The Impact of Four Nitrogen Levels on Grain-Filling, Agronomic, and Physiological Traits of Different Maize Varieties

Abstract

This study evaluated the impact of four nitrogen levels on grain filling, agronomic, and physiological traits of different maize (Zea mays L.) varieties. The study adopted a split-plot randomized complete block design with two treatments (factors). The first treatment was nitrogen levels with four levels (0, 46, 138, and 184 kg N ha-1 ) applied as main plots. The second treatment was maize variety, with three distinct maize varieties (Hybrid-BISI18, Composite-Sukumaraga, and Local-Tambin) assigned as sub-plots. Results highlighted significant effects of both treatments on grain filling, agronomic, and physiological traits of maize plants. Specifically, the type of maize variety significantly affected 100-grain weight, cob weight, cob circumference, cob length, weight of grains per cob, number of grains per row, grain yield per 16- plants per plot, plant heights at all weeks of observation, and stem diameter at the 4th and 6th weeks after planting. Nitrogen application significantly influenced cob circumference, plant height at the 8th week, stem diameter at the 6th week after planting, and photosynthesis rate at silking (R1) stage. Additionally, the interaction between maize variety and nitrogen significantly influenced plant heights at the 6th week after planting, cob circumference, photosynthesis rate at silking (R1) stage, and number of leaves at the silking (R1) growth stage. In contrast, the 100-grain weight, cob weight, cob length, rows per cob, weight of grains per cob, grains per row, grain yield per 16-plant plot, plant height at weeks 3 and 4, and stem diameter at week 4 were not affected by nitrogen level or interaction. Furthermore, the number of leaves at the V6 stage of growth and stem diameter at week 8 were not affected by the treatments, either separately or in combination. The study concludes that both maize variety and nitrogen application significantly influence various agronomic and physiological traits, with their interaction further affecting specific growth parameters, highlighting the importance of tailored agronomic practices for enhancing grain-filling potential, and eventually optimizing maize yield