Ecological considerations for successful application of arbuscular mycorrhizal fungi inoculum

Abstract

Research on arbuscular mycorrhizal fungi (AMF) in the 1970s and 1980s was dominated by the search for ‘superstrains’ capable of increasing plant biomass under any environmental and soil conditions. The desire to exploit AMF as natural biofertilizers for the agricultural biotechnology industry was understandable, but it became clear that more knowledge was needed of the fungal biology to allow commercial exploitation. Many inoculant companies have tried to commercialise the use of AMF in the past but with an increasingly environmentally-aware market developing for mycorrhizal products, greater care is needed in producing inocula which can lead to mycorrhization of plants in most circumstances (a minimum requirement from a commercial mycorrhiza product). Many mycorrhizal fungi inoculants, used in research or sold, comprise the same fungal consortia and aim to mycorrhize plants in all target environments. The problem being, that changing environmental conditions can sometimes reveal the limited adaptation of the fungi used. There is also the problem of where inocula are to be used, in monoculture production (agriculture or horticulture) or in land restoration, where complex communities of plants need to be encouraged to establish in degraded soil conditions. Van der Heijden et al. (1998a, b) showed that belowground diversity of AMF is a major factor in the maintenance of plant biodiversity and to ecosystem stability and function.