Evaluation of Salt Stress Tolerance in Lettuce (Lactuca sativa L.) Cultivars Under Hydroponic Conditions

Abstract

Salt stress is one of the most important abiotic stress factors that significantly negatively affect plant growth and yield. This study evaluated the morphological and physiological responses of eight lettuce (Lactuca sativa L.) varieties to salt stress under hydroponic conditions. The lettuce varieties were grown in an aerated hydroponic system under control (1.8 dS/m) and salt stress (6.0 dS/m) conditions. The results showed that salt stress caused significant reductions in shoot biomass, particularly compared to root biomass characteristics. The varieties with the greatest reductions in biomass parameters under salt stress conditions were Chicarita, Triplex, and Levistro, while Baeza and Cherokee produced higher biomass. Morphological characteristics such as leaf number, stem diameter, plant height, and leaf area were also significantly affected by salt stress, with leaf area—the edible part of the lettuce—being the most affected by salt stress. As with other parameters, the Baeza, Kireve, and Cherokee varieties were more stable in these parameters. The Chicarita variety again showed the lowest performance in these parameters. Leaf color parameters such as L, a*, b*, chroma, and hue angle were significantly affected by salt stress. Under salt stress conditions, the Expedition and Kireve varieties had more vibrant colors than other varieties. Chlorophyll-a, chlorophyll-b, and total chlorophyll content increased in some varieties due to salt stress, while they decreased in others. Salt stress generally increased leaf sap EC and SSC values. The effect of salt stress on fruit juice pH was not statistically significant. In conclusion, salt stress negatively affected shoot parameters in lettuce varieties, while in some varieties it caused an increase in root morphology. These differences in response to salt stress are related to stress adaptation ability, so the parameters used in this study can be used as selection criteria for lettuce or other plants. Additionally, the varieties identified as salt-tolerant in this study can be used in breeding programs aimed at growing plants under saline conditions.

Keywords

• Lettuce
• Salt stress
• Chlorophyll
• Leaf color

Ethical Statement

Ethics committee approval was not required for this study because of there was no study on animals or humans.

Thanks

I would like to thank the JISTUAM – Geothermal Advanced Greenhouse Technologies and Production Techniques Research and Application Center, where this study was conducted.

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