Arbuscular mycorrhizal contribution to copper, manganese and iron nutrient concentrations in crops - A meta-analysis

The micronutrients copper (Cu), manganese (Mn) and iron (Fe) are essential for crop plant development and productivity. However, a quantitative, data-based consensus has yet to be reached on the role of arbuscular mycorrhizal fungi (AMF) in Cu, Mn and Fe nutrition in crops. Thus, we performed a meta-analysis to quantitatively synthesize the findings of 233 single publications and to test the impact of 10 moderator variables on the AM fungal mediated Cu, Mn and Fe aboveground tissue concentration. AMF had overall a significantly positive effect on crop Cu nutrition (on average 29%). For Fe, a positive AM fungal mediated effect was detectable only for intermediate 'experimental duration' (lasting 56-112 days). AMF only produced a positive effect on Mn nutrition in herbs, while for other plant types, edaphic and study-related factors we documented neutral or negative results. The application of AMF for crop plant fortification is still in its infancy. Here we found evidence for a significant role of AMF for Cu, Fe and (to a limited extent) Mn crop plant nutrition. This highlights that more efforts should be devoted to harnessing the potential beneficial effects of these symbionts not just for yield but also nutritional quality, especially considering increasing demands for food quality in the future. (C) 2014 Elsevier Ltd. All rights reserved.