A pot experiment was conducted in growth room of Biology Department of Mugla University from 1 September to 5 November 2004. Seeds of Triticum durum cv. Gediz-75 and Triticum aestivum cv. Izmir-85 were surface sterilized with HgCl2 (1.0 g/L) for 5 min, rinsed thoroughly with distilled water, and germinated on moist filter paper for 3 days in an incubator at 25 °C. After germination, the seeds were sown in quartz sand in the growth room at room temperature. When the second leaf emerged, seedlings of uniform size were planted into hydroponics plastic pots fitted with insulated covers. Each pot was covered with a polythene lid through which seven plants were supported over the nutrient solution. The pot contained 1000 mL of continuously aerated full-strength Hoagland nutrient solution which was renewed every other day. Daily photoperiod was 12 h and maximum temperature was 25 °C while the daily minimum temperature at night was adjusted to 15 °C. The pH of the nutrient solution was adjusted to 6.0 daily using 0.01 mol/L KOH and/or H2SO4.
The experiment was a 2 × 2 factorial arrangement with two levels NaCl in nutrient solution, 0 mM (control-C) and 100 mM, and two levels of Si in nutrient solution, 0.25 and 0.5 mM, as Na2SiO3. Control plants were treated with an equivalent amount of NaCl. Double-distilled water was used for the nutrient solution. Seedlings were grown on for further 7 weeks. Salinity was created adding 100 mM NaCl into nutrient solution. Composition of nutrient solution was given in Table 1. Each treatment was replicated four times and each replicate included five pots.