Rapid axillary bud proliferation and ex vitro rooting of herbal spice, Mentha piperita L.

Abstract

Efficient protocol for rapid multiplication of the herbal spice Mentha piperita L. through axillary bud multiplication and ex vitro rooting was established using Murashige and Skoog (MS) medium. Media prepared with tap water and commercial sugar, and those prepared with double distilled water and tissue culture grade sucrose did not show significant difference in the in vitro induction of shoots/node, and roots/shoot. MS medium fortified with 4.44 μM N-benzyladenine (BA) and 2.32 μM kinetin (Kn) was the best for proliferation of shoots; induced a mean of 4.1 shoots/node explant. The shoots attained a height of more than 4.5 cm bearing more than 5 nodes within 40 days. Excision and culture of in vitro derived node segments on medium with 3.33 μM BA and 2.32 μM Kn facilitated enhanced axillary bud proliferation. Shoots developed were rooted best on half-strength MS medium with 0.49 μM indole-3-butyric acid (IBA); induced a mean of 10.3 roots. In vitro rooted shoots exhibited 100% survival in field conditions. Dipping of the basal end of shoots harvested from multiplication medium in 0.49 μM IBA solution for 10 days induced a mean of 8 roots and its transfer to small pots facilitated survival of 95% rooted shoots. Ex vitro rooting by direct transfer of the shoots from multiplication medium to small pots showed 72% survival. Commercial sugar and tap water and ex vitro rooting make the protocol economic.