Abstract:

The paper aims to study the response of lettuce to seawater stress, explore the suitable seawater concentration for lettuce growth, providing guidance for the cultivation of seawater lettuce. This experiment used bolting resistant lettuce as the experimental material, five treatment groups with different seawater concentrations of 0% (CK), 5%, 10%, 15%, and 20% were set up to impose stress on lettuce seeds and seedlings. The germination index of lettuce seeds, as well as the growth index, cell membrane permeability index, and antioxidant enzyme activity of lettuce seedlings were measured. The experimental results showed that with the continuous increase of seawater concentration, the germination and growth indicators of lettuce showed a downward trend. During the growth process, the relative salt damage rate, electrical conductivity, soluble protein content, MDA content, and physiological indicators such as SOD, CAT, POD, activity of lettuce showed an upward trend. When the seawater concentration was less than 5%, the germination and growth development of lettuce were basically not affected. When the seawater concentration was greater than 10%, the germination and growth of lettuce were inhibited, and the development of roots and stems was significantly less vigorous than that of the control. When the seawater concentration reached 15%, the relative salt damage rate reached 34.12%, which was significantly higher than the control. Seawater treatment inhibited lettuce seed germination and seedling development, and lettuce could tolerate seawater stress at lower concentrations (<5%), and its salt tolerance was related to the regulation of antioxidant system and the maintenance of membrane stability. This concentration range could provide a theoretical basis for the utilization of seawater in agriculture.

Key words: seawater stress, lettuce, seed germination, germination rate, growth, enzyme activity, resistance