Macro and micro-propagation of red stinkwood [Prunus africana (Hook. F.) Kalkman (1965) in Kenya
Macharia, Muchoki Stephen
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Protocols for micro-propagation and macro-propagation of red stinkwood (Prunus africana (Hook F.) Kalkman (1965)] were developed. Shoot tip and uni-nodal explants were cultured in vitro on either full strength or modified Murashige and Skoog's (1962) medium augmented with plant growth regulating substances. The effects of different combinations and concentrations of 6-benzylaminopurine (BAP) , 6-furfurylaminopurine (Kinetin) , 6-(4-hydoxy-3 methl-but-trans-2-enyl) aminopurine (Zeatin), indole acetic acid (IAA),indole butyric acid (IBA) and naphthalene acetic acid (NAA) on axillary shoot proliferation were studied for P.africana shoot explants. The presence of a cytokinin either alone or in combination with an auxin was found to be necessary for the induction and proliferation of axillary shoots on explants. Media containing zeatin alone or in combination with an auxin gave the best results. The influence of different auxins on in vitro rooting of P.africana second generation microcutting was also investigated. The addition of an exogenous auxin was found to be necessary for root induction. Irrespective of the concentrations used, both IBA and NAA induced low rooting percentages (<40%). However, NAA was significantly better than IBA on inducing root in vitro on P.africana shoots. The effects of different combinations and concentration of the growth regulating substances 2, 4-dichlorophenoxy acetic acid (2,4-D), IAA, NAA, BAP and zeatin on callus induction and subsequent regeneration of shoot was also investigated. Media supplemented with 2,4-D or NAA gave the fastest growing callus. However no regeneration of shoots from callus was observed. The possibility of regenerating P.africana from stem cuttings was also investigated. Stem cutting derived from juvenile plants regenerated roots easily. However, cutting collected from mature plants gave low rooting percentage (< 10%). Auxins proved to be essential for the inducting rooting of P.africana stem cuttings. The results of this indicate that it is possible to regenerate p. africana using both macro-propagation and micro-propagation. The use of the above two methods of vegetative propagation in conjunction with seed propagation will help in alleviating the current biological problems that limit reforestation of P. africana and at the same time encourage investment through improved yields better quality of bark and shorter breeding cycles.