A molecular approach to ascertain the success of in situ AM fungi inoculation in the revegetation of a semiarid, degraded land

The positive effect of arbuscular mycorrhizal fungi inoculation on plant establishment under field conditions has been shown. However, whether this effect is related to the survival of the AMF and how the AMF inoculum affects the colonisation of plant roots by the native AMF remain uncertain. In this study, we assessed the AMF community composition in O. europaea roots inoculated in situ with three types of AMF inoculum: Glomus sp., G. intra radices and a mixture of Glomus sp. and G. intra radices. All the AMF isolates inoculated showed a good percentage of persistence. Mycorrhizal inoculation with the mixture of Glomus sp. and G. intraradices was the most effective treatment for increasing the AMF diversity in roots 14 months after plantation. Plant growth was increased significantly by all the inocula tested, although plant biomass was not correlated with variation in the AMF diversity or with the AMF inoculum persistence. Thus, it seems that this positive effect was mediated by the interaction between the AMF inoculum and the natural colonisation. Therefore, the application of native AMF isolates in the planting hole may be considered a good strategy for the revegetation of semiarid, degraded soils, in order to reactivate the indigenous AMF populations and improve the performance of O. europaea seedlings, particularly when mixtures of native isolates are used. (C) 2011 Elsevier B.V. All rights reserved.