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.
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.
The present study investigates the effect of zinc oxide nanoparticles (ZnO-NPs) on rice plants growth and their role in management of brown spot disease caused by the causal agent Helmenthosporium oryza. The antifungal activity of ZnO-NPs (20 to 35 nm particle size) was evaluated at different concentrations. Spores germination percentage, colony formation and sporulation of H. oryza were reduced at concentrations 25 and 50 ppm, in vitro. The greenhouse results showed that seed soaking treatment and foliar spray 5 day before inoculation (DBI) of ZnO-NPs leaded to reduce infection percentage of brown spot without significant difference between ZnO-NPs concentrations. Foliar spray ٢ days post-inoculation (DPI) with the lower concentrations 10 and 25 ppm of ZnO-NPs were able to reduce infection percentage of brown spot. Under field conditions, During 2013 and 2014 seasons at El-sirw Agriculture Research Station, Dammietta, Egypt, rice varieties Giza 177, Giza 178 and Giza 179 under ZnO-NPs level (0, 10, 20 and 30 ppm) as foliar spray twice at mid tillering and panicle initiation stages were evaluated. Application of ZnO-NPs at level 20 ppm effectively reduced brown spot disease severity and discolored grains of all tested varieties. The studied rice varieties were varied in their growth, yield attributes, grain yield and brown spot severity whereas Giza 178 and Giza 179 had good performance under ZnO-NPs treatments. Therefore both Giza 178 and Giza 179 had showed significant salt tolerance at 20 ppm of ZnO-NPs. The performance of Giza 177 as a salinity-sensitive variety was improved at 20 ppm ZnO-NPs. The all ZnO-NPs treatment positively improved rice growth, yield attributes, rice grain yield and brown spot severity over control treatment. Finally, ZnO-NPs can be used as future "nanofertilizers".
Salinity is a common abiotic stress that seriously negatively affects rice production in the world. The investigation was carried out at the Experimental Farm of El-Sirw Agricultural Research Station, Damietta governorate, Egypt to investigate the effect of soil salinity levels (6 and 11 dS m -1) on the morphological, leaf chemical constituents and yield traits and phenotypic and genotypic parameters of twelve rice genotypes (
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