Yield and Nitrogen Use Efficiency of Wheat as Influenced by Different Levels of Nitrogen and Corn, Rapeseed, Sunflower and Wheat Residues

In order to evaluate the effect of different rates of nitrogen (N) and corn, rapeseed, sunflower and wheat residues on plant height, biological and grain yield and N use efficiency of wheat, an experiment was conductedduring 2010-2011 at Agricultural College of Shiraz University. The experimental design was split-split plot based on RCBD with four replications. Treatments were N (45, 90, 135 and 180 kg ha-1) as main factor, type of plant residues (no residues, corn, rapeseed, sunflower and wheat) as sub factor and rates of crop residues (25 and %50) as sub-sub factor. Results indicated that rates of N, types and rates of crop residues had significant effects on plant height, yield components, biological and grain yields, and N use efficiency. The highest yield components, grain yield and N use efficiency were achieved by 180 and 45 kg ha-1 N, respectively. Increasing the rate of residues from 25 to %50, decreased all of traits except plant height and spikes per m2. The highest grain yield was obtained from no residues treatment. Wheat grain yield significantly decreased with residues incorporation and this reduction was lowest with sunflower residues.