Arbuscular mycorrhizal fungus richness in the soil and root colonization in vineyards of different ages

Abstract

Vineyards in southern Brazil have high copper levels due to the application of products to control fungal diseases. High soil concentrations of this element can have toxicity to young plants. Arbuscular mycorrhizal fungi (AMF) can alleviate this effect, but the beneficial effect depends on the plant and AMF. AMF have different ecological strategies and respond differently to environmental and management variables. We analyzed AMF species richness, root mycorrhizal colonization, and soil physicochemical attributes in soil and grapevine root samples from vineyards with different growing times (<10, between 30 and 40 and < 60 years old) from Vale da Uva Goethe, Southern Brazil. There were higher phosphorus levels, copper, potassium, and organic matter in the 60 year old vineyard than in the other two vineyards. That affected mycorrhizal colonization, which reached 87% in the oldest vineyard, and 27% in the youngest, 10 year old vineyard. The lowest AMF richness in the oldest vineyard, with nine species, had a correlation with the high levels of copper, phosphorus, and potassium. The Glomeraceae family had the highest occurrence in this environment. In the youngest vineyard, which had 16 AMF species, the low pH was linked to species of Acaulosporaceae, which did not occur in the oldest vineyard. Glomus ambisporum was the dominant species, and high soil copper levels and pH above 6.0 were negatively related to the presence of AMF species of Acaulosporaceae. We conclude that in high-copper soils there is an increase in mycorrhizal root colonization and a predominance of ruderal AMF species, such as those of the Glomeraceae family.