3. Results and discussion
3.1. Influence of types and concentrations of cytokinins on shoot
proliferation
With the exception of KIN treatments, all other cytokinin treatments
significantly increased shoot production when compared to the control
(Table 1). Although there was an increase in the number of shoots produced with
an increase in KIN concentration, none of the concentrations
tested produced any significant increase in shoot production when
compared to the control. This finding suggests that KIN is a relatively
weak cytokinin for shoot proliferation from shoot-tip explant in this
species. Kinetin concentrations much higher than those used in this
study may be required to achieve a significant increase in shoot production.
Similar observations regarding the low effectiveness of KIN
compared to other cytokinins such as BA have been reported in other
Rutaceae species such as in Phebalium spp (Jusaitis, 1995), Ruta
graveolens (Bohidar et al., 2008) and Aegle marmelos (Narayan et al.,
2010). However, the longest shoot and highest number of adventitious
shoots greater than 10 mm in length were observed in the treatment
with 2.5 μM KIN. The length of the longest shoot and shoot fresh weight
decreased with an increase in cytokinin concentration in treatments
with KIN and MemTTHP. Overall, a large proportion of the regenerated
shoots in all the treatments (except 2.5 μM KIN) are small in size (5–
10 mm in length).