Several studies had been reported regarding the effects of plant
growth regulators on callus growth of different plant species
(Nadia and Li, 2011). When using different concentrations in
single auxin treatment, the addition of 2.4-D increased the
growth in the rhizome callus of R. coreanum with the maximum
at 0.2 mg/l of 2.4-D, but increasing the levels of 2.4-D
suppressed the callus growth (Table 2).
A combination of cytokinin BAP at 0.2 mg/l with the best
auxin treatment (0.2 mg/l 2.4-D), produced profuse amounts
of whitish and friable callus (Table 2). When kinetin was used
instead, the amount of biomass recorded lowered than that of
the best BAP (0.2 mg/l) (Table 2).