Optimization of the nitrogen fertilizer management of wheat in Gorgan: Rate and time of nitrogen application

Nitrogen (N) is one of the most important nutritious element limiting yield crop. In order to study the effects of rate and time of nitrogen application management on leaf area index at anthesis, biological yield, harvest index, and grain yield in wheat (Triticum aestivum L.), a factorial experiment based on a randomized complete blocks design with four replications was done on the research field of Gorgan University of Agricultural Sciences and Natural Resources during growing seasons 2011-2012 and 2012-2013. Experimental treatments in first year included four net nitrogen fertilizer rates of 0, 100, 175 and 250 kg N ha-1 and 0, 60, 120, 180 kg N ha-1 in second year; which were split in four stages of planting, tillering, stem elongation and booting. The result showed that rate and time of nitrogen application management had significant effect on leaf area index at an thesis, biological yield, and grain yield of wheat. In this study, the maximum yield was 5529.9 kg ha-1 that achieved at 78 kg net N ha-1. Thus, 78 kg net N ha-1 (170 kg ha-1 of urea fertilizer) should be used in splitting manner for gaining the optimum yield of wheat so that 12.5% in planting stage, 37.5 % in tillering stage, 37.5 % in stem elongation stage and 12.5 % in booting stage should be applied and it seems better to apply nitrogen fertilizer earlier in stem elongation stage.