Glyphosate decreases mycorrhizal colonization and affects plant-soil feedback

Abstract

Our aim was to study the effects of glyphosate, tilling practice and cultivation history on mycorrhizal colonization and growth of target (weeds) and non-target (crops) plants. Glyphosate, the world's most widely used pesticide, inhibits an enzyme found in plants but also in microbes. We examined the effects of glyphosate treatment applied in the preceding fall on growth of a perennial weed, Elymus repens (target plant) and a forage grass, Festuca pratensis (non-target plant) and their arbuscular mycorrhizal fungal (AMF) root colonization in a field pot experiment. Non-target plants were sown in the following spring. Furthermore, we tested if glyphosate effects depend on tillage or soil properties modulated by long cultivation history of endophyte symbiotic grass (E+ grass). AMF root colonization, plant establishment and growth, glyphosate residues in plants, and soil chemistry were measured. Glyphosate reduced the mycorrhizal colonization and growth of both target and non-target grasses. The magnitude of reduction depended on tillage and soil properties due to cultivation history of E+ grass. We detected glyphosate residues in weeds and crop plants in the growing season following the glyphosate treatment. Residues were higher in plants growing in no-till pots compared to conspecifics in tilled pots. These results demonstrate negative effects of glyphosate on non-target organisms in agricultural environments and grassland ecosystems.

Effects of a glyphosate-based herbicide on soil animal trophic groups and associated ecosystem functioning in a northern agricultural field

“…While this was in line with our prediction, we expected that enchytraeids would respond to hoeing. Their numbers have been shown to respond to the availability of decomposing plant material 31 and changes in soil density 39,44 , which both were likely affected by hoeing. It might be, however, that the effects of hoeing on the physical and nutritional conditions of enchytraeids did not significantly differ from those caused by the earlier tilling of the experimental field.…”

“…in the soil adhered to plant roots) as well as in bulk soil 25–28 . Disrupting effects of glyphosate on earthworms 29 and their interactions with symbiotic mycorrhizal fungi 30,31 have also been reported. However, there is much controversy about the effects of glyphosate on soil microbial communities and activities 32–34 and notably, few studies have so far been carried out in field conditions 35 .…”

Herbicide Glyphosate: Toxicity and Microbial Degradation

“…Right from the lower invertebrates up to higher chordates, all the animals are found to be affected by this herbicide. Invertebrates like earthworms are majorly affected as determined by some parameters like a reduced rate of reproduction, loss of biomass, DNA damage and reduced casting activity [ 44 , 45 , 46 ]. Glyphosate and its formulation Roundup were used for toxicity evaluation on two different populations of Daphnia magna (one population was taken from laboratory cultures and other was wild-collected species).…”

Cover cropping system and mulching can shape soil microbial status in fruit orchards

“…The possible negative impact of herbicide was confirmed by the soil microbial growth results, whereas manual weed control and mulching treatments did not lead to significant improvements. Glyphosate is known to affect microorganisms, including the reduction of mycorrhizal colonization and growth of both target and non-target grasses by 23 % and by around 44 % arbuscules (Helander et al, 2018). Soil chemical characteristics may change the soil biological activity when herbicide, such as the glyphosate, is added, especially soil microbial biomass and soil respiration (Sumalan et al, 2010).…”