in most experimental variants, whereas further increasing the density to 80 thousand plants/ha was accompanied by a certain decrease in this parameter. At the same time, the maximum starch yield per unit area – 10.19 t/ha in hybrid P8436 and 10.18 t/ha in hybrid P9255 – was formed at plant densities of 80 and 70 thousand plants/ha, respectively, under the N150P120K120 background combined with the nitrogen fixer. It was established that crude protein content in P8436 grain ranged from 8.35 to 10.05 %, while in P9255 it ranged from 8.65 to 10.35 %, with the highest values (10.05 and 10.35 %, respectively) ensured by combining a plant density of 60 thousand plants/ha with the application of the maximum fertilizer rate and the nitrogen fixer. It was confirmed that increasing the level of mineral nutrition in combination with the nitrogen fixer contributed to the accumulation of crude protein in the grain of both hybrids. Conclusions. It was proven that increasing the level of mineral nutrition in combination with the nitrogen fixer contributed to an increase in crude protein content in the grain of both hybrids. It was determined that the optimization of plant density and the mineral-biological nutrition system ensured the differentiated formation of grain quality parameters depending on the hybrid genotype. It was revealed that P9255 was characterized by a slightly higher crude protein content, whereas P8436 exhibited a higher starch concentration and maximum starch yield.