Nitrification inhibition by polyphenols from invasive Fallopia japonica under copper stress

Abstract

Background:The invasive plant species Fallopia japonica is suspected to use polyphenols as a novel weapon to inhibit nitrification in soil. Both specific polyphenols and their entry pathways are yet to be determined. As plants may increase the production of polyphenols under copper (Cu) stress, an additive effect can be expected in contaminated (riparian) areas.Aims: This study aimed to identify the entry pathways of total and specific polyphenols in F. japonica and to test whether polyphenols inhibit nitrification with Cu contamination. Methods: Combining F. japonica and a Cu gradient in a 2-year mesocosm experiment, total polyphenol, emodin, and resveratrol concentrations were analyzed in the plant (roots, root exudates, vital and senescent leaves) and soil (rhizosphere, non-rooted soil) representing different entry pathways. We measured the potential nitrification rate (PNR) under stress caused by F. japonica and Cu as well as the response of PNR under resveratrol and emodin addition.Results: Emodin and resveratrol were detected in all plant tissues. Emodin concentrations significantly increased in senescent leaves under Cu stress, while no Cu effect was observed for resveratrol or total polyphenols. Resveratrol decreased the PNR. The stressors had neither a synergistic nor additive effect. Nitrification inhibition was lower in the rhizosphere compared to the non-rooted soil, suggesting that F. japonica reduced nitrate availability for co-occurring plants.Conclusions: Joint occurrence of F. japonica and Cu did not amplify the PNR inhibition over the individual effect. Our study emphasizes the effectiveness of F. japonica in inhibiting the PNR in invaded riparian ecosystems with potentially negative effects on biodiversity.

Soil science challenges—An interdisciplinary overview of current and future topics

“…Furthermore, certain plants were found to produce polyphenols that inhibit nitrification and thus the risk of denitrification and subsequent N 2 O emissions as presented by Girardi et al. (2022) in this issue. Eysholdt et al.…”

“…In this issue,Kollah et al (2022) report enhanced N 2 O emissions with fertilizer application when larger biochar particles (0.25-2.00 mm) were applied in tropical vertisols, but organic fertilizer together with smaller biochar particles (< 0.25 mm) reduced the emissions. Furthermore, certain plants were found to produce polyphenols that inhibit nitrification and thus the risk of denitrification and subsequent N 2 O emissions as presented byGirardi et al (2022) in this issue Eysholdt et al (2022). outline in this issue that incorporating site-specific soil, water, and land use characteristics in models are promising to indirectly estimate N 2 O emissions suitable to represent mitigation measures.…”

SystemLink: Moving beyond Aquatic–Terrestrial Interactions to Incorporate Food Web Studies

“…In SystemLink, aquatic–terrestrial research is conducted at different scales: (A) Ecotoxicological studies at the batch‐scale; (B) The Joint‐Pot Experiment at the site‐scale, in which the effects of soil contamination via flooding can be assessed on soil processes and microbial communities as well as plant parameters (Girardi et al 2022; Schmitz et al 2023). (C) The outdoor Landau Stream Mesocosm Facility (site‐scale) comprises 16 independent concrete stream mesocosms, which can be used to study the aquatic fate and effects of contaminants, and also the potential links to terrestrial ecosystems, for example, via stable isotope analysis.…”

Limnology and Oceanography Bulletin Volume 32 Number 2 May 2023 41‐87

“…2. In SystemLink, aquatic-terrestrial research is conducted at different scales: (A) Ecotoxicological studies at the batch-scale; (B) The Joint-Pot Experiment at the site-scale, in which the effects of soil contamination via flooding can be assessed on soil processes and microbial communities as well as plant parameters (Girardi et al 2022;Schmitz et al 2023). (C) The outdoor Landau Stream Mesocosm Facility (site-scale) comprises 16 independent concrete stream mesocosms, which can be used to study the aquatic fate and effects of contaminants, and also the potential links to terrestrial ecosystems, for example, via stable isotope analysis.…”