We conducted a hydroponic pot experiment with three types of herbs, namely common thyme (Thymus vulgaris L.), dill (Anethum graveolens L.), and coriander (Coriandrum sativum L.) in order to evaluate the herbs response to the presence of 100 mM NaCl in the nutrient solution. We analyzed the content of photosynthetic pigments, relative chlorophyll content, total phenols, total volatile content, and individual volatile compounds characteristic of each herb. Herbs grown in saline conditions had a lower yield than herbs grown in control conditions. The addition of NaCl to the nutrient solution reduced the chlorophyll and carotenoid content in common thyme. In dill, the differences between the treatments were statistically significant in chlorophyll a, chlorophyll b, and carotenoid content. Coriander had higher chlorophyll a and chlorophyll b content under control conditions only at the second sampling date. In the analysis of total phenols of the selected herbs, we did not record any differences between the treatments. In the analysis of volatile compounds in common thyme, we recorded higher total volatile compound content in the first sampling period under saline conditions. In dill, we observed higher contents of the characteristic volatile compounds limonene and α-phellandrene under saline conditions in the third sampling period, and higher contents of dimethyl ether in the first sampling period, also under saline conditions. In coriander, characteristic volatile compounds showed higher contents in saline conditions, namely n-decanal in the second sampling period and 2-E-decenal in the first sampling period. Based on the results of the analyses we performed during the experiment, we can conclude that the selected concentration of 100 mM NaCl is not suitable for improving the quality of the selected herbs. We found that this salt concentration has a negative effect on plant growth, which is reflected in poorer vitality and, consequently, lower yields. Although the quality of the yield was slightly improved in the content of characteristic volatile compounds, so the use of 100 mM NaCl is not an effective approach for improving the quality of herbs in our experiment.
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