In this paper, the causes of early embryo abortion in the reciprocal crosses between Phaseolus vulgaris L. (a cultivar) and Phaseolus coccineus L. (a wild form) were studied. Methacrylate resin sections, 3-5 lm thick, of 3 to 14 day-old seeds were used to examine the embryo developmental stages and the state of seed tissue. It was observed that, embryos aborted at different developmental stages (globular to early cotyledon) depending on the maternal parent. The use of P. coccineus cytoplasm resulted in a higher number of abortion than in reciprocal crosses. Many of them took place between 5 and 6 days after pollination (DAP). Histological analyses permitted to observe that the embryo development was slower in the cross between P. coccineus and P. vulgaris, compared to parental seeds. It would be related to a deficient endosperm development in reciprocal crosses and, in some extent, hypertrophy of the suspensor might be the main cause of early embryo abortion. Then, it would be practical to overcome this incompatibility by rescuing the embryo at the globular stage of development.

Le scolyte des baies de café (Hypothenemus hampei Ferrari) limite fortement la production caféière au Sud-Est du Gabon. La présente étude vise à tester l'effet des extraits végétaux de Jatropha curcas L. et Tabernanthe iboga Baill. sur ce ravageur, comparativement à un insecticide chimique dont la matière active est l'Endosulfan. Suite au dénombrement et à l'élevage des scolytes, des extraits bruts de T. iboga et de J. curcas ont été mis au contact des insectes. Une évaluation des dégâts a suivi pour estimer les taux d'attaque des cerises du caféier. L'étude révèle l'action de ces extraits sur la mortalité et la réduction des dégâts causés par les scolytes. En effet, les extraits des feuilles de J. curcas non dilués tuent 100% des scolytes au même titre que l'insecticide organophosphoré dénommé Sultan 350 EC. Par ailleurs, les extraits des feuilles de T. iboga non dilués exercent une action répulsive sur le scolyte et les cerises sont protégées jusqu'à 66,67%. Ces extraits obtenus des végétaux naturels du Gabon constituent une alternative certaine aux insecticides de synthèse qui sont devenus inefficaces contre le scolyte des baies de café. © 2015 International Formulae Group. All rights reserved.Mots clé : Extraits végétaux, Jatropha curcas L., Tabernanthe iboga Baill., scolyte, cerises du caféier, mortalité. Effect of the extracts of Jatropha curcas L. and Tabernanthe ibogaBaill. in the fight against the coffee berry borer (Hypothenemus hampei Ferrari) in the South-East of Gabon ABSTRACTCoffee berry borer (Hypothenemus hampei Ferrari) strongly limits the coffee production in the SouthEast of Gabon. The present study aims to testing the effect of Jatropha curcas L. and Tabernanthe iboga Baill.P. NGUEMA NDOUTOUMOU et al. / Int. J. Biol. Chem. Sci. 9(6): 2764-2775, 2015 2765 plant extracts on this devastating insect, compared to a synthetic insecticide whose active compound is Endosulfan. After the enumeration and the breeding of the borers plant extracts of T. iboga and J. curcas were put in contact within sects. An evaluation of the damage and the estimation of the rates of attack of berries were under taken. The study reveals the action of these extracts on the mortality and the reduction of the damage caused by the borers. Indeed, the undiluted leaf crude extracts of J. curcas kill 100% of the insect similar to the rate observed using the insecticide « Sultan 350 EC ». In addition, the undiluted leaf crude extracts from of T. iboga exert a repulsive action on the borer and the berries are protected up to 66,67%. These extracts obtained from the natural plants of Gabon constitute an alternative to the synthetic insecticides which became ineffective against the coffee berry borer.

Fruit size and shape are important quality parameters for product appreciation by consumers. However, aspect ratio (width over length) was used to perform the choice of ratios for fruits shape determination and mass for fruit category. This study was carried to quantitative classify Safou size and shape in bush butter (Dacryodes edulis (G. Don) H.J. Lam) fruits using fruit mass, as well as outer length and width measurements (aspect ratio). Results obtained showed that mass and aspect ratio can be used to classify Safou fruit size (small, medium and large) and shape (ellipsoidal, Obovate and spheroidal), respectively.Medium-sized fruits were the most represented. Irrespective of thefruit size, the ellipsoidal shape was most frequent and spheroidal shape was mostly found amongst small fruits and not amongst large fruits.

Banana (Musa spp.) is grown throughout the tropical and subtropical areas. The Black Sigatoka, however, represents a major threat to world production. This study evaluates the effect of the arbuscular mycorrhizal fungus (AMF) Rhizophagus irregularis MUCL 41833 on four plantain cultivars with different resistance against Mycosphaerella fijiensis. The mycorrhized banana plantlets of four cultivars were grown under greenhouse and the effect of AMF on micropropagated banana plantlets was evaluated. After 35 days, the height and the diameter of the pseudostem, then the leaf area were measured. The significant effect of the cultivar on the height of the pseudostem and the leaf area and significant effect of M. fijiensis on the diameter of the pseudostem, the height of the pseudostem and the leaf area were obtained. Plants infected with M. fijiensis show more symptoms of the disease than healthy plants. Symptoms were delayed in bananas inoculated with AMF compared to bananas not inoculated with AMF. The disease progressed more rapidly in cultivars Bâtard and C292 than in cultivars CRBP39 and F568. These results suggest that AMF may decrease symptoms of Sigatoka, at the early stage of infection with M. fijiensis. AMF may be a promising tool for the pre-adaptation of micropropagated banana plantlets. Keywords: Plantain, Rhizophagus irregularis, arbuscular mycorrhiza fungi, Mycosphaerella fijiensis, disease control method.

Le Banana Bunchy Top Disease (BBTD) est la maladie virale la plus dévastatrice du bananier impactant considérablement sa production. Le BBTD a été signalé au Gabon pour la première fois par la FAO avec une prévalence de plus de 90%. La présente étude vise à déterminer la prévalence du BBTD, la sévérité et l’importance du vecteur dans la zone de Ntoum. Après une enquête, 1800 pieds de bananiers dans 6 foyers d’infestation, ont été examinés de façon aléatoire avec un système de notation randomisé en transect croisé X. La méthode d’enquête par observation visuelle des symptômes du BBTD avec une échelle de notation de 1 à 5 a été utilisée. Les foyers d’infestation retenus présentent une sévérité de la maladie avancée avec le symptôme visuel de niveau 5 prépondérant et une prévalence moyenne de 21%. Le vecteur, Pentalonia nigronervosa est un insecte présent dans la zone mais à des niveaux d’importance variable. Il serait souhaitable d’évaluer la résistance variétale des Musa spp. et de montrer l’influence des facteurs biotiques et abiotiques sur la propagation de la maladie.Mots clés : Bananier, Pentalonia nigronervosa, foyers d’infestation, sévérité, importance du vecteur.   English Title: Prevalence of Banana Bunchy Top Disease (BBTD) in the Ntoum area in Gabon Banana Bunchy Top Disease (BBTD) is the banana's most devastating viral disease, with a significant impact on its production. BBTD was first reported in Gabon by FAO with a prevalence of more than 90%. This study aims to determine the prevalence of BBTD, the severity and importance of the vector in the Ntoum area. After a survey, 1800 feet of banana trees in 6 outbreaks, were examined randomly with a randomized scoring system in transect crossed X. The method of visual observation of BBTD symptoms with a rating scale of 1 to 5 was used. The selected outbreaks have an advanced disease severity with the predominant level 5 visual symptom and an average prevalence of 21%. The vector, Pentalonia nigronervosa is an insect present in the area but at varying levels. It would be desirable to assess the varietal resistance of Musa spp. and to show the influence of biotic and abiotic factors on the spread of the disease.Keywords: Banana, Pentalonia nigronervosa, source of infestation, severity, importance of vector.