effects of plant density and nitrogen rates on yield, nitrate and protein of silage maize

in order to study the effects of plant density and nitrogen rates on yield, nitrate and protein of silage maize (ksc 704) in shahrekord area, an experiment was conducted during 2007 growing season at the agricultural research farm of shahrekord university. the experimental design of the experiment was randomized complete blocks with factorial arrangement with four replications. treatment consisted of four levels of plant density (92600, 104200, 119000 and 138900 plants ha-1) and nitrogen rates (200, 240, 280 and 320 kg ha-1) were conducted. the results showed that increase in plant density led to a significant decrease in single plant yield and protein of grain. but, fresh forage and protein yield were significantly increased with increasing plant density. increase in nitrogen rate resulted in a significant increase in protein of plant shoot and protein yield. stalk no3 was not significantly different among plant density and n treatments. plant density x nitrogen rate interactions were not observed for all traits in this study. the maximum dry matter was obtained with 320 kg n ha-1, but it had no significant difference with 240 and 280 kg n ha-1 levels of n fertilization. the results indicated that, planting of silage maize with at least 138900 plants ha-1 and 240 kg n ha-1 might be appropriate for optimum production under conditions similar to this experiment.