Plant density and nitrogen effects on some traits of maize (Zea mays L.)

Maize (Zea mays L.) is one of the most important food crops. The study of the effects of plant density and soil fertility on some agronomic traits in newly released hybrids is important. The experiment was conducted at the Agriculture Research Station, University of Tehran, Iran. It was a split-split plot design with three replications with corn hybrids as the main plots, plant density as the sub-plots and nitrogen levels as the sub-sub-plots. Grain yield per plant and unit area, biomass, harvest index, ear number, kernels per ear and 1000-kernel weight were measured. The interactions of factors were significant. Maximum grain yield.ha-1 was achieved by the hybrid KSC601 at the density of 8 plants.m-2 with the application of 230 kg N.ha-1. The hybrid KSC601 at the density of 7 plants.m-2 with no N fertilizer application showed the maximum harvest index (70.36%). The highest kernel number per ear was obtained at the density of 6 plants.m-2, and the hybrid KSC601 at the density of 6 plants.m-2 and 230 kg N.ha-1 produced the highest 1000-kernel weight. Increasing N application rate from 0 to 230 kg.ha-1 increased 1000-kernel weight by 12%.