Holcus Lanatus Research Articles

Comparison of pasture types in the tropical Andes: Species composition, distribution, nutritive value and responses to environmental change

Pastoralism is the main land use in the humid tropical Andes of South America. Wide areas of mountain rainforest have been cleared for gaining pastureland. Due to the lack of indigenous useful grasses in the pristine forests, mainly exotic grass species have been used for establishing the pastures. In the Ecuadorian Andes, Axonopus compressus, Melinis minutiflora, Pennisetum clandestinum and Holcus lanatus are common pasture grass species. Their preference for certain microsites resulted in a mosaic of different pasture types, which reflect the differing ecological conditions on the undulating terrain of the mountain slopes. During the last decades, however, another exotic grass species, Setaria sphacelata has widely been introduced which, because of its fast growth on some of the sites could successfully suppress the formerly dominant plant species. With respect to the changing microclimate and cattle stocking rates the present study explored, whether planting Setaria is the best option for the common low-input type of pasture farming in these tropical mountains. In a study over twenty years, the development of four main pasture types, dominated by the above-mentioned grass species was investigated in areas with and without Setaria, and their topographical occurrence on the sloping terrain was analyzed. On forty-eight plots a pairwise (with or without Setaria) comparison of species composition and diversity, biomass production, forage quality and soil properties was performed. Although Setaria grows faster than the other grass species, its productivity was only higher on flat terrain. The nutritive value of the Setaria plots was at best equivalent to that of the former pastures, while species richness was consistently lower. Our results suggest the maintenance of a terrain-adapted diversification of the pastures and in particular the use of Setaria only on flat terrain.

Arbuscular mycorrhizal inoculation and plant response strongly shape bacterial and eukaryotic soil community trajectories

Arbuscular mycorrhizal (AM) fungi and terrestrial plants form one of the most important and ubiquitous symbioses on the planet. Although the central role of AM fungi in rhizosphere processes is well established, the extent of their influence on the development of the whole soil microbial community is less well characterized. We assessed the temporal dynamics of the bacterial and eukaryotic soil microbial communities in mesocosms where AM fungi were inoculated on a grass (Holcus lanatus L.) and a clover (Trifolium pratense L.). This allowed us to evaluate whether 1) inoculation with AM fungi changes the overall structure of soil communities and 2) if these changes are partially mediated by the altered plant phenotype, as indicated by increases in growth and photosynthetic activity. We observed changes in the community composition of both microbial groups, largely associated with relative decreases in Proteobacteria, Nematoda and some protistan groups (Ciliophora and Lobosa) and relative increases in Gastrotricha and Firmicutes. Plant productivity doubled with mycorrhizal inoculation, while other plant performance measures increased by 10–50%. We conclude that the interaction between AM fungi and plants shapes the surrounding soil microbial communities, probably because enhanced growth of host plants changes the amount, timing, and form of carbon inputs into soil.

Bracken-induced increase in soil P availability, along with its high P acquisition efficiency, enables it to invade P-deficient meadows

Abstract Changes in soil chemistry after invasion by bracken (Pteridium aquilinum) have been studied in heathlands, but comparable studies in meadows are lacking. We investigated if bracken invasion into P-deficient meadows alters the soil nutrient-resource pool, as well as the mechanisms behind it linked to soil processes and bracken nutrition. Furthermore, we investigated how community composition responds to differences in soil chemistry before and after the invasion. Soil and plant material sampling, along with vegetation survey, were performed during bracken peak biomass. Data analyses included analysis of variance and canonical correspondence analysis (CCA). Bracken invasion increased soil P availability, soil organic C concentration, as well as C:N, C:S and N:S ratios, while decreasing Fe and Co concentrations. Bracken pinnae were rich in P, and its rhizomes were rich in K, whereas N:P of pinnae and rhizomes was low. CCA showed contrasting abundance patterns of frequent meadow species related to P and K availability. Holcus lanatus exhibited competitive advantage under extremely low P availability. Increase in P availability under bracken may have occurred through promoting the leaching of Fe and Al. By increasing P availability for its growth and increasing N limitation for other species, bracken can gain a competitive advantage from the soil resource-niche perspective. Its ability to increase soil P availability, along with the physiological mechanisms behind its high P acquisition efficiency, seem to differentiate bracken from other species of competitive ecological strategy, which are mainly confined to nutrient-rich environments. This enabled bracken to invade P-deficient meadows.

The herbicide cycloxydim is an effective alternative to propyzamide or glyphosate for the control of the forest grass weeds Molinia caerulea, Calamagrostis epigejos, Deschampsia flexuosa and Holcus lanatus

Abstract We tested the efficacy of a range of herbicides to see if they might be potential substitutes for the use of propyzamide or glyphosate to control grass weed species that, if left unchecked, often outcompete recently planted trees in UK forests. Applications of 0.45kg a.i. ha−1 cycloxydim in late April–early May gave good control of wood small reed (Calamagrostis epigejos (L.) Roth), Yorkshire fog (Holcus lanatus L.), and wavy hair grass (Deschampsia flexuosa (L.) Trin.)) for at least 12 weeks after application. When coupled with a sequential application of 0.15kg a.i. ha−1 propaquizafop made 5 weeks later, purple moor grass (Molinia caerulea (L.) Moench) was controlled for at least 21 weeks. Sequential applications of 0.45 kg a.i. ha−1 cycloxydim in October, then 0.45 kg a.i. ha−1 cycloxydim in late April, was the most effective treatment for minimizing competition from purple moor grass, wood small reed or wavy hair grass and equally effective as propyzamide on Yorkshire fog. The herbicides carbetamide, clethodim, clodinafop-propargyl and fenoxaprop-p-ethyl were not as effective as cycloxydim. We conclude that cycloxydim is effective on a broader range of grass weeds than previously thought. Cycloxydim and propaquizafop are both highly selective and unlike the broad-spectrum herbicide glyphosate will not harm young trees, even if they are oversprayed when in active growth. If applied at the correct time of year, cycloxydim is likely to be as effective as glyphosate on most grasses, and for wood small reed, purple moor grass and wavy hair grass considerably more effective than propyzamide. A sequential application of cycloxydim or possibly propaquizafop in the autumn, followed by a second spray in late April of the following spring, is likely to be the most effective means of maximizing tree growth and survival in grass dominated new planting or restock sites in UK forests.

Influence of parental nitrogen : phosphorus stoichiometry on seed characteristics and performance of Holcus lanatus L. and Parnassia palustris L.

Nitrogen (N) and phosphorus (P) availability affect plant sexual reproduction performance. Seed as the main product of sexual reproduction is expected to be affected by N and P availability in parent plant. We experimentally test how parental N:P stoichiometry affected seed characteristics and performance of two grassland species. Seeds of a common species (Holcus lanatus) and an endangered species (Parnassia palustris) were collected from parent plants under two different N:P ratio growth conditions in a grassland reserve in the Netherlands. We measured the following traits of the two species from the two parental N:P ratio growth conditions: seed N concentration and content, seed P concentration and content, seed length, seed area, seed weight, seed germination, and offspring survival. No significant inter-location difference was found in seed weight of the collected seeds for either of the two species. However, the stronger P-limited conditions at the locations of the parent plants affected seed length and seed area negatively in H. lanatus and positively in P. palustris. Stronger P-limited conditions also decreased seed P concentration and content and increased seed N:P ratio of H. lanatus, but no inter-location nutrient difference was found in seeds of P. palustris. Surprisingly, contrary to what could be expected from seed P concentration and content there was no inter-location difference in seed germination for H. lanatus. For P. palustris, stronger P-limited conditions in the parental environment significantly enhanced seed germination, whereas stronger P-limited conditions in the offspring environment decreased offspring survival, suggesting that P limitation may negatively affect P. palustris rejuvenation. Our results suggest the possibility of different influences of parental N:P ratio and especially of P limitation on seed characteristics and performance of a common and an endangered species.

Evidence for nickel mobilisation in rhizosphere soils of Ni hyperaccumulator Odontarrhena serpyllifolia

Rhizosphere processes are known to modify uptake of elements from soil, but limited information is available for hyperaccumulators. We investigated labile Ni fractions and their kinetics of replenishment in the rhizospheres of the Ni-hyperaccumulator Odontarrhena serpyliffolia, the Ni-excluder Holcus lanatus and in bulk soils collected at the same serpentine outcrop. Labile Ni fractions in rhizosphere and bulk soil were evaluated using conventional extractions and also by the Diffusive Gradients in Thin Films (DGT) technique. DGT data were used to predict the kinetics of Ni resupply using DIFS modelling. Chemical imaging of Ni distribution along roots using DGT coupled with laser-ablation was conducted. Labile Ni forms were higher in both rhizosphere than in bulk soils, together with an increase in dissolved organic C, cation exchange capacity and the Ca/Mg ratio. Ni fractionation indicated a shift towards less stable Ni fractions in the rhizosphere, particularly in the hyperaccumulator. DIFS modelling showed that the rhizosphere of the excluder was able to sustain the initially lower soluble Ni concentration through replenishment from the solid phase, while Ni resupply in the rhizosphere of the hyperaccumulator was not sufficient to maintain the initially high concentrations of soluble Ni. However, the amount of DGT-labile Ni was higher in the rhizosphere of the hyperaccumulator compared to the excluder in all deployment times. Our data suggest that compounds derived from root activity, in particular DOC, are important controls of Ni availability to plants growing on serpentine soil.

Winter bird gets the worm: consumption of earthworms (Lumbricidae) by striated caracaras (Phalcoboenus australis) in invasive Yorkshire fog (Holcus lanatus) in the Falkland Islands (Malvinas)

Biological invasions can drive ecosystem change and alter predator ecology by providing trophic subsidies that mitigate the effects of seasonally pulsed resources. Striated Caracaras (Phalcoboenus australis) are near threatened, non-migratory falconids who inhabit the southern coasts of South America and the Falkland Islands (Malvinas) and feed on seasonally migratory colonial seabirds. Here we report the first multi-day observation of caracaras foraging extensively for earthworms (Lumbricidae) and beetle larvae (Coleoptera) in introduced Yorkshire fog (Holcus lanatus) on New Island, Falkland Islands. Our results suggest that invertebrates may be a more important winter resource than previously thought, and that caracaras benefit indirectly from introduced grasses in the Falklands, a relationship that merits special consideration when identifying ecological restoration plans.

Identification, molecular and biological characterization of two novel secovirids in wild grass species in Belgium

High throughput sequencing was performed on virion-associated nucleic acids (VANA) from a pool of fifty asymptomatic rough bluegrasses (Poa trivialis L.) collected in a Belgian grazed pasture. Bioinformatics analyses produced some contigs presenting similarities with secovirid genomes, in particular nepoviruses and waikaviruses. Three distinct positive-sense single-stranded RNAs including 5’ and 3’ UTR were reconstructed and they represented two novel viruses infecting rough bluegrass, for which the provisional names poaceae Liege nepovirus A (PoLNVA, 7298 nt for RNA1 and 4263 nt for RNA2) and poaceae Liege virus 1 (PoLV1, 11,623 nt) were proposed. Compared to other Secoviridae members, the highest amino acid identity reached 90.7 % and 66.7 % between PoLNVA and nepoviruses for the Pro-Pol and CP regions respectively, while PoLV1 presented the highest amino acid identity with waikaviruses but with lower identities, i.e. 41.2 % for Pro-Pol and 25.8 % for CP regions, far below the ICTV demarcation criteria for novel secovirid. Based on sequence identity and phylogenetic analyses, PoLNVA was proposed to belong to the genus Nepovirus and PoLV1 as an unclassified secovirids. Detection of the two novel viruses was confirmed in high prevalence in rough bluegrass and ten other wild Poaceae species (Agropyron repens, Agrostis capillaris, Apera spica-venti, Anthoxanthum odoratum, Cynosorus cristatus, Festuca rubra, Holcus lanatus, Lolium perenne, Phleum bertolini and Phleum pratense) by RT-PCR and Sanger sequencing, revealing a diverse host range within Poaceae for these novel secovirids. Seed transmission was evaluated and confirmed for PoLNVA.

Looking for Hidden Enemies of Metabarcoding: Species Composition, Habitat and Management Can Strongly Influence DNA Extraction while Examining Grassland Communities.

Despite the raising preoccupation, the critical question of how the plant community is composed belowground still remains unresolved, particularly for the conservation priority types of vegetation. The usefulness of metabarcoding analysis of the belowground parts of the plant community is subjected to a considerable bias, that often impedes detection of all species in a sample due to insufficient DNA quality or quantity. In the presented study we have attempted to find environmental factors that determine the amount and quality of DNA extracted from total plant tissue from above- and belowground samples (1000 and 10,000 cm2). We analyzed the influence of land use intensity, soil properties, species composition, and season on DNA extraction. The most important factors for DNA quality were vegetation type, soil conductometry (EC), and soil pH for the belowground samples. The species that significantly decreased the DNA quality were Calamagrostis epigejos, Coronilla varia, and Holcus lanatus. For the aboveground part of the vegetation, the season, management intensity, and certain species—with the most prominent being Centaurea rhenana and Cirsium canum—have the highest influence. Additionally, we found that sample size, soil granulation, MgO, organic C, K2O, and total soil N content are important for DNA extraction effectiveness. Both low EC and pH reduce significantly the yield and quality of DNA. Identifying the potential inhibitors of DNA isolation and predicting difficulties of sampling the vegetation plots for metabarcoding analysis will help to optimize the universal, low-cost multi-stage DNA extraction procedure in molecular ecology studies.

Root-Associated Mycobiomes of Common Temperate Plants (Calluna vulgaris and Holcus lanatus) Are Strongly Affected by Winter Climate Conditions

Winter temperatures are projected to increase in Central Europe. Subsequently, snow cover will decrease, leading to increased soil temperature variability, with potentially different consequences for soil frost depending on e.g. altitude. Here, we experimentally evaluated the effects of increased winter soil temperature variability on the root associated mycobiome of two plant species (Calluna vulgaris and Holcus lanatus) at two sites in Germany; a colder and wetter upland site with high snow accumulation and a warmer and drier lowland site, with low snow accumulation. Mesocosm monocultures were set-up in spring 2010 at both sites (with soil and plants originating from the lowland site). In the following winter, an experimental warming pulse treatment was initiated by overhead infrared heaters and warming wires at the soil surface for half of the mesocosms at both sites. At the lowland site, the warming treatment resulted in a reduced number of days with soil frost as well as increased the average daily temperature amplitude. Contrary, the treatment caused no changes in these parameters at the upland site, which was in general a much more frost affected site. Soil and plant roots were sampled before and after the following growing season (spring and autumn 2011). High-throughput sequencing was used for profiling of the root-associated fungal (ITS marker) community (mycobiome). Site was found to have a profound effect on the composition of the mycobiome, which at the upland site was dominated by fast growing saprotrophs (Mortierellomycota), and at the lowland site by plant species-specific symbionts (e.g. Rhizoscyphus ericae and Microdochium bolleyi for C. vulgaris and H. lanatus respectively). The transplantation to the colder upland site and the temperature treatment at the warmer lowland site had comparable consequences for the mycobiome, implying that winter climate change resulting in higher temperature variability has large consequences for mycobiome structures regardless of absolute temperature of a given site.

Producción de leche real vs la calculada a partir de la ENL estimada por el algoritmo de análisis de imágenes red-green-blue de gramíneas

ABSTRACT: Knowledge about the net lactation energy (NLE) contained in the dry matter of grasses is necessary to make decisions about forage and the balance of diets for grazing cattle. Its determination is made in laboratories using wet or dry chemistry methods, which are costly, delayed, and sometimes present sampling- or process-related reliability problems. An algorithm, which analyzes the red-green-blue (RGB) images of grasses taken by drone, has been developed as a technological alternative. This has allowed us estimating the NLE level, reducing costs, and changing the sampling system and analysis method. The objective of the present study was to compare the milk production, which was calculated from the NLE and estimated using the algorithm for analysis of RGB images of grasses (included in the TaurusWebs® software), vs the actual milk production. The study was conducted in 15 dairy farms belonging to the dairy control system of the Colácteos dairy cooperative, which are located in the upper tropical region (Department of Nariño, Colombia). The prairies evaluated were composed of mixtures of Kikuyo (Pennisetum clandestinum), Raigrás (Lolium spp), and False Poa (Holcus lanatus). The result was analyzed using a linear regression model (R²=0.86; R=0.93). In the Student´s t-test, the actual and estimated milk production averages were equal (P>0.05). In conclusion, the NLE calculated using the algorithm satisfactorily explains the study livestock production, and the information generated by the algorithm can be used to calculate the NLE of grasses.

Germination and Early Development of Three Spontaneous Plant Species Exposed to Nanoceria (nCeO2) with Different Concentrations and Particle Sizes.

This study aimed to provide insight regarding the influence of Ce oxide nanoparticles (nCeO2) with different concentrations and two different particle sizes on the germination and root elongation in seedlings of spontaneous terrestrial species. In a bench-scale experiment, seeds of the monocot, Holcus lanatus and dicots Lychnis-flos-cuculi and Diplotaxis tenuifolia were treated with solutions containing nCeO2 25 nm and 50 nm in the range 0–2000 mg Ce L−1. The results show that nCeO2 enters within the plant tissues. Even at high concentration, nCeO2 have positive effects on seed germination and the development of the seedling roots. This study further demonstrated that the particle size had no influence on the germination of L. flos-cuculi, while in H. lanatus and D. tenuifolia, the germination percentage was slightly higher (+10%) for seeds treated with nCeO2 25 nm with respect to 50 nm. In summary, the results indicated that nCeO2 was taken up by germinating seeds, but even at the highest concentrations, they did not have negative effects on plant seedlings. The influence of the different sizes of nCeO2 on germination and root development was not very strong. It is likely that particle agglomeration and ion dissolution influenced the observed effects.

Mycorrhizal colonisation in roots ofHolcus lanatus(Yorkshire Fog) in a permanent pasture under conditions of reduced precipitation

The UK climate is projected to become warmer, with more frequent hotter, drier summers. Many governments and international organisations are concerned about how climate change will affect food production and security. Mycorrhizal fungi are an essential part of agricultural systems and yet little is known about how climate change will affect mycorrhizal fungi. We investigated the effect of reduced precipitation on levels of arbuscular mycorrhizal (AM) colonisation in the top 10 cm of soil in the grass Holcus lanatus L. (Yorkshire Fog) in a permanent pasture in South Gloucestershire, UK. Incident rainfall was reduced, by approximately 50%, using clear gutters supported on steel frames. Over three growing seasons we observed little difference in levels of AM colonisation and numbers of intra-root fungal structures between the roots of H. lanatus grown with reduced or full incident rainfall. Time of year when water stress occurred had a stronger effect on levels of colonisation than the absolute amount of precipitation received. In H. lanatus, growing in a permanent pasture, levels of AM colonisation were around 40%–50%, across a range of precipitation, from 18% above to 36% below the long-term average. The results highlight the complex relationships between mycorrhizal fungi, host plant, and abiotic stress.

Evaluation of the grassland sward floristic composition of the Wadowice commune

The quality of the botanical composition of meadows and pastures is decisive in the profitability of livestock farming. The aim of this study was to examine the floristic composition of meadows and pastures of the Wadowice commune and to assess their feed value. Field explorations were carried out in June 2016 throughout the commune. Floristic lists were made on 51 designated plots using the estimated Klapp method. Four groups of similar plots with the following dominant species were distinguished in the analysed area: I – plots with Phleum pratense and Vicia cracca, II – plots with Dactylis glomerata and Trifolium repens, III – plots with Holcus lanatus, and IV – plots with Arrhenatherum elatius. The results of the research showed that, in the area of this commune, meadows and pastures were characterised by average and good pasture values, which favours their use for agricultural purposes. Improving the quality of the botanical composition of plots of medium fodder value could be achieved through proper care and sustainable use.

Mechanism and role of seeded native grasses to immobilize nitrogen on harvested blanket peat forests for protection of water courses.

Forest harvesting activities on peatlands have long been associated with nutrient leaching and deterioration of downstream water quality. This study aims to assess the effect of grass seeding practice on harvested blanket peatlands to immobilize N and reduce its export to water courses. First, a plot-scale field experiment was conducted by seeding with two grass species (Holcus lanatus and Agrostis capillaris) to study the N uptake potential from a harvested area. Secondly, a simulated rainfall experiment was conducted to study the effect of these grasses on reducing N leaching from surface peat using laboratory flume approach. In the end, the role of seeded grasses in removing N from nutrient-rich throughflow water was assessed using simulated overland flow experiment. The results showed that the seeded grasses had the potential to uptake over 30 kg ha-1 of N in the first year after seeding on harvested peatlands, whereas it takes over 2.5 years to establish the same level of N uptake by natural re-vegetation (non-grassed). In the simulated rainfall experiment, the inorganic N (NH4+-N and NO3--N) leaching in surface runoff from grassed flumes was 72% lower (453 mg m-2) than non-grassed flumes (1643 mg m-2). In the simulated overland flow experiment, the N retention by grassed flumes was significantly higher (98%) as compared to non-grassed flumes (70%) in the simulated overland flow experiment. Comparatively higher concentrations of NH4+-N and NO3--N in soil porewaters of non-grassed flumes suggest that this N retention by non-grassed flumes is less sustainable and is likely to be leached in runoff in subsequent flow events. The results from all three experiments in this study suggest that seeded grasses are a major sink of N on harvested blanket peatland forests. Immobilization of N onsite using the grass seeding and mini-buffer practice could be an efficient and a feasible mean of reducing N export from harvested blanket peatland forests in order to protect the sensitive water courses. However, the sustainability of retention and immobilization of N by grasses needs to be studied further in long-term field-scale experiments on multiple peatland sites.

Use of Predicted Behavior from Accelerometer Data Combined with GPS Data to Explore the Relationship between Dairy Cow Behavior and Pasture Characteristics.

Our aim in this study was to investigate whether the behaviors of dairy cows on pasture, predicted with accelerometer data and combined with GPS data, can be used to better understand the relationship between behaviors and pasture characteristics. During spring 2018, 26 Holstein cows were equipped with a 3D-accelerometer and a GPS sensor fixed on a neck-collar for five days. The cows grazed alternatively in permanent and in temporary grasslands. The structural elements, soil moisture, slope and botanical characteristics were identified. Behaviors were predicted every 10 s from the accelerometer data and combined with the GPS data. The time-budgets expressed in each characterized zone of 8 m × 8 m were calculated. The relation between the time-budgets and pasture characteristics was explored with a linear mixed model. In the permanent grassland, dairy cows spent more time under a tree to ruminate (p < 0.001) and to rest (p < 0.001) and more time to graze in areas with Holcus lanatus (p < 0.001). In the temporary grassland, behavior was influenced by the external environment (presence of other animals on the farm; p < 0.05). Thus, this methodology seems relevant to better understand the relationship between the behaviors of dairy cows and grazing conditions to develop precision grazing.

Plants increase silicon content as a response to nitrogen or phosphorus limitation: a case study with Holcus lanatus

AimsSilicon (Si) has been shown to beneficially affect plant performance under stressful environmental conditions, such as water or nutrient deficiency. Here we tested the effects of two important plant nutrients, nitrogen (N) and phosphorus (P), on Si content in different plant organs in the grass species Holcus lanatus.MethodsWe studied trait responses to N limitation, balanced nutrient availability and P limitation. Single plant individuals were grown in sand-filled pots in a greenhouse for 2 months. Nitrogen, phosphorus, carbon and silicon contents were determined in leaves, stems and roots, as were leaf and roots traits, biomass production and root enzyme activity.ResultsSi content was lowest under balanced nutrient supply in all plant organs. Under P limitation Si content was highest in leaves and stems, in roots it was highest under N limitation. Si:C ratios were lowest under balanced conditions, and highest under nutrient limitation. Root phosphatase activity was highest under P limitation and chlorophyll content was lowest under N limitation.ConclusionsOur model species assimilated less ‘high cost C’ and took up more ‘low cost Si’ under nutrient limitation, especially under P deficiency. Si potentially plays an important role in different environments, such as nutrient or light limitation, which in turn may be related to different plant strategies, for example higher stem rigidity in high Si plants versus higher stem flexibility in low Si plants. More research is needed to further elucidate the role of silicon in different concepts of trait-environment relationships.

Arsenic Uptake by Two Tolerant Grass Species: Holcus lanatus and Agrostis capillaris Growing in Soils Contaminated by Historical Mining.

The study focused on two grass species Holcus lanatus and Agrostis capillaris abundant in the sites of former As mining and processing in the Sudetes. Arsenic uptake from soils was examined to assess a risk associated with its accumulation in grass shoots and to check its dependence on soil fertilization. The research involved a field study and greenhouse experiment. In the field study, soil and plant samples were collected from 33 sites with 72–98,400 mg/kg total soil As. Arsenic uptake by grasses differed widely. Both species indicated a strategy typical for eliminators, although As concentrations in more than 50% of the shoot samples exceeded 4 mg/kg, a maximum permissible value for fodder. In the greenhouse experiment, commercial cultivars of both species were grown in five soils containing 394–19,600 mg/kg, untreated and fertilized. All seedlings died in the soil with highest total As, and considerable phytotoxicity was observed in other soils, particularly in nonfertilized ones. Fertilization resulted in the improvement of plant growth and reduction of As uptake except for Agrostis capillaris fertilized with manure. Further research should focus on identifying tolerant genotypes growing in extremely enriched sites and analysis of factors that will efficiently reduce As phytoaccumulation.

Below-ground competition alters attractiveness of an insect-pollinated plant to pollinators.

Competitive interactions between plants can affect patterns of allocation to reproductive structures through modulation of resource availability. As floral traits involved in plant attractiveness to pollinators can be sensitive to these resources, competition with any neighbouring species may influence the attractiveness of insect-pollinated plants. While pollination research has primarily focused on above-ground interactions, this study aims at investigating if the presence of a competitor plant can modulate neighbouring insect-pollinated plant attractiveness to pollinators and resulting fecundity, especially through below-ground competitive interactions for soil resources. We set up a plot experiment in which we grew an insect-pollinated plant, Sinapis alba (Brassicaceae), in a mixture dominated by a wind-pollinated plant, Holcus lanatus (Poaceae). Individuals of S. alba were either subjected to or isolated from (with buried tubes in the soil) below-ground competition. Across the flowering season, floral traits involved in attractiveness of S. alba and pollinator visitation were followed at the plot and plant level to investigate different scales of attractiveness. At the end of the experiment, seeds were harvested to assess plant fecundity. Competition had a significant negative effect on plot and plant floral display size as well as flower size while nectar traits were not affected. When plants of S. alba were in competition, the time to first visit was altered: the proportion of plots that received a visit was smaller for a given time; in other words, it took more time for a given proportion of plots to be visited and some plots were even never visited. Moreover, pollinators made fewer visits per plots. The proportion of viable seeds produced by S. alba in competition was lower and probably linked to the competition itself rather than changes in pollinator visitation. This study suggests that competitive interactions between plants can modulate pollination interactions even when competing plant species are not insect-pollinated.

Effects of the Clonostachys epichloë fungal hyperparasite on the symbiotic interaction between Botanophila flies and Epichloë fungus

Botanophila flies are associated with Epichloë fungi in a symbiotic relationship in which the flies benefit from stromata as a food source for both adults and larvae, and the fungus benefits from the transfer of conidia by the flies, resulting in fertilization. Derogations from this pattern indicate that the Epichloë-Botanophila interaction cannot be clearly defined. The situation may be complicated by reports of new elements of the interaction, e.g., Wolbachia bacteria present in Botanophila larvae. The present study investigates the impact of Clonostachys epichloë (Speg.) Schroers, the fungal hyperparasite of Epichloë stromata, on the Botanophila-Epichloë interaction.The interaction between C. epichloë and Botanophila flies associated with Epichloë typhina subsp. clarkii (J.F. White) Leuchtm. & Schardl stromata was studied in the Holcus lanatus L. grass population. C. epichloë was present on 76.5% of stromata, covering on average 44.8 ± 32.1% of its surface and influencing the final perithecial coverage to the same extent as larval feeding. C. epichloë began to appear on stromata much later than the fly eggs and did not affect the preference for Botanophila egg laying. On the other hand, C. epichloë reduced larval hatching success and increased the mortality of the larvae. Clonostachys was responsible for 76.0% of all deaths, overgrowing brood chambers, and its mycelium was present both on and within larvae in all cases. Overall, as a result of the presence of C. epichloë, the number of Botanophila fly offspring decreased by 52.7%. Of the 26 surviving larvae, 10 (38.5%) were affected by C. epichloë, and their weight was significantly lower than that of unaffected larvae.Results show that C. epichloë, a new element of the interaction between E. typhina fungus and Botanophila flies, negatively affects both fungal reproduction and the offspring success of flies. This is the first report on the entomopathogenic activity of C. epichloë against Epichloë-associated Botanophila flies.