Effects of salinity on iceberg lettuce production in floating hydroponics

The experiment was carried out in an unheated plastic tunnel in Izmir, Turkey. Three different salinity levels (EC1, EC2 and EC3) were compared, 8.76 and 17.52 mM NaCl was added for EC2 and EC3, respectively, into the nutrient solution used as control (EC1). NaCl application was started when leaves and roots of the plants began to develop, and continued up to harvest. Temperatures of greenhouse air and nutrient solution, changes in EC of nutrient solution, head weight, nitrate concentration of the leaves, consumption of nutrient solution, and element contents of the leaves were determined. The trial was repeated in three different periods: from December 16 to March 13 (Experiment 1), from March 24 to May 2 (Experiment 2) and from May 18 to June 28 (Experiment 3). Plants were grown successfully during the first two trials; on the other hand, all plants died 41 days after transplanting due to the high temperatures in Experiment 3. In the first trial, head weight changed according to salinity of nutrient solution, and the highest value (464 g) was obtained at EC2 compared to EC3 (419 g) and EC1 (438 g). There were no significant differences between EC levels of nutrient solution in respect to head weight changing between 535 and 588 g in the second trial. Nitrate concentration of the leaves decreased by increasing EC of nutrient solution. © 2020 International Society for Horticultural Science. All rights reserved.