PROTOCOL OPTIMIZATION FOR IN VITRO PROPAGATION OF THREE SELECTED ENSET (Ensete ventricosum (Welw.) Cheesman) VARIETIES; YANBULE, MESENA AND ENDALE THROUGH SHOOT TIP CULTURE

Abstract

Enset (Ensete ventricosum (Welw.) Chessman) has socio-cultural, ethno-medicinal and economic use values. Nearly all enset genotypes are being threatened by bacterial wilt disease upon conventional propagation. Therefore, this research was designed to develop mass in vitro propagation protocol for three elite enset varieties from shoot tip explants. The experiment was laid out in CRD with three replications in factorial arrangement. Apart from ethanol (70%), sodium hypochlorite (NaOCl) in three concentration levels (1, 2 and 3%) was used for surface sterilization. For shoot initiation explants were aseptically cultured on MS basal medium supplemented with 1.5, 2.5, 3.5 and 4.5 mg/l of BAP alone or in combination with 0.5 and 1mg/l of NAA, and incubated in dark for 4 weeks at room temperature. After 9 weeks of incubation, the initiated shoots were transferred to MS basal media supplemented with 2, 3.5, 5 and 6.5 mg/l of BAP or 2, 3.5, 5, 6.5 mg/l Kn alone or in combination with 0.5 mg/l of NAA. MS media without plant growth regulators were used as control. The initiated cultures were then incubated for five weeks at 25 ± 2 0 C and 16 hours photoperiod of white fluorescent light of (20 μ mol/ m2 /s) intensity. For root induction, about 5 to 8 cm of well regenerated shoots were cultured on half strength MS medium supplemented with 1.5, 3, 4.5 mg/l NAA or 1.5, 3 and 4.5 mg/l of IBA alone or in combination with 0.25 mg/l of BAP. Half strength MS medium without hormone was used as control. The cultures were maintained in a growth room for a month at a temperature of 25 ± 20C and 16 hour photoperiod. Plantlets were planted on different mixes of red soil, sand and compost in different mix ratios. Results of sterilization experiment showed that 2% NaOCl was found to be effective in giving contamination free explants. Compared to the control, almost all levels of hormone treatments had positive impact on all parameters measured from shoot initiation and multiplication, and rooting experiments. However, of all hormonal treatments, only specific hormone types, concentrations and mixes resulted in better performance in shooting and rooting experiments(p<0.05). Results of acclimatization experiment showed that red soil and sand mixed in 2:1 ratio resulted in better plantlet survival. The three tested enset varieties responded differently to the treatments. Overall, the results of this study could be followed for in vitro propagation of the three tested enset varieties