Quantitative assessment of vegetative and rhizhospheric responses of maize cultivar “Swabi White” under varying plant densities and nitrogen regimes

Abstract

Optimizing agronomic practices such as nitrogen (N) management and planting density is crucial for enhancing maize (Zea mays L.) productivity, particularly in regions with distinct environmental constraints. A field study was conducted to evaluate the vegetative and rhizhospheric responses of the open-pollinated maize variety 'Swabi White' to different plant densities and nitrogen application rates in Swabi, Pakistan. The experiment used a split-plot design with three replications. The main plots consisted of three plant densities (P1: 100,000; P2: 66,666; and P3: 50,000 plants ha⁻¹), and the sub-plots included three nitrogen rates (N1: 100; N2: 150; and N3: 200 kg N ha⁻¹). Results indicated that increasing nitrogen application significantly enhanced stem diameter, leaf number, leaf area, root length, and biological yield, with the 200 kg N ha⁻¹ rate yielding the most vigorous growth. Conversely, individual plant morphology was negatively affected by higher plant densities; lower densities resulted in taller plants with thicker stems and larger leaves. However, total biological yield per unit area was optimized at an intermediate density. A significant interaction between nitrogen and plant density was observed for biological yield, with the highest yield (8,875.6 kg ha⁻¹) achieved at a density of 66,666 plants ha⁻¹ combined with 200 kg N ha⁻¹. These findings suggest that a balanced approach, integrating moderate plant densities with optimal nitrogen inputs, is a viable strategy for maximizing maize yield and resource-use efficiency in similar agroecological zones. Keywords: Zea mays L., Plant Population, Nitrogen Fertilization, Sustainable Agriculture, Yield Optimization.