Rice production under salinity stress is a critical challenge facing many countries, particularly those in arid and semi-arid regions. This challenge could be handled by applying novel approaches to overcome yield limiting factors and improve resource use efficiency. The usage of nanoparticles (NPs) could be a beneficial approach to managing the growing problem of soil salinity. The aim of our study was to investigate the advantageous effects of soaking and foliar application of silicon (Si) and selenium (Se), (NPs-Si at 12.5 mg L−1 and NPs-Se at 6.25 mg L−1) on root characteristics, moropho-physiological traits, and yields of two rice varieties (i.e., Giza 177 as a salt sensitive and Giza 178 as a salt tolerant) grown in saline soil compared to untreated plants (control treatment). Results showed that soaking NPs-Se resulted in the highest value of root thickness for Giza 178 (0.90 mm, 0.95 mm) and root volume (153.30 cm3, 154.30 cm3), while Giza 177 recorded 0.83 mm, 0.81 mm for root thickness and 143.30 cm3, 141.30 cm3 for root volume in the 2018 and 2019 seasons, respectively. Soaking NPs-Se, NPs-Si and foliar application of NPs-Se at BT resulted in the highest relative water content and dry matter, while foliar application of NPs-Si at BT gave the highest leaf area index of rice plants compared to the other treatments. Giza 178 (i.e., salt tolerant variety) significantly surpassed Giza 177 (i.e., salt sensitive variety) in the main yield components such as panicle number and filled grains/ panicle, while Giza 177 significantly exceeded Giza 178 in the panicle weight, 1000-grain weight, and unfilled grains number/ panicle. Soaking NPs-Se and foliar application of NPs-Si at BT resulted in the highest grain yield of 5.41 and 5.34 t ha−1 during 2018 and 5.00 and 4.91 t ha−1 during 2019, respectively. The salt sensitive variety (Giza 177) had the highest Na+ leaf content and Na+/K+ ratio as well as the lowest K+ leaf content during both seasons. Applying nano nutrients such as NPs-Si and NPs-Se improved the yield components of the salt sensitive variety (Giza 177) by enhancing its ion selectivity. Both NPs-Si and NPs-Se had almost the same mode of action to mitigate the harmful salinity and enhance plant growth, and subsequently improved the grain yield. In summary, the application of NPs-Si and NPs-Se is recommended as a result of their positive influence on rice growth and yield as well as minimizing the negative effects of salt stress.

For optimizing rice grain yield under saline conditions; the current trail has been performed during 2009 and 2010 seasons at El-Sirw Agriculture Research Station, Damietta province, Egypt. The main objective of this attempt is to find out the response of six different rice varieties namely, Sakha101, Sakha102, Sakha104, Giza177, Giza 178 and Egyptian hybrid one (Sk2034H) to various phosphorous rates i.e. 0, 30, 60 and 90 kg P2O5 ha -1 under newly reclaimed saline soil. The experiments were performed in a split plot design with four replications where, rice varieties were arranged in the main plots and phosphorous rates were occupied the sub plots. The salinity levels of the experimental site were 8.0 and 7.50 dSm-1in 2009 and 2010 seasons, respectively with clay soil texture. Growth parameters, nitrogen and phosphorous leaf contents at heading as well as grain yield and yield attributing characteristics were measured at harvest.The obtained results could be summarized as following, the tested rice varieties were significantly differed in their salt tolerance and in their response to phosphorous rates under saline conditions. Giza 178 and SK2034H hybrid one were the most salt tolerant varieties.Phosphorous application significantly improved rice growth parameters (dry matter, LAI and chlorophyll content). Nitrogen and phosphorous leaf content were significantly increased by increasing phosphorous rates up to 90 kg P2O5 ha -1 . Phosphorous application was found to be effective in enhancing rice grain yield and all yield attributing characteristics. Grain yield respond to P application up to 90 kg P2O5 ha -1 , while most of yield component up to 60 kg P2O5 ha -1 Interestingly, the high yielding rice varieties in the terms of Giza 178 and Sk2034H significantly responded to application of phosphorous up to 90 kg P2O5 ha -1 . In addition, the rest rice varieties were significantly responded to phosphorous application up to 60 kg P2O5 ha -1 .So, in case of newly reclaimed saline soil conditions, it could be recommended to grow Giza 178 and Egyptian hybrid one rice varieties under the same conditions with adding 90 kg P2O5 ha -1 .

Two filed experiments were conducted during 2015 and 2016 seasons at the Research Farm of El-Sirw Agricultural Research Station, Damietta Governorate, Egypt. The experiments were performed to study the response of Giza179 rice cultivar to eight nitrogen sources Viz; ammonium sulfate (AS), ammonium nitrate (AN), urea (U), Di-ammonium phosphate (DAP), mono ammonium phosphate(MAP), calcium ammonium nitrate (CAN), and calcium nitrate (CN) and potassium nitrate (KN) under saline sodic soil conditions. The experimental soil was clay with salinity level 7.5 and 7.3 dSm-1 and sodicity (ESP) level 41and 40% dSm-1 in 2015 and 2016 seasons, respectively. The experiment was performed in randomized complete block design and repeated four times. The main obtained results could be summarized as follows; The nitrogen source had significant differences on nutrients leaf contents (NPK), rice growth (leaf area index, dry mater production and chlorophyll content), yield attributes and grain yield in both seasons. Ammonium sulphate showed good and better regarding nitrogen leaf content, while, CAN and KN recorded the highest values of K leaf content. However, DAP and MAP recorded the highest values of P leaf content in both seasons. Ammonium sulphate recorded the highest values of studied growth traits while, the sources contain nitrate (AN, CAN, CN and KN) had the lowest values. The DAP and MAP were comparable regarding their favorable effect on rice growth occupying the second position after ammonium sulphate. The ammonium sulphate had high yield component giving high grain yield followed by DAP and then MAP. Generally, urea or ammonium nitrate as well as any sources contains nitrate is not efficient to apply it for rice under the same saline sodic soil conditions.

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