# The Effects of Local Weed Species on Arbuscular Mycorrhizal Fungal Communities in an Organic Winter Wheat (Triticum durum L.) Field in Lebanon

## TL;DR

This study explores how local weeds affect arbuscular mycorrhizal fungi in an organic wheat field in Lebanon.

## Contribution

The study reveals that weeds influence the composition of AMF communities without altering their diversity or colonization in wheat.

## Key findings

- Weeds changed the composition of AMF communities in wheat but not their diversity or colonization.
- Soil covered with wheat and weeds had higher AM propagules and nutrient content compared to soil with only wheat.
- Greenhouse experiments showed better plant growth and mycorrhizal intensity with soil from wheat associated with weeds.

## Abstract

We examined the potential effects of weed species on the arbuscular mycorrhizal fungi (AMF) in an organic winter wheat (Triticum durum) field in Lebanon. In this agroecosystem, the field and its surroundings were covered with spontaneous vegetation corresponding to local weeds. The coexistence between wheat and weeds did not modify AM fungal community diversity and colonization in T. durum but changed their composition. We evidenced 22 operational taxonomic units (OTUs) specifically shared between wheat associated with weeds (Tdw) and weeds, regardless of their localization and 12 OTUs with an abundance of variation between wheat without neighboring weeds (Td) and Tdw. The number of AM propagules and total C and N contents were higher in soil covered with wheat associated with weeds (TdWsoil) vs. wheat without neighboring weeds (Tdsoil). In greenhouse experiments, the shoot biomass and root mycorrhizal intensity of Medicago sativa, used as a trap plant, were higher using TdWsoil vs. Tdsoil as the inoculum. Positive correlations were observed between soil AM propagule numbers and M. sativa shoot biomass, on the one hand and M. sativa mycorrhizal intensity, on the other hand. Weeds seemed to exert significant effects on root AM fungal composition in T. durum and these effects may contribute to enhanced AMF development in the field.