Macropropagation and micropropagation of Ziziphus spina-christi Macropropagação e micropropagação de Ziziphus spina-christi

Christ's thorn (Ziziphus spina-christi (L.) Desf.) is a cross-pollinated plant with a wide range of genetic variability in nature and, for this reason, vegetative propagation assumes importance for improvement programs. The objective of this work was to evaluate cutting, T budding and tissue culture methods for this species. Shoots of 22-25 cm length were treated by two culture media and three shoot diameters for cutting trial. The T budding treatments consisted of three and five collection dates in spring and autumn, respectively. Tissue culture nodal segments bearing axillary buds were removed from shoots of mature trees at different seasons. Experiments to determine the best disinfectant chemical, appropriate conditions and materials to prevent phenolic compound exudation, explant characteristics, media type and cytokinin-auxin ratios were carried out. Successful rooting happened only on the sand beds and with cuttings greater than 8 mm diameter. The effects of T budding seasons on budtake percentage were significantly different. The best time for explant harvesting was mid of summer. Amount of rooting on media containing IBA as well as activated charcoal and disinfection with Ca(OCl)2 at concentration of 5% for 20 minutes were the best treatments.<br>Ziziphus spina-christi (L.) Desf. é uma planta de polinização cruzada com grande variabilidade genética na natureza e, por isso, sua propagação vegetativa assume importância para o melhoramento genético. O objetivo deste trabalho foi avaliar os métodos de estaquia, borbulhia em T e cultura de tecido na propagação vegetativa desta espécie. No ensaio de estaquia, partes aéreas da planta com 22-25 cm foram cultivadas em dois meios de cultura e com três diâmetros. O ensaio de borbulhia consistiu na coleta do material em três datas na primavera e em cinco datas no outono. Os segmentos nodais contendo gemas axilares foram removidos da parte aérea de árvores maduras, em diferentes estações do ano, e avaliados em relação à esterilização química, exudação de compostos fenólicos e cultivo. O enraizamento ocorreu apenas em camas de areia e em estacas maiores do que 8 mm. Houve efeito significativo da estação do ano sobre a porcentagem de brotação. O melhor período para coleta do explante foi no verão. O meio contendo IBA e carvão ativado apresentou maior quantidade de raízes e o melhor desinfestante foi Ca(OCl)2 na concentração de 5%, por 20 minutos

Advances in domestication of indigenous fruit trees in the West African Sahel

Fruit trees play an important nutritional role for livelihoods of rural people in the West African Sahel through provision of energy and nutrients such as vitamins, minerals, and proteins. Research on the domestication of local fruit trees has started recently through projects concentrating on some of the most important indigenous species of dry West Africa, i.e. Adansonia digitata, Parkia biglobosa, Tamarindus indica, Vitellaria paradoxa and Ziziphus mauritiana. We present a status of finalised and ongoing domestication research with the aim of defining research gaps that would need to be covered by future research activities to obtain higher yields and better quality fruits. Germplasm collection in central West Africa has been intense compared to elsewhere in the species' distribution areas, but conservation status of the material is poor since it is only planted in few trials. Knowledge of genetic parameters, especially for fruit traits, is almost absent, but characterisation of genotypes is underway for some of the species. Mating systems and patterns are still unknown for many species. Efficient vegetative propagation based on simple techniques was shown to be possible for all species except P. biglobosa. In order to secure immediate as well as long term gains, we recommend combining clonal propagation of selected plus individuals with recombination and breeding of selected genotypes. We discuss whether local institutions in the Sahel have the financial capacity to carry out long term breeding programmes, and suggest that efforts should be made to find new ways of disseminating improved germplasm