Changes in growth parameter and essential oil composition of sage (Salvia officinalis L.) leaves in response to various salt stresses

Salt stress imposes major limitations on the growth, development, crop productivity, and quality in many regions of the world. Therefore, the studies concerned with salinity and its effects on plants are of the fundamental interests for agricultural issues. Herein, the present study was designed to investigate the effects of different salt compounds (NaCl, KCl, MgSO₄, MgCl₂, Na₂SO₄, and CaCl₂) with different salinity levels (0, 50, 100, 150, and 200 mM) on growth and leaf essential composition of sage (Salvia officinalis L.). In this context, sage seedlings were irrigated with different salinity levels for forty-days. Concerning the composition, twenty-two compounds were collectively identified using gas-chromatography coupled with headspace system. Of those compounds (over 5% content), α-pinene, camphene, 1, 8-cineole, α-thujone, β-thujone, and camphor are of the major compounds. Along with the study, α-pinene and camphor percentages increased under all salt stress but depending concentration and salt compound. The percentage of camphene was also augmented under all stress types except CaCl₂ treatment whereas β-thujone percentage increased except MgCl₂ treatment. Moreover, NaCl and KCl treatments decreased the percentage of α-thujone while other treatments caused an increase in the percentage. 1,8-cineole percentage was not influenced by NaCl treatments. However, CaCl₂ and MgCl₂ treatments decreased the percentage of 1,8-cineole whereas other salt treatments increased the percentage of the compound. It should be emphasized that the degree and severity of the stress were also variable according to the treatments and compounds. Herewith the study, due to the high number of treatments and compounds identified, principal component analysis was applied to reduce, discriminate and identify the treatments according to their effects on essential components. The results were well clarified, visualized and discriminated according to the treatments. As a conclusion, the chemical composition of the common sage was found to be strongly affected by salt treatments and concentration of the salt compounds because each salt treatment with their concentration induced different new chemotypes in essential oil composition of common sage. The results also suggest the plausible role of metabolites in response to the changing environmental conditions.