Arbuscular mycorrhiza in landrace and modern wheat : its impact on plant performance and how it is influenced by plant breeding and modern cropping practices

Sammanfattning: Modern agriculture has a negative impact on climate and environment and is challenged by climate change. A transition to a more sustainable, secure and yet high food production is necessary. Landrace cereals attract attention for their ability to sustain nutrient deficiency, drought and harsh climate conditions. Arbuscular mycorrhiza is a common symbiosis with ancient origin between plant roots and fungi. The aim of this thesis is to review the current knowledge on arbuscular mycorrhiza regarding its impact on wheat landrace performance during cultivation, and to understand if arbuscular mycorrhiza in wheat has been affected by breeding and conventional cropping practices. Arbuscular mycorrhiza may contribute to uptake of phosphorous and other nutrients and enhance drought resistance in wheat. However, the response to arbuscular mycorrhiza in plants is highly variable and dependent on genetical and environmental factors and cropping practices. This thesis concludes that the ability of wheat landrace cereals to adapt to nutrient deficiency and drought stress are most likely not dependent on arbuscular mycorrhiza under Swedish conditions. In addition, input of fertilizers reduces the plant responsiveness to arbuscular mycorrhiza, the crop rotation system might favour or disfavour arbuscular mycorrhiza depending on which crops are included, tillage disfavours arbuscular mycorrhizal fungi and fungicides might reduce spore germination. Thus, conventional practices might have a negative impact on arbuscular mycorrhiza in wheat, even though the farmer’s choice of cultivation methods are more important for arbuscular mycorrhiza than the type of cropping system. Finally, it is concluded that more molecular genetic research is needed in order to understand if arbuscular mycorrhiza in wheat has been affected by breeding for conventional cropping systems.