This study is conducted to investigate the effect of irrigation intervals in combination with soil application and / or foliar spray of potassium fertilizer and soaking in some vitamins (ascorbic acid and pyridoxine) on wheat yield, certain nutrients and amino acid contents in grains, as well as field water use efficiency. The main aim of the study is to save of the irrigation water without reduction of wheat yield with facility of practical application. The grain yield and its components were significantly affected by the main treatments i. e. irrigation frequencies, vitamins and potassium fertilizer. The irrigation every 21-day interval gave higher values of grain yield and all studied characters as compared with the other irrigation frequencies (28-day and 35-day intervals) in two seasons. The soaking in pyridoxine gave higher values of grain yield and all other characters as compared with control and ascorbic acid in both seasons. The superior grain yield of wheat per Feddan which resulted from treatment with potassium as foliar spray during growing seasons was applied.The interaction effects between irrigation frequencies, every 21-day and soaking in pyridoxine vitamin gave higher values of grain yield of wheat and all other characters only except harvest index as compared with the other treatments in both seasons. The highest values of grain yield of wheat and all other characters were obtained when irrigation every 21-day and application of all potassium as foliar spray in both seasons.The highest values of the grain yield and its components were obtained when irrigation was applied every 21-day, with soaking in pyridoxine vitamin and application of potassium fertilizer as foliar spray in both seasons. However, the lowest values of the grain yield and its components were recorded by applied irrigating the plants every 35-day, soaking in water and without potassium fertilizer in 2005/2006 and 2006/2007 seasons.

This study followed the effect of salicylic acid on growth criteria, photosynthetic pigments, photosynthesis, respiration, proline and the activities of some antioxidant enzymes of stressed Scenedesmus obliquus cultured for 7 days.The growth criteria (cell number and dry weight) and total pigments of nonstressed and stressed Scenedesmus obliquus cultures were significantly increased, when the algal cultures were subjected to 200 mM NaCl and treated with 100and 200 ppm of salicylic acid. Also, Photosynthesis (oxygen evolution), respiration (dark oxygen uptake), proline, amino acids and catalase enzyme of non-salinized and salinized Scenedesmus obliquus cultured were significantly increased, when the algal cultures were subjected to 200 mM NaCl and treated with 100and 200 ppm of salicylic acid. However, both respiration (oxygen uptake) , lipid peroxidation as termed (malondialdhyde) and peroxidase were significantly decreased, when the algal cultures were subjected to 200 mM NaCl and treated with 400 ppm of salicylic. These values were compared with that of the control cultures.

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