**5. Conclusions**

In *H. cannabinus*, the NaCl treatment increased the proline, soluble sugars, soluble protein, total phenolic content, and total flavonoid contents while lowering plant growth, K, Ca, Mg, and P levels. More osmolytes and antioxidants may improve its resistance to salinity stress. In addition, the NaCl treatment significantly enhanced the antioxidant capacity. The salt stress significantly affected the constituents of volatile compounds in *H. cannabinus*. The production of 1-heptacosanol was stimulated at low salinity but disappeared after the severe salt treatment. Moreover, the salt stress induced the biosynthesis of new compounds such as heptacosane, 1-octadecanesulphonyl chloride, and tetratetracontane. Therefore, the emergence of chemotypes at various salt concentrations may be an advantageous consequence of salinity stress in some plants, causing them to create substances with industrial and therapeutic significance.

**Author Contributions:** Conceptualization, Y.D., D.L. and Z.M.B.; data curation, D.Y., A.X., L.L., C.Z. and Z.M.B.; formal analysis, D.Y., A.X., L.L. and Z.M.B.; investigation, Z.M.B.; methodology, Y.D., D.L., A.X., L.L., A.B., S.D. and Z.M.B.; supervision, Y.D., M.L. and D.L.; validation, Y.D., M.L. and D.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the China Agriculture Research System of MOF and MARA (CARS-16-E5), and the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences (ASTIP-IBFC03).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
