Development and Management of Arbuscular Mycorrhizal Fungi Inocula for Smallholder Farmers: Challenges and Opportunities

To a certain extent, most of the terrestrial plants in their natural habitats have been known to exist primarily under the influence of a special group of soil microorganisms called arbuscular mycorrhizal fungi (AMF). Existence of AM fungi in the soil was discovered about 100 years ago although full scientific attention grew gradually in the past 45 years. The aim of this review paper is to assess scientific literature relevant to development and management of AMF inoculum for smallholder farming: explore isolation of AMF spores from the soil, establishment of AMF cultures, AMF identification, mass production of AMF, as well as beneficial effects of AMF to host plants. Association of plant roots and AMF leads to formation of arbuscular mycorrhizal symbiosis whereby the fungi provide essential nutrients to the plants, thus resulting in enhanced plant growth, host plant protection, and enhancement of soil quality. The AMF create a filamentous network in the soil with plant roots which in turn increases bi-directional nutrient movement whereby beneficial nutrients (mainly nitrogen and phosphorus) and water move to the host plant, whereas the fungal network receives plant photosynthates. This filamentous network created by AMF in the soil occurs in most land plants such as cereals, horticultural plants, vegetables, and most major crops. Several factors ranging from host crop dependency to mycorrhizal colonization, inorganic and organic fertilization, tillage system, to AM fungi inoculum’s potential have shown to have a significant effect on host plant response to mycorrhizae. The cultivation of AMF strains and subsequent maintenance of the resulting AM fungal inocula require methodologies which are somehow different from those employed in other microbial inoculum production. Currently, there has been tremendous interest in AM fungi propagation for agriculture because of their vital role in provision of soil nutrients, enhancement of plant health, and soil aggregate stability. In this chapter, we discussed suitable methodologies involved in the production of AMF inoculum for improving the profitability, productivity, and sustainability of smallholder farmers.