In the present study, the treatment of P. helferi
cultured on 3 mg/L BA with 0.1 mg/L IAA in MS media gave the
highest percentage (±SE) of callus formation (93.33 ± 6.67%) in
3wk (Table 3). The calli obtained were mostly green and compact in
appearance (Fig. 2A). They were then sub-cultured for further
proliferation in the same media for a further 3 wk, during which a
large number of new shoots were seen to develop from the calli
(Fig. 2B). The MS media without BA had a significant number of
induced new shoots. P. helferi axillary buds given a treatment of
0.3 mg/L IAA without BA were able to produce the highest number
(±SE) of new shoots per explant of 6.58 ± 0.85 (Table 4). However,
an increasing concentration of BA resulted in a decreasing number
of new shoots, possibly due to the inhibition of organogenesis and