Effects of water and salinity stresses on growth, yield, and water use of iceberg lettuce.

Abstract

Salinity and drought stresses have become widespread in many regions of the world. Although there are several studies, their findings about the response of lettuce to water and salinity stresses are contradictory. This paper therefore aims to evaluate the effects of water deficit and irrigation water salinity on growth, yield, and water consumption of iceberg lettuce. For these purposes, two experiments were carried out under Mediterranean conditions. The water yield response factors (Ky ) determined for the lettuce plant grown under stress conditions caused by water (Ky =1.69) and irrigation water salinity (Ky =2.62) were quite different from each other. The classical salinity tolerance model did not reflect the results accurately because the fresh yield and plant water consumption of lettuce increased sharply with increasing soil salinity up to 2.17 dS m-1 and then decreased slightly after this value. Thus, a new model was created to reflect both the increase and decrease in fresh yield. The actual salt tolerance model for iceberg lettuce plant showed that the optimum salinity is 1.84 dS m-1 with relative yield decreases of 8.26 and 22.7% per unit salinity increase above and below the optimum salinity level, respectively. Lettuce fresh yield at soil salinity below the optimum salinity experienced greater reduction than at soil salinity above the optimum value. The results reveal that the use of low-salinity irrigation water should be preferred to increase fresh yield in iceberg lettuce cultivation. © 2021 Society of Chemical Industry.