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Abstract This research was conducted in the greenhouse at The City of Scientific Research and Technological Applications in the Borg El-Arab area during the seasons of 2020 and 2021. The goal of this study is to compare the effectiveness of silica, nanosilica, chitosan, and nanochitosan on rootstocks. High productivity from Sour oranges and Volkamer lemons, even when subjected to stressors such salt water treatment. Sour orange (Citrus aurantium, L.) and Volkamer lemon (Citrus volkameriana) rootstocks, each one-year-old, were planted individually in black polyethylene plastic bags containing approximately 2 kg of mixed sandy and clay loam soil. Forty citrus seedlings from two experimental rootstocks, as uniform as possible in size and length, were used. A Split-SplitPlot Design was used to set up the test plants, with four independent sets of plants for each treatment. Therefore, this study employed 80 plants (2 rootstocks × 2 salinity levels x 5 sprayed compounds × 4 repetitions). The chosen seedlings were split into two groups, with each group consisting of 40 plants: 0 (Tap water; control) and 50 mM NaCl. Seedlings were subjected to salinity treatments by receiving 500 mL of water twice weekly for three months. Treatments as a foliar spray: 1. Control. 2. Silicon in normal size (50 ppm). 3. Nano silicon (50 ppm). 4. Chitosan in normal size (50 ppm). 5. Nano chitosan (50 ppm). Leaf area, plant length, stem diameter, growth number, root fresh weight, root dry weight, plant fresh weight, plant dry weight, leaf proline concentration, leaf mineral content (N, P, K, Ca, Mg, Na, Cl), and activity of antioxidant defense enzymes were all assessed over the two growing seasons. The result obtained throughout this study in 2020 and 2021 seasons could be summarized as follows: 1. Morphological performance Our analysis revealed that salinity stress using Irrigation with 50 mM NaCl significantly decreased all morphological parameters including; growth rate, leaf area, stem diameter, growth number, root and plant fresh weight and root and plant dry weight in both seasons. Among all fabricated materials, Nano-Si have remarkable impact for alleviating salinity stress which achieved the highest fresh and dry weight of plant, leaf area and stem diameter (70.00, 46.25, 28.91, 10.75 respectively) in sour orange rootstock in 2020 season whereas, Volkamer lemon 64 rootstock (40.00, 25.00, 17.73, 7.28 respectively) under 50 mM NaCl salinity stress. In addition, NaCl treatment drastically inhibited root growth (Fig. 4). Both the wet and dry root weights dropped dramatically after irrigation with 50 mM NaCl. Whereas, the highest plant length, fresh and dry weight of roots were observed with Nano-Chi (95.38, 27.50, 16.75, respectively) in sour orange rootstock in 2020 season whereas, Volkamer lemon rootstock (94.13, 30.00, 15.00, respectively). However, the sour orange rootstock revealed significant increase in all treatments with NMs. |