Garcinia kola phenophases in Benin: Influence of phytodistrict and age of subjects

Garcinia kola est une espèce à usage multiple dont la mauvaise gestion contribue à sa rareté. L’Union Internationale pour la Conservation de la Nature (UICN) l’a déclarée « vulnérable ». L’objectif de cette étude est de déterminer l’influence du phytodistrict et de l’âge sur les phénophases de Garcinia kola au Bénin. Un échantillonnage stratifié a été réalisé sur 42 arbres qui ont été aléatoirement sélectionnés parmi ceux en cours de production de fruits dans les districts phytogéographiques de Pobè et de la Vallée de l’Ouémé. Des relevés et  observations phénologiques ont été effectués chaque mois. Les données collectées ont été utilisées pour calculer et analyser les fréquences relatives des différents processus phénologiques (feuillaison, floraison, fructification) en considérant les âges et les districts grâce au logiciel R. Les résultats ont montré que les périodes de phénophases varient suivant le district phytogéographique et l’âge de l’espèce. Ces résultats impliquent que la restauration de l’espèce ainsi que sa conservation in situ en zone guinéo-congolaise au Bénin, peuvent significativement se réaliser aussi bien dans le district phytogéographique de Pobè que dans celui de la Vallée de l’Ouémé, avec un avantage de précocité des phenophases dans le district phytogéographique de Pobè. Mots clés: Garcinia kola, feuillaison, floraison, fructification, Sud-BéninGarcinia kola is a multiple-use species whose poor management contributes to its scarcity. The International Union for Conservation of Nature (IUCN) has declared it "vulnerable". The objective of this study is to determine the influence of phytodistrict and age on the phenophases of Garcinia kola in Benin. Stratified sampling was carried out on 42 trees which were randomly selected from those currently producing fruit in the phytogeographic districts of Pobè and the Ouémé Valley. Recordings and phenological observations were made every month. The data collected were used to calculate and analyze the relative frequencies of the different phenological processes (leafing, flowering, fruiting) by considering the ages and the districts thanks to the R software. The results showed that the periods of phenophases vary according to the phytogeographic district and the age of the species. These results imply that the restoration of the species as well as its in situ conservation in the Guinean-Congolese zone in Benin can be significantly achieved both in the phytogeographic district of Pobè and in that of the Ouémé Valley, with an advantage of early phenophases in the phytogeographic district of Pobè. Keywords: Garcinia kola, leaves, flowering, fruiting, South-Beni

Survey of farmers’ knowledge of cassava mosaic disease and their preferences for cassava cultivars in three agro-ecological zones in Benin

Abstract Background Cassava is an important crop in Africa that is widely cultivated for its starchy tuberous root, which constitutes a major source of dietary carbohydrates. Cassava mosaic disease (CMD) is the most devastating disease affecting cassava in Africa and causes enormous losses in yield. In Benin, specifically, cultivars resistant to CMD are not commonly planted, and even when CMD is observed in fields, farmers do not implement control measures, presumably because they lack proper knowledge and training. Our study aimed to evaluate farmers’ knowledge of CMD to determine whether there is consistency between farmers’ criteria for selecting cassava cultivars and the currently CMD-recommended cassava varieties. Methods We conducted structured interviews with 369 farmers in 20% of townships in each of three agro-ecological zones in Benin between November 2015 and February 2016. Farmers were selected randomly in each household, and their fields were assessed for CMD incidence and severity. Results All farmers surveyed, representing a broad demographic pool with regard to education level, age group, and years of experience in cassava production, successfully recognized CMD symptoms in photos, but most (98.60%) said they did not know the causes and vectors of the disease. Most farmers (93.51%) reported that they obtain planting material from neighboring fields or their own fields. In total, 52 unique cultivars were identified, of which 3 (5.76%) were preferred based on their yield and precocity and 3 (5.76%) were preferred based on taste or ability for transformation. The assessment of disease incidence and severity showed that the areas most affected by CMD were Comè Township (37.77% of fields affected) and agro-ecological zone VIII (26.33%). Conclusion Farmers already know how to recognize the symptoms of CMD and could implement control measures against it if they are trained by researchers. Across all surveyed areas, we identified six preferred cultivars based on the four most commonly stated preference criteria (precocity, yield, gari, and taste. Our results suggest that farmers will be more likely to use CMD-resistant cultivars and clean plant material if the plants meet their existing preference criteria. We suggest that CMD-resistant cultivars will be embraced only if the recommended cultivars are strategically aligned with the characteristics desirable to the cassava farmers in each region

Response of cassava cultivars to African cassava mosaic virus infection across a range of inoculum doses and plant ages.

Cassava production in Africa is constrained by cassava mosaic disease (CMD) that is caused by the Cassava mosaic virus (CMV). The aim of this study was to evaluate the responses of a range of commonly cultivated West African cassava cultivars to varying inoculum doses of African cassava mosaic virus (ACMV). We grafted 10 cultivars of cassava plants with different inoculum doses of CMV (namely two, four, or six CMD-infected buds) when the experimental plants were 8, 10, or 12 weeks old, using non-inoculated plants as controls. Three cultivars showed disease symptoms when grafted with two buds, and four cultivars showed disease symptoms when grafted with four or six buds. Most cultivars became symptomatic six weeks after inoculation, but one ('TMS92/0326') was symptomatic two weeks after inoculation, and two ('Ntollo' and 'Excel') were symptomatic after four weeks. Root weight tended to be lower in the six-bud than in the two-bud dose, and disease severity varied with plant age at inoculation. These results indicate that the level of CMD resistance in cassava cultivars varies with inoculum dose and timing of infection. This will allow appropriate cultivars to be deployed in each production zone of Africa in accordance with the prevalence of CMD