**Abstract**

This study aims to reveal the responses of biofertilizers to the detrimental effects of salt stress on lettuce cultivation. Presidential variety lettuce seeds belonging to Syngenta company were used as plant material. Microalgae *Chlorella vulgaris*, beneficial bacteria, and mycorrhizal fungi are used to reduce salt damage in lettuce plants grown under salt stress. The experiment was carried out on eight different applications; (1) control, (2) salt (50 to 75 mM NaCl), (3) micro microalgae, (4) microalgae + salt, (5) bacteria (6) bacteria + salt, (7) mycorrhiza, (8) mycorrhiza + salt. The biofertilizers decreased the salt's detrimental effects and increased the lettuce weight. Compared to salty conditions, microalgae + salt, mycorrhiza + salt, and bacteria + salt applications increased lettuce weight by 19.2, 21.3, and 20.08%, respectively. Biofertilizers increased pH, EC, total soluble solids, titratable acid, and total dry matter in lettuce leaves under salt stress. Biofertilizers had a stress-reducing effect under salinity and increased leaf osmotic potential, leaf water relative content, and leaf stomatal conductance. Microalgae *Chlorella vulgaris*, mycorrhiza, and beneficial bacteria are recommended as stress relievers when growing lettuce in saline agricultural soils or with saline irrigation water.

**Keywords:** microalgae, mycorrhiza, beneficial bacteria, stomatal conductance, lettuce weight
