Qualitative and quantitative effects of drought stress on essential oil compositions of hyssop (Hyssopus officinalis L.)

Drought is one of the most significant abiotic stress that affect plant growth, development and biochemical processes, such as the production of secondary metabolites and aromatic compounds. Hyssopus officinalis is one of the most important medicinal herbs which in addition to having medicinal properties, is also used as a flavoring and condiment in the food industry. This study was carried out in order to investigate the effects of water deficit stress on the quantity and quality of chemical compounds of Hyssop essential oil in pots at the field of Islamic Azad University of Shahrekord in 2017. Irrigation levels included normal, mild drought (60% F.C) and severe drought stress (30% F.C). The experiments were carried as factorial based on a completely randomized design with three replications. The essential oils obtained from aerial part of hyssop by hydro-distillation and analyzed by Gas Chromatography-Mass Spectrometry. Totally, 33 compounds identified representing more than 89-95% of the oil composition. The predominant components of hyssop oil were cis-pinocamphone (37.93 – 45.65%) and β-pinene (11.88 – 17.33%). In general, the results of this study showed that mild and severe drought stress did not have a significant effect on the percentage of hyssop essential oil, but on the percentage of its components was effective. The percentage of chemical constituents of essential oil increased at both levels of drought stress and it was higher in mild stress. It seems that with mild drought stress, both the effective materials of hyssop can be improved and the water can be saved.