Arbuscular mycorrhizal populations associated with natural and cultivated vegetation on a site of Buenos Aires province, Argentina

Abstract.

The influence of tillage and monoculture on arbuscular mycorrhizae (AM) fungal species diversity in a field site of the Buenos Aires province (Argentina) was investigated through the morphological characterization of AM spores. Glomalean spores were isolated by wet sieving and decanting from three plots cropped either to wheat, barley or clover and from a grassland at the margins of the cultivated plots. Seventeen different Glomalean species were detected overall and seven of them were identified. Total species number as well as spore and species richness found in grassland and clover soil were higher than those found in soils planted either with barley or wheat. The most frequently occurring species in the site were Glomus mosseae, Scutellospora pellucida, Glomus sp. 7 and Gigaspora sp. 1. The first three were also the most dominant species and were found in the four types of analysed soils. In grassland soil and wheat, the dominant species was Glomus sp. 6. S. pellucida was dominant in barley, and in red clover the dominant species were G. mosseae and S. pellucida. Tillage and cereal monoculture negatively affected diversity of AM fungal species. Natural re-colonization of indigenous AM fungi was observed in cultivated soil with red clover for 3 years, suggesting that this host could be used as a cover crop to increase AM fungal inocula in disturbed soils. Arbuscular mycorrhizal populations were associated with natural and cultivated vegetation on a site of Buenos Aires province, Argentina.