Fungal communities in viticulture: cultivation practices change the balance

Created by Lukas Maschek | |   Sektion für Landwirtschaft

Fungal communities play an essential role in plant health, whether as pathogens or beneficial symbionts. They are present in every agricultural soil, but are also found above ground on all parts of the plant, and by no means all of them lead to damage or disease. A team of researchers led by Katharina Steng has investigated how different agricultural systems affect the composition of above-ground fungal communities. Their aim is to promote healthy and productive plants and develop strategies for sustainable agriculture.

Modern agriculture is increasingly recognizing the importance of the microbiome for sustainable systems. Vineyards, where pesticides are often used intensively, are a good place to study the impact of different agricultural systems on microbial communities.

The study took place in a vineyard planted with Riesling vines in Geisenheim, Germany, in 1991. Since 2006, some plots have been cultivated either biodynamically, organically or according to the guidelines of integrated agriculture. Samples were taken from the bark, leaves and grapes of the vines. These were then analyzed using DNA sequencing to determine the diversity and functional characteristics of the fungal communities.

Figure 1: Different abundance of fungal species and their primary function on the bark, leaf and grape of grapevines. Left bar: integrated agriculture. Middle bar: organic farming. Right bar: biodynamic agriculture.

The results can be broken down into three different types of diversity:

  • Alpha diversity (species diversity) showed no significant differences between the farming systems, but was different for bark, leaf and grape in each case. Species diversity decreased from bark to leaf to grape.
  • Beta diversity (community composition) was significantly influenced by management practices for leaves and grapes. Bark samples showed no differences. Fungal communities differed significantly between bark, leaf and grape.
  • Functional diversity examines the function of the fungi studied in an ecosystem. In integrated systems, more fungal species were found that feed parasitically on other fungi.

According to the study, the agricultural system influences the composition rather than the biodiversity of the fungal communities. Integrated farming appears to promote the presence of parasitic fungi, while organic and biodynamic practices can lead to higher pathogen abundance. Based on these results, appropriate management strategies can be refined to improve sustainability and productivity in vineyards.

Commentary

It is rather difficult to derive management practices from microbiological gene sequences and to draw conclusions about the quality of an agricultural system. Nevertheless, the results obtained in this study are valuable in several respects.

  • The study strengthens the statement that the agricultural system influences the composition of fungal communities. Similar findings have already been reported for the fungal communities in the soil of vineyards.
  • The conversion to biodynamic / organic farming only took place in 2006. As the DOK trial, among others, shows, such a conversion takes place slowly but steadily. In the case of vineyards in particular, it can also be assumed that many fertilizer and pesticide residues from previous cultivation remain in the soil, which can further delay the effects of conversion.
  • Looking at the fungal communities and their functions, there are no huge differences between the agricultural systems. However, it is worth noting that in integrated farming, intensive use of pesticides is necessary to achieve this rather small difference, while the other two systems cause significantly less environmental damage.

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