UBC Theses and Dissertations
Establishment persistence and efficacy of commercial arbuscular mycorrhizal fungi Kokkoris, Vasileios Anastasios
Arbuscular mycorrhizal fungi have been used as bio-fertilizers in agriculture and horticulture for more than 30 years, yet the efficacy of such products in agro-systems has not been well established. Although they have the potential to provide a variety of benefits to their plant hosts, the lack of knowledge of their ecology and functional traits among and within species along with the unknown effects of continuous in vitro cultivation on AM fungal functionality, makes it difficult to predict inoculation outcomes. The ability to track commercial AM fungi in the field after inoculation has limited the ability to evaluate their utility thus far. Recent developments in molecular biology makes it possible to track single fungal genotypes in the field. These tools will help improve the success of AM fungal products by evaluating conditions that increase their establishment and persistence. The objectives of this thesis are to determine whether (1) commercial AM fungal inoculants can effectively establish and persist under different agricultural conditions, (2) there is an environmental risk following inoculation with commercial AM fungi, (3) in vitro cultivation affects the efficacy of AM fungal inoculants by altering life history traits and functionality of AM fungi. Establishment and persistence of a commercial fungal inoculant was site specific since none of the manipulated practices contributed to the establishment and abundance of the inoculant in roots. When I grew two isolates of Rhizoglomus irregulare with crop and wild plants, I found that wild plants are more sensitive to differences in mutualistic quality among fungal isolates and all plants associating with the commercial fungus had lower leaf P. Finally, I found that In vitro cultivation leads to increased germination rates, increased fungal spore production but reduced plant shoot phosphorus benefit. We need to re-consider the way AM fungal inoculants are mass produced but we also need to re-evaluate the field inoculation practices using fungal inoculants. Not only via continuous in vitro cultivation we are choosing for traits that are not beneficial to the symbiosis, introducing alien isolates during field inoculation with commercial products can also be detrimental for natural plant communities beyond the agricultural fields.
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