Effect of the number of years of soil exploitation by saffron cultivation in Morocco on the diversity of endomycorrhizal fungi

Abstract

The diversity of endomycorrhizal fungi in the rhizosphere of Crocus sativus has been studied at five sites in the Taliouine region (Tinfat), located in Taroudant Province (Morocco), according to the number of years of soil exploitation by Saffron cultivation. In all sites, the roots of Crocus sativus carry structures of endomycorrhizal fungi. Root mycorrhizal frequencies are very high in site 1 (93.33%); site 2 (96.67%); site 4 (90%) and in site 6 (93.33%). In these sites, the spore density is, respectively, 39, 58, 138, 99 spores / 100 g of soil. The frequency of root mycorrhization is lower at the site (76.66%) which also exhibited a spore density of 27 spores / 100 g of soil. The identification of isolated spores made it possible to note the presence of 36 species belonging to 6 genera: Glomus (15 species), Acaulospora (10 species), Scutellospora (6 species), Gigaspora (2 species), Pacispora (2 species), Entrophospora (1 species). Species such as Glomus clarum, G. etunicatum, G. aggregatum, G. intraradices, Acaulospora laevis, Scutellospora coralloidea, were present in all studied sites. The greatest richness of MA fungi was registers in the site at four successive years of exploitation by Saffron (24 species), with a Shannon diversity index H '= 2.82 which is the highest among all studied sites, followed by the site at six years of occupation by Saffron (21 species), with H '= 2.61, while the lowest number of species was recorded in sites of two, three and ten years of exploitation of sol by Saffron, with H '= 1.77, respectively; 2.12 and 2.44. This decrease in endomycorrhizal species richness confirms that Crocus sativus residues are probably the cause. In fact, the prolonged occupation of plots with safrana has an allelopathic effect on mycoflora and on the yield of Saffron.