Essential oil of Iranian damask rose has high quality because of its desirable climatic and growing conditions. In the present study, an RCBD design was used to investigate the morphology and phytochemical characteristics of six damask rose landraces, collected from East Azerbaijan province. The investigated landraces showed a significant difference among morphological traits. According to the morphological characteristics, the landraces were grouped in two distinct classes including thorny and thornless. Qazi Jahan, Nadilu, and Kharaju (thornless) were the most suitable ecotypes in terms of flower yield and growth. Interestingly, petal, bud, and flower fresh and dry weight, bud number per branch, and essential oil content had a positive and significant correlation with flower yield. Essential oil analysis showed that citronellol, geraniol and n-nonadecane were the major components of the rose landraces. The amount of citronellol in the thorny genotypes was higher than that in thornless ones. On the other hand, n. nonadecane was the dominant component in the thornless genotypes. Our results demonstrated significant differences among the two classes of genotypes (with/without thorn) in terms of essential oil quality and flower yield. The important indices that influenced yield and percentage of essential oil of damask rose were petal fresh/dry weight, flower weight, petal length/width, and petal number among the 14 morphological traits, in addition to yield and essential oil percentage. There was a significant difference in odor between the thorny landraces and thornless ones. There was no significant difference in leaf length and width and number of branches per area between different landraces. These differences introduced a new variety of damask rose for breeding programs and industry.
