Status of endogenous endomycorrhizal fungi associated with cowpea (Vigna unguiculata L.) in the Sudano-Sahelian zone of Cameroon

Abstract

The Sudano-Sahelian part of Cameroon is known for its severe climatic conditions and low soil fertility. Local farmers use chemical fertilisers to increase crop production, usually without moderation. As a result, there is environmental pollution such as soil acidification, production of greenhouse gases, and increased eutrophication. To face this situation, scientific research recommends ecological solutions such as bio-fertilisers to enhance soil fertility. In this context, the mycorrhiza symbiosis technology deserves special attention. Indeed, it is a beneficial association between soil fungi (Glomeromycota) and the roots of more than 85% of plants; the evaluation of the agronomic potential of these microorganisms has shown spectacular results under field conditions. This study analyses the status of indigenous arbuscular mycorrhizal fungi in the cowpea rhizosphere in the agro-ecological zone 1 of Cameroon. For this purpose, soil samples were collected from the Far North and North regions of Cameroon. Composite soil samples were obtained by mixing soils collected from three divisions per region. Cowpea was grown in pots on these composite soil samples for 3 months. At maturity, spores of mycorrhizal fungi were isolated and parameters including mycorrhization frequency and intensity, the specific spore’s density and richness were evaluated. The spores were characterised according to morpho-anatomical criteria. The results established that between localities, mycorrhization frequency varied between 7-19%; mycorrhization intensity, 7-17.28%; specific density, 0.66-44% and specific richness, 2-4%. Eight specimens of arbuscular mycorrhizal fungi in six genera were characterised: Acaulospora (A. kentinensis, A. myriocarpa); Ambispora sp; Diversispora epigae, Funneliformis mossea, Glomus (G. constrictum, G. manihotis, and G. maculosum) and Rhizophagus intraradices. G. constritum was predominant in all the studied sites, followed by R. intraradices, while Acaulospora myriocarpa was the rarest. These results pave the way for the selection of indigenous arbuscular mycorrhiza fungi for ecological cowpea production in this area.