evaluation of nitrogen fertilizer on yield and yield components of bread and durum wheat genotypes

the present study aimed at investigating the effect of different levels of nitrogen on yield and yield components of bread and durum wheat. to this end the experiment was conducted in 2010-2011 in south west of iran as split plots based on randomized complete block design with three replications. main plot included four levels of nitrogen 60, 120, 180, 240 kg.ha-1 and the sub plot included four wheat genotypes (chamran, s-85-19, dena, and behrang). the results showed that effect of nitrogen fertilizer on biological yield and grain yield was significant at 1% level and on the number of spike per area unit, number of spikelet per spike, number of grain per area unit, 1000-grain weight, and harvest index at 5% probability level was significant. the highest grain yield and biological yield by 554.60 and 1271 g.m-2, belonged to treatment with application of 240 kg.ha-1 nitrogen, respectively. the highest harvest index by 46.71% belonged to the control treatment. finally, the results indicated that among the genotypes, the highest number of grains per spike by 30 grain belonged to dena cultivar and highest grain yield, biological yield, and harvest index by 524.34, 1168.80 g.m-2, and 45.42% belonged to chamran cultivar, respectively