DISTRIBUTION AND ABUNDANCE OF ARBUSCULAR MYCORRHIZAL FUNGI OF Argania spinosa TREE AND MYCORRHIZAL INFECTIOUS POTENTIAL OF RHIZOSPHERIC SOIL OF 15 ARGANIA GROVES IN SOUTHWESTERN MOROCCO

Although some studies have characterized endomycorrhizal fungi population occuring in rhizosphere soils of argan trees grown in the southwest of Morocco, numerous sites of this area remained unexplored. There is a need to study additional soil samples which cover more sites of argan tree stands. Hence, we studied endomycorrhizae diversity and the mycorrhizogenic infectious potential (MIP) of rhizosphere soils collected from 15 argan forest stands (Lakhssas, Smimou, Ait Baha, Tamanar, Essaouira, Taroudante (Elkoudia), Ighrm, Guelmim, Immsouane, Anzi, Tiznit, Taghazoute, Ait Melloul, Bouizakarne and Oulad Teima) .The results revealed the presence of different AMF structures such as vesicles and arbuscules in the root cortex of the argan tree with a respective frequency of mycorrhization in the range of 90% and 100%. The total number of AMF spores isolated from the rhizosphere were between 561 spores/100g of soil (Smimou) and 69 (Tiznit). 39 morphotypes of endomycorrhizal fungal spores were identified representing 7 genera: Glomus (15 species), Scutellospora (3 species), Entrophospora (4 species), Pacispora (2 species), Gigaspora (4 species), Acaulospora (10 species) and Ambispora (1 species). This AMF community was dominated by the species Glomus macrocarpum whose appearance frequency reached 12.64%. It was found that 3g of rhizosphere soil of argan trees from different sites in southwestern Morocco promoted mycorrhization of sorghum plants at rate of 50% which reflected a high infectious potential under bioassay conditions. This potential offers an opportunity for production of vigorous argan seedlings that can resist to natural environment constraints.