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Species that repeatedly evolve phenotypic clines across environmental gradients have been highlighted as ideal systems for characterizing the genomic basis of local environmental adaptation. However, few studies have assessed the importance of observed phenotypic clines for local adaptation: conspicuous traits that vary clinally may not necessarily be the most critical in determining local fitness. The present study was designed to fill this gap, using a plant species characterized by repeatedly evolved adaptive phenotypic clines. White clover is naturally polymorphic for its chemical defence cyanogenesis (HCN release with tissue damage); climate‐associated cyanogenesis clines have evolved throughout its native and introduced range worldwide. We performed landscape genomic analyses on 415 wild genotypes from 43 locations spanning much of the North American species range to assess the relative importance of cyanogenesis loci vs. other genomic factors in local climatic adaptation. We find clear evidence of local adaptation, with temperature‐related climatic variables best describing genome‐wide differentiation between sampling locations. The same climatic variables are also strongly correlated with cyanogenesis frequencies and gene copy number variations (CNVs) at cyanogenesis loci. However, landscape genomic analyses indicate no significant contribution of cyanogenesis loci to local adaptation. Instead, several genomic regions containing promising candidate genes for plant response to seasonal cues are identified — some of which are shared with previously identified QTLs for locally adaptive fitness traits in North American white clover. Our findings suggest that local adaptation in white clover is likely determined primarily by genes controlling the timing of growth and flowering in response to local seasonal cues. More generally, this work suggests that caution is warranted when considering the importance of conspicuous phenotypic clines as primary determinants of local adaptation. [ABSTRACT FROM AUTHOR]

Introducing beneficial productivity and nutritional traits into food, feed and forage crops utilising the tools of biotechnology can lead to improvements via genetic modification that cannot be achieved by traditional plant breeding. The timelines and costs are significant, and the regulatory hurdles can lead to some promising traits failing to be commercialised. These challenges mean that large commodity crops are the primary beneficiaries of biotechnology. New Zealand being primarily a grazing pastoral agricultural market and small in international terms, faces greater challenges. The species used in pastoral agriculture have relatively small seed markets and therefore limited investment for genetic improvement. The nutritional quality of feed and forages both in composition and in energy density per ha has a major influence on animal productivity and the environmental impacts of agriculture. Through government and private industry support, AgResearch has developed novel approaches to improve plant photosynthesis, energy density, and nutritional quality that has applications in crops globally. This review discusses the different challenges and solutions to improving plant nutrient density and outlines the benefits of these novel biotechnology traits in animal forage and feed crops. [ABSTRACT FROM AUTHOR]

This study examines the potential of 23 plant species, comprising 10 legumes, 9 grasses, and 4 forbs, as cover crops to enhance carbon (C) sequestration and soil nitrogen (N) in vineyards. After a 120-day evaluation period, cover crop biomass was incorporated into the soil, and grapevine seedlings were planted in its place. Among the established cover crops, the C input potential ranged from 0.267 to 1.69 Mg ha−1, and the N input potential ranged from 12.3 to 114 kg ha−1. Legume species exhibited up to threefold greater shoot dry weight (SDW) compared to grass species. Ladino white clover, Dutch white clover, and Clover blend were superior in SDW, total dry weight (TDW), total C content, and total N content. Legumes exhibited slightly higher root dry weight (RDW) than grasses, with the exception of Fall rye leading at 15 g pot−1, followed by Ladino white clover and Dutch white clover at an average of 12 g pot−1. Legumes, particularly clover blend and Alsike clover, displayed high shoot N concentration at an average of 2.95%. Root N concentration in Legumes (Fabaceae) were significantly higher at 1.82% compared to other plant families at 0.89%, while their root C/N ratio was lower at 18.3, contrasting with others at 27.7, resulting in a faster turnover. Biomass production exhibited a negative relationship (R2 = 0.51) with soil residual NO3−. Fall rye, Winfred brassica, and buckwheat had the highest N utilization efficiency (NUtE) values (ava. 121 g g−1). Alsike clover, Ladino white clover, and clover blend showed the highest N uptake efficiency (NUpE) values (ava. 75%). The Readily Available N (RAN) Reliance Index (RANRI) is introduced as a novel indicator for quantifying the extent to which a plant relies on RAN for its total N requirement. The RANRI value represents the percentage of the plant's total N sourced from RAN, ranging from 11% for legumes to 86% for grasses. This implies a substantial influx of nitrogen through a pathway independent of RAN in legumes. Grape shoot N concentration positively correlated with soil NO3− (R2 = 0.31) and cover crop C/N ratio (R2 = 0.17) but negatively correlated with cover crop TDW (R2 = 0.31). This study highlights legume plants as more effective in C and N assimilation during establishment but cautions about potential soil mineral N depletion before reaching their full biological N fixation capacity. [ABSTRACT FROM AUTHOR]

[Objective] The study aimed to explore the effects of four weed populations on apple photosynthetic characteristics and fruit quality formation, and screen out suitable grass for planting in Zhaotong orchards. [Method] We conducted a field experiment with Fuji apples and set orchard clear-cutting as the control, and explored the effects of Artemisia absinthium(Artemisia lavandulaefolia DC), Artemisia stellate (Stellaria vestita Kurz.), Ryegrass (Lolium perenne L.) and White-flowered cheatgrass (Trifolium repens Linn) on the leaf chlorophyll content, photosynthetic characteristics and fruit quality of the fruit trees. [Result] White-flowered cheatgrass treatment could increase leaf total chlorophyll content, net photosynthetic rate (P), intercellular CO₂ concentration (C₁), stomatal conductance(G) and carboxylation efficiency (CE), while the water use efficiency (WUE) of the fruit trees was significantly reduced. The Artemisia absinthium treatment could increase leaf G, and improve C, to a certain extent, but it would reduce the total chlorophyll content and leaf CE. Artemisia stellate treatment could increase C, and the total chlorophyll content as well as leaf transpiration rate (T,) were reduced. Ryegrass treatment significantly increased WUE and CE, but significantly reduced T. Quality aspect, the various raw grass treatments increased fruit solids content by 0.88% 13.87%, reduced reducing sugar content by 2.30% 15.71%, increased total antioxidant capacity by 10.03%-40.92%, and the ryegrass treatment reduced hydrogen peroxide content by 41.80% and superoxide anion scavenging capacity by 12.92%, as compared to clear tillage. Using fuzzy membership function analysis, the comprehensive evaluation value of clear tillage, white clover, mugwort, stellaria and ryegrass were 0.4858, 0.6044, 0.5548, 0.4894 and 0.6059, respectively. [Conclusion] Different weed populations can improve the photosynthetic capacity of fruit leaves and improve fruit quality to a certain extent. Scientific evaluation of four weed populations is beneficial to screen out more reasonable grass types in orchards. [ABSTRACT FROM AUTHOR]

Historically, white clover (Trifolium repens) seed was included in turfgrass seed mixtures to provide biodiversity and nitrogen (N) to lawns. White clover dicultures have been studied recently for inclusion in both warm- and cool-season turfgrasses, with the goals of reducing fertilizer applications and providing pollinator forage in lawns; however, other clovers have not been as widely researched in turfgrass. The objectives of this study were to evaluate 1) if white, strawberry (T. fragiferum), crimson (T. incarnatum), and rose (T. hirtum) clovers can persist in dicultures with Kentucky bluegrass (Poa pratensis); 2) if clover inclusion in dicultures impacts broadleaf weed cover; and 3) if low levels of N fertilization impact clover persistence or quality of clover-bluegrass dicultures. Kentucky bluegrass was grown as a monoculture or as a diculture with each of the four clover species. Each mono- or diculture was then treated with a low rate of N fertilizer (48.8 kgha-1 N) or no N fertilizer to determine quality and percentage of grass, clover, or weed and bare-soil cover. Dicultures contained similar or less weed and bare-soil cover, and maintained similar or greater quality compared with bluegrass monocultures, indicating clover and Kentucky bluegrass dicultures are suitable alternatives to Kentucky bluegrass monoculture lawns, and can potentially lead to reduced fertilizer and pesticide requirements. Fertilizer generally had no effect on cover, likely because of the low rates of N applied. [ABSTRACT FROM AUTHOR]

In the absence of chemical control with its negative side effects, fungal pathogens can cause large yield losses, requiring us to develop agroecosystems that are inherently disease resistant. Grassland biodiversity experiments often find plant species diversity to reduce pathogen pressure, but whether incorporating high biodiversity levels in agricultural fields have similar effects remains largely unknown.We tested if undersown plant species diversity could reduce barley disease, and whether the effect was mediated through above‐ or below‐ground mechanisms, by combining an agricultural field trial with a soil transplant experiment.As predicted, barley disease decreased in the presence of undersown plants. Undersown species richness had no effect, but their abundance led to early season disease reduction. Above‐ground mechanisms underpinned this disease reduction. Barley yield slightly decreased with increasing undersown species richness, and undersown species varied in their impact on yield.We identified two undersown species, Trifolium repens and T. hybridum, that contributed most to disease reduction and had the potential to increase barley yield. Furthermore, our results indicate that above‐ground mechanisms caused this. We show that agroecosystem functioning can be improved without trade‐offs on yield by targeted selection of undersown species. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Azotobacter chroococcum and Bacillus subtilis were selected as fermentation strains, and biogas residue after anaerobic digestion of kitchen waste and residual sludge was used as fermentation substrate. A single factor optimization test was used to optimize the solid-state fermentation parameters of biogas residue with the number of viable bacteria and the number of spores as indexes. The results showed that the optimum inoculation conditions involved the following: 55% initial moisture content, 15% initial inoculation amount, 30 ℃, and 1:1 initial inoculation ratio for 13 days. Pot experiment showed that the prepared three kinds of bacterial fertilizers could not only effectively promote the growth of white clover, improve the composition of soil nutrients, but also change the structure of soil bacterial community, which is of great significance to the health of soil ecosystem in white clover. [ABSTRACT FROM AUTHOR]

Abstract Background White clover (Trifolium repens L.) is an excellent leguminous cool-season forage with a high protein content and strong nitrogen-fixing ability. Despite these advantages, its growth and development are markedly sensitive to environmental factors. Indole-3-acetic acid (IAA) is the major growth hormone in plants, regulating plant growth, development, and response to adversity. Nevertheless, the specific regulatory functions of Aux/IAA genes in response to abiotic stresses in white clover remain largely unexplored. Results In this study, we identified 47 Aux/IAA genes in the white clover genome, which were categorized into five groups based on phylogenetic analysis. The TrIAAs promoter region co-existed with different cis-regulatory elements involved in developmental and hormonal regulation, and stress responses, which may be closely related to their diverse regulatory roles. Collinearity analysis showed that the amplification of the TrIAA gene family was mainly carried out by segmental duplication. White clover Aux/IAA genes showed different expression patterns in different tissues and under different stress treatments. In addition, we performed a yeast two-hybrid analysis to investigate the interaction between white clover Aux/IAA and ARF proteins. Heterologous expression indicated that TrIAA18 could enhance stress tolerance in both yeast and transgenic Arabidopsis thaliana. Conclusion These findings provide new scientific insights into the molecular mechanisms of growth hormone signaling in white clover and its functional characteristics in response to environmental stress.

ABSTRACT: The objective of this study was to quantify the farm gate nitrogen (N) offset potential of perennial ryegrass (Lolium perenne L.; PRG) white clover (Trifolium repens L.; WC) swards by comparing the herbage and milk production from dairy farmlets that were simulations of full farming systems. A study was established where 120 cows were randomly assigned to 4 farmlets of 10.9 ha (stocking rate: 2.75 cow/ha), composed of 20 paddocks each. Cows were fed 526 kg of DM of concentrate on average each year. The 4 grazing treatments were PRG-only at 150 or 250 kg of N/ha and PRG-WC at 150 or 250 kg of N/ha. Cows remained in their treatment group for an entire grazing season and were re-randomized as they calved across treatments each year. As cows calved in the spring as standard practice in Ireland, they were rotationally grazed from early February both day and night (weather permitting) to mid-November, to a target postgrazing sward height of 4.0 cm. Mean sward WC content was 18.1% and 15.4% for the 150 and 250 kg of N/ha PRG-WC treatments, respectively over the 3-yr period. When WC was included, lowering the N rate did not reduce pregrazing yield, pregrazing height, or herbage removed, but those factors decreased significantly when WC was absent. Total annual herbage DM production was 13,771, 15,242, 14,721, and 15,667 kg of DM/ha for PRG-only swards receiving 150 or 250 kg of N/ha and PRG-WC swards receiving 150 or 250 kg of N/ha, respectively. In addition, when WC was present, compressed postgrazing sward heights were lower (4.10 vs. 4.21 cm) and herbage allowance (approximately 17 kg/cow feed allocation per cow per day) higher than the high-N control (+ 0.7 kg of DM/cow per day). There was a significant increase in milk production, both per cow and per hectare, when WC was included in PRG swards. Over the 3-yr study, cows grazing PRG-WC had greater milk (+304 kg) and milk solids (+31 kg of fat + protein) yields than cows grazing PRG-only swards. This significant increase in milk production suggests that the inclusion of WC in grazing systems can be effectively used to increase milk production per cow and per hectare and help offset nitrogen use. This result shows the potential to increase farm gate N use efficiency and reduce the N surplus compared with PRG-dominant sward grazing systems receiving 250 kg of N/ha, without negatively affecting milk solids yield or herbage production, thus increasing farm profit by €478/ha.

Extreme heat poses a major threat to plants and pollinators, yet the indirect consequences of heat stress are not well understood, particularly for native solitary bees. To determine how brief exposure of extreme heat to flowering plants affects bee behaviour, fecundity, development and survival we conducted a no-choice field cage experiment in which Osmia lignaria were provided blueberry (Vaccinium corymbosum), phacelia (Phacelia tanacetifolia) and white clover (Trifolium repens) that had been previously exposed to either extreme heat (37.5°C) or normal temperatures (25°C) for 4 h during early bloom. Despite a similar number of open flowers and floral visitation frequency between the two treatments, female bees provided with heat-stressed plants laid approximately 70% fewer eggs than females provided with non-stressed plants. Their progeny received similar quantities of pollen provisions between the two treatments, yet larvae consuming pollen from heat-stressed plants had significantly lower survival as larvae and adults. We also observed trends for delayed emergence and reduced adult longevity when larvae consumed heat-stressed pollen. This study is the first to document how short, field-realistic bursts of extreme heat exposure to flowering host plants can indirectly affect bee pollinators and their offspring, with important implications for crop pollination and native bee populations. [ABSTRACT FROM AUTHOR]

Allelopathy is a biological process in which one organism releases biochemicals that affect the growth and development of other organisms. The current investigation sought to determine the allelopathic effect of Rumex acetosella on white clover (Trifolium repens) growth and development by using its shoot extract (lower IC50 value) as a foliar treatment. Here, different concentrations (25, 50, 100, and 200 g/L) of shoot extract from Rumex acetosella were used as treatments. With increasing concentrations of shoot extract, the plant growth parameters, chlorophyll and total protein content of Trifolium repens decreased. On the other hand, ROS, such as O2.− and H2O2, and antioxidant enzymes, including SOD, CAT, and POD, increased with increasing shoot extract concentration. A phytohormonal study indicated that increased treatment concentrations increased ABA and SA levels while JA levels were reduced. For the identification of allelochemicals, liquid‒liquid extraction, thin-layer chromatography, and open-column chromatography were conducted using R. acetosella shoot extracts, followed by a seed bioassay on the separated layer. A lower IC50 value was obtained through GC/MS analysis. gammaSitosterol was identified as the most abundant component. The shoot extract of Rumex acetosella has strong allelochemical properties that may significantly impede the growth and development of Trifolium repens. This approach could help to understand the competitive abilities of this weed species and in further research provide an alternate weed management strategy. [ABSTRACT FROM AUTHOR]

Lactic acid bacteria (LAB) are commonly used as silage inoculants. Manganese sulphate (MnSO4) has been proposed to protect certain LAB during oxygen exposure and improve silage aerobic stability (ASTA). The aim of the present study was to assess the efficacy of inoculants in preservation of different forages. A short‐term screening trial investigated the effect of 24 additive treatments, compared to a negative control, on ensiling perennial grass in mini‐silos (2.75 L) for 7 d. The additive treatments comprised different ratios of Lactiplantibacillus plantarum [IMI 507026, IMI 507027, and IMI 507028] and Pediococcus pentacaceus [IMI 507024 and IMI 507025], with or without MnSO4. Target parameters, such as low levels of fresh matter loss, pH, acetic acid, ammonia‐nitrogen fraction (NH3–N/Total N), and high levels of lactic acid and ASTA, were considered for treatment selection. Eight treatments were selected based on a principal component analysis and hierarchical clustering of the target parameters. These selected treatments subsequently underwent a 100 d long‐term trial using lucerne, perennial grass, and perennial grass‐white clover forages. All silages treated with the eight additives exhibited an improved homolactic fermentation and a lower (p <.001) pH, acetic acid, and ethanol content than the control. Although DM losses and ASTA markedly improved in the treatments containing MnSO4 in the short‐term trial, these effects were not observed in the long‐term trial. These outcomes suggest that the selected additives can improve silage fermentation quality across a broad range of forages, but further studies are required to assess the impact of MnSO4 on ASTA. [ABSTRACT FROM AUTHOR]

Urine patches from grazing ruminants contain high concentrations of nitrogen (N) and are the main source of N leaching from grazed pastoral farming systems. While there have been various options identified to substantially reduce N leaching, in general these practices increase the cost of production or reduce production per hectare. In New Zealand, multi‐species pastures were evaluated as a cheaper option that would potentially retain productivity. Early research showed these pastures had lower urinary N excretion from grazing animals and increased plant N uptake, compared with standard New Zealand perennial ryegrass/white clover (PR‐WC) pastures. Further research highlighted the beneficial attributes of the pasture herb narrow‐leaved plantain (Plantago lanceolata; PL), specifically: reduced urine N concentration, reduced urine N excretion, and reduced rate of soil nitrification. Significant reductions (14%–89%) in N leaching were found from cow urine applied to lysimeters with pastures including PL, compared with PR‐WC pasture. Paddock‐scale measurements confirmed the effects of PL, with 20%–60% lower N leaching when PL comprised 30%–40% of the dry matter (DM) of PL‐PR‐WC grazed pastures. There were no negative effects on milk production and composition when feeding PL to dairy cows, but small positive effects on fatty acid profiles. However, weed and pest management, palatability and persistence remain challenging in pastures containing PL on commercial farms. Management options need to be clarified to ensure successful establishment and maintenance of PL. Additionally, the cultivar differences in secondary compounds and their impact on nitrification rate and N leaching need to be better understood. [ABSTRACT FROM AUTHOR]

Aims: To develop a methodology to study uptake and redistribution by plants of NH4+ from deep soil, applying it to investigate deep root N uptake by cultivated grassland species. Methods: A slow-release 15NH4+ label adsorbed to clinoptilolite was placed into soil (depth 42 cm) well below the densest root zone in well-established monospecific stands of five grass and two clover species. Species showing a variety of deep rooting patterns, N acquisition strategy, forage qualities, and persistence in hemiboreal conditions were chosen. The label was placed in early spring and tracked throughout one or two growing seasons in two repeated experiments. Results: After two growing seasons ~ 90% of the label was tracked in the soil and harvested herbage of grasses, less in clovers. Deep N uptake was limited in spring, increased during mid-season, and was strongest in autumn in all species, despite lower herbage yield in autumn. Species differed in ability to recover and maintain 15N in the soil–plant system. In one growing season, Lolium perenne L., Phleum pratense L., Schedonorus pratensis (Huds.) P.Beauv. and Schedonorus arundinaceus (Schreb.) Dumort herbage recovered ~ 65% of the label, Poa pratensis L. 54%, and Trifolium pratense L. and Trifolium repens L. 36–48%. Label transport to topsoil was observed, mainly attributable to plant nutrient redistribution rather than physical diffusion. Conclusions: The innovative slow-release 15N label enabled tracing species differences and seasonal changes in uptake of NH4+ from deep soil. Among the tall-growing grasses, growth vigor appeared as important for deep N uptake as expected root depth. [ABSTRACT FROM AUTHOR]

Purpose: Dissolved organic matter (DOM) plays a key role in agroecosystems' carbon cycling. However, the DOM evolutionary signatures and the timing of equilibrium being achieved in dryland inter-planting systems remain unclear. This study aimed to determine the characteristics of DOM dynamics using a three-dimensional fluorescence excitation-emission matrix combined with parallel factor analysis (EEMs-PARAFAC). Methods: DOM contents, different related components accumulation were assessed using clear tillage (CT) as the control, white clover (Trifolium repens L.) of three different ages (4, 8, 12 years), representing a chronosequence, in apple orchards on the Loess Plateau. Results: At a depth of 0–10 cm, DOM concentration decreased with depth and significantly increased with longer inter-planting, and the five fluorescence components contents of soil DOM showed a similar trend. Moreover, the relative abundances of humic-like (C2, C3) was higher than CT, but the protein-like was lower. The ultraviolet–visible spectral and optical indices indicated that DOM mainly originated from mixed sources, and gradually tended towards greater DOM molecular complexity with increasing time since sowing. Microbial biomass nitrogen and soil organic carbon (SOC) were the most important two factors affecting DOM over time, contributing to 87% and 77% of the total variation. Conclusions: This study demonstrated that inter-planting time and soil depth played important roles in determining DOM content and component accumulation. Overall, inter-planting with white clover in orchards can effectively improve the accumulation of macro-molecular humic-like DOM, which probably promotes SOC storage. Long-term experiments are required exploring DOM dynamics and the timing of equilibrium being reached. [ABSTRACT FROM AUTHOR]

Sprouts' consumption has become popular due to their wide availability, easy cultivation process, and proven biological activity. Moreover, stress factors, such as limited access to light or disturbed gravity during growth, may contribute to the increased activity and the synthesis of bioactive compounds. In this study, for the first time, the examination of the impact of darkness and simulated microgravity conditions on the white clover sprouts from the Fabaceae family was conducted. Among several species, used in the preliminary attempts, only white clover was satisfactory sprouting in the disturbed gravity conditions, and thus was chosen for further examination. A random positioning machine setup was used during the cultivation process to simulate microgravity conditions. Additionally, the sprouts were cultivated in total darkness. Simulated microgravity and/or darkness during the first few days of the sprouts' growth caused biomass reduction, the increased synthesis of bioactive compounds (isoflavones and phenolics), and changes in the level of abscisic acid and phenylalanine ammonia-lyase. Moreover, it increased the antioxidant properties of the sprouts, while the enhancement of their cytotoxic impact was observed only for androgen-dependent prostate cancer LNCaP cells. To conclude, the presented results are promising in searching for novel functional food candidates and further studies are necessary, directed at other plant families. [ABSTRACT FROM AUTHOR]

Parthenium hysterophorus L. has become a weed of global concern owing to its fast expansion and invasive character. In order to study the status of this noxious weed and its impact on floristic diversity in Dhauladhar foothills, the study was conducted during the year 2021–2022 in culturable wastelands of Dhauladhar ranges in Kangra district of Himachal Pradesh, India. The impact of Parthenium hysterophorus L. on associated species at different altitudes and aspects was observed. Our observations depicted that Parthenium hysterophorus L. has been growing more vigorously in the northern aspect than the southern aspect with the density of 37.78 m−2 and 21.62 m−2, respectively. The highest density of this noxious weed was recorded in the altitudinal range of 600–1200 m (34.32 m−2) while it was not observed beyond 1805 m above sea level. The invasion of Parthenium hysterophorus L. significantly affected the plant density of other species. The descending order of the species as per dominance was observed as Cynodon dactylon, Trifolium repens, Oxalis latifolia, Parthenium hysterophorus L., and Ageratum houstonianum. The average number of species and species density were observed more in non-invaded sites (9.35 and 27.67 m−2) than in invaded sites (7.10 and 20.60 m−2). Species abundance and plant cover were observed more in non-invaded sites (28.73 and 657.90 m2 ha−1) than in invaded sites (22.70 and 322.30 m2 ha−1). Species diversity, richness, and evenness were reported to decline in invaded sites (1.56, 0.95, and 0.81, respectively) with respect to the non-invaded sites (1.94, 1.16, and 0.88, respectively). The study highlights the significant concerns associated with the invasive weed within the plant communities. Understanding its invasive status holds considerable implications for local afforestation initiatives, forest management strategies, and conservation policies. Furthermore, this investigation lays a foundational groundwork for implementing effective measures to get rid of this alien weed. [ABSTRACT FROM AUTHOR]

The study investigated compounds present in the invasive grass Hordeum murinum L. subsp. murinum and tested the allelopathic potential of this plant against common meadow species Festuca rubra L. and Trifolium repens L. Gas chromatography–mass spectrometry (GC–MS) performed separately on the ears and stalks with leaves of wall barley revealed 32 compounds, including secondary metabolites, that may play an important role in allelopathy. Two compounds, N-butylbenzenesulfonamide (NBBS) and diphenylsulfone (DDS), were described for the first time for wall barley and the Poaceae family. The presence of 6,10,14-trimethylpentadecan-2-one (TMP) has also been documented. Aqueous extracts of H. murinum organs (ears and stalks with leaves) at concentrations of 2.5%, 5%, and 7.5% were used to evaluate its allelopathic potential. Compared to the control, all extracts inhibited germination and early growth stages of meadow species. The inhibitory effect was strongest at the highest concentration for both the underground and aboveground parts of the seedlings of the meadow species tested. Comparing the allelopathic effect, Trifolium repens proved to be more sensitive. In light of the results of the study, the removal of wall barley biomass appears to be important for the restoration of habitats where this species occurs due to its allelopathic potential. [ABSTRACT FROM AUTHOR]

Planting a cover crop living mulch between plastic mulch beds in fresh market vegetable production can reduce soil erosion and runoff, and offers an opportunity to grow an income generating cash crop alongside a soil building cover crop. However, potential negative impacts on yield, variable weed control, unclear impacts on soil health, and limited management recommendations challenge adoption of this practice, despite grower interest. In a two-year study in southwest Michigan, living mulches were evaluated in the production of plasticulture organic summer squash (Cucurbita pepo cv. Lioness) and bell pepper (Capsicum annuum cv. Paladin). Strategies evaluated included three common grower practices (cultivation, dead straw mulch, mowing ambient weeds) and three mowed living mulch treatments (Italian ryegrass [Lolium multiflorum] monoculture, rye [Secale cereale] monoculture, and a Dutch white clover [Trifolium repens]/rye mixture). We determined the impact of these strategies on weed control, organic matter inputs, vegetable crop performance, nitrogen retention, and soil microbial communities. We found that cultivation and dead mulch provided superior in-season weed control, reducing weed biomass by an average of 86% compared to 18% among living mulch treatments, with associated reductions in the weed seedbank compared to living mulches and mowed weeds. In most cases, living mulch establishment was a challenge and weed biomass on average accounted for 99, 74, and 94% of organic matter inputs in rye, ryegrass, and clover/rye treatments, respectively. Squash performance was unaffected by our treatments, but pepper yield reductions ranged from 41 to 54% in all treatments relative to cultivation in one of two years. Living mulches and the weedy treatment showed the ability to reduce end-of-season potentially leachable nitrogen by 61% compared to cultivation and dead mulching. Soil microbial abundance and functional diversity were similar across treatments, but extracellular enzyme activity was higher in dead mulch, living mulch and weedy treatments compared to cultivation. Results from this study help quantify tradeoffs between common grower practices for managing weeds and soil between plastic mulch beds, highlight key challenges with living mulch alternatives, and identify areas for future research. [ABSTRACT FROM AUTHOR]

During the period 2020-2022, the following types of meadow legume crops were tested on light gray pseudopodzolic soil on the territory of the experimental field of Research Institute of Mountain Stockbreeding and Agriculture-Troyan: Lotus corniculatus L., Trifolium hibridum L., Medicago sativa L., Trifolium pretense L., Trifolium repens L. The matter yield, the biodiversity of the species in the grass stand and the impact of the factors, such as conditions of the year and the type of grass stands were studied to determine the acclimatization of meadow legume crops under mountain conditions. It was established that the tested legume forage species realized a high yield of dry matter under mountain conditions, which varied from 836.68 to 971.13 kg/da, which determined their good adaptability for cultivation under the conditions of light gray pseudopodzolic soils. The low values of their variation coefficients by year and average yield of 909.35 kg/da of all species show that they are suitable for inclusion in the structure of farms in mountain conditions. Alfalfa proved to be the most rational for cultivation, followed by red clover. The botanical composition of the grass stands depends on the rate of growth and development of the herbaceous species. The high productivity of alfalfa corresponds to its high presence in the grass stand, which also indicates its high productivity. Natural factors determine the productivity of the grass stands of the various legume species, and subsequently the economic efficiency in the production of fodder. [ABSTRACT FROM AUTHOR]

Urbanization frequently alters the biotic and abiotic environmental context. Variation in both the biotic and abiotic environment can result in selection mosaics that lead to locally adapted phenotypes. Ecological changes to urban environments can result in evolutionary responses across a diverse array of plants and animals, but the effects of urbanization on local adaptation and coevolution between species remain largely unstudied.Using a common garden experiment of 30 populations and 1080 plants, we tested for local adaptation in the mutualism between white clover (Trifolium repens) and rhizobia (Rhizobium leguminosarum symbiovar trifolii) along an urbanization gradient. We asked: (Q1) are white clover and rhizobia locally adapted? (Q2) Does nitrogen (N) addition mediate the strength of local adaptation? (Q3) Is the strength of local adaptation in host plants related to the strength of local adaptation in rhizobia, as expected if white clover and rhizobia are coadapting? And (Q4) how does the degree of local adaptation vary with urbanization?We found evidence for local adaptation for both white clover and rhizobia, with stronger signatures of local adaptation for rhizobia than white clover (Q1). While N addition positively affected plant biomass and negatively affected nodule density, N addition did not consistently mediate patterns of local adaptation (Q2). The strength of local adaptation was positively related between white clover and rhizobia under N addition, suggesting that soil N mediates coadaptation between white clover and rhizobia (Q3). We did not find a consistent relationship between measures of urbanization and local adaptation (Q4). Additionally, fitness responses for white clover and rhizobia were unrelated to Rhizobium abundance and local adaptation was unrelated to the broader bacterial microbiome in the soil inoculants or root endosphere.Synthesis. Our results show a spatial mosaic in local adaptation, with stronger local adaptation for rhizobia than white clover. While urbanization does influence the ecology of plant–microbe interactions, our study suggests urbanization does not disrupt local adaptation and coevolution among mutualists. [ABSTRACT FROM AUTHOR]

Bacteria belonging to the genus Micromonospora are recognized as microorganisms with the potential to be used in biotechnology processes, given their beneficial influence on plant growth and the biocontrol of phytopathogens. In this study, nineteen Micromonospora isolates originating from the root nodules of white clover plants were taxonomically assigned based on the phylogenetic analysis of the 16S rRNA gene and four housekeeping genes. The antifungal properties of the bacteria against phytopathogenic Botrytis cinerea, Fusarium oxysporum, Fusarium equiseti, Sclerotinia sclerotiorum, and Verticillium albo-atrum were tested with the agar plug test and the dual culture test. The ability to produce various metallophores was determined with the agar plug diffusion test on modified chrome azurol S (CAS) agar medium. International Streptomyces Project-2 medium (ISP2) broth amended with 0.2% L-tryptophan was used to indicate the bacterial ability to produce auxins. The strains belonging to M. tulbaghiae, M. inaquosa, and M. violae showed in vitro potential as antimicrobial agents against the tested fungi. M. inaquosa strain 152, M. violae strain 126, M. violae strain 66, and M. violae strain 45 were recognized as the most efficient metallophore producers. M. alfalfae strain 55 and M. lupini strain 5052 were identified as the most promising auxin compound producers and, therefore, show potential as plant-growth-promoting bacteria. [ABSTRACT FROM AUTHOR]

In this work, we present and describe a spectral library (SL) with 15 vascular plant species from Montesinho Natural Park (MNP), a protected area in Northeast Portugal. We selected species from the vascular plants that are characteristic of the habitats in the MNP, based on their prevalence, and also included one invasive species: Alnus glutinosa (L.) Gaertn, Castanea sativa Mill., Cistus ladanifer L., Crataegus monogyna Jacq., Frangula alnus Mill., Fraxinus angustifolia Vahl, Quercus pyrenaica Willd., Quercus rotundifolia Lam., Trifolium repens L., Arbutus unedo L., Dactylis glomerata L., Genista falcata Brot., Cytisus multiflorus (L'Hér.) Sweet, Erica arborea L., and Acacia dealbata Link. We collected spectra (300–2500 nm) from five records per leaf and leaf side, which resulted in 538 spectra compiled in the SL. Additionally, we computed five vegetation indices from spectral data and analysed them to highlight specific characteristics and differences among the sampled species. We detail the data repository information and its organisation for a better understanding of the data and to facilitate its use. The SL structure can add valuable information about the selected plant species in MNP, contributing to conservation purposes. This plant species SL is publicly available in Zenodo platform. [ABSTRACT FROM AUTHOR]

Excessive aluminum (Al) in acidic soils is a primary factor that hinders plant growth. The objective of the present study was to investigate the effect and physiological mechanism of exogenous silicon (Si) in alleviating aluminum toxicity. Under hydroponic conditions, 4 mM Al significantly impeded the growth of white clover; however, pretreatments with 1 mM Si mitigated this inhibition, as evidenced by notable changes in growth indicators and physiological parameters. Exogenous silicon notably increased both shoot and root length of white clover and significantly decreased electrolyte leakage (EL) and malondialdehyde (MDA) content compared to aluminum treatments. This positive effect was particularly evident in the roots. Further analysis involving hematoxylin staining, scanning electron microscopy (SEM), and examination of organic acids (OAs) demonstrated that silicon relieved the accumulation of bioactive aluminum and ameliorated damage to root tissues in aluminum-stressed plants. Additionally, energy-dispersive X-ray (EDX) analysis revealed that additional silicon was primarily distributed in the root epidermal and cortical layers, effectively reducing the transport of aluminum and maintaining the balance of exchangeable cations absorption. These findings suggest that gradual silicon deposition in root tissues effectively prevents the absorption of biologically active aluminum, thereby reducing the risk of mineral nutrient deficiencies induced by aluminum stress, promoting organic acids exudation, and compartmentalizing aluminum in the outer layer of root tissues. This mechanism helps white clover alleviate the damage caused by aluminum toxicity. [ABSTRACT FROM AUTHOR]

Background: White clover (Trifolium repens L.) is an excellent leguminous cool-season forage with a high protein content and strong nitrogen-fixing ability. Despite these advantages, its growth and development are markedly sensitive to environmental factors. Indole-3-acetic acid (IAA) is the major growth hormone in plants, regulating plant growth, development, and response to adversity. Nevertheless, the specific regulatory functions of Aux/IAA genes in response to abiotic stresses in white clover remain largely unexplored. Results: In this study, we identified 47 Aux/IAA genes in the white clover genome, which were categorized into five groups based on phylogenetic analysis. The TrIAAs promoter region co-existed with different cis-regulatory elements involved in developmental and hormonal regulation, and stress responses, which may be closely related to their diverse regulatory roles. Collinearity analysis showed that the amplification of the TrIAA gene family was mainly carried out by segmental duplication. White clover Aux/IAA genes showed different expression patterns in different tissues and under different stress treatments. In addition, we performed a yeast two-hybrid analysis to investigate the interaction between white clover Aux/IAA and ARF proteins. Heterologous expression indicated that TrIAA18 could enhance stress tolerance in both yeast and transgenic Arabidopsis thaliana. Conclusion: These findings provide new scientific insights into the molecular mechanisms of growth hormone signaling in white clover and its functional characteristics in response to environmental stress. [ABSTRACT FROM AUTHOR]

The objective of this study was to quantify the farm gate nitrogen (N) offset potential of perennial ryegrass (Lolium perenne L.; PRG) white clover (Trifolium repens L.; WC) swards by comparing the herbage and milk production from dairy farmlets that were simulations of full farming systems. A study was established where 120 cows were randomly assigned to 4 farmlets of 10.9 ha (stocking rate: 2.75 cow/ha), composed of 20 paddocks each. Cows were fed 526 kg of DM of concentrate on average each year. The 4 grazing treatments were PRG-only at 150 or 250 kg of N/ha and PRG-WC at 150 or 250 kg of N/ha. Cows remained in their treatment group for an entire grazing season and were re-randomized as they calved across treatments each year. As cows calved in the spring as standard practice in Ireland, they were rotationally grazed from early February both day and night (weather permitting) to mid-November, to a target postgrazing sward height of 4.0 cm. Mean sward WC content was 18.1% and 15.4% for the 150 and 250 kg of N/ha PRG-WC treatments, respectively over the 3-yr period. When WC was included, lowering the N rate did not reduce pregrazing yield, pregrazing height, or herbage removed, but those factors decreased significantly when WC was absent. Total annual herbage DM production was 13,771, 15,242, 14,721, and 15,667 kg of DM/ha for PRG-only swards receiving 150 or 250 kg of N/ha and PRG-WC swards receiving 150 or 250 kg of N/ha, respectively. In addition, when WC was present, compressed postgrazing sward heights were lower (4.10 vs. 4.21 cm) and herbage allowance (approximately 17 kg/cow feed allocation per cow per day) higher than the high-N control (+ 0.7 kg of DM/cow per day). There was a significant increase in milk production, both per cow and per hectare, when WC was included in PRG swards. Over the 3-yr study, cows grazing PRG-WC had greater milk (+304 kg) and milk solids (+31 kg of fat + protein) yields than cows grazing PRG-only swards. This significant increase in milk production suggests that the inclusion of WC in grazing systems can be effectively used to increase milk production per cow and per hectare and help offset nitrogen use. This result shows the potential to increase farm gate N use efficiency and reduce the N surplus compared with PRG-dominant sward grazing systems receiving 250 kg of N/ha, without negatively affecting milk solids yield or herbage production, thus increasing farm profit by €478/ha. [ABSTRACT FROM AUTHOR]

Weed control and replenishing soil moisture and fertility are important areas in fruit production. The number of studies focused to determine whether living mulches in tree rows can fulfil these tasks increases recently. In the paper the results of an 11-year experiment on the effect of two such mulches (Trifolium repens L. and Agrostis capillaris L.) on the growth, yield, and fruit quality of three pear cultivars ('Alfa', 'Dolores', 'Amfora') in relation to herbicide fallow are presented. In the experiment, a single sowing of covering plants without additional treatments was used. A statistically significant reduction in yield (20-22%) was found for both mulches used, which was related to weakening the vegetative growth of trees. The average fruit mass did not change significantly, but the percent share of large fruits increased significantly (about 17%) in the A. capillaris mulch. Fruits from trees growing in T. repens contained significantly more soluble solids and Ca. However, that mulch became heavily infested with weeds after a few years. The obtained results allow us to recommend the use of the living mulch A. capillaris in the tree rows of a commercial pear orchard. The 'Dolores' and 'Amfora' cvs are particularly recommended. [ABSTRACT FROM AUTHOR]

The clover seed weevil, Tychius picirostris Fabricius, a serious pest of white clover, Trifolium repens L. grown for seed in western Oregon, causing feeding damage to flowers and developing seeds. Since 2017, white clover seed producers have anecdotally reported T. picirostris control failures using foliar pyrethroid insecticide applications. This mode of action (MoA) is an important chemical control option for T. picirostris management. To evaluate insecticide resistance selection to pyrethroids (bifenthrin) and other MoAs labeled for T. picirostris management (malathion and chlorantraniliprole), adult populations were collected from 8 commercial white clover grown for seed fields in the Willamette Valley, OR, in 2022 and 2023. Among collected Oregon populations, very high resistance ratios (RR50 = 178.00–725.67) were observed to technical grade bifenthrin and low to high resistance ratios (RR50 = 7.80–32.80) to malathion in surface contact assays compared to a susceptible Canadian field population. Moreover, >2.73 times the labeled rate of formulated product containing bifenthrin as the sole MoA was required to kill >50% of T. picirostris in topical assays. Synergistic assays with a mixed-function oxidase inhibitor, an esterase inhibitor, and a glutathione- S -transferase inhibitor revealed phase I and II detoxification enzymes are present in Oregon T. picirostris populations and confer metabolic resistance to bifenthrin. This is the first report of T. picirostris insecticide resistance selection to pyrethroid and organophosphate insecticides. Results will inform continued monitoring and insecticide resistance management strategies to slow the evolution of T. picirostris insecticide resistance selection in Oregon's white clover seed production. [ABSTRACT FROM AUTHOR]

Ramularia sphaeroidea was primarily identified based on the characteristics of its conidia and several sequences. The fungus causes severe leaf spot disease on hairy vetch (Vicia villosa var. glabrescens) in Yunnan Province in China. The growth, sporulation, fungicide efficacy, and host range of the pathogen were evaluated to aid in disease management. Different types of culture media and carbon and nitrogen sources were used to evaluate the growth of R. sphaeroidea. Oatmeal, maltose, and potassium nitrate agar had a higher amount of sporulation. Difenoconazole (10%) was the most effective fungicide against the leaf disease caused by R. sphaeroidea. In addition, foliar inoculation sprays were used to assess the host range of R. sphaeroidea in six different plant species, including alfalfa (Medicago sativa L.), sainfoin (Onobrychis viciifolia Scop.), erect milkvetch (Astragalus adsurgens Pall.), common vetch (Vicia sativa L.), red clover (Trifolium pratense L.), and white clover (Trifolium repens L.). R. sphaeroidea successfully infected these plants, indicating that it has a wider host range than hairy vetches. [ABSTRACT FROM AUTHOR]

Research was carried out to assess the yield and quality of fruits from the new Polish apple tree 'Chopin'—a 'green peel', scab-resistant cultivar under grass living mulch management. Blue fescue and red fescue were tested in experiment no. 1. In experiment no. 2, meadow grass and perennial ryegrass were used. Every species of grass was sown in two doses of 50 and 150 kg per ha. Herbicide fallow was introduced as a control in both experiments. Strongly variable temperatures and precipitations in the years of evaluation made it possible to estimate year—a function of variable environmental conditions—as an additional experimental factor. An unexpected effect of the presence of living mulch was its significant impact on the appearance of blush on the 'green peel' fruit. However, living mulches had little effect on weight and fruit size. Cool days during apple ripening enhanced the process of fruit skin red coloration. The effect of both agrotechnical and environmental factors on fruit quality was more visible in the case of less vigorous trees, which were more susceptible to experimental, stressful conditions. However, increasing the sowing dose of each grass seed did not influence red blushing, weight, or fruit size. An additional difficulty for the trees was the competition caused by the early germination of these living grass mulches, reinforced by the presence of Trifolium repens L. [ABSTRACT FROM AUTHOR]

The spread of morning glory (Ipomoea spp.) in Japanese soybean (Glycine max (L.) Merr.) fields has severely decreased soybean yields. Field levees are believed to be a source of this invasion. The introduction of Zoysia japonica Steud. is expected to suppress weed growth and reduce the required labor for weed management on the levees. In this study, field experiments were conducted on the soybean levees of turf (Z. japonica), bare, and weed (mainly broad leaf weeds such as white clover) from 2017 to 2019 to compare its effects on the occurrence, growth, and seed production of I. hederacea (L.) Jacq. var. integriuscula A. Gray. The canopy height in the turf levee was the lowest, and the vegetation cover rate was the highest. At the flowering and fruiting stage of I. hederacea var. integriuscula (September), the largest number of I. hederacea var. integriuscula that survived were on the turf levee; however, the plant length, dry weight, and the number of fruits were the least. Additionally, the stems of the morning glory on the turf levee were slight and spindly, and their growth and seed productivity were suppressed. Consequently, vegetation conversion to Z. japonica on the soybean field levees can be an effective strategy to suppress the colonization and growth of morning glory, thereby, improving soybean yields. [ABSTRACT FROM AUTHOR]

The scientific aim of this article is to investigate the potential benefits of implementing a multi-cropping system, specifically focusing on the incorporation of caraway, to improve soil agrochemical and biological properties, prevent soil degradation and erosion, and ultimately enhance soil quality and health to better adapt to climate change. This study aims to provide valuable insights into the comparative analysis of various soil parameters and biological indicators to showcase the promising perspectives and importance of perennial crop production for improving soil quality and agricultural sustainability. These crops are designed to provide multiple benefits simultaneously, including improved yields, enhanced ecosystem services, and reduced environmental effects. However, an integrated assessment of their overall effects on the agroecosystem is crucial to understand their potential benefits and trade-offs. The field experiment was conducted over three consecutive vegetative seasons (2017 to 2021) at the Experimental Station of Vytautas Magnus University Agriculture Academy (VMU AA) in Kaunas district, Lithuania. The experimental site is located at 54°53′7.5″ N latitude and 23°50′18.11″ E longitude. The treatments within a replicate were multi-cropping systems of sole crops (spring barley (1), spring wheat (2), pea (3), caraway (4)), binary crops (spring barley–caraway (5), spring wheat–caraway (6), pea–caraway (7)), and trinary crops (spring barley–caraway–white clover (8), spring wheat–caraway–white clover (9), pea–caraway–white clover (10)) crops. However, an integrated assessment of their impact on the agroecosystem is needed to understand their potential benefits and processes. To determine the complex interactions between indicators, the interrelationships between indicators, and the strength of impacts, this study applied an integrated assessment approach using the comprehensive assessment index (CEI). The CEI values showed that integrating caraway (Carum carvi L.) into multi-cropping systems can have several positive effects. The effect of the binary spring barley and caraway and the trinary spring barley, caraway, and white clover crops on the agroecosystem is positively higher than that of the other comparative sole, binary, and trinary crops. Caraway, after spring wheat together with white clover, has a higher positive effect on the agroecosystem than caraway without white clover. Specifically, this study addresses key aspects, such as soil health, nutrient cycling, weed management, and overall agricultural sustainability, within the context of multi-cropping practices. By evaluating the effects of these cropping systems on soil agrochemical properties and ecosystem dynamics, the research provides valuable insights into sustainable agricultural practices that promote environmental conservation and long-term soil health. [ABSTRACT FROM AUTHOR]

Objective: To determine the in vitro digestibility and gas production, and to estimate the methane emissions from Kikuyu grass pastures, and Kikuyu grass overseeded with rye. Design/methodology/approach: Two pastures were assessed. One was the subtropical grass Kikuyu (Cenchrus clandestinus) (KY), and the other was Kikuyu grass plus overseeding with rye (Secale cereale) (KYCEN), both associated with white clover (Trifolium repens cv. Ladino). Sample collection was in June and July 2021. In vitro digestibility of dry matter (MS), organic matter (MO), and Neutral Detergent Fibre (FDN), as well as the methane emissions were estimated. The in vitro digestibility and gas production variables were analysed with a split-plot experimental design, and the methane emission variables were analysed with a doble cross-over design. Results: There were no significant differences between treatments for dry matter (MS), organic matter (MO) or Neutral Detergent Fibre (FDN) in vitro digestibility, nor in methane emissions (P>0.05). Limitations on study/implications: The in vitro assessment of digestibility, gas production and the estimation of methane emissions of Kikuyu grass pastures and Kikuyu plus rye enable the implementation of feeding strategies for small-scale livestock production systems that do not only benefit the farmers but also the environment. Findings/conclusions: It is concluded that Kikuyu grass pastures and Kikuyu with rye are a viable feeding option for small-scale dairy systems. [ABSTRACT FROM AUTHOR]

Trifolium repens L. (white clover) and Lolium perenne L. (ryegrass) are green manures widely used in conservation tillage systems worldwide. Eleusine indica L. (goosegrass) is a globally recognized noxious weed. Herein, we investigated the effects of aqueous extracts, decomposed liquids, and different straw-to-soil ratios on the germination and growth of goosegrass. The results showed that high concentrations (= 30%) of aqueous extracts or decomposed liquids of both green manures significantly inhibited germination-related parameters of goosegrass. The strongest inhibitory effect was observed for the 7-day decomposition treatment, and white clover's inhibitory effect was greater than ryegrass's. A pot experiment showed that non-photochemical quenching, catalase, and peroxidase activity levels of goosegrass leaves were significantly increased. At the same time, the net photosynthetic rate significantly decreased. Seedling growth was inhibited when the straw-to-soil ratio was greater than 3:100. The ryegrass treatments inhibited goosegrass seedlings more than the white clover treatments. This study demonstrated the inhibitory potential of white clover and ryegrass straw return on seed germination and seedling growth of goosegrass. The study has also helped to identify weed-resistant substances in these green manures so that their weed-control properties can be used more effectively and herbicide usage can be reduced. [ABSTRACT FROM AUTHOR]

Uptake of heavy metals from the soil by perennial legumes was measured over two- and four-year periods, and their accumulation measured in succeeding crops of winter wheat. Of the legumes tested: lucerne, red clover, sand sainfoin, white sweet clover, bird's foot trefoil, and eastern goatweed, sainfoin exhibits the greatest bioaccumulation over 2 years but all the studied legumes are effective. Moreover, we observe optimisation of the environment for the following crops, including the conversion of mobile forms of heavy metals in the soil into hard-to-reach forms that cannot migrate into the plant under simultaneous influence on the biological and mineral components. [ABSTRACT FROM AUTHOR]

The accident at the Chernobyl nuclear power plant on 26 April 1986 contaminated tracts of Europe with radionuclides. In Ukraine, two million hectares with radiation levels greater than 5.55 × 1011 Bq/km2 were removed from agriculture and 137Cs, with a half-life of 30 years, is still with us. Phytoremediation by vegetation that accumulates toxic elements has been widely applied. White sweet clover (Melilotus albus) accumulates caesium and heavy metals in its biomass but, at the same time, produces nectar and pollen of a safely low level of 137Cs; so this culture is safe for beekeeping in the Chernobyl contamination zone. Growing M. albus over two years (2021–2) on a sandy sod podzolic soil within the Zhytomyr region increased the soil's easily-hydrolysable N by 29.9%, decreased mobile phosphorus by 18.2%, and mobile forms of Cd by 38.5%, Hg by 25%, Pb by 24.5%, Cu by 18.5%, Zn by 14.9%, 137Cs by 8%. [ABSTRACT FROM AUTHOR]

Context. Root symbionts affect forage production by influencing host plant growth, but their specific effects on canopy intercepted photosynthetically active radiation (IPAR) and its conversion to plant biomass have not been investigated. Aims. We evaluated the extent to which changes in plant biomass resulting from arbuscular mycorrhizal fungi (AMF) and rhizobia can be explained by alterations in IPAR and aboveground and total radiation-use efficiency (RUE: the ratio between shoot or total biomass and IPAR). Methods. Under controlled greenhouse conditions, we evaluated single and dual inoculation effects of AMF and rhizobia on the forage legume white clover (Trifolium repens L.). Experimental units comprised canopies created in trays (50 cm by 34 cm by 13 cm deep). Key results. On average, AMF inoculation increased IPAR by 43%, owing to greater leaf area and density, and decreased total RUE by 30%. Aboveground RUE was lower in AMF-inoculated plants without rhizobial inoculation, despite their higher leaf phosphorus status and greenness during the vegetative and reproductive stages, respectively. Rhizobial inoculation reduced the negative effect of AMF inoculation on aboveground RUE. Conclusions. Both AMF and rhizobia alter white clover structure and function at canopy level. These variations may not be detected if the analysis considers only the impact of root symbionts on plant biomass. Implications. These findings offer valuable insights into the intricate interactions between root symbionts and canopy-level processes, providing a basis for further research at agricultural scale. [ABSTRACT FROM AUTHOR]

Urbanization is a global threat to biodiversity due to its large impact on environmental changes. Recently, urban environmental change has been shown to impact the evolution of many species. However, much remains unknown about how urban environments influence evolutionary processes and outcomes due to the non‐linearity and discontinuity of environmental variables along urban–rural gradients. Here, we focused on the evolution of hydrogen cyanide (HCN) production and its components (presence/absence of cyanogenic glycosides and the hydrolytic enzyme linamarase) in the herbaceous plant white clover Trifolium repens, which thrive in both urban and rural areas. To comprehensively elucidate how plants evolve and adapt to heterogenous urban environments, we collected 3299 white clover plants from 122 populations throughout Sapporo, Japan. We examined the spatial variation in environmental factors, such as herbivory, sky openness, impervious surface cover, snow depth, and temperature, and how variation in these factors was related to the production of HCN, cyanogenic glycosides, and linamarase. Environmental factors showed complex spatial variation due to the heterogeneity of the urban landscape. Among these factors, herbivory, sky openness, and impervious surface cover were highly related to the frequency of plants producing HCN in populations. We also found that impervious surface cover was related to the frequency of plants producing cyanogenic glycosides, while herbivory pressure was not. As a result, the cyanogenic glycoside frequency showed a clearer trend along urban–rural gradient rather than HCN frequency, and thus, the predicted spatial distributions of HCN and cyanogenic glycosides were inconsistent. These results suggest that urban landscape heterogeneity and trait multifunctionality determines mosaic‐like spatial distribution of evolutionary traits. [ABSTRACT FROM AUTHOR]

On dairy farms, fertilization of grass-clover swards ensures stable grass yields but may increase the potential for nitrate leaching on light-textured soils. The aim of this study was to quantify the N use efficiency and nitrate leaching under fertilized grass-clover leys. The study was conducted over 2 years at two sites, with increasing applications of mineral fertilizer (0–480 kg available N ha−1) alone or in combination with a basic application of cattle slurry. For plots fertilized with mineral N, the N soil surface balance was independent of the application rate and in the same range as for unfertilized plots (− 11 to 51 kg N ha−1). However, when plots were fertilized with slurry N (+ mineral N), the surplus was substantially increased owing to the fraction of organic N applied in slurry (95–100 kg N ha−1) and higher biological N2 fixation inputs (55–228 kg N ha−1). The type of fertilizer had no effect on nitrate leaching across the full range of application rates. Nitrate leaching increased quadratically as a function of application rate, with a range of 3–117 kg N ha−1 (0.33–17 mg l−1 in soil solution sampled with suction cups) in the first year and less in the second year, when clover proportion was lower due to the self-regulatory nature of grass-clover mixtures. Importantly, the rate of marginal leaching increased with fertilization level: below 150 kg N ha−1 there was no additional leaching from fertilization and at 200 kg N ha−1 around 5% of additional fertilizer-N was leached. This is less than generally found for arable crops and thus even in intensive dairy systems, grass-clover leys are an environmentally favorable crop. [ABSTRACT FROM AUTHOR]

Objective: To determine the productive performance and forage consumption (Trifolium repens L.) of Mexican Creole and Sasso chickens, under two rearing systems (confinement or grazing). Design/Methodology/Approach: One-hundred twenty-eight chickens (64 Mexican Creole (MC) and 64 Sasso (S)) of 35 d of age were randomly distributed in two production systems to obtain four repetitions (eight chickens per repetition) of each of the following genotype × system combinations: Mexican Creole in grazing, Mexican Creole in confinement, Sasso in grazing, and Sasso in confinement. A completely randomized experimental design with a 2×2 factorial arrangement was used, with genotype and production system as its main factors. The following variables were evaluated: feed consumption, weight gain, and feed conversion. Additionally, forage consumption in grazing birds was determined. Results: The productive performance variables were not affected by the production system factors or by its interaction with the bird genotype. However, the genotype did influence the variables considered: the Sasso birds recorded better values (p≤0.05) than Mexican Creole specimens. Regarding forage consumption, no differences were observed (p≤0.05) between bird genotypes and, in both cases, the accumulated consumption at the 49 d of study was close to 60 g of DM. Study Limitations/Implications: It is necessary to carry out a socioeconomic study as well as a defoliation level analysis with the aim of improving the use of the resource. Findings/Conclusions: Mexican Creole birds had a lower productive performance with a similar forage consumption. [ABSTRACT FROM AUTHOR]

White clover (Trifolium repens L.) is an allopolyploid plant and an excellent perennial legume forage. However, white clover is subjected to various stresses during its growth, with cold stress being one of the major limiting factors affecting its growth and development. Beta-amylase (BAM) is an important starch-hydrolyzing enzyme that plays a significant role in starch degradation and responses to environmental stress. In this study, 21 members of the BAM gene family were identified in the white clover genome. A phylogenetic analysis using BAMs from Arabidopsis divided TrBAMs into four groups based on sequence similarity. Through analysis of conserved motifs, gene duplication, synteny analysis, and cis-acting elements, a deeper understanding of the structure and evolution of TrBAMs in white clover was gained. Additionally, a gene regulatory network (GRN) containing TrBAMs was constructed; gene ontology (GO) annotation analysis revealed close interactions between TrBAMs and AMY (α-amylase) and DPE (4-alpha-glucanotransferase). To determine the function of TrBAMs under various tissues and stresses, RNA-seq datasets were analyzed, showing that most TrBAMs were significantly upregulated in response to biotic and abiotic stresses and the highest expression in leaves. These results were validated through qRT-PCR experiments, indicating their involvement in multiple gene regulatory pathways responding to cold stress. This study provides new insights into the structure, evolution, and function of the white clover BAM gene family, laying the foundation for further exploration of the functional mechanisms through which TrBAMs respond to cold stress. [ABSTRACT FROM AUTHOR]

Phytoremediation is a biological soil remediation technique using plants and their associated microorganisms to clean-up contaminated soils and improve soils' quality. We tested whether a co-culture between Miscanthus x giganteus (MxG) and Trifolium repens L. would enhance the soil biological quality. The objective was to determine the influence of MxG in mono- and in co-culture with white clover on the soil microbial activity, biomass and density. MxG was tested in mono- and in co-culture with white clover in a mesocosm over 148 days. The microbial respiration (CO2 production), the microbial biomass and the microbial density of the technosol were measured. Results showed that MxG induced an increase in microbial activity in the technosol compared to the non-planted condition with the co-culture having a greater impact. Regarding the bacterial density, MxG in mono- and in co-culture significantly increased the 16S rDNA gene copy number. The co-culture increased the microbial biomass, the fungal density and stimulated the degrading bacterial population, contrary to the monoculture and the non-planted condition. We can conclude the co-culture between MxG and white clover was more interesting than MxG monoculture in regards to the technosol biological quality and its potential for PAH remediation improvement. Our precedent results have shown the benefits of using Miscanthus x giganteus in association with Trifolium repens L. to improve polycyclic aromatic hydrocarbons dissipation and decrease soil ecotoxicity compared to monocultures. In this study we focused on the plant species' influence on the soil's biological quality to improve MxG biomass productivity in the long term and phytoremediation. Many bioindicators were used such as microbial activity, microbial biomass as well as bacteria, fungi and PAH-degrading bacteria density. We showed it was more beneficial to use co-culture instead of MxG monoculture to improve biological technosol quality and in particular microbial activity and biomass as well as fungi and PAH-degrading bacteria density. [ABSTRACT FROM AUTHOR]

Aims: Mixed communities of plant species with different functional traits or microbial associations can more fully utilize soil nutrient pools. However, there is a gap in our understanding of the synergistic influences of arbuscular mycorrhizal (AM) fungi in nutrient capture and resource partitioning across different soil depths in mixed plant communities, as well as their possible effects on plant coexistence. To address these knowledge gaps, we assessed the effect of AM fungi on nutrient uptake and competition between shallow- and deep-rooted pairs of grass and legume species. Methods: To quantify the mycorrhizal mediation of N uptake at different soil depths, 15N tracer was injected into soil at 3- and 25-cm depths of microcosms planted with monoculture or bi-species mixtures, with or without AM fungi. Results: AM symbioses reduced plant competition by equalizing access to N and subsequently increasing shoot N and P concentrations of plant species on mixed communities. Niche differentiation had minimal effects on grass and legume competitive interactions. Both deep-rooted plant species, i.e., Medicago sativa and Dactylis glomerata, and shallow-rooted species, i.e., Lolium perenne and Trifolium repens, primarily acquired nutrients from shallow soil layers. However, AM fungi significantly enhanced nutrient uptake and facilitated N2 fixation in legumes at 3 and 25 cm soil depths. Conclusion: Our results suggest AM fungi strongly influence host-plant competitiveness and vertical nutrient capture in mixed plant communities, underscoring that microbial mutualist-mediated nutrient acquisition is a key driver of gains in productivity of grass–legume mixtures. [ABSTRACT FROM AUTHOR]

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Excessive aluminum (Al) in acidic soils is a primary factor that hinders plant growth. The objective of the present study was to investigate the effect and physiological mechanism of exogenous silicon (Si) in alleviating aluminum toxicity. Under hydroponic conditions, 4 mM Al significantly impeded the growth of white clover; however, pretreatments with 1 mM Si mitigated this inhibition, as evidenced by notable changes in growth indicators and physiological parameters. Exogenous silicon notably increased both shoot and root length of white clover and significantly decreased electrolyte leakage (EL) and malondialdehyde (MDA) content compared to aluminum treatments. This positive effect was particularly evident in the roots. Further analysis involving hematoxylin staining, scanning electron microscopy (SEM), and examination of organic acids (OAs) demonstrated that silicon relieved the accumulation of bioactive aluminum and ameliorated damage to root tissues in aluminum-stressed plants. Additionally, energy-dispersive X-ray (EDX) analysis revealed that additional silicon was primarily distributed in the root epidermal and cortical layers, effectively reducing the transport of aluminum and maintaining the balance of exchangeable cations absorption. These findings suggest that gradual silicon deposition in root tissues effectively prevents the absorption of biologically active aluminum, thereby reducing the risk of mineral nutrient deficiencies induced by aluminum stress, promoting organic acids exudation, and compartmentalizing aluminum in the outer layer of root tissues. This mechanism helps white clover alleviate the damage caused by aluminum toxicity.

AbstractThe GRAS transcription factor (TF) is a plant-specific regulator that plays a critical role in plant growth, development and response to various abiotic stresses. While the functions of many GRAS TFs have been extensively studied in numerous model plants with fully sequenced genomes, the GRAS TFs in white clover (Trifolium repens L.) remain elusive despite the sequencing of its genome. To bridge this knowledge gap, homologs of GRAS TFs from Arabidopsis were employed and subjected to a genome-wide blast against white clover proteins. This analysis identified and characterized 102 putative GRAS genes, designated as TrGRAS, based on the presence of GRAS domains in positive blast hits. Concurrently, an exploration of their gene structures, classification, evolutionary relationships and conservative motifs provided insights into the distinctive features of TrGRAS in white clover. Furthermore, gene duplication analysis revealed an expansion of TrGRAS genes in the PAT1 and LISCL subfamilies, indicating functional diversity within the white clover genome. Lastly, RNA-seq and quantitative reverse transcription-PCR (qRT-PCR) experiments confirmed their higher expression during the early or intermittent responses to cold stress, suggesting their potential and crucial roles in determining the cold tolerances of white clover. The analysis of TrGRAS genes, coupled with expression studies, contributes to the functional characterization of TrGRAS genes in white clover. This knowledge is pivotal for informing genetic improvement strategies in future breeding efforts aimed at enhancing cold tolerance in white clover.

Plant functional traits serve as a bridge between plants, the environment, and ecosystem function, playing an important role in predicting the changes in ecosystem function that occur during ecological restoration. However, the response of grassland ecosystem function to plant functional traits in the context of ecological restoration in areas of karst desertification remains unclear. Therefore, in this study, we selected five plant functional traits [namely, plant height (H), specific leaf area (SLA), leaf dry matter content (LDMC), root length (RL), and root dry matter content (RDMC)], measured these along with community-weighted mean (CWM) and functional trait diversity, and combined these measures with 10 indexes related to ecosystem function in order to investigate the differences in plant functional traits and ecosystem function, as well as the relationship between plant functional traits and ecosystem functions, under four ecological restoration models [Dactylis glomerata (DG), Lolium perenne (LP), Lolium perenne + Trifolium repens (LT), and natural grassland (NG)]. We found that: 1) the Margalef index and Shannon–Wiener index were significantly lower for plant species in DG and LP than for those in NG (P<0.05), while the Simpson index was significantly higher in the former than in NG (P<0.05); 2) CWMH, CWMLDMC, and CWMRDMC were significantly higher in DG, LP, and LT than in NG, while CWMSLA was significantly lower in the former than in NG (P<0.05). The functional richness index (FRic) was significantly higher in DG and LP than in NG and LT, but the functional dispersion index (FDis) and Rao’s quadratic entropy index (RaoQ) were significantly lower in DG and LP than in NG and LT (P<0.05), and there was no significant difference between DG and LP, or between NG and LT (P>0.05); 3) ecosystem function, including ecosystem productivity, carbon storage, water conservation and soil conservation, was highest in LT and lowest in NG; and 4) CWMLDMC (F=56.7, P=0.024), CWMRL (F=28.7, P=0.024), and CWMH (F=4.5, P=0.048) were the main factors affecting ecosystem function. The results showed that the mixed pasture of perennial ryegrass and white clover was most conductive to restoration of ecosystem function. This discovery has important implications for the establishment of vegetation, optimal utilization of resources, and the sustainable development of degraded karst ecosystems. [ABSTRACT FROM AUTHOR]

The paper studies the genetic diversity of microorganisms isolated from root nodules of wild populations of the legumes Lathyrus pratensis L., Vicia cracca L., Trifolium repens L., and Astragalus schelichowii Turcz. collected near Norilsk (Arctic Russia). The taxonomic position of the 19 isolates obtained was determined by sequencing the 16S rRNA gene (rrs). The isolates were assigned to four genera of the order Hyphomicrobiales: Rhizobium, Pararhizobium, Bosea and Tardiphaga. Nine fast-growing isolates belonged to the genera Rhizobium and Pararhizobium. ITS region sequencing clarified the species identity of 6 rhizobial isolates. Isolates from V. cracca nodules were identified as Pararhizobium sp., P. herbae. Microsymbionts from T. repens were assigned to Rhizobium sp. and to the species R. beringeri, while isolates from L. pratensis were identified as P. herbae and R. beringeri. Symbiotic nodA and nodC genes were found in the Rhizobium strains P8/5-2, P9/1-1 and P9/3-2 from L. pratensis and T. repens nodules, nodA gene was detected in the Pararhizobium strains P7/3-1, P7/4-1, P7/5-1 from V. cracca nodules. Nine out of ten slow-growing isolates were assigned to the genus Bosea. Three isolates from the nodules of V. cracca were assigned to the species B. psychrotolerans. Six isolates from the nodules of A. schelichowii were identified as B. vaviloviae, B. lathyri and Bosea sp. The strain P22/3-5 isolated from the nodule of A. schelichowii was identified as Tardiphaga robiniae. Simultaneous presence of strains belonging to different genera of the order Hyphomicrobiales was detected in the nodules of V. cracca and A. schelichowii. [ABSTRACT FROM AUTHOR]