Iran has valuable resources of medicinal and ornamental plants. Due to the importance of medicinal herbs, many researches of plant sciences have been studied the various aspects of these plants. About 15 percent of the country's land is facing a salinity problem, one of the biggest limiting factors for plant growth and crop production in the world. Stachys lavandulifolia From the Lamiaceae family,is an important medicinal plant that is used in the pharmaceutical and sanitary industry and has a large distribution in Iran. One of the important goals in the study of medicinal plants is to increase the amount of antioxidant compounds that are important in these plants. Therefore, in this study 10 samples Stachys , based on randomized complete randomized design with three replications, were evaluated for morphological traits, phenolic compounds, flavonoids and antioxidant activity under four levels of salt stress (control), 2, 4 and 6 (ds/m) were studied. The results of analysis of variance showed a significant difference amoung genotypes in four levels of salinity in relation to the studied traits. Salinity stress reduced morphological traits while increasing the amount of phenol and flavonoids and antioxidant activity. The highest height, leaf length, internode length and fresh weight were observed in genotype Shahrekord 1. The highest leaf diameter and stem diameter were obtained in genotype Damaneh 6 and the highest septum length and width in genotype Damaneh 1. The highest number of main and lateral branches and dry weight were observed in genotype Damaneh 4, the highest number of florets and leaf widths in the genotype Damaneh 3 and semirum1 respectively. The highest total phenol and flavonoids were found in Genotype Damaneh 1 and Semirom 2, respectively. The results of cluster analysis of samples in non-salinity conditions were justified in terms of significant role such as antioxidant activity and antimicrobial properties and pharmaceutical uses. Also, genotypes of Damaneh 4 and Shahrekord 1 were introduced due to favorable morphological characteristics including number of leaves, leaf size, number of branches and number of florets as cover plants. Key Words : tachysS , Salinity stress, Morphological characteristics, Phenolic compounds
