NITROGEN FERTILIZER OPTIMUM ECONOMIC RATE FOR BREAD WHEAT YIELD

Abstract

Two field experiments were conducted at Giza Agric. Res. Station, Agric. Res. Cent. during the two seasons of 2009/2010 and 2010/2011. The response degree of four wheat cultivars namely: Giza 168, Sakha 94, Gemmeiza 10 and Sids 12 to different nitrogen fertilizer levels i.e. 0, 25, 50, 75, 100 and 125 kg N/fad was determined in order to estimate the economic optimum N rate. The most variables in the total variability of the grain yield were detected using some multivariate procedures i.e. simple correlation, multiple regression, stepwise regression and path coefficient. The strip-plot design in three replicates was used. Cultivars in the vertical and nitrogen in horizontal. The economic optimum N rate ranged from 54.98 to 87.47 kg N/fad. Grain yield produced by adding economic optimum N rate ranged from 2056.19 to 2669.25 kg/fad and net return ranged from £E 5029.34 to £E 6344.63. Grain yield exhibited highly significant and positive correlation with each of plant height (r = 0.723**), flag leaf area (r = 0.639**), number of spikes/m2 (r = 0.753**), spike length (r = 0.627**), number of spikelets/spike (r = 0.804**), number of kernels/spike (r = 0.785**), weight of kernels/spike (r = 0.689**) and weight of1000 kernels (r = 0.826**). The results of the studied multivariate approaches revealed that weight of 1000 grains and number of spikelets/spike were the important contributing variables in the total variability grain yield of wheat.