Harnessing native arbuscular mycorrhizal fungi for sustainable potato production in South Africa

Practicing sustainable agriculture in potato production using arbuscular mycorrhiza (AM) fungi requires knowledge of associating species, their densities and infection capabilities. However, AM fungi species which associate with Sifra and Mondial varieties are unknown. To introduce sustainable agriculture in South Africa’s potato production, this study identified AM fungi species from Sifra and Mondial rhizospheric soils in the field across 3 developmental stages. AM fungi species were distinguished through their morphology with potato root analysis of AM fungi structures measuring their colonizing capabilities. Morphological analysis successfully identified Funneliformis mosseae and Rhizophagus intraradices in Mondial soils whilst Sifra soils were more dominated by Funneliformis species, Paraglomeraceae and Gigasporaceae species suggesting these as the most beneficial AM fungi towards Sifra and Mondial growth. Correlation analysis of spore numbers with environmental factors were carried out to explore the relationship. Notably, Sifra exhibited higher spore densities in comparison to Mondial with pH (KCl) identified as the most influential environmental factor. This suggests that an interaction of variety and soil acidity greatly influences spore density. Tuber bulking in both varieties had the highest spore densities which suggests this as a crucial step in potato AM fungi inoculation/maintenance. Despite the high spore densities, Sifra root colonization ranged between 17% - 20% whilst Mondial colonization was between 22% -25% suggesting a negative impact of colonization by soil pH or herbicide use. Overall, this study identified AM fungi species with potential for Sifra and Mondial sustainable agriculture as well as factors that may affect their proliferation.