عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In order to evaluate the effect of different nitrogen application methods on yield and yield components of winter wheat, a field experiment with split plot arrangement in completely randomized blocks design with four replicates was conducted in 2006. Basal dressing in three levels (1- with no basal dressing, 2- strip and 3- distributing nitrogen fertilizer) as main plot and top dressing in six levels (1- distributing on tillering, 2- two distributing on tillering and before spike appearance, 3- foliar application of fertilizer along with herbicide on tillering and before spike appearance, 4- foliar application of fertilizer on tillering and before spike appearance, 5- two applications: one distributing on tillering and one foliar application before spike appearance and finally, 6- three foliar application of fertilizer on tillering, before spike appearance and milking period) as subplot were carried out. The amount of fertilizer in strip, and all compartmented applications were two thirds of distributing fertilizer method. The highest biomass was recorded in distributing fertilizer (19090 kg ha-1) which was greater 14 and 28 percent in comparison with strip application and no basal dressing, respectively. The highest number of grain per spike belonged to band application of basal nitrogen fertilizer, that was significantly higher than two other treatments. Distributing fertilizer produced the highest grain yield (8525 kg ha-1); however, its differences with strip application was not statistically significant. Top dressing affected grain yield and the greatest yields was observed in one stage distributing, two stage distributing, distributing plus foliar application fertilizing and two stage foliar application fertilizing with herbicide. Grain production in these treatments was statistically greater than two and three stage foliar application of nitrogen fertilizer. The grain protein percent for no basal dressing was significantly lower than broadcasting nitrogen application. The grain protein percent for one stage distributing of top dressing nitrogen fertilizer was significantly higher that other treatments. Based on this research findings, with combined and split application strategies can achieve high yield while saving in nitrogen fertilizer usage.
Keywords: Wheat, Yield, Yield component, Nitrogen fertilizer application methods