Afin d'optimiser l'usage des mycorhizes en agriculture, douze inoculants commerciaux de champignon mycorhizien arbusculaire (CMA) furent évalués en serres sur le maïs. Dans un premier temps, les inoculants furent propagés en pots sur sable stérilisé afin d'évaluer leur potentiel sur la colonisation racinaire du maïs par rapport à celui d'un sol agricole du Kenya et d'inventorier les espèces CMA contenues dans les inoculants. Trois inoculants augmentèrent le taux de colonisation racinaire comparé au sol agricole. Treize espèces AMF furent isolées des inoculants dont 5 non déclarées. Quatre des 12 espèces annoncées n'ont pas sporulé. Dans une seconde expérience, les inoculants furent utilisés en combinaison avec le sol agricole afin d'évaluer leur impact sur le rendement du maïs. Six semaines après le semis, 7 inoculants augmentèrent le taux de colonisation racinaire par rapport au sol témoin alors que 3 inoculants entraînèrent une légère augmentation de la biomasse aérienne. Ces évaluations démontrent la nécessité d'effectuer une pré-évaluation des inoculants commerciaux sur une culture et un sol donnés avant de les implanter à grande échelle. (Résumé d'auteur

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A green house study was conducted to investigate the ability of an isolate of Trichoderma harzianum (P52) and arbuscular mycorrhizal fungi (AMF) in enhancing growth and control of a wilt pathogen caused by Fusarium oxysporum f. sp. lycopersici in tomato seedlings. The plants were grown in plastic pots filled with sterilized soils. There were four treatments applied as follows; P52, AMF, AMF + P52 and a control. A completely randomized design was used and growth measurements and disease assessment taken after 3, 6 and 9 weeks. Treatments that significantly (P < 0.05) enhanced heights and root dry weights were P52, AMF and a treatment with a combination of both P52 and AMF when compared the control. The treatment with both P52 and AMF significantly (P < 0.05) enhanced all growth parameters (heights; shoot and root dry weight) investigated compared to the control. Disease severity was generally lower in tomato plants grown with isolate P52 and AMF fungi either individually or when combined together, though the effect was not statistically significant (P 0.05). A treatment combination of P52 + AMF had less trend of severity as compared to each individual fungus. T. harzianum and AMF can be used to enhance growth in tomato seedlings.

The African Mycological Association (AMA) promotes mycology amongst members in Africa and globally. The AMA has about 200 members, mostly from African states but also with strong representation from Europe and USA, amongst others. Recent efforts by members of the AMA focused on reviving and developing mycological research and networking in Africa. A great deal must, however, still be done to promote the AMA under African mycologists, and those elsewhere with interests in Africa. African mycologists also experience challenges typical of the developing world and a great deal of fungi still needs to be discovered. This can also be seen as representing great opportunities for research and collaboration. Several issues pertinent to mycology in Africa were discussed during Special Interest Group sessions of the 9th International Mycological Congress in 2010, and through several opinion pieces contributed by AMA members in the AMA newsletter, MycoAfrica. This contribution serves as a document to summarise these in a form that can be presented to fellow mycologists, biologists and other scientists, relevant government departments, funding bodies and Non-Governmental Organizations and that pins down the importance of mycology, the status thereof in Africa and the need to promote it more.

Prokaryotic communities play key roles in biogeochemical transformation and cycling of nutrients in the productive mangrove ecosystem. In this study, the vertical distribution of rhizosphere bacteria was evaluated by profiling the bacterial diversity and community structure in the rhizospheres of four mangrove species (Sonneratia alba, Rhizophora mucronata, Ceriops tagal and Avicennia marina) from Mida Creek and Gazi Bay, Kenya, using DNA-metabarcoding. Alpha diversity was not significantly different between sites, but, significantly higher in the rhizospheres of S. alba and R. mucronata in Gazi Bay than in Mida Creek. Chemical parameters of the mangrove sediments significantly correlated inversely with alpha diversity metrics. The bacterial community structure was significantly differentiated by geographical location, mangrove species and sampling depth, however, differences in mangrove species and sediment chemical parameters explained more the variation in bacterial community structure. Proteobacteria (mainly Deltaproteobacteria and Gammaproteobacteria) was the dominant phylum while the families Desulfobacteraceae, Pirellulaceae and Syntrophobacteraceae were dominant in both study sites and across all mangrove species. Constrained redundancy analysis indicated that calcium, potassium, magnesium, electrical conductivity, pH, nitrogen, sodium, carbon and salinity contributed significantly to the species–environment relationship. Predicted functional profiling using PICRUSt2 revealed that pathways for sulfur and carbon metabolism were significantly enriched in Gazi Bay than Mida Creek. Overall, the results indicate that bacterial community composition and their potential function are influenced by mangrove species and a fluctuating influx of nutrients in the mangrove ecosystems of Gazi Bay and Mida Creek.

The study investigated diversity and frequency of occurrence of glomale (Arbuscular-or Vesicular Arbuscular-) mycorrhizal fungi on three farming systems in a drought prone and nitrogen deficiency site in southern Malawi. The farming systems comprised of two agroforestry systems of Sesbania sesban (L) Merr intercropped with maize and Sesbania macrantha E Phillips & Hutch. intercropped with maize and a maize monocrop systems without fertilizer, with nitrogen, phosphorus and a combination of nitrogen and phosphorus. Species diversity and species frequency of occurrence were examined in soil samples obtained in the dry and wet seasons. Twelve glomale mycorrhizal species were recorded, four species being in the genus Acaulospora, four in Glomus, two in Gigaspora and two in Scutellospora. Species diversity in the two agroforestry systems were not significantly (p £ 0.05) different but had lower species diversity than maize monocrop with only Sesbania macrantha intercropped with maize significantly (p £ 0.05) lower. Species diversity was significantly increased by the inorganic nitrogen fertilizer. Inorganic phosphorus fertilizer had no effect. The study shows that the occurrence and persistence of glomale species are influenced by agroforestry combinations, and that the spores of most species are tolerant to dry conditions. Only four species responded to fertilizer application with the occurrence of spores of some species high and some low. Management practices have great implication in the persistence of spore propagules of glomale species.

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