Can we predict arbuscular mycorrhizal inoculation effects on vine plants?

Scientific literature has demonstrated for more than 50 years the positive effect of arbuscular mycorrhiza (AM) on plant growth and stress resistance. But it has been in the last 10 years that its application was implemented in agricultural systems. Recent reviews point to AM as key to viticulture. In order to identify the most effective mycorrhizal species and detect the rootstocks most dependent on inoculation we reanalyzed published experiments were AM were inoculated in vine plants. . To do that, we created a database where we included all the results comparing the development of vine plants that have been inoculated with AM against a control. We calculated inoculation dependence ID= ((Mean of inoculate treatment - Mean of control)/ Mean of inoculate treatment)*100) to compare the effect of AM inoculation on the vine between very different experiments. Only two species of mycorrhiza (Rhizophagus irregularis and Funneliformis mosseae) have been studied on the same rootstock measuring the same variables in more than one study. If we analyze all the AM species used together, for the majority of measured response variables there are no differences in the ID of the different rootstocks. Without considering the different rootstocks, we did not find significant differences in the ID between the different mycorrhizal species used. The results obtained showed that plants cannot always benefit from AM inoculation, and the effect of mycorrhizae can be positive or negative. The effect of mycorrhizal inoculation in vineyards is context dependent. This study has shown the need for prior pilot testing to determine the effect of a specific mycorrhizal species on certain rootstocks under specific growing conditions before their use can be recommended.