Evaluating the potential of arbuscular mycorrhizal fungi for improving apple (Malus pumila) orchard sustainability

Developing agricultural systems which are able to balance productivity and sustainability is critical for ensuring future food security. Arbuscular mycorrhizal fungi (AMF) are an important component of the soil microbial community and play a vital role in a range of essential ecosystem functions. Arbuscular mycorrhizal symbiosis is characterised by the exchange of carbon from host plants in return for nutrients captured in the soil by the fungi, however AMF may also provide important non-nutritional benefits such as improving host plant resistance to pathogens. AMF are known to form symbiosis with over 80% of land plants including many major crop plants and have therefore received recognition as a potential tool for improving sustainability of agro-ecosystems.
Apple is the fourth most widely planted fruit crop globally and is known to form symbiosis with AMF. The potential for AMF to improve orchard sustainability has been recognised by the cider apple industry and led to the overarching aim of this thesis which is to evaluate the potential benefits of AMF for cider apple production and sustainable management.
Using the combination of a semi-controlled growth experiment and a landscape scale sampling approach, this study has examined the benefit AMF can provide to growth, health and productivity of cider apple trees. Understanding impacts of orchard management upon AMF communities has been a key aim of this work due to the increasing body of research reporting reduced abundance and functioning of AMF within intensively managed agricultural environments. This study has characterised AMF communities naturally found within three major cider apple orchard management types and investigated how AMF communities are impacted by aspects of orchard management.
Results from this thesis provide evidence that AMF are able to provide disease resistance benefits to apple and are therefore beneficial to apple production. Furthermore data from this thesis shows that irrespective of management, cider apple orchards are able to host naturally diverse AMF communities which show similarities to the AMF communities of woodland. Results from this thesis have significant implications for orchard management and have highlighted several areas for potential future research.