Performance and genetic parameters for some wheat genotypes under different nitrogen fertilizer levels in new reclaimed land

. Three experiments were conducted side by side, included three different nitrogen levels (N1=120, N2---180 and N3=240 Kg I ha), one level for each experiment. Fourteen bread wheat genotypes were evaluated and used to estimate coefficient of variability, heritability and expected genetic advance for grain yield, its components and some agronomic characters. The results indicated highly significant differences between the two seasons for number of kernels per spike, 1000-kernel weight and plant height under low nitrogen fertilizer level (NI). On the other hand, seasons mean squares were highly significant for grain yield t/ha, number of kernels per spike, 1000-kernel weight, harvest index and plant height in N2 and N3, respectively. However, all wheat genotypes, at the highest amount of nitrogen level (N3), produced higher grain yield, number of spikes/m2, number of kernels / spike and 1000-kernel weight, compared with NI or N2. Genotype No. 7 gave the highest value of grain yield (3.96 t/ha) under low nitrogen level (Ni), while, genotype No. 14 had the highest mean value of number of spikes/m2 and 1000kernel weight under high nitrogen level (N3). In general, all garin yield components decreased with decreasing nitrogen fertilizer levels. The genotypic coefficients of variability (GCV) values for all studied characters were lower than those of phenotypic coefficient of variability (PCV) under all nitrogen levels. PCV values were quite higher for biological yield (30.49), harvest index (29.96), grain yield (23.14) and number of spikes /m2 (21.43) in Nl selection. GCV values for biological yield, grain yield, harvest index and number of spikes /m2 also, were high under all nitrogen levels, except for number of spikes /m2 in N2. Heritability, in broad sense, ranged from 51 %, for number of spikes /m2' to 98 % for the number of days to maturity and plant height..