## 2 Materials and Methods  
### Plant Materials  
The field experiment was conducted in a randomized complete block design with three replications. To generate a wide range of genetic variability in salt tolerance, the experiment included 56 recombinant inbred lines (RILs) of spring wheat, which were developed from the following genetic crosses: between the salt-tolerant genotype Sakha 93 and moderately salt-tolerant genotype Sids 1 (28 RILs), between Sakha 93 and the salt-sensitive genotype Sakha 61 (28 RILs), in addition to five commercial cultivars (Kharchia 65, Misr-1, Shandawel-1, Gemiza-9, and Kawz). These commercial cultivars demonstrated differences in their salt tolerance based on their previous evaluations for salinity tolerance at different growth stages using various agronomic and physiological traits [57; 58; 59]. All plant material was evaluated under high-salinity levels (150 mM NaCl) during two growing seasons, from 2019 to 2020 and from 2020 to 2021, at the Dierab Research Station of King Saud University in the middle of Saudi Arabia (24\({}^{\circ}\)25\({}^{\prime}\) N, 46\({}^{\circ}\)34\({}^{\prime}\) E; elevation, 400 m) (Figure 1). At the research station and during the wheat growing season, which is about 150 days, the mean temperature and rainfall ranged from 12.9 \({}^{\circ}\)C to 32.2 \({}^{\circ}\)C and from 4.0 to 20.0 mm, respectively. Soil texture was sandy loam with electrical conductivity of 1.12 dS m\({}^{-1}\), pH of 7.85, organic matter of 0.46%, bulk density of 1.48 g cm\({}^{-3}\), field capacity of 0.101 m\({}^{3}\) m\({}^{-3}\), and water-holding capacity of 0.066 m\({}^{3}\) m\({}^{-3}\)[60].  
The seeds of each genotype were sown on 25 November 2019, and 17 November 2020 in five 1.5 m-long rows spaced 0.2 m apart (1.5 m\({}^{2}\) in the total area) and at a seeding rate of 15 g m\({}^{-2}\). All genotypes were fertilized with a nitrogen-potassium-phosphorus (NPK) fertilizer at a rate of 150, 120, and 100 kg ha\({}^{-1}\), respectively. The entire amount of phosphorus (as calcium superphosphate, 18.5% P\({}_{2}\)O\({}_{5}\)) and 50 kg ha\({}^{-1}\) of each nitrogen (as ammonium nitrate, 33.5 N) and potassium (as potassium chloride, 50% K\({}_{2}\)O) were applied before sowing. The plants were fertilized again with 50 kg ha\({}^{-1}\) of nitrogen at the late tillering growth stage (Zadoks scale, ZS 28) and with 50 kg ha\({}^{-1}\) of nitrogen and potassium at the late booting growth stage (Zadoks scale, ZS 47). The phenology growth stages were defined based on the scale created by [PERSON] et al. [61]. Weeds were removed manually, whereas pests and diseases were chemically treated when necessary.  
Each genotype was irrigated with fresh water for the first three weeks after sowing to avoid the negative impacts of salinity on germination and seedling establishment. Thereafter, the genotypes were irrigated with artificial saline water containing 150 mM NaCl L\({}^{-1}\) solution. The genotypes were irrigated with saline water using a low-pressure surface irrigation system. To deliver saline water from plastic water tanks (5.0 m\({}^{3}\)) to each plot, the irrigation system consisted of a main line (76 mm in diameter) that branched off to the sub-main hoses at each plot and that was equipped with a manual control valve. Irrigation (frequency and rate) was adjusted according to environmental conditions and plant phenology. On the basis of this information, the genotypes were irrigated with saline water 10 times during their growth stages, with the amount of water totaling 4800 m\({}^{3}\) ha\({}^{-1}\).