الفهرس 
REVIEW OF LITERATURESOnly 14 pages are availabe for public view
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Abstract
SUMMARY AND CONCLUSION
Pots and field experiments were conducted to evaluate the possibility of using potassium foliar application with different sources (potassium sulfate and potassium silicate) at different concentrations to mitigate drought stress on wheat (Triticum aestivum).
The pot experiment was conducted to find out the appropriate concentrations of either sources to evaluate their ability in mitigating drought stress under greenhouse conditions. After seed germination, irrigation was carried out up to 100% of the readily available water (RAW) based on the daily weighting of the experimental pots. The water stress treatments started by irrigation when the water content in the growth medium of wheat reached 80, 60 and 40% of the RAW. Three foliar sprays of potassium sulfate and potassium silicate at concentrations of 0, 0.5, 1.0 and 2.0% as K2O were applied. This was repeated three times during growth season at 21, 42 and 63 days of sowing.
The field experiment included similar irrigation and foliar potassium treatments as in the pot experiment. At the end of the pots and field experiments or after 152 and 148 days from sowing, respectively, wheat plants were harvested, and the weight of wheat grain yield, water use efficiency and the total amount of water use were determined and recorded for each treatment.
With regard to the effects of potassium foliar applications on some growth parameters of wheat, significant increases were found for shoot dry weight. But, a slight increase in shoot length was obtained due to foliar spay of the two potassium sources at different K2O concentrations and under 40% than 60 or 80% RAW. However, this was clearer under greenhouse conditions than under field condition, and with potassium silicate than sulfate.
Concerning the effects of potassium foliar applications on the nutrient contents of wheat shoots, obtained data declared significant increases in both nitrogen and potassium content, but not with phosphorus content either under greenhouse or field conditions.
Regarding to the effects of potassium foliar applications on wheat grain yield and water use efficiency, the results indicated significant increases in both under greenhouse and field conditions. However, these increases were more pronounced with potassium silicate than sulfate and at 2%, 1% under greenhouse and field conditions, respectively. This was revealed to the texture of the growth media.
Hence, the obtained data suggest the use of potassium silicate instate of potassium sulfate especially under field conditions as drought mitigator for wheat and to improve grain yield beside decreasing the amount used of water for irrigation as potassium has an actively role in opening and closing of stomata so under limited moisture conditions.