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Soil and root samples were collected from the rhizosphere of olive trees growing in fifteen plots in five
different oil-producing regions to assess the level of root mycorrhization and to identify arbuscular
mycorrhizal fungi from the spores collected. The results obtained have revealed the presence of
arbuscular endomycorrhizal fungi in all samples. The frequency of root mycorrhization of the olive tree
ranges from 20% (Zouala 2) to 83.33% (Zagora 1). The highest intensity of mycorrhization is in the order
of 12% (site of Essaouira 1) and the lowest is of 1.26% (Zouala 1). Moreover, the arbuscular content is
very low in both sites of Taounate (Taounate 1 and 2) and the three sites of Zouala 1, 2 and 3 (below 8)
and the highest was recorded in the site of Zagora (30.23%). As for the vesicular content, it varies
between 0.25% (Taounate 2) and 3.27% (Taounate 3).
The spores density in the rhizosphere of olive trees also vary between 1218 (Taza 1) and 104 spores/100
g of soil (Essaouira 1). Preliminary, tentative identifications have allowed us to note that isolated spores
belong to 25 species of Glomales, divided into four genera (Glomus, Gigaspora, Acaulospora,
Entrophospora) and 3 families (Glomaceae, Gigasporaceae and Acaulosporaceae).
This study of the natural diversity of arbuscular mycorrhizal fungi in the rhizosphere of the olive tree is a
starting point to develop inoculants suitable for use in the nurseries to get olive plants more robust and
resistant against pathogens and drought stress after transplanting.
Key words: Morocco, Olea europaea cultivated rhizosphere, arbuscular mycorrhizal fungi (AMF),
diversity, Glomus, Acaulospora, Gigaspora, Entrophospora.