الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Two field Experiments were carried out at the Experimental Farm of Etay El-Baroud Agricultural Research Station in Elbehira Governorate, ARC, Egypt through 2008/09 and 2009/10 wheat growing seasons to study the effect of water stress and potassium fertilization levels levels on yield and its components in some wheat cultivars.
A split split-plot design with three replications was used in both seasons of the experimentation. Irrigation treatments were distributed at random within the main plots, whereas the wheat cultivars were distributed randomly in the sub-plot and the three levels of potassium fertilization levels is located randomly in the sub sub-plot.
The experimental treatments were:
Irrigation treatments: three irrigation treatments were conducted
I1: skipping the second irrigation (during vegetative growth period).
I2: skipping the third irrigation (during fruit growth period).
Control treatment: take full irrigation (four irrigations).
Wheat cultivars: three wheat cultivars were used in the experiment:
● V1 = Sids 12
● V2 = Gemiza 9
● V3 = Sakha 94
Potassium fertilization: three potassium fertilization levels were used
● K1 = Zero Kg/fed.
● K2 = 24 Kg/fed.
● K3 = 48 Kg/fed.
Studied Characteristics:
A- Growth characters:
1. Leaf area index (L.A.I).
2. Plant height (P.H) in cm.
3. Days to heading (day).
4. Days to maturity (day).
5. Grain Filling Period (G.F.P) (day).
6. Grain filling rate (G.F.R) (Kg/fed/day).
B-Yield and its components characters:
1. Number of spikes/m2(s/m2).
2. Spike length (cm).
3. Number of grains/spike.
4. 1000-grain weight (1000-GW) (g).
5. Grain yield (ton/fed).
6. Straw yield (ton/fed).
7. Biological yield (ton/fed).
8. Harvest index.
C- Chemical analysis of grains:
1. Chlorophyll content in leaves.
2. Potassium percentage in grains.
3. Protein percentage in grains.
The resulted findings of the present investigation during both seasons of study could be summarized as follows:
irrigation treatments effect:
There was significantly increase in grain yield /fed ,straw yield/fed, biological yield /fed ,number of spikes /m2 number of grains/spike, 1000grain weight and spike length by giving full irrigation, while there was significant decrease in grain yield/fed, number of grains/spike and spike length by holding an irrigation during vegetative growth period. Also, straw yield/fed, biological yield/fed and 1000 grain weight were significantly decreased by holding irrigation during fruit growth period.
There was significant increase in heading date, physiological maturity date, grain filling period and grain filling period and grain filling rate under full irrigation, while there was significant decrease in physiological maturity date, grain filling period and grain filling rate by holding irrigation during fruit growth period.
Leaf area index and plant height were significantly increased by giving full irrigating while they were significantly decreased by holding irrigation during vegetative growth period in the second season and during fruit growth period in the first season.
Protein percentage in grains was significantly increased by holding irrigation during fruit growth period, but it had significantly decreased by giving full irrigation. Irrigation treatments hadn’t significant effect on protein percentage in grains and chlorophyll in leaves.
Wheat cultivars effect :
Gemmiza 9 significantly surpassed sids 12 and Sakha 94 cultivars in some characters i.e. grain yield/fed, straw yield/fed, biological yield/fed, number of grains/spike, heading date and physiological maturity date.
Gemmiza9 cultivar significantly surpassed Sids 12 and Sakha 94 cultivars in leaf area index, heading date and protein percentage in grains. While wheat cultivars hadn’t significant effect on potassium percentage in grains and chlorophyll content in wheat leaves.
Sakha 94 significantly surpassed other cultivars in some characters; Leaf area index and number of spikes/m2.
Sids 12 significantly surpassed other cultivars in 1000 grain weight, while it had a significant decrease in most of studied characters i.e. grain yield/fed, straw yield/fed, heading date, protein percentage in grains.
potassium fertilization levels effect:
Applying treatments of 24 and 48 kg k2o/fed significantly increased grain yield, straw yield, biological yield/fed and 1000grain weight ,while 48kg/fed gave the highest number of grains/spike.
significant effect on heading date protein percentage in grains, and potassium percentage ingrains.
Potassium fertilization levels had no significant different in some characters i.e. physiological growth date, grain filling period and grain filing rate.
The interactions:
- The highest number of spikes/m2 was obtained from the addition of 48 kg K2O/fed with the cultivar Sakha 94 in the first season.
- The highest number of grains/spike was obtained from the interaction:
Sids 12 x the second irrigation treatment in the first season
control irrigation treatment x 48 kg K2O/fed in the first season control irrigation treatment x zero kg K2O/fed in the second season.
zero kg K2O/fed x cultivar Sids 12 cultivar in both seasons.
- The highest 1000 grain weight value was showed by adding 24 kg K2O/fed with the cultivar Sids 12.
- Growing the cultivar Sids 12 under the control irrigation treatment gave the highest spike length in the second season.
- Applying zero kg K2O/fed with the control irrigation treatment gave the highest spike length.
- The highest value of grain yield was obtained from the interactions: