Row spacing, population density and nitrogen fertilization in maize

The alteration of spatial distribution of plants is an option to increase the grain yield. For high-yielding materials more information about the influence of nitrogen fertilization is needed. Thus, the influence of row spacing, population densities and nitrogen rates on the leaf nitrogen concentration, estimated concentration of chlorophyll, number of grains per ear, mass of thousand grains, grain yield, and protein content were evaluated. This study was carried out in the 2000 /2001 growth season; the treatments were two row spacings (0.60 and 0.80 m); three population densities (40,000, 60,000 and 80, 000 plants ha(-1)) and four nitrogen rates (0, 50, 100, and 150 kg ha(-1) N). Increased nitrogen rates in top dressing led to a increase in the leaf nitrogen and estimated chlorophyll concentration, number of grains per ear, mass of thousand grains, grain yield and protein content of grains. Higher grain yield was achieved with increasing top dressed N rates in combination with a 0.80 m row spacing and a plant density of 80.000 plants ha(-1).