The effects of water stress on the growth and physicochemical parameters in pot herbs

Abstract

This work investigates the effects of water stress on the growth and physicochemical characteristics of three types of potted herbs, namely basil (Ocimum basilicum), mint (Mentha spicata), and sage (Salvia officinalis). The herbs were grown in compost premium peat moss. Seedling were treated with four different water regimens at 100%, 50%, 25% and 12.5% compost water capacity over a period of 72 days during August and September 2017. From the plant growth characteristics, it was observed that the order of herbs tolerant to water stress was basil, followed by mint and lastly sage. Mint was affected by water stress but managed to regenerate and recover from injury for those plants that experienced wilting and death. On the other hand, sage was the least tolerant, and several losses were observed. Physicochemical analysis revealed that the status of phytochemicals in the mint was superior to that of sage and lastly basil and that water stress affected the phytochemical status for all three species to various extents. This showed that although basil was tolerant to water stress, it did not yield the optimum metabolite yield. Qualitative analysis of the essential oil revealed that the major constituent of basil was eugenol, for mint, these were menthol and pulegone, while for sage oil, these were thujone and cineole. With regards to minerals, a conclusion cannot be drawn from these results, meaning that mineral content could not be used to distinguish between the three species or how water stress affected minerals in leaves. This study revealed the possible use of these three plants as pot herbs in an urban setup. This may extend the aesthetic and culinary use of herbs in urban setups to be alternatively developed into medicines, food supplements and cosmetics.