Development of clonal propagation protocols for Uapaca kirkiana and Pappea capensis, two southern African trees with economic potential

Experiments were carried out with the objectives of developing propagation protocols for Uapaca kirkiana and Pappea capensis tree species of southern Africa, and evaluating the graft compatibility within U. Kirkiana tree clones, provenances and species. Reverse phase high performance liquid chromatography (RP-HPLC), Folin-Ciocalteau reagent, fluorescence microscopy and callus fusion methodologies were used to diagnose graft compatibility. Results indicated that U. Kirkiana culture asepsis was achieved with 0.1% w/v mercuric chloride HgCl2) and using pre-conditioned grafted trees. Sodium hypochlorite (NaOCl) improved P. Capensis seed asepsis and germination, and discarding floating seeds improved germination. Murashige and Skoog (MS) medium with 2.0 mg l-1 benzylaminopurine (BAP) and 0.3 mg l-1 casein hydrolysate (CH) was superior in shoot multiplication and 0.5 mg l-1 indole-3-butyric acid (IBA) for rooting of P. Capensis microshoots. For somatic embryogenesis, three quarter strength MS medium with 0.05 mg l-1 thidiazuron (TDZ) and 0.3 mg l-1 CH, or 0.2 mg l-1 BAP with 0.3 mg l-1 CH, were effective in germination of P. Capensis somatic embryos. For U. Kirkiana lateral shoot explants, shoot multiplication was superior on three quarter strength MS medium with 0.1 mg l-1 BAP and 0.3 mg l-1 CH. Rooting of micro-cuttings (36%) was achieved on ½ MS with 2.5 mg l-1 IBA. RP-HPLC, fluorescence microscopy and callus fusion studies showed that phenolic compounds play a major role in U. Kirkiana graft incompatibility. Less graft compatible combinations showed an increase in phenol deposits above the union and graft incompatibility was more pronounced above the union than below the union. Proliferation of parenchymatous tissues was better below the union than above the union. Fluorescence microscopy showed presence of flavonoids and polymers above the union of less graft compatible combinations. The chromatograms showed that ferulic acid was abundant and responsible for wood discolouration. The chromatograms also isolated ρara-coumaric acids which were predominant above the union of the less compatible combinations. Therefore, ρara-coumaric acids, flavonoids and polymers were implicated in graft incompatibility of U. kirkiana trees. CopyrightThesis (PhD)--University of Pretoria, 2008.Plant Production and Soil Scienceunrestricte

A simple method of formulating least-cost diets for smallholder dairy production in subSaharan Africa,”

Smallholder dairy farmers in sub-Saharan Africa are constrained by inadequate supply of good quality protein sources particularly during the dry season. Commercial protein concentrates are expensive and not readily accessible. Multipurpose forage legumes and other non-conventional protein sources available on-farm have been promoted as alternative cheaper protein sources. The major problem faced by smallholder dairy farmers however is the formulation of diets balanced for the key nutrients and also being cost-efficient. This paper presents a step by step spreadsheet based procedure of diet formulation for smallholder dairy production. The procedure ensures that the diet is balanced for all the key nutrients, is low-cost and the user has significant control over the formulation process. An example using this formulation method incorporating the fodder legumes Leucaena diversifolia, Leucaena pallida, Leucaena esculenta, Acacia angustissima and Calliandra calothyrsus indicate a cost reduction from 10% on C. calothyrsus to 30% on L. diversifolia inclusion when compared to the conventional dairy meal concentrate (US$ 0.34/kg). This ration formulation method is recommended for use by livestock extension advisors and smallholder dairy farmers to quickly formulate low-cost diets using locally available feed sources so as to optimise the feeding of dairy animals at the farm level