Influence of seasonality and management practices on diversity and composition of fungal communities in vineyard soils

The increase in vineyard cultivation for the production of grapes or wine is producing a considerable reduction in soil quality. This is a consequence of management practices principally based on frequent tillage and use of herbicides. This type of management disrupts fungal communities which can lead to a reduction in crop production along with an increase in diseases caused by microorganisms that habitually coexist harmlessly in the soil. The objective of this research was the evaluation of the effect of soil management practices and environmental conditions on the soil fungal communities throughout the year in vineyard. For this, the diversity of the fungal communities in soils with different agricultural practices were evaluated. The samplings were carried out in two vineyards, the first was subjected to manage based on tillage where tillage in the alleys and pesticide treatments in the rows were done. The second was managed without tillage allowing colonialization of spontaneous vegetation in the alleys; the rows, as in the other vineyard, which were treated with herbicides. The soil samples were taken every season coinciding with the key growth stages of the vineyard. The samples were processed using the traditional in vitro method. More than 193 different fungal taxa were found; of them 18% were presented in higher abundance than 1% of the total. The majority of these were generalists; however, there were differences in the relative abundance based on the soil treatment (Tr, Ta, NTr, NTa), season and weather. The fungal communities were formed by more than 60% of generalist taxa; the genus Aspergillus was the most frequent. Ten percent of the total taxa were specific to concrete environmental conditions (season and weather) and soil treatment; Penicillium and Trichoderma were the most frequent. The factor most predictive of the composition of communities was attributed to the season in which the soil samples were collected. In terms of soil management, 27% of taxa were specific of management. Significant differences in the fungal compositions of the communities were found. The fungal communities from soils treated with chemical pesticides (rows) contained a substantial number of specific taxa, being 23% of total. These results show that seasonal dynamics of fungal populations in productive vineyards are sensitive to changes caused by soil treatment.