Abstract Entering the T-DNA of Agrobacterium rhizogenes plasmid to plant genome causing induction of hairy roots which have high biosynthetic capacity to produce secondary metabolites. This study aimed to optimize bacterial OD and explants type to induce hairy root in Rashe cultivar by A. rhizogenes strain A4 was conducted in a factorial experiment. Three bacterial OD 0.6, 0.8 and 1.0 as well as explants nodes, internodes and petioles were compared. The high percentage of root induction and maximum length of hairy root are determined in internodes explants in bacterial OD 0.8. Significant difference in root length and induction rate was observed between bacterial OD and explants types. Petioles explants and control samples did not produce any roots.
