Enhanced micropropagation protocol of Morinda citrifolia L. through nodal explants

Abstract

We report an improved in vitro propagation protocol for Morinda citrifolia L. in the present communication using nodal segments as explants from a 4 year old plant. Murashige and Skoog (MS) medium was used to inoculate the sterilized explants. Under laboratory conditions, 4.6±0.48 shoots were regenerated from the nodal meristem of an explant on the combination of MS medium fortified with 4.0mg/L 6-benzylaminopurine (BAP). Semi-solid (with agar) and liquid MS medium was used for the multiplication of shoots in vitro. Combined effect of BAP and kinetin in shoot multiplication was reported favorable in semi-solid (10.6±0.17 shoots per vessel) and liquid MS medium (11.4±0.47 shoots per vessel). The shoots were rooted in vitro on half-strength agar-gelled MS medium supplemented with 1.0mg/L indole-3 butyric acid (IBA) and 44.30 roots per shoot were observed from the cut ends of the shoots. All the shoots were also rooted by ex vitro method and maximum 36.12 roots per shoot were induced by treating the shoots with 300mg/L IBA for 5min. The in vitro rooted and ex vitro treated plantlets were transferred to the soilrite containing paper cups for hardening in the greenhouse. The plantlets were shifted to nursery bags after 4 weeks. Finally the hardened plantlets were planted in the field with 100% rate of survival under natural conditions. The ex vitro rooting was reported more advantageous than in vitro rooting in terms of cost, time and percent survival of plantlets.