International Journal of the Physical Sciences Vol. 7(7), pp. 1083 - 1087, 9 February, 2012 Available online at http://www.academicjournals.org/IJPS DOI: 10.5897/IJPS11.414 ISSN 1992 - 1950 © 2012 Academic Journals Full Length Research Paper Evaluation of different ratios of auxin and cytokinin for the in vitro propagation of Streptocarpus rexii Lindl. Jade J. North 1 and Patrick A. Ndakidemi 2 * 1 Faculty of Applied Sciences, Cape Peninsula University of Technology, P.O. Box 652, Cape Town 8000, South Africa. 2 The Nelson Mandella African Institute of Science and Technology, P.O. Box 447, Arusha-Tanzania. Accepted 23 January, 2012 A successful means of in vitro propagation of Streptocarpus rexii Lindl. using leaf tissue as the explants is described. Secondary explants were placed on several regeneration media supplemented with various concentrations of indole-acetic acid (IAA) and benzyladenine (BA). Optimal shoot proliferation was obtained on Murashige and Skoog basal media containing 0.1 mg/L IAA in combination with 0.5 mg/L BA. The growth of explants, as quantified by their fresh and dry weights, was significantly higher in the 1 mg/L IAA with 1 mg/L BA treatment as compared with the 0.1 mg/L IAA plus 1.0 mg/L BA. The increasing concentrations of BA reduced the percentage of explants forming roots. From regeneration media, shoots were transferred to Murashige and Skoog medium supplemented with 1 mg/L IAA for root induction. After six weeks, the rooted plantlets were removed from culture and successfully hardened off in the shade house. For the multiplication of S. rexii Lindl., the best combination was the one involving 1 mg/L IAA and BA. This treatment obtained a highest shoot count and had the highest growth rate. This could play a key role in the large scale mass propagation of this plant. Key words: Streptocarpus rexii Lindl., initiation, rooting. INTRODUCTION The genus Streptocarpus belongs to the family Gesneriaceae. The genus is comprised of 132 species (Burtt and Hilliard, 1971), of which 87 species originate from South Africa, 41 species from Madagascar and the Comoro Islands and 4 species are found in Asia, which are not closely related to the African and Madagascar species (Afkhami-Sarvestani et al., 2006). Streptocarpus species are divided into two subgenera according to their morphological characteristics. The subgenus Streptocarpella (44 species) (Afkhami-Sarvestani et al., 2006) have well-developed stems, numerous small leaves *Corresponding author. E-mail: ndakidemipa@gmail.com. Abbreviations: ANOVA, Analysis of variance; BA, benzyladenine; cm, centimetres; g/L, grams per litre; HCI, hydrochloric acid; IAA, indole-acetic acid; MS, Murashige and Skoog; Min, minutes; mg/L, milligrams per litre; ml, millilitres; mm, millimetres. and auxiliary inflorescences usually marked by having 30 chromosomes (Burtt and Hilliard, 1971). The subgenus Streptocarpus (88 species) show long peduncles, have 32 chromosomes and a rosette growth habit (Burtt and Hilliard, 1971; Afkhami-Sarvestani et al., 2006). Streptocarpus rexii Lindl., occurring eastward in South Africa from George to Kwazulu-Natal (Goldblatt and Manning, 2000), was the first species of the genus to be discovered, as it occurs further to the south west than Cape Town, where botanical exploration began (Burtt and Hilliard, 1971). Introduced into cultivation from the first discovered plants, it has become by far the best known species of Streptocarpus and the basis of the garden strains developed by its hybridization with various other species (Burtt and Hilliard, 1971). This plant is a rosulate perennial, up to 20 cm in height, and flowers in October to April. Flowers are funnel-shaped, tube flaring, with streaks in the throat (Goldblatt and Manning, 2000). Streptocarpus spp. Are propagated conventionally either sexually by seeds or vegetatively by divisions and leaf