مشخصات پژوهش

Stachys lavandulifolia Vahl. is a native plant that is widely distributed in different regions of Iran and known as “Chaye-e-Kohi”[1]. This plant is used as herbal tea and a medicinal plant in Iranian folk medicine [2]. We evaluated the relationship between the essential oil content (EO) of S. lavandulifolia populations from the northwest of Iran with average annual rainfall and average annual temperature. Samplings were done at flowering from early June to early July 2020. Results show that Azarshahr and Zanjan Soltanieh populations have the highest and lowest contents of EO, respectively, with 0.565 and 0.096%. Moreover, Heris, Sarab, Mianeh, Mahabad, Hamadan Razan, Oskou, and Meshkinshahr populations showed higher EO content than the average of the total population. This study found that the low average annual rainfall and high average annual maximum temperatures in Azarshahr and Sarab were responsible for the high content of EO in these populations. It was observed that the content of EO had a positive and high correlation with the average maximum temperature, and a negative correlation with the average annual rainfall variable. Therefore, selection based on the high temperatures and decreases in rainfall, resulting in an improvement in the EO of S lavandulifolia.