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Biological Nitrification Inhibition (BNI) encompasses primarily NH4+‐induced release of secondary metabolites to impede the rhizospheric nitrifying microbes from performing nitrification. The intermediate wheatgrass Thinopyrum intermedium (Kernza®) is known for exuding several nitrification inhibition traits, but its BNI potential has not yet been identified. We hypothesized Kernza® to evince BNI potential through the presence and release of multiple BNI metabolites. The presence of BNI metabolites in the biomass of Kernza® and annual winter wheat (Triticum aestivum) and in the root exudates of hydroponically grown Kernza®, were fingerprinted using HPLC‐DAD and GC–MS/MS analyses. Growth bioassays involving ammonia‐oxidizing bacteria (AOB) and archaea (AOA) strains were conducted to assess the influence of the crude root metabolome of Kernza® and selected metabolites on nitrification. In most instances, significant concentrations of various metabolites with BNI potential were observed in the leaf and root biomass of Kernza® compared to annual winter wheat. Furthermore, NH4+ nutrition triggered the exudation of various phenolic BNI metabolites. Crude root exudates of Kernza® inhibited multiple AOB strains and completely inhibited N. viennensis. Vanillic acid, caffeic acid, vanillin, and phenylalanine suppressed the growth of all AOB and AOA strains tested, and reduced soil nitrification, while syringic acid and 2,6‐dihydroxybenzoic acid were ineffective. We demonstrated the considerable role of the Kernza® metabolome in suppressing nitrification through active exudation of multiple nitrification inhibitors.

Background Perennial cropping systems are increasingly recognized for their potential to enhance microbial biodiversity and beneficial soil functions compared to annual crops. The impact of perennialization on the rhizomicrobiome and endophyte community was assessed by comparing intermediate wheatgrass ( Thinopyrum intermedium , commercialized as Kernza®, hereafter called ‘Kernza‘) and annual wheat ( Triticum aestivum ) associated communities across a north–south European agroclimatic gradient (Sweden, Belgium, and France) over two growing seasons and at two depths. Results Between the 2 years, the Kernza-associated rhizomicrobiome was more stable and exhibited greater homogeneity across depths compared to annual wheat. Kernza harboured a significantly more diverse set of crop-associated amplicon sequence variants (ASVs) and had a higher number of core ASVs than annual wheat. Furthermore, Kernza had a significantly higher proportion of rhizobacterial populations in root tissues than annual wheat. Environment-wide association analyses revealed that the Kernza rhizosphere had higher proportions of grassland-associated and rhizosphere-dwelling microbiomes compared to annual wheat. Despite these noteworthy differences, the greatest variation in the rhizomicrobiome composition was driven by factors such as country, year, and depth, rather than crop type. For instance, Actinobacteriota dominated rhizobacterial communities in both Kernza and annual wheat. Conclusions Overall, Kernza conferred modest yet clear improvements in rhizomicrobiome community stability and selective endophyte recruitment, supporting its ability to enhance sustainable, microbially-mediated soil functions. Moreover, Kernza hosted significant grassland-associated taxa, suggesting a similarity between Kernza fields and grassland ecosystems.

The intensification of agriculture has led to environmental degradation, including the loss of biodiversity. This has prompted interest in perennial grain cropping systems to address and mitigate some of these negative impacts. In order to determine if perennial grain cultivation promotes a higher microbial diversity, we assessed the endophytic microbiota of a perennial grain crop (intermediate wheatgrass, Thinopyrum intermedium L.) in comparison to its annual counterpart, wheat (Triticum aestivum L.). The study covered three sampling sites in a pan-European gradient (Sweden, Belgium, and France), two plant genotypes, three plant compartments (roots, stems, and leaves), and two sampling time points. We observed that the host genotype effect was mainly evident in the belowground compartment, and only to a lesser extent in the aboveground tissues, with a similar pattern at all three sampling sites. Moreover, intermediate wheatgrass roots harbored a different bacterial community composition and higher diversity and richness compared to their annual counterparts. The root bacterial diversity was influenced by not only several soil chemical parameters, such as the carbon:nitrogen ratio, but also soil microbial parameters, such as soil respiration and dehydrogenase activity. Consistent findings across time and space suggest stable mechanisms in microbiota assembly associated with perennial grain cropping, underscoring their potential role in supporting biodiversity within sustainable agricultural systems.

Biological nitrification inhibition (BNI) refers to the plant-mediated process in which nitrification is inhibited through rhizospheric release of diverse metabolites. While it has been assumed that interactive effects of these metabolites shape rhizosphere processes, including BNI, there is scant evidence supporting this claim. Hence, it was a primary objective to assess the interactive effects of selected metabolites, including caffeic acid (CA), vanillic acid (VA), vanillin (VAN), syringic acid (SA), and phenylalanine (PHE), applied as single and combined compounds, against pure cultures of various ammonia-oxidising bacteria (AOB, Nitrosomonas europaea , Nitrosospira multiformis , Nitrosospira tenuis , Nitrosospira briensis ) and archaea (AOA, Nitrososphaera viennensis ), as well as soil nitrification. Additionally, benzoic acid (BA) was examined as a novel biological nitrification inhibitor. All metabolites, except SA, tested as single compounds, achieved varied levels of inhibition of microbial growth, with CA exhibiting the highest inhibitory potential. Similarly, all metabolites applied as single compounds, except PHE, inhibited soil nitrification by up to 62%, with BA being the most potent. Inhibition of tested nitrifying microbes was also observed when compounds were assessed in combination. The combinations VA + PH, VA + CA, and VA + VAN exhibited synergism against N. tenuis and N. briensis , while others showed antagonism against N. europaea , N. multiformis , and N. viennensis . Although all combinations suppressed soil nitrification, their interactions against soil nitrification revealed antagonism. Our findings indicate that both antagonism and synergism are possible in rhizospheric interactions involving BNI metabolites, resulting in growth inhibition of nitrifiers and suppression of soil nitrification.

Purpose – How trust affects political, social, and economic phenomena have been studied by scholars for many years. However, not many studies have examined what factors determine trust among people and trust in public institutions. There is particularly a dearth of research on trust in Ghana. The paper aims to discuss this issue. Design/methodology/approach – The authors use data from the 2012 Afrobarometer Surveys to mimic four sets of variables that Alesina and La Ferrara (2002) find as significant determinants of trust – recent traumatic experiences, having been historically discriminated against, being economically unsuccessful, and living in a mixed community. The authors apply these variables to the Ghanaian context to explore how they affect generalized trust, trust in relatives, neighbors, and other people the respondent knows, as well as trust in six public institutions (i.e. The President, Parliament, Electoral Commission, Police, Army, and the Courts of Law). Findings – The authors find that trust among Ghanaians is generally low. Women are significantly less trusting of public institutions, although they do not trust people (e.g. relatives, neighbors, etc.) any less than men. Both people of the North and South are generally less trusting of public institutions compared to people of the Volta Region. The authors also find that, to a large extent, satisfaction with democracy and political affiliation are significantly correlated with trust in public institutions. Practical implications – Because trust is very crucial for political, economic, and social development, especially good governance, there is an urgent need for public policy interventions that could increase trust among Ghanaians. Originality/value – The authors provide a Ghanaian perspective on the determinants of trust.