Journal of Crop Production and Processing

This study was conducted to evaluate the effects of nitrogen fertilizer and plant density on the capacity of photosynthesis (leaf area index, the number of leaves and the chlorophyll contents), yield components and yield of maize. The experiment laid out as split plot based on a randomized complete block design with three replications in 2011 summer planting at research station of Kurdistan University. Nitrogen fertilizer on three levels (115, 184 and 253 kg ha^-1) assigned to main plots and plant density on four levels (8, 10, 12 and 14 plants m^-2) to subplots. Results showed that Increasing the nitrogen fertilizer and plant density did not affect the number of leaves, but increased leaf area and the content of the chlorophyll. Thus, Biological yield, yield components and seed yield was consequently increased. The highest grain yield (6927 kg ha^-1) was obtained from 184 kg ha^-1 nitrogen and 12 plants m^-2. Increasing the nitrogen and plant density more than mentioned amounts did not increase the seed yield significantly. therefore, more nitrogen and plant density in trail location and other locations with similar conditions is not recommended in order to save production costs and avoid environmental pollutions.