Management of the mycorrhizal soil infectivity with Crotalaria ochroleuca, an indigenous wild legume in the tropics: Impacts on microbial functional diversity involved in phosphorus mobilization processes in a sahelian soil

It is well known that the over exploitation of soil resources decreases the density and diversity of arbuscular mycorrhizal (AM) fungal propagules. It has been postulated that agricultural practices could promote the occurrence and functioning of remaining and resilient AM fungal ecotypes in order to benefit from AM associations. Using C. ochroleuca, a highly mycotrophic plant species, the aims of this study were to determine in controlled conditions, the impact of this legume species on: (i) the mycorrhizal soil infectivity (MSI), (ii) the Rock Phosphate (RP) solubilising activity and (iii) the soil microbial functions. The expected benefits of C. ochroleuca cultivation have been evaluated by comparing its biological influences with those recorded with a non-mycorrhizal plant species, Brassica oleracea in order to attest of the importance of the AM potential in RP weathering and soil functioning. The results show that: C. ochroleuca was effective in improving the mycorrhizal soil potential, (ii) functional abilities of soil microflora were influenced by the cultured plant species and the mycorrhizal soil potential and (iii) the efficiency of rock phosphate amendment on plant growth depended on the level of mycorrhizal soil potential and was linkedto the extent of the mycorrhizal network.The C. ochroleuca impact was significantly reinforced with KRP amendment (i.e. +29.3% for the Catabolic Eveness, +45.7% for the hyphal length). According to these results, it could be concluded that agricultural strategies based on the management of local biodiversity (i.e. the use of native legume species) could be considered as a sustainable practice to optimally manage AM fungi and to ensure their functionalities in order to maintain a sustainable production of food crops in the tropics.