Rapid in vitro propagation system through shoot tip cultures of Vitex trifolia L.-an important multipurpose plant of the Pacific traditional Medicine

A rapid and efficient plant propagation system through shoot tip explants was established in Vitex trifolia L., a medicinally important plant belonging to the family Verbenaceae. Multiple shoots were induced directly on Murashige and Skoog (MS) medium consisting of different cytokinins, 6-benzyladenine (BA), kinetin (Kin) and 2-isopentenyl adenine (2-iP), BA at an optimal concentration of 5.0 mu M was most effective in inducing multiple shoots where 90 % explants responded with an average shoot number (4.4 +/- 0.1) and shoot length (2.0 +/- 0.1 cm) after 6 weeks of culture. Inclusion of NAA in the culture medium along with the optimum concentration of BA promoted a higher rate of shoot multiplication and length of the shoot, where 19.2 +/- 0.3 well-grown healthy shoots with an average shoot length of 4.4 +/- 0.1 cm were obtained on completion of 12 weeks culture period. Ex vitro rooting was achieved best directly in soilrite when basal portion of the shoots were treated with 500 mu M indole-3-butyric acid for 15 min which was the most effective in inducing roots, as 95 % of the microshoots produced roots. Plantlets went through a hardening phase in a controlled plant growth chamber, prior to ex-vitro transfer. Micropropagated plants grew well, attained maturity and flowered with 92 % survival rate. The results of this study provide the first report on in vitro plant regeneration of Vitex trifolia L. using shoot tip explants.