For callus induction, leaf explants were placed on MS medium incorporated with different concentrations (1.0–3.0 mg l1 ) of 6-benzyladenine (BA) and 2,4-dichlorophenoxyacetic acid (2,4-D) alone (0.5–4.0 mg l1 ) or in combination with BA (0.5–3.0 mg l1 ).