Effect of inoculation with native and commercial arbuscular mycorrhizal fungi on growth and mycorrhizal colonization of olive (Olea europaea L.)

•The tested AMF species were all infective and effective for the mycorrhization of olive tree var. Ferkani.•Native AMF gave the best results of mycorrhizal colonization and olive plantlet growth.•The controlled inoculation improved the growth of all plantlets compared to the AMF-free plantlets.•All olive plantlet growth traits increased when mycorrhizal parameters increased.•AMF isolated from drylands have higher potential to increase growth of plants compared to most commercial AMF. In order to improve the production of olive (Olea europaea L.), plantlets of Variety Ferkani were inoculated with three arbuscular mycorrhizal fungal (AMF) spores (Glomus sp.1, Glomus sp.2, Septoglomus constrictum) isolated from a hot-arid zone in Algeria and three commercial AMF (Rhizophagus intraradices, Funneliformis mosseae, Gigaspora margarita). Mycorrhization parameters and nine growth traits were estimated in two-year-old plantlets, then the variation of growth traits following mycorrhizae parameters of various AMF inoculums was tested. The tested AMF species were all infective and effective for the mycorrhization of Ferkani variety. Native species Glomus sp.1 gave the best results for mycorrhizal colonization and growth parameters. Indeed, the highest colonization frequency (F%) was recorded in plantlets inoculated with Glomus sp.1 (58 ± 6.5 %), whereas the highest values of colonization intensity of in the root system (M%) were obtained with Rhizophagus intraradices (2.45 ± 1.46 %) and Glomus sp.1 (2.26 ± 0.76 %). Abundances of arbuscules were low for all AMF inoculums. The controlled inoculation improved the growth of all plantlets compared to the AMF-free plantlets. AMF-inoculated plantlets showed significantly higher growth in terms shoot height, fresh and dry weights of shoot and root, and number of leaves and nodes. Statistical models revealed that all the latter growth parameters including mycorrhizal responsiveness increased significantly when mycorrhizal parameters increased, and that F% was most strongly correlated with plant growth compared to other mycorrhizal parameters. Findings of this controlled inoculation research underline the importance of local AMF isolated from the rhizosphere of Ferkani variety in rapidly and extensively infecting the root system and then increasing growth of the host.