Effect of Plant Density and Nitrogen Rates on Morphological Characteristics Grain Maize

Nitrogen and plant density are considered some of the most important factors affecting on grain yield. So the effects of plant density and nitrogen on yield and yield components of maize (Zea mays L.) were evaluated during spring 2005 in Koohdasht region, Lorestan, Iran. The experimental design was designed as Randomized Complete Block arrangement in split plot with three replications. Three nitrogen levels (160, 200 and 250 kg N ha -1 ) applied to main plots and three plant densities (65000, 70000, and 75000 plants ha -1 ) allocated to sub plots. The results showed that, there was significant difference among nitrogen levels regarding ear weight. The lowest ear weight was related to the lowest nitrogen level while the highest ear weight was observed the highest nitrogen level. In contrast there was not significant difference among nitrogen levels on harvest index. Increase of nitrogen levels enhanced final seed yield due to increase of seed number in each ear. Also, plant density had not any significant effect on harvest index. Increase of plant density decreased number of seed in ear and ear weight. Therefore, enhancement of seed yield was due to increase of plant density. This increase compensates yield reduction in each plant. In general, the highest seed yield (14827.3 kg.ha -1 ) was achieved from 240 kg.ha -1 nitrogen and the highest plant density (75000 plants.ha