effect of seeding and nitrogen rates on yield and yield components of wheat grown in rapeseed residues

in order to evaluate the effect of nitrogen (n) and seeding rate and presence of rapeseed residues on yield and yield components of wheat, a field experiment was conducted in cropping year 2011- 12 at college of agriculture, shiraz university (badjgah), shiraz, iran as split-split plot arranged in randomized complete blocks design with three replications. treatment included presence and absence of rapeseed residues as main plot, four n rates (82, 96, 110 and124 kg ha-1) as sub plots and three seeding rates (220, 245 and270 kg ha-1) as sub subplots. results showed that seed yield of no crop residues plots were significantly higher than when residue was present. rapeseed residues, significantly decreased seed yield by 23.12% compared with no residues. seed yield significantly increased 24.78% with increased n from 82 to 124 kg ha-1. the highest seed yield was obtained with 124 kg n ha-1, 270 kg seeding rates with no significant difference with 110 kg n ha-1. with increasing per unit of nitrogen and seed per hectare, seed yield increased 28 and 19.98 respectively. therefore nitrogen application and plant density, as two agronomic practices, play an important role in increasing wheat yield. the highest wheat grain yield was obtained with 270 kg ha-1 of seed and 124 kg n ha-1 when it is grown in rapeseed residues.