African Journal of Biotechnology Vol. 6 (14), pp. 1670-1676, 18 July 2007   

ISSN 1684–5315 © 2007 Academic Journals        

Full Length Research Paper

Effective preconditioning methods for in vitro propagation of Uapaca kirkiana Müell Arg. tree species

Simon A. Mng’omba^{1, 2 *}, Elsa S. du Toit¹, Festus K. Akinnifesi² and Helena M. Venter³

¹Department of Plant Production and Soil Science, Faculty of Natural and Agricultural Sciences, University of Pretoria, 0002 Pretoria, South Africa.

²World Agroforestry Centre, SADC - ICRAF, Agroforestry Programme, Chitedze Agricultural Research Station, P.O. Box 30798, Lilongwe 3, Malawi.

³CSIR NRE, Forestry Program, Tree Improvement, SERA Plant Propagation and Cultivation Technologies, P.O. Box 195, Pretoria 0001, South Africa.

*Corresponding author.  E-mail: s23368854@tuks.co.za.

Accepted 14 June, 2007

The objective of the study was to determine efficient preconditioning methods for in vitro multiplication of Uapaca kirkiana plant materials from mature stock plants. The efficacy of sodium hypochlorite (NaOCl), calcium hypochlorite {Ca(OCl₂)₂} or mercuric chloride (HgCl₂) as surface sterilant was evaluated in decontaminating explants excised from grafted and field-collected U. kirkiana trees. Different Murashige and Skoog (MS) medium supplements were evaluated for shoot multiplication and root regeneration. Results indicated that preconditioning grafted U. kirkiana trees before excising explants and decontaminating explants in 0.1% w/v HgCl₂ were effective methods in establishing aseptic cultures (80%). Lateral shoots (new shoots) responded positively to shoot multiplication on ¾ strength MS medium supplemented with a combination of 0.1 mg/L benzylaminopurine, 0.04 mg/L naphthaleneacetic acid and 0.3 mg/L casein hydrolysate. High concentrations of thidiazuron (>0.1 mg/L) suppressed bud break. Rooting (36%) was achieved with ½ MS medium supplemented with 2.5 mg/L indole-3-butyric acid. Plantlets were successfully hardened off. In vitro multiplication of mature U. kirkiana plant materials was achieved using lateral shoots excised from grafted U. kirkiana trees after preconditioning with fungicides.

Key words: Decontaminants, fungi, euphorbiaceae, phenols, rejuvenation.