**2. Material and method**

#### **2.1 Plant material and growing conditions and experimental design**

The present study was conducted in a glasshouse between the spring and the summer of 2019 at the University of Cukurova, Adana, Turkiye (36°59'N, 35°18'E, 20 m above sea level). Lettuce seeds (*Lactuca sativa* L. var. l*ongifolia* "Presidental") were provided by Syngenta seed company. Seed sowing was done on 28 October 2019 and seedlings were planted on 13 December 2019 (**Figure 1**). The lettuce plant was grown in a two-liter capacity pot filled with cocopeat substrate and irrigated nutrient solution. Lettuce plants were grown with eight treatments and three replications. Randomized blocks experimental design, with 10 plants in each replication (30 plants per treatment) was used. The treatments are as follows:


The pH and EC of the nutrient solution during the trial were measured daily. The pH was kept between 5.5 and 6.0, and the EC was fixed at 1.5 and 2.7 μS cm−1. Two stock solutions for nutrition were used: stock A (Potassium nitrate, calcium nitrate, ammonium nitrate, and Fe-EDDHA) and stock B (potassium sulfate, mono-potassium sulfate, magnesium sulfate, microelements, zinc sulfate, boric acid, manganese sulfate, and ammonium molybdate). The nutrient solution consists of nitrogen (N) 212 ppm, phosphorus (P) 30 ppm, potassium (K) 305 ppm, calcium (Ca) 205 ppm, magnesium (Mg) 60 ppm, Iron (Fe) 3.0 ppm, manganese (Mn) 0.4, Boron (B) 0.40 ppm, Zinc (Zn) 0.50 ppm, copper (Cu) 0.05 ppm, and molybdenum (Mo) 0.07 ppm. The first salt application of 50 mM NaCl was made on February 28, 2020. The salt concentration was increased to 75 mM NaCl on 20 March 2020. Lettuce plants were harvested on April 6, 2020.

**Figure 1.** *Lettuce seedlings were transferred to pots containing cocopeat.*
