Methodological approaches for the selection of genotypes in a progeny trial of Dacryodes edulis (G. Don) H. J. Lam in Cameroon

The World Agroforestry Centre (ICRAF) initiated a program in Cameroon for the selection of improved genotypes of Dacryodes edulis for domestication. There are major challenges in such selection because superior performance of individual trees may be based on site conditions rather than on genetic differences. Open-pollinated seeds were collected from mother trees in four provenances in Cameroon and planted in a progeny trial at Minkoameyos, Cameroon. Progeny from the same mother tree are referred to as family. After one year of growth in the field, growth traits were measured annually for five years and fruit traits were measured in two successive years. Three methodological approaches were investigated: family and within-family selection (combined selection), ranking for phenotypic selection and correlation for multi-trait and early selection. Variation in growth and fruit traits among families was not significant for most provenances, indicating that family selection would not be effective for the selection of genotypes in the trial. Phenotypic selection resulted in the retention of a small number of individuals of all families in the trial. There were strong positive correlations between fruit traits and between fruit and growth traits, while negative correlations were found between fruit traits and yield. The correlations indicate that selecting for one fruit trait may also improve the other fruit traits but reduce fruit yield. Positive and significant juvenile-mature correlations for growth were also found in this trial, indicating that early selection may be possible based ongrowth. Based on these results, phenotypic selection is recommended in the progeny trial for the domestication program in Cameroon and further research on early selection is needed as the trial advances in age

Influence de la provenance du géniteur et du type de pollen sur la fructification sous pollinisation contrôlée chez Dacryodes edulis (Burseraceae) au Cameroun

Très peu de travaux ont été réalisés sur l’amélioration variétale des espèces locales. L’amélioration de leur germoplasme aboutit à l’obtention du matériel végétal amélioré destiné à la création de nouveaux cultivars. Des essais de pollinisations croisées contrôlées ont été menés sur Dacryodes edulis dans le but d’évaluer l’influence de la provenance des géniteurs et du type de pollen sur la fructification de 14 accessions femelles issues de 03 provenances. Les croisements ont été effectués selon un schéma en bloc imbriqué. Pour chaque croisement effectué, le nombre de fleurs pollinisées, le nombre de fruits noués et le nombre de fruits arrivés à maturité ont été évalués; le taux de nouaison (TN), l’indice de fructification (IF) et le taux de chute des fruits (TC) calculés et soumis à une analyse de variance. A partir des moyennes obtenues, les différentes combinaisons ont été classées en fonction de leur performance à l’aide du ‘cluster analysis’. Les résultats obtenus ont montré que l’indice de fructification qui détermine le rendement de l’espèce étudiée varie uniquement et de manière significative (p=0,010) sous l’action combinée des trois facteurs étudiés. Six meilleures combinaisons caractérisées principalement par un taux de nouaison, un taux de fructification élevés et un faible taux de chute de fruits après nouaison (plus de 70%, plus de 50% et moins de 20% respectivement) ont été identifiées. Les graines des fruits (hybrides F1) issues de cette étude ont été caractérisées et les plants ont été produits en pépinière. Ces derniers serviront de matériel de base d’un essai clonal dans un futur proche.Mots clés: Banque de gènes, essai clonal, germoplasme, safoutier, pollinisation contrôlé

Soil water regime under rotational fallow and alternating hedgerows on an Ultisol in southern Cameroon

Article purchasedSoil moisture depletion during dry seasons by planted hedgerows to lower levels than under natural fallow, would reduce drainage and nutrient losses in the following rainy season when food crops are grown. The volumetric water content of the 0–150 cm soil profile was measured under planted hedgerows (alternating Leucaena leucocephala and Gliricidia sepium) and natural fallow, both either annually cropped to sole maize or in a two-year crop/two-year fallow rotation, in the humid forest zone (annual rainfall 1700 mm) of southern Cameroon during the 1995–1996 and 1996–1997 dry seasons. Hedgerows were cut to 0.05 m height, largely eliminating trees’ water consumption during cropping phases. Differences in total soil water content at 0–150 cm depth, between systems, occurred only in the early phases of the 1996–1997 dry season. In both dry seasons, differences between systems in water content were found in some soil layers, all within 0–60 cm depth, yet, without consistent advantage of any system in exploiting the topsoil water resources. Soil water content was lower under L. leucocephala than G. sepium at 20–40 cm depth only. Below 60 cm depth, no differences in water regimes between systems were found. Under southern Cameroonian conditions it is unlikely that any of the systems has an advantage in accessing or recovering water and thus, if available, nutrients from the sub-soil. None of the systems examined was capable of delaying drainage and thus it appears unlikely that downward displacement of nutrients is delayed after the start of the rains

Perspectives for sustainable Prunus africana production and trade

This brief documents current knowledge about pygeum (Prunus africana). It aims to inform decision makers in governments in producing and consumer countries, international and civil society organisations and researchers, about sustainable (international) trade and governance of the species

Ensuring the future of the pygeum tree (Prunus africana)

This report is aimed at trainers and support organisations for farmers and tree owners, as well as commercial tree nursery operators, government extension agencies and NGOs, among others, who are interested in cultivating the pygeum tree

Sprechhilfe

Zusammenfassung: Das Thema dieser Studienarbeit ist die Entwicklung und der Aufbau einer Sprechhilfe für einen Patienten. Der Patient spricht zwar deutlich, aber so leise, daß er sich auch in einem kleinen Kreis von Zuhörern nicht ausreichend verständlich machen kann. Außerdem nimmt die ohnehin schon geringe Lautstärke seiner Sprache mit lang anhaltender Sprechdauer deutlich ab. Diese Mängel werden mit dem hier vorgestellten, tragbaren, elektroakustischen Gerät behoben. Im Gegensatz zu anderen Geräten für Sprachbehinderte, die mit Kegelkopfabtastung arbeiten und dadurch den natürlichen Klang der Sprache sehr verändern, hat dieses Gerät eine natürliche Klangwiedergabe, eine automatische Lautstärkeregelung und enthält ein einstellbares Präsenzfilter zur Verbesserung der Verständlichkeit. Die komplette Anlage besteht aus einem kleinen Lavailier-Ansteckmikrofon, einem elektronischen Signalverarbeitungsteil und einem kleinen, flachen Lautsprecher. Die verwendeten Komponenten sind auf geringen Eigenenergieverbrauch hin optimiert. Auch wird die Energieversorgung während langer Sprechpausen unterbrochen. Ein steckbares Teil des Gehäuses enthält wiederaufladbare Kleinbatterien für die Energieversorgung. Die sehr kleine Baugröße ermöglicht es, die komplette Anlage am Körper bzw. in den Brusttaschen unauffällig zu tragen. Es ist ein Anschluß für eine Erweiterungsschaltung vorgesehen, um das Problem der akustischen Rückkopplung zu lösen. In dieser Arbeit wird dieses Problem ausführlich behandelt und ein Lösungskonzept vorgeschlagen, das auf dem Frequenzverschiebungsverfahren basiert. Vorgesehen ist ein Anschluß für ein Diktiergerät oder eine Aktivlautsprecherbox. Möglich ist auch ein Einsatz der Schaltung als hochwertiger Mikrofonvorverstärker in Sprech- oder Gesanganlagen. Technische Daten: * Betriebsspannung: ±9V * Maximale Ausgangsleistung: 1,2W (an 8Ω) * Eingangsempfindlichkeit: 2mV * Klirrfaktor: <1

Oil and Gas Production, Environmental Health and Livelihood Vulnerability in the West Coast of Ghana

The paper has examined the level of communities’ knowledge about associated environmental health and livelihood risks of oil exploration and development along the western coast of Ghana. Data was collected from selected stakeholders in three coastal towns: Axim, Half Assini and Asanta in the Western Region of Ghana. Data was analysed thematically using SPSS (Version 16) and MS Excel. The study has found very low levels of awareness with regards to the impacts of oil production on environmental health and livelihoods in the communities. There is a high level of susceptibility of the coastal communities to violations of their health, as well as their environmental and livelihood rights. Respondents’ level of education significantly influences their level of knowledge about potential health and livelihood impacts of the oil production in the area. It was also found that oil and gas companies have not created enough awareness of the impact of their operation in the communities. The study concludes that the rights of the communities to good health, clean environment, sustainable livelihood and social development are susceptible to violation by oil and gas firms. The study recommends an immediate intervention to build the capacity of communities to defend their rights, particularly their health, environment and livelihood rights. Key Words: Oil and gas, environmental health, livelihood, vulnerabilit

Soil water regime under rotational fallow and alternating hedgerows on an Ultisol in southern Cameroon

Abstract Soil moisture depletion during dry seasons by planted hedgerows to lower levels than under natural fallow, would reduce drainage and nutrient losses in the following rainy season when food crops are grown. The volumetric water content of the 0-150 cm soil profile was measured under planted hedgerows (alternating Leucaena leucocephala and Gliricidia sepium) and natural fallow, both either annually cropped to sole maize or in a two-year crop/two-year fallow rotation, in the humid forest zone (annual rainfall 1700 mm) of southern Cameroon during the 1995-1996 and 1996-1997 dry seasons. Hedgerows were cut to 0.05 m height, largely eliminating trees&apos; water consumption during cropping phases. Differences in total soil water content at 0-150 cm depth, between systems, occurred only in the early phases of the 1996-1997 dry season. In both dry seasons, differences between systems in water content were found in some soil layers, all within 0-60 cm depth, yet, without consistent advantage of any system in exploiting the topsoil water resources. Soil water content was lower under L. leucocephala than G. sepium at 20-40 cm depth only. Below 60 cm depth, no differences in water regimes between systems were found. Under southern Cameroonian conditions it is unlikely that any of the systems has an advantage in accessing or recovering water and thus, if available, nutrients from the sub-soil. None of the systems examined was capable of delaying drainage and thus it appears unlikely that downward displacement of nutrients is delayed after the start of the rains