In vitro and macropropagation of Warburgia Ugandensis (Sprague) in Kenya
Kiriba, Mary Gathegu
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Experiments were set up to develop protocols for in vitro and macropropagation of W. ugandensis. A randomised complete block design was used to investigate the main and interaction effects of different growth regulators on culture establishment from juvenile and mature tissues. In the first experiment the effects of cytokinis on shoot multiplication, and elongation were investigated. A concentration of 0.30 mgl-1 BAP in combination with kinetic scored the highest mean for shoot height (9.24 cm) and shoot multiolication (15.21 shoots). For mature tissues the optimum concentration of growth regulators required for in vitro establishment was found to be slightly higher than that required for establishment of juvenile tissues. A concentration of 0.40 mgl-1 BAP in combination with 0.40 mgl-1 kinetic scored the highest mean for shoot height (7.79 cm) and shoot multiplication (11.66 shoots). The effects of combining cytokinins and auxins on shoot multiplication and elongation was investigated. Addition of auxins to cytokinins resulted in an increase in shoot multiplication. BAP at 0.50 mgl-1 in combination with IBA at 0.50 mgl-1 was the best combination resulting in production of a mean of 15.84 shoots. However combination of cytokinins and auxins resulted in a decrease in shoot elongation. In the third experiment the effect of auxins (IAA, IBA and NAA) on rooting of explants was investigated. In vitro rooting was not achieved, W. ugandensis proved to be a difficult species to root. Indirect organogenesis (callus culture) was carried out using shoot tips of aseptically germinated W. ugandensis. The explants were cultured on modified half MS medium supplemented with 2, 4-D at different concentrations or combinations of NAA and IAA with cytokinins (BAP and zeatin). Callus was apparent on the wound surfaces of most explains. However few shoots were regenerated from the callus. The effect of growth retardants on elongation of in vitro cultured shoots was investigated. Maleic hydrazide at concentration of 0.20 mgl-1 was more effective in showing growth of W. ugandensis micro-shoots than mannitol at the same concentration. Macropropagation using stem cuttings was carried out. In the first experiment cuttings were treated with auxins (IAA, IBA and NAA) at different concentrations. The most effective auxin in both stem elongation and rooting was IBA at a concentration of 6.00 mgl-1. This resulted in production of shoots that were on average 37.42 cm in height, and an average of 24.72 roots. In the second experiment the effects of four different types of rooting media and three types of cuttings on percentage rooting was investigated. Basal cuttings performed better than other cuttings with 47.80% rooting, while sand with a rooting of 58.17% was more effective than the other media used. The basal cuttings planted in sand performed better than other cuttings planted in other media, with 75.30% rooting.
- MST-Zoological Sciences