Abstract
BackgroundArbuscular mycorrhizal fungi (AMF) are known for their beneficial effects on plants. However, there is increasing evidence that some ruderal plants, including several agricultural weeds, respond negatively to AMF colonization. Here, we investigated the effect of AMF on the growth of individual weed species and on weed-crop interactions.Methodology/Principal FindingsFirst, under controlled glasshouse conditions, we screened growth responses of nine weed species and three crops to a widespread AMF, Glomus intraradices. None of the weeds screened showed a significant positive mycorrhizal growth response and four weed species were significantly reduced by the AMF (growth responses between −22 and −35%). In a subsequent experiment, we selected three of the negatively responding weed species – Echinochloa crus-galli, Setaria viridis and Solanum nigrum – and analyzed their responses to a combination of three AMF (Glomus intraradices, Glomus mosseae and Glomus claroideum). Finally, we tested whether the presence of a crop (maize) enhanced the suppressive effect of AMF on weeds. We found that the growth of the three selected weed species was also reduced by a combination of AMF and that the presence of maize amplified the negative effect of AMF on the growth of E. crus-galli.Conclusions/SignificanceOur results show that AMF can negatively influence the growth of some weed species indicating that AMF have the potential to act as determinants of weed community structure. Furthermore, mycorrhizal weed growth reductions can be amplified in the presence of a crop. Previous studies have shown that AMF provide a number of beneficial ecosystem services. Taken together with our current results, the maintenance and promotion of AMF activity may thereby contribute to sustainable management of agroecosystems. However, in order to further the practical and ecological relevance of our findings, additional experiments should be performed under field conditions.
Highlights
Weeds represent one of the most serious problems in crop production, with a potential crop loss of up to 34% each year [1]
Our results show that (1) biomass of four of the investigated weed species was significantly reduced by G. intraradices while none of the weeds significantly benefited from inoculation with this Arbuscular mycorrhizal fungi (AMF), (2) growth of the weed species E. crus-galli, S. viridis and S. nigrum was reduced by a combination of AMF and (3) the presence of a crop further amplified the negative effect of AMF in one out of the three weed species tested
Previous work had shown that some weeds responded negatively to soil fungi [28,29] and that weeds grown together with a crop can be suppressed by AMF [30]
Summary
Weeds represent one of the most serious problems in crop production, with a potential crop loss of up to 34% each year [1]. We focus on weed interactions with a particular group of symbiotic soil fungi, the arbuscular mycorrhizal fungi (AMF). It is to be expected that a host plant will benefit directly from the AM symbiosis through increased nutrient uptake, and, consequentially, increased growth. This is not always the case; some plants do not show any growth increase while others even seem to be negatively affected by AMF colonization [10,11,12]. Arbuscular mycorrhizal fungi (AMF) are known for their beneficial effects on plants. We investigated the effect of AMF on the growth of individual weed species and on weed-crop interactions
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