A field experiment was conducted at Sakha Agricultural Research Station farm, Kafr El-Sheikh Governorate, Egypt during 2008/2009 winter season, to assess response of some wheat (Triticum aestivum L.) varieties to the nitrogen fertilization levels by determining the dry plant weight, daily increase, N% in the dry matter, nitrogen uptake during the growing periods and nitrogen uptake during the physiological stages. Split plot design with four replicates was used, the main plots were assigned by four wheat varieties of Gimiza 9, Sakha 61, Sakha 93 and Giza 168. The subplots were assigned by four nitrogen levels of 0, 30, 60 and 90 kg N fed.1 (ha = 2.4 fed.). Eight plant samples were collected during the growth periods to determine the previous traits.
The obtained results can be summarized as follow:
Gimiza 9 and Giza 168 had the higher dry plant weight of 6.64 and 6.95 (g/plant) compared to Sakha 61 and Sakha 93 of 5.97 and 5.98 (g/plant).
Dry plant weight was increased with increasing nitrogen levels.
The highest daily increase of Gimiza 9 was (138 mg/day) at 97-111 days period, Sakha 61 was (97 mg/day) at 69-83 days period, Sakha 93 was (102 mg/day) at 83-97 days period and Giza 168 was (140 mg/day) at 61-69 days periods.
Nitrogen % was higher in the first growth period and decreased with time and was increased with increasing the nitrogen levels.
Giza 168 had the highest nitrogen uptake (145.27 mg N/plant) there was no significant difference between Gimiza 9, Sakha 61 and Sakha 93.
Nitrogen uptake was increased from 71.16 to 129.04, 158.18 and 173.3 (mg N/plant) with increasing the nitrogen levels from 0 to 30, 60 and 90 kg N fed.-1 respectively.
Gimiza 9 absorbed 23.57% of total nitrogen uptake at tillering, 46.12% at head development stage and 30.32% at flowering stage.
Sakha 61 absorbed 26.06%, 49.19% and 24.76% from total nitrogen uptake at tillering, head development and flowering stages, respectively.
Sakha 93 absorbed 23.55%, 42.22% and 34.23% from total nitrogen uptake at tillering, head development and flowering stages, respectively.
Giza 168 absorbed 22.54%, 46.34% and 31.12% from total nitrogen uptake at tillering, head development and flowering stages, respectively.