Culture conditions and salt effects on essential oil composition of sweet marjoram (Origanum majorana) from Tunisia

Abstract

Culture conditions and salt effects on essential oil composition of sweet marjoram (Origanum majorana) from TunisiaO. majoranashoots were investigated for their essential oil (EO) composition. Two experiments were carried out; the first on hydroponic medium in a culture chamber and the second on inert sand in a greenhouse for 20 days. Plants were cultivated for 17 days in hydroponic medium supplemented with NaCl 100 mmol L-1. The results showed that theO. majoranahydroponic medium offered higher essential oil yield than that from the greenhouse. The latter increased significantly in yield (by 50 %) under saline constraint while it did not change in the culture chamber. Under greenhouse conditions and in the absence of salt treatment, the major constituents were terpinen-4-ol andtrans-sabinene hydrate. However, in the culture chamber, the major volatile components werecis-sabinene hydrate and terpinen-4-ol. In the presence of NaCl, new compounds appeared, such as eicosane, spathulenol, eugenol, and phenol. In addition, in the greenhouse, with or without salt, a very important change oftrans-sabinene hydrate concentration in EO occurred, whereas in the culture chamber change appeared incis-sabinene hydrate content.