الفهرس 
ACKNOWLEDGMENT
The experimental factorsOnly 14 pages are availabe for public view
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Abstract
Effect of Different Sowing Dates and Irrigation Regimes on Growth, Yield and Consumptive Use for Some Wheat Varieties under Sohage Governorate Conditions.
Field experiments were conducted at Shandaweel Agricultural Research Station, during the three winter successive seasons 2012/2013, 2013/2014 and 2014/2015 to find out the effect of two different sowing dates 20th November and 5th December and irrigation regimes intervals 21, 28 and 35 days on growth, yield and consumptive use of three wheat varieties Shandaweel-1, Giza-168 and Sides-12 under Sohage governorate conditions. The experiment was laid out in a split – split plot design with three replications.
The experiment was laid out in a split – split plot design with three replications. The plot area was 42.0 m2 (6 x 7 m). The main plots were devoted to sowing dates of S1 = first sowing date (20th November) S2 = second sowing date (5th December); the sub plots were assigned to the irrigation regime as intervals of I1= 21 days, I2= 28 days, and I3= 35 days, and the sub_ sub plots were assigned to three wheat cultivars including V1 = Shandaweel 1, V2 = Giza 168 and V3 = Sides 12. Results revealed that sowing dates, irrigation regimes intervals and wheat cultivars were resulted in significant differences in most studied traits through the three seasons.
The obtained results could be summarized as follows:-
1- Water relations for wheat.
1. 1. Irrigation water applied.
The average of irrigation water applied for wheat crop through the three seasons 2012/13, 2013/14 and 2014/15 for irrigation treatments 21, 28 and 35 days intervals were 4364, 3730 and 3008 m3 /fed, respectively these for the first sowing date 20th November, where in the second sowing date 5th December were 4425, 3587 and 3089 m3/fed, in the same respective.
1. 2. Actual evapotranspiration (ETa) for wheat.
The mean average of ETa for the first sowing date 20th November were 1908, 1857 and 1778m3/fed and it were 1855, 1879 and 1777 m3/fed for the second sowing date 5th December through the three growth seasons 2012/13, 2013/14 and 2014/15, respectively.
The mean average of ETa was affected by the irrigation intervals, where the irrigation treatment 21days interval recorded the highest rate of ETa 2194, 2104 and 2030 m3/fed through the three growth seasons 2012/13, 201314 and 2014/15, respectively, these for increased in the irrigation applied number and the increased in the available soil moisture after each irrigation .
Wheat cultivar Giza 168 produced the highest value for the estimated ETa, where wheat cultivar sides12 was the lowest in ETa.
Actual evapotranspiration rate was low in the begging of the season during the early stage they increased to reach their maximum values in third stage mid-season due to the maximum temperature and plant canopy, and then tended to decline again until the crop maturity due to crop canopy changes.
1. 3. water use efficiency ( WUE).
The second sowing date 5th December recorded the highest values of WUE 1.255, 1.323 and 1.409 kg of wheat grain/m3 through the three growth seasons 2012/13, 2013/14 and 2014/15, respectively.
The irrigation at 21 days interval produced the highest value of WUE 1.251 kg of wheat grain/m3 during the first season 201/13, while the irrigation treatment 35 days interval recorded the highest values of WUE 1.382 and 1.380 kg of wheat grain/m3 through the second and third seasons 2013/14 and 2014/15, respectively.
Wheat cultivar Shandaweel 1 recorded the highest rates for WUE 1.145, 1.340 and 1.332 kg of wheat grain/m3, through the three seasons.
1.4. Reference evapotranspiration (ET0) & Crop evapotranspiration (ETc).
Penman equation recorded the highest ET0 l values through the three seasons.
The maximum monthly values of ET0 calculated using Penman Monteith, Modified Penman, Doornbos and Pruitt, Jensen and Haise, evaporation Pan, Blaney- Criddle and Turc equations for Wheat crop were found in April in the three studied seasons this due to the increased in the air temperature during this month. ETc results take the same direction of ETc through the three seasons but, the maximum monthly calculated values of ETc for wheat crop were in mid season stage in March.
1. 5. Crop coefficient (Kc).
Evaporation Pan recorded the highest value of Kc, while modified penman equation recorded the lowest value of Kc, through the three growth seasons, at the beginning of the growing season the values of Kc were low, because plant vegetation growth has not established yet and so the loss of moisture is mostly by evaporation from soil surface. As the plant growth stages developed, a gradual increase is observed in crop coefficient. The crop coefficient reached their peaks in the third growth stage. After reaching the peak of vegetation development, the rate of crop coefficient pronouncedly decrease during the late season.