Effects of cytokinin types and their concentration on in vitro shoot induction and multiplication of korarima

Korarima (Aframomum corrorima (Braun) P.C.M. Jansen) is a herbaceous perennial plant that belongs to the family Zingiberaceae in which lack of a steady supply of quality planting material is one of the bottlenecks for the exploitation of the export potential. Thus, the use of micropropagation is suggested to alleviate these problems. In micropropagation, in vitro seed germination and multiplication of hypocotyls/shoot tips to regenerate shoots is preferred because it minimizes sterilization cost. So far, there was no available efficient protocol optimization on in vitro propagation of korarima in Ethiopia. Therefore, an experiment was conducted to determine the optimum concentration of Kinetin (KIN) and N-6-benzyladenine (BA) on in vitro regenerating of korarima explants from hypocotyls/shoot tips. Multiplied shoots were subcultured on hormone free medium for four weeks to avoid carryover effect. The different concentrations of KIN (0, 0.5, 1.0, 1.5 and 2.0 mg/l) and/or BA (0, 1.5, 3.0, 4.5 and 6.0 mg/l) were arranged in randomized complete design (CRD) with four replications. Results indicate that medium containing 6.0 mg/l of BA alone was found to be optimum for shoot induction after six weeks. High level of BA alone was found the best for excess shoot proliferation, but high level of KIN mostly enhances longer shoots and regenerates minor roots. Generally, it can be concluded that Korarima can successfully induce shoot from hypocotyls that originated from seeds without any contamination on the initial inoculation of the explants and higher concentration of BA (6.0 mg/l) could be used to obtain desirable shoot regeneration of korarima.    Key words: Cytokinins, N-6-benzyladenine (BA), hypocotyls, kinetin (KIN), shoot induction, shoot Multiplication, in vitro.