Effect of weeds on microbial community in vineyards soil

Weeds, in particular agrestals, represent a threat for a variety of cultivated plants, because they compete for nutrients, water and sunlight. In addition they may affect the crops by producing toxic compounds through a mechanism called allelopathy. Their presence leads to huge economical losses, but on the other hand their control, especially through herbicides, could negatively affect the environment. Therefore weed control through different strategies of prevention, control and eradication by means of sustainable approaches is a priority worldwide. Almost nothing is known on the interaction between weeds and soil microorganisms, for example if weeds could play a role in the interaction with beneficial soil microbes and in preserving soil microbiological quality. In this study we determine the effect of different weeds on total bacterial and fungal abundance in different soils under controlled conditions. We collected soil samples in four vineyards in northern Italy and three weeds, Poa trivialis, Taraxacum officinale and Trifolium repens, were selected based on their ubiquitous presence in the original soils. Each weed was planted in each soil type. The total amount of fungi and bacteria during different plant stages development was assessed. Total fungi are poorly affected by the plant introduction, even if, at the true leaf stage of T. officinale and T. repens, an increase was observed. Total bacteria community at true leaf stage also showed a significant increment with T. officinale and T. repens in some soils. The monocotyledon P. trivialis globally did not affect the bacterial and fungal communities. Even if a general trend cannot be inferred, we demonstrate an interaction with the combination of weed species and soil.