Study of genetic variation of Rosa damascena Mill. genotypes of Iran using multivariate statistical methods

To evaluate the genetic variation of Rosa damascena as an important aromatic and medicinal species, 38 genotypes of this species were studied for the diversity of phenological and morphological traits (flowering period, plant height, canopy diameter, number of leaves at the plant, total green area of the plant, number of flowers per plant, fresh weight and percentage of dry matter content of flowers and flower yield per plant) in a randomized complete block design with three replications in Zalleh Research Station of Sanandaj, Iran during 2004-2008. The results showed significant differences (p < /em>≤ 0.01) among the genotypes, in terms of the studied traits. The average total yield of fresh flowers was 2427.4 g/plant. The genotypes belonging to temperate and cool areas had lower flower yields than those originated from hot and dry areas. Flower yield showed a significant  and positive correlation with the crown height and diameter, the number of leaves, total green surface, and the number of flowers per plant (p ≤ 0.01). The results of stepwise regression showed that the flower weight and number positively, while the total green surface and flowering period negatively correlated with flower yield. The results of cluster analysis (CA) grouping were relatively consistent with segregation based on the flower yield and characteristics of genotypes origin areas. The results of principal component analysis (PCA) showed high consistency with the CA results, but the genotypic separation in PCA method was clearer. The overall results of this study along with CA and PCA analyzes showed considerable rich genetic variation among the genotypes in terms of phenological and morphological traits and the possibility of using this diversity in Iranian Damask rose breeding such as improving flower yield through direct and indirect selections (through flower yield components) or hybridization of genotypes with a greater genetic distance for the use of higher heterosis.