Formation of maize grain quality indicators under the influence of seeding rates and field productivity zones

Maize grain quality is an important indicator of the effectiveness of agrotechnologies and is shaped by the spatial heterogeneity of soil and climatic conditions and the level of intra-crop competition. The aim of the study was to determine the effect of field productivity zones and variable seeding rates on yield and maize grain quality indicators, in particular test weight, thousand-kernel weight, starch, protein and fat content. Field experiments were conducted during 2023-2025 within three field productivity zones (high, medium and low), identified on the basis of long-term yield maps and spatial analysis. The experiment was established using five seeding rates: 65, 70, 75, 80 and 85 thousand seeds per hectare. The results showed that the productivity zone was the dominant factor in the formation of yield and grain quality indicators, while the seeding rate determined the degree to which the potential was realised within each zone. The highest average yield (11.3 t/ha) was obtained in the high-productivity zone at a seeding rate of 80 thousand seeds per hectare, whereas in the low-productivity zone the maximum values did not exceed 7.7 t/ha. Grain test weight and thousand-kernel weight decreased from high to low productivity zones, indicating a deterioration of grain filling conditions under limited resource availability. Starch content was higher in high-productivity zones (up to an average of 72.5%), while medium and low zones showed an increased concentration of protein and fat, reflecting an adaptive response of the crop to stress conditions and reduced yield. The obtained results confirm the feasibility of applying zonally differentiated seeding rates as a tool for simultaneous optimisation of maize grain yield and quality