Two field experiments were conducted in two successive seasons of
2015/2016 and 2016/2017 at the Research Farm Al-Kawthar, Faculty of Agriculture,
Sohag University, to determine the effect of two planting dates (15 November
and10 December) and three nitrogen fertilizer levels (50, 75 and 100 kg
N/fed.) on yield and its components of four bread wheat genotypes (Sids 12, Giza
168, NGB 6404 and NGB 10893). A randomized complete block design (RCBD)
in split- split plot with four replications was used. Data indicated that the planting
dates were significantly effects on all studied traits except spike length and straw
yield in both seasons, as well as nitrogen fertilizer levels and genotypes had significantly
effect on the all studied traits; plant height (cm), spike length (cm),
1000-grain weight (g), grain yield (ard./fed.), biological yield (ton/fed.), straw
yield (ton/fed.) and harvest index(%) in the both seasons. Increasing N up to 100
kg/fed increased yield and its attributes of wheat in both growing seasons except
plant height (cm), spike length (cm) and harvest index (%). Sids 12 and NGB
10893 genotypes produced the highest values of grain yield compared to other
genotypes in both seasons. Moreover, NGB 10893 accession produced the
maximum values of spike length (cm) and1000-grain weight (g) in both seasons,
while NGB 6404 accession produced the tallest plants. Late planting (10 December)
increased significantly plant height (cm), spike length (cm), 1000-grain
weight, grain yield (ard./fed.), biological and straw yields (ton/fed.).In general
the highest grain yields (21.59 and 21.04 ard./fed.) were obtained by Sids 12
genotype when planted in 10 December and application of 100 kg N/fed., and
NGB 10893 genotype when planted in 10 December and fertilized with 75kg
N/fed. interaction treatments, respectively.