Effect of water supply on Satureja hortensis L. (summer savory) ‘Budakalászi’ cultivar was investigated. Three saturation levels (70–50–30%) of soil water capacity (SWC) applied in climatic chamber resulted in significant changes of physiological parameters of savory plants. Compared to the control treatment (70% of SWC) the driest condition (30% SWC) caused more than 20% decrease of the relative water content (RWC) of plants and an almost 5-fold lower water potential. SPAD values indicated 45% higher chlorophyll content in the lowest watering regime. The reduction of SWC (30%) significantly affected the production of savory: fresh weight was reduced by 54% while dry weight decreased by 46%. No changes were detected in the leaf mass/total shoot mass ratio. The highest essential oil (EO) concentration of leaves (5.300 ml·100 g⁻¹) was measured in plants of moderate drought stress (50% SWC) while the control plants and plants exposed to severe water stress treatment showed lower essential oil accumulation (4.922 and 4.782 ml·100 g⁻¹, respectively). The EO production calculated from the values of fresh yield, and the EO concentration were the lowest in the case of plants grown in pots of lowest soil water content. The main components of the oil were carvacrol (56.7–60.6% EO) and γ-terpinene (29.7–32.3% EO) in each treatment. Water supply did not modify significantly the quantitative composition of the EO, however, it influenced noticeably the headspace volatiles (HS). In contrast with the former practice we found that without a proper water supply the cultivation of summer savory cannot be efficient.
The reactions of lemon balm, marjoram, peppermint, thyme were investigated and compared in a pot experiment, adjusting 70% and 40% of soil water capacity (SWC). Biomass, total phenolic content (TPC), rosmarinic acid content (RA) and antioxidant capacity (FRAP, DPPH) of both the shoots and roots were measured. As an universal phenomenon the water stress (40% SWC) decreased the total biomass production of all species drastically. The highest increase was observed in the shoot mass of peppermint and lemon balm (decreased from 52.6 g·plant–1 to 11.3 g·plant–1 and from 236.8 g·plant–1 to 58 g·plant–1, respectively). The reaction of marjoram was much more moderate. The accumulation level of TPC was accelerated in the aboveground parts of the studied species, universally. The reactions in the roots were less characteristic. The largest increase of TPC was measured in the shoots of lemon balm (from 359.015 mg GAE· g–1 d.w. up to 412.44 GAE·g–1 d.w.). The reaction of marjoram was the less characteristic in this respect, as well. The parallel changes of biomass and TPC level might allow the total phenolic content to function as an adequate marker in predicting the lack of appropriate water supply. RA content showed species characteristics. Thyme, marjoram and peppermint reacted by a significant elevation (by 23–127%) of the RA content to the lack of water. The highest proportions were accumulated in shoots of the stressed thyme plants (3.45% d.w.).
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