Abstract: This work aims to lay the primary foundation for breeding salt-tolerant fiber flax plant induced from the callus. The hypocotyl segments from sterile seedlings of 3 kinds of fiber flax were treated in the orthogonal test with EMS induction and salt stress，and cultured through bud and callus induction. Further，the physicochemical characteristics of the buds and callus were explored. The optimal treatment combination for adventitious buds derived from “Fanny”，“Tianxin 3” and “Shuangya 5” all were 0.025% EMS for 2 h or 4 h，and then 150 mmol/L NaCl for 12 h. Total bud yield from high to low were the hypocotyls segments of “Fanny”，“Tianxin 3” and “Shuangya 5”. The order of factors affecting the emergence and growth of the adventitious buds was concentration of NaCl>concentration of EMS>treating time with EMS. The optimal medium for the induction of adventitious buds from 3 species fiber flaxes was MS+0.000 2 mg/L TDZ+0.02 mg/L KT+0.005 mg/L NAA+0.3% sucrose+0.1 g/L inositol+3.3 g/L phytogel. The callus was treated with 0.025% EMS for 4 h then 150 mmol/L NaCl for 12 h and screened through salt and salt-free medium twice alternately，and the physicochemical properties of which were determined. The results showed that proline content，soluble sugar content，soluble protein，SOD activity and POD activity in the callus of treated group of 3 species fiber flax all increased remarkably(P<0.05)compared with their control group. Conclusively，the callus of treated group with 0.025% EMS for 4 h then 150 mmol/L NaCl for 12 h possessed solid salt tolerance.

Key words: fiber flax, EMS mutation, NaCl stress, orthogonal test, physicochemical property