Fagopyrum esculentum Alters Its Root Exudation after Amaranthus retroflexus Recognition and Suppresses Weed Growth

Abstract

Weed control by crops through growth suppressive root exudates is a promising alternative to herbicides. Buckwheat (Fagopyrum esculentum) is known for its weed suppression and redroot pigweed (Amaranthus retroflexus) control is probably partly due to allelopathic root exudates. This work studies whether other weeds are also suppressed by buckwheat and if the presence of weeds is necessary to induce growth repression. Buckwheat and different weeds were co-cultivated in soil, separating roots by a mesh allowing to study effects due to diffusion. Buckwheat suppressed growth of pigweed, goosefoot and barnyard grass by 53, 42, and 77% respectively without physical root interactions, probably through allelopathic compounds. Root exudates were obtained from sand cultures of buckwheat (BK), pigweed (P), and a buckwheat/pigweed mixed culture (BK-P). BK-P root exudates inhibited pigweed root growth by 49%. Characterization of root exudates by UHPLC-HRMS and principal component analysis revealed that BK and BK-P had a different metabolic profile suggesting that buckwheat changes its root exudation in the presence of pigweed indicating heterospecific recognition. Among the 15 different markers, which were more abundant in BK-P, tryptophan was identified and four others were tentatively identified. Our findings might contribute to the selection of crops with weed suppressive effects.

Allelopathic influence of common buckwheat root residues on selected weed species

“…Common buckwheat can alter its root exudation after weed recognition and suppresses its growth, as was found for Amaranthus retroflexus (Gfeller et al 2018). Kumar et al (2008) reported that buckwheat residues in soil suppress Powell amaranth (Amaranthus powellii S.…”

“…Despite many studies, there is no conclusive evidence of which compounds are directly responsible for the phenomenon of allelopathy in buckwheat. Probably, the whole set of compounds present in buckwheat tissues is involved in this phenomenon, along with microorganisms present in the soil (Gfeller et al 2018). Moreover, Kumar et al (2008) suggested that the mechanisms by which buckwheat residue can suppress weeds may include biological control of fungal pathogens and decreased nitrogen availability.…”

Sensitivity of yellow foxtail (Setaria glauca L.) and barnyardgrass (Echinochloa crus‐galli L.) to aqueous extracts or dry biomass of cover crops

“…Consistent with our results, S. alba has been shown to delay emergence of early-season weeds in potato, pea and soybean fields, 29,30 sinalbin from S. alba seeds inhibited germination of Stellaria media L. (98%) and Poa annua L. (73%) 31 and S. alba mulch reduced broadleaf weeds (83%) in sugar beet fields. 32,33 The strong allelopathic effects of S. alba may reflect its content of the allelochemicals glucotropaeolin (45 mg kg -1 ), glucosinalbin (7.2 mg kg -1 ) and glucobrassicin (<0.1 mg kg -1 ). 20 For example, hydrolysis products of glucosinolates, like isothiocyanates, can inhibit or delay germination.…”

Root extracellular traps versus neutrophil extracellular traps in host defence, a case of functional convergence?

“…This phenomenon of anti‐microbial ‘cloud’ formation and RET spreading is expected to be amplified upon microbial attack or recognition of microbial‐derived elicitors by AC‐DCs. It could also be influenced by communication among plants in the rhizosphere, a well‐known process that occurs through allelochemicals, electric signals or mycorrhizal networks (Johnson & Gilbert, ; Gfeller et al , ; Gilroy, Trebacz & Salvador‐Recatalà, ).…”