TWO field experiments were conducted at Ras-Sudr Research …… Station, South Sinai Governorate during two successive seasons, 2011/2012 and 2012/2013, to study the effect of three levels of silicon as KAlSi3O8 incorporated into the soil at (100, 200 and 300 kg/ fed) compared to control (without silicon) on two wheat cultivars Sakha 94 (salt-tolerant) and Gimeza 10,( salt-sensitive). Both cultivars were irrigated from two wells different in salinity levels (4236 and 4748 ppm, moderate level) and (7001 and 7360 ppm high level) in the first and second seasons, respectively.
Obtained results showed that increasing irrigation water salinity from (4236 up to 7001 ppm) in the first season and from (4748 to 7360 ppm) in the second season, decreased the grain yield and its components in Sakha 94 and Gimeza 10. Gimeza 10 was superior to Sakha 94 in all yield criteria in the two growing seasons except protein yield was superior in Sakha 94. The highest level of silicon (300 kg KAlSi3O8 /fed) had the superiority effect in decreasing the soil salinity hazard and consequently increased significantly all yield criteria of the two cultivars.
The effect of second order interaction indicated that incorporated soil by silicon (300 kg/fed) planted with Gimeza 10 which irrigated by (4236 and 4748 ppm) produced the highest grain yield and yield components in both seasons. However, the highest protein yield has resulted in Gimeza 10 treated with silicon (300 kg/fed). Grain yield was significantly improved in Gimeza 10, than Sakha 94, with the application of silicon (300 kg/fed).
Potassium content was significantly increased in grain wheat cultivars due to soil application of silicon under saline soil conditions. Sodium content was higher in grain wheat, cv. Sakha, 94, under saline soil condition; however Si application significantly reduced Na content in grain, while it significantly increased in K: Na ratio. High K and low Na contents in grain wheat cultivars may be one of the possible mechanisms of increasing salinity tolerance by silicon application.
In general, the current research suggested that Si application not only increased the quantity but also enhanced the quality of wheat cultivars grown under salt stress conditions. Therefore, silicon at the rate of 300kg/fed and Gimeza 10, which irrigated with a moderate level of salinity (4236 ppm) encourage the farmers to use of silicon to give promising grain yield.