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Title La "domestication" du samba: l'experience ecossaise.CEH Staff publications
Name(s) Longman, K A (Alan)
Leakey, R.R.B. (Roger)
Publication 1995
Subjects T01060a2; CEH staff publication;
Abstract Triplochiton scleroxylon (obeche) is an indigenous hardwood of West Africa (fig 1), which has been widely exploited for timber, but only established in small plantations because of poor seed availability and short seed viability. Techniques have however been developed for low temperature (- 18 degrees C) seed storage. In addition, vegetative propagation techniques have been developed to provide an alternative form of planting stock. Single-node cuttings (fig 2A) root well when the stockplants have been managed correctly. Rooting is enhanced by applications of auxin (fig 3), with an optimum dose of 40 mu g per cutting. Trimming the leaf to about 50 cm(2) optimises rooting, giving the best balance between photosynthesis and transpiration (ie carbon/water content). Rooting ability is strongly influenced by stockplant condition and physiological status. In addition, the origin of the cutting within a shoot (fig 4) and the position of the shoot within the stockplant pre-determine rooting ability. The differences in the rooting of cuttings from different shoots are affected by the level of competition between shoots for light (fig 5). Both the level of irradiance and its spectral composition influence this pre- conditioning effect of light through influences on leaf and stem morphology and their physiological status. To promote the implementation of these techniques in developing countries, improved, high- humidity non-mist poly-propagators have been developed. Through vegetative propagation, clones are formed, so offering the opportunity for selection of genetic superiority (fig 2B, C). Pronounced clonal variation in yield and form has been identified in Nigeria (fig 6), with the highest-yielding 4% giving a genetic gain of about 100% above the average of unselected material. A simple predictive test for branching habit has been developed (figs 7 and 8). This can greatly reduce the numbers of genotypes that need to be tested in field trials. Precocious flowering of obech
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