Evaluation and comparison of ten ecotypes of Teucrium polium L. in tolerance to drought stress

Medicinal plants, as important agricultural products, can be considered as the greatest national wealth for any country because of their vital role in promoting national goals for health and also as genetic treasures. Having a diversity of climates, Iran has a great variety of medicinal plants. Detecting the growth status of medicinal plants under drought stress conditions can lead to the cultivation of resistant plants in dry or semidry areas. In the present study, we investigated the morphological and physiological responses of ten ecotypes of the medicinal plant Teucrium polium L. native to southeastern Iran under drought stress. For this purpose, a factorial greenhouse experiment was conducted in a completely randomized design with three replications. In this experiment, moisture treatments of 100, 70, and 40% of field capacity were applied. Analysis of the data showed that the morphological traits under study including stem length and fresh and dry weight of shoots decreased by 5% with increasing drought stress. Drought stress also increased root length, proline content, and phenolic compounds while decreasing chlorophyll a, b, total chlorophyll, and protein contents. The highest resistance to stress was shown by ecotypes growing in Sarcheshmeh and Kuhpayeh regions and the lowest resistance was shown by plants in Shahdad and Anbarabad regions. The results of the study indicated the relative resistance of this plant to drought stress. Therefore, it is a very suitable medicinal plant for cultivation in dry and low water areas of Iran. Among the studied ecotypes, the plants of Sarcheshmeh and Kuhpayeh regions responded 40% better to drought stress conditions and cultivation of these ecotypes in stressed areas can be recommended with more confidence.