Kn-NAA combinations responded to PLB induction in 45-50% explants according to the concentration of Kn and NAA (data not shown). BA-NAA combinations increased the rate of PLB induction and the optimum concentration of BA and NAA for PLB induction was 2.0 and 0.5 mg l-1, respectively, in which 80% of the cultures produced a maximum of 15 PLBs per explant (Table I).