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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]

Background and aims: The introduction of ley in cropping systems can provide multiple services, including high quality forage production and C and N inputs into arable soils. Little is known about the dynamics of these services in degrading grassland and the extent to which trade-offs regarding the use of fixed N for either forage production or as a source of N in the rotation can be found. Methods: A six-year field experiment compared the performance of an alfalfa-tall fescue (A-FE) mixture versus the single species alone (A, FE) in terms of forage production, forage quality and root biomass available as residues for the following crop. N mineralisation potential was then simulated for different grassland destruction scenarios using the STICS model. Result: The forage production, proportion of legumes, and forage quality all declined in the A-FE mixture after year 3 to reach less than 7 T.ha−1 and 20% legume in year 6. The yield advantage of A-FE compared to monospecific grasslands increased over time and was strongly associated with greater species complementarity, resulting from higher N transfer to grasses and increased asynchrony in the seasonal growth of A and FE. Root residue quantities and the potential for N supply to the rotation were not reduced when a degraded legume proportion was reached. Conclusion: The advantage of A-FE mixture over monospecific stands was greater integrated over a long period of time. No major risk of losing the N legacy effect by delaying mixture destruction was detected up to the first year after a sharp legume decline. [ABSTRACT FROM AUTHOR]

Fruit fly ground-dwelling stages (late third instar larvae, pupae, and teneral adults) are susceptible to predation from generalist ground-dwelling predators and to infection by entomopathogenic fungi (EPF). The effect of predators can be enhanced with cover crops and that of EPF by augmentative releases. However, whether these two biological control methods could be combined has not been studied under field conditions yet. Here, we studied in the field whether the enhanced activity of predators against the medfly, Ceratitis capitata, already observed in a Lolium arundinaceum ground cover could be impaired by a soil application of Metarhizium brunneum. Our results show that C. capitata adult emergence was reduced by this EPF for up to three months after fungal application, with the combination of the cover and M. brunneum being the most effective at reducing C. capitata emergence relative to bare soil (92.5% reduction). Although M. brunneum reduced the activity density of ground-dwelling predatory beetles up to 93 days after application, it showed no clear negative effects on earwigs, no effects on spiders, and a positive effect on ants up to 65 days after application. Therefore, the combined use of a ground cover of L. arundinaceum and M. brunneum against the soil-dwelling stages of C. capitata seems to work synergistically and appears as a strong and sustainable control tactic against the medfly and other fruit orchard pests. [ABSTRACT FROM AUTHOR]

Contamination of soil and water with petroleum hydrocarbons and metals can pose a significant threat to the environment and human health. This study aimed to investigate the establishment and growth of tall fescue and agropyron in two petroleum-contaminated soils (soil S1 and soil S2) with previous landfarming treatments, and to assess the phytoremediation potential for heavy metal removal from these polluted soils. The results showed that the presence of petroleum hydrocarbons significantly (P < 0.05) reduced plant growth, but plant development was facilitated in soils with prior landfarming treatments. Urease activity in the rhizosphere of agropyron for soil S1 was about 47% higher than the unplanted control soil. The rhizosphere of agropyron and tall fescue eliminated more than 40% and 20% of total hydrocarbon amounts in soil S1, respectively, compared to the unplanted soil. Moreover, the plants grown in the landfarming treatment exhibited higher concentrations of metals (Fe, Zn, Mn, Cu, and Ni) than the control. Based on the findings, the combination of landfarming and phytoremediation techniques can provide an optimal solution for removing mixed pollutants, including petroleum hydrocarbons and metals, from the environment. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the anti-erosion potential of taproots and fibrous roots with different diameters in alluvial loess under the concentrated flow. Materials and methods: A pot experiment was conducted in the greenhouse. Alluvial loess widely distributed in north China was used for plant growing. Two herbs, alfalfa (Medicago sativa) with taproots and tall festuca (Festuca arundinacea) with fibrous roots, were selected for single and mixed planting. Root configuration and soil detachment capacity (Dc) at different depths were measured, then the anti-erosion potential of taproots and fibrous roots with different diameters was analyzed. Results and discussion: Fibrous roots exhibited greater root length density (RLD) and fine root (0–1 mm) ratio at all depths, while taproots had larger mean diameter and root volume density (RVD). The Dc was reduced by 25.3–56.6% in the presence of roots compared to soil without roots, and the Dc of single fibrous roots treatment was significantly lower than that of single taproots and mixed roots. Whether in soil containing taproots or fibrous roots, Dc was only significantly negatively correlated with the density of very fine roots (< 0.5 mm). In fibrous roots, the direct path coefficient of very fine roots to Dc was significantly higher than that of roots at other diameter classes, while in taproots, the direct path coefficient of coarse roots (> 2 mm) to Dc was highest. Conclusions: Variations in root diameter (< 0.5, 0.5–1, 1–2, > 2 mm) distribution and root density are important factors contributing to differences in Dc at different depths. In alluvial loess with low clay and high silt content, the high density of very fine roots (< 0.5 mm) in fibrous roots is critical for demonstrating greater anti-erosion potential. The presence of more medium roots (1–2 mm) and coarse roots (> 2 mm) is the main reason for decreasing in the anti-erosion potential of taproots. [ABSTRACT FROM AUTHOR]

Riparian plant species can differ in their responses to streamflow variation in ways that strongly influence the composition and functioning of riparian plant communities. Quantifying these differences and the potential asymmetry of responses to low- versus high-flow phases of stream fluctuations is important for predicting and managing vegetation responses to variation in flow regimes. We measured the physiological response of two riparian plant species with different habitat preferences to an experimental flow that progressed from a low-flow to high-flow phase. Schedonorous arundinaceus, a hydric grass growing in near-channel habitat, exhibited significant and biologically substantial declines in stem water potential (SWP) during the low-flow phase of the experiment and a saturating increase in leaf relative water content (LRWC) during the high-flow phase. These patterns are consistent with cavitation risk in response to low-flow anomalies and saturating responses to high-flow anomalies in this hydric species. Pluchea sericea, a mesic shrub growing at intermediate elevations above the channel, exhibited a decrease in LRWC during the low-flow phase and an increase in SWP during the high-flow phase. These patterns are consistent with protection from stem cavitation risk during drought through leaf dehydration and opportunistic increases in water status in response to high-flow anomalies in this mesic species. The asymmetrical responses of both species to low- versus high-flow phases demonstrate unique physiological responses to flow anomalies of contrasting directions attributable to species habitat preferences and functional strategies that can be used by managers to predict non-linear vegetation responses to flow variation. [ABSTRACT FROM AUTHOR]

Complex environmental conditions like heavy metal contamination and elevated CO2 concentration may cause numerous plant stresses and lead to considerable crop losses worldwide. Cadmium is a non-essential element and potentially highly toxic soil metal pollution, causing oxidative stress in plants and human toxicity. In order to assess a combination of complex factors on the responses of two genotypes of Festuca arundinacea (75B and 75C), a greenhouse experiment was conducted on plants grown in two Cd-contaminated soil conditions and two soil textures under combined effects of elevated ambient CO2 (700 ppm) and Epichloë endophyte infection. Plant biomass, Cd, Fe, Cu, Zn, and Mn concentrations in the plant shoots and roots, Fv/Fm, chlorophyll (a & b), and carotenoid contents were measured after 7 months of growth in pots. Our results showed that endophyte-infected plants (E+) grown in elevated CO2 atmosphere (CO2+), clay-loam soil texture (H) with no Cd amendment (Cd−) in the genotype 75B had significantly greater shoot and root biomass than non-infected plants (E−) grown in ambient CO2 concentration (CO2−), sandy-loam soil texture (L) with amended Cd (Cd+) in the genotype 75C. Increased CO2 concentration and endophyte infection, especially in the genotype 75B, enabled Festuca for greater phytoremediation of Cd because of higher tolerance to Cd stress and higher biomass accumulation in the plant genotype. However, CO2 enrichment negatively influenced the plant mineral absorption due to the inhibitory effects of high Cd concentration in shoots and roots. It is concluded that Cd phytoremediation can be positively affected by the increased atmospheric CO2 concentration, tolerant plant genotype, heavy soil texture, and Epichloë endophyte. Using Taguchi and AIC design methodologies, it was also predicted that the most critical factors affecting Cd phytoremediation potential were CO2 concentration and plant genotype. [ABSTRACT FROM AUTHOR]

Abstract—The association of degradation of membrane-bound chlorophyll with changes in the dark respiration rates and photosynthesis in Festuca arundinacea Schreb. leaves under the influence of various concentrations of limited and aromatic hydrocarbons present in technogenic emissions was studied. One day after intoxication, a negative correlation between the content of non-phytol forms of pigments and the rate of photosynthesis was found. A positive correlation was found between the content of (1) phytol forms and the rate of photosynthesis and (2) non-phytol forms and the respiration rate. The relationships between the processes changed three days after characterizing the detoxifying and adaptive abilities of plants. [ABSTRACT FROM AUTHOR]

Tall fescue (Lolium arundinaceum (Schreb.) Darbysh.) is a cool-season perennial grass widely grown for forage and turf. Tall fescue lives in association with a fungal endophyte that helps the grass overcome abiotic and biotic stressors. The endophyte is asexual and transmits vertically from the tall fescue plant to the next generation through the seed. Producers of endophyte-infected tall fescue must have endophyte infection in at least 70% of their seed. Therefore, endophyte seed transmission is vital in breeding and seed production. Transfer of endophytes from their native host to different backgrounds of elite tall fescue cultivars can lead to a low seed transmission of the endophyte to the seed. This study screened 23 previously uncharacterized endophyte strains for transmissibility when artificially inoculated into continental and Mediterranean-type host tall fescue. We found no correlation between the rate of successful inoculation and the seed transmission rate of the endophyte in the new host. Nor did the seed transmission rate of the endophyte strains in their native host correlate with the seed transmission rate of the endophyte in the new host. Five strains exhibited seed transmission above 70% in both Mediterranean and Continental host backgrounds and will be characterized further for potential use in cultivar development. [ABSTRACT FROM AUTHOR]

Exploring the effects of chlorogenic acid (CA) can allow its use in the sustainable management of natural fiber-producing grass species. Herein, the pH-dependent effect of CA on germination and the physiological response in tall fescue (Festuca arundinacea) seeds in comparison to gibberellic acid (GA3) and fluridon (FD) was investigated. All CA treatments conferred significant reduction in germination index (GI), seed vigour, fresh seedling weight, coleoptile length, primary root length and root hairs compared to the control nutrient solution at pH 4. Above 2.82 mM CA, higher expression of total soluble protein, catalase and superoxide dismutase activities, lipid peroxidation, electrolyte leakage levels, and an induced prominent 28.4 KDa peptide were observed. CA (8.46 mM) significantly inhibited seed germination (50%, F = 4.56, P = 0.031, P < 0.05) at pH 4, and by contrast, conferred a strong stimulating effect at pH 6.8. The impact of pH on CA activity was significantly correlated to GI and percentage inhibitory and stimulatory effects (r = 0.96, p = 0.001). It is demonstrated that buffered CA differentially modified the expression of antioxidant enzymes activities and seed physiology thereby inhibiting seed germination at pH 4 compared to the herbicide FD (or the growth hormone) GA3. [ABSTRACT FROM AUTHOR]

Caffeic acid-O-methyltransferase (COMT), an important enzyme governing the process of lignification in plants, functions at the level of caffeic acid methylation along with 3-O-methylation of monolignol precursors. The present investigation was carried out to decipher the role of COMT in tall fescue lignification and to clone and characterize the COMT gene. The study on COMT activity variation at different growth stages of tall fescue exhibited a significant increase in activity over all the growth stages of tall fescue. A significant relative increase of 47.8% was observed from the first vegetative to reproductive stage. COMT activity exhibited a strong positive correlation with lignin content suggesting it to be an important enzyme of tall fescue lignification. Amplification and sequencing of tall fescue COMT gene resulted in an amplicon of size 1662 (Accession No.-MW442832) and an ORF of 346 amino acids. The deduced protein was hydrophobic, thermally stable and acidic with molecular formula C1679H2623N445O482S20, molecular mass 37.4 kDa and theoretical pI of 6.12. The protein possesses a conserved dimerization domain with a highly conserved SAM binding site. The COMT protein was found to be a homo-dimer with 1 catalytic SAH/SAM ligand per monomer interacting with 14 amino acid residues within 4 Å region. [ABSTRACT FROM AUTHOR]

Some evidence showed symbiosis with particular strains of Epichloë fungal endophyte eliminates self-incompatibility in host grasses which is ecologically important for seed and endophyte dispersal. This study was performed to investigate the effect of endophytic infection on genetic variances of forty full-sib families of tall fescue with their ten male parents, free from endophyte, and two female parents (75B and 75C) with both endophyte-infected (E+) and non-infected (E-) counterparts over two years. In addition, the effect of endophyte infection on selfing ratio and seed production via selfing was evaluated between endophyte-infected progenies and their non-infected counterparts. Genetic compatibility between the host and fungus was also evaluated by leaf sheath endophyte intensity (LSEI) and seed endophyte infection percentage (SEI%) indices. The results showed that genetic compatibility between the host and endophytic fungus was different between two infected female genotypes and their progenies. Compatibility parameters, leaf sheaths endophyte intensity, and seed endophyte infection rate were higher (2.78- and 1.2-fold, respectively) in 75B+ than in 75C+. Plant traits' genetic variances were estimated higher among full-sib endophyte infected progenies of 75B+ compared to non-infected counterparts. On the contrary, the genetic variances of plant traits were lower in full-sib endophyte-infected progenies of 75C+ compared to E- counterparts. It seems that higher compatibility in host-endophyte interaction leads to a higher estimate of genetic variances after outcrossing. Based on the results, it is possible to develop new breeding programs with different purposes in tall fescue based on the genetic diversity created by endophyte infection. [ABSTRACT FROM AUTHOR]

Plants can serve as sensitive bioindicators of the presence of contaminant vapors in the atmosphere. This work describes a novel laboratory-based gas exposure system capable of calibrating plants as bioindicators for the detection and delineation of the atmospheric contaminant hydrogen fluoride (HF) as a preparatory step for monitoring release emissions. To evaluate changes in plant phenotype and stress-induced physiological effects attributed to HF alone, the gas exposure chamber must have additional controls to simulate otherwise optimal plant growth conditions including variables such as light intensity, photoperiod, temperature, and irrigation. The exposure system was designed to maintain constant growth conditions during a series of independent experiments that varied between optimal (control) and stressful (HF exposure) conditions. The system was also designed to ensure the safe handling and application of HF. An initial system calibration introduced HF gas into the exposure chamber and monitored HF concentrations by cavity ring-down spectroscopy for a 48-h period. Stable concentrations inside the exposure chamber were observed after approximately 15 h, and losses of HF to the system ranged from 88 to 91%. A model plant species (Festuca arundinacea) was then exposed to HF for 48 h. Visual phenotype stress-induced responses aligned with symptoms reported in the literature for fluoride exposure (tip dieback and discoloration along the dieback transition margin). Fluoride concentrations in exposed tissues compared to control tissues confirmed enhanced fluoride uptake due to HF exposure. The system described herein can be applied to other reactive atmospheric pollutants of interest in support of bioindicator research. [ABSTRACT FROM AUTHOR]

Background and aims: Plants continuously interact with soil microbiota. These plant-soil feedbacks (PSFs) are considered a driving force in plant community dynamics. However, most PSF information comes from inter-family studies, with limited information on possible causes. We studied the variation of PSFs between and within grass species and identified the soil microbes that are associated with the observed PSFs effects. Methods: We grew monocultures of ten cultivars of three grass species (Lolium perenne, Poa pratensis, Schedonorus arundinaceus) using a two-phase PSF experiment. We measured plant total biomass to determine PSFs between and within species and correlated it with sequenced rhizosphere bacteria and fungi. Results: In the soil conditioning phase, grass species developed microbial legacies that affected the performance of other grass species in the feedback phase. We detected overall negative interspecific PSFs. While we show that L. perenne and P. pratensis increased their performance respectively in conspecific and heterospecific soils, S. arundinaceus was not strongly affected by the legacies of the previous plant species. Contrary to our expectation, we found no evidence for intraspecific variation in PSFs. Bacterial taxa associated with PSFs included members of Proteobacteria, Firmicutes, Verrucomicrobia and Planctomycetes whereas fungal taxa included members of Ascomycota. Conclusion: Our results suggest differences in PSF effects between grass species, but not between cultivars within species. Thus, in the studied grass species, there might be limited potential for breeding on plant traits mediated by PSFs. Furthermore, we point out potential microbial candidates that might be driving the observed PSF effects that could be further explored. [ABSTRACT FROM AUTHOR]

Aims: The bacterial endophyte Streptomyces albidoflavus UYFA156 was isolated from seeds of tall fescue, Festuca arundinaceae cultivar SFRO Don Tomás, promoting growth specifically in its host cultivar. Under the hypothesis that along with the growth promotion effect by UYFA156, a shift of the endophytic bacterial community occurs, we aimed to explore the effect of inoculation of this strain on the endophytic bacterial microbiota in F. arundinaceae cultivars SFRO Don Tomás and in cultivar Tacuabé, in which no growth promotion has been observed. Methods: Initially, growth inhibition of fourteen bacterial endophytes from both cultivars was tested in vitro, and then endophytic microbiota of plants and seeds were explored through high throughput sequencing of 16S rRNA. Results: Diversity and composition in the seeds, along plant development, and in response to inoculation were examined in both cultivars, finding significant differences between them. In 7 days old uninoculated plants, endophytic bacterial diversity was lower in cultivar SFRO Don Tomás than in cv. Tacuabé. However, upon inoculation, Simpson's diversity index in the cultivar in which growth promotion was observed increased significantly, approximately two-fold in inoculated plants with respect to uninoculated plants. However, no differences were observed in cultivar Tacuabé. In addition, microbiota composition was significantly altered in plants of the cultivar SFRO Don Tomás, whereas in Tacuabé plants, changes by inoculation did not reach statistical significance. Conclusion: Our results show that growth promotion by UYFA156 is accompanied by an early effect in endophytic diversity and composition and encourage further explorations in the relationship between the observed community modulation and plant growth promotion. [ABSTRACT FROM AUTHOR]

Tall fescue (Festuca arundinacea) from Poaceae family is an allohexaploid (2n=6x=42) and cross pollinated plant that is used throughout the world as a forage plant. This research was conducted to identify the genomic regions associated with 10 agro-morphological traits using 15,881 SNP markers in a diverse tall fescue germplasm. UPGMA, Structure, and PCA analyses illustrated high genetic differentiation between forage, turf, and hybrid tall fescue samples. Correcting r2 for population structure and kinship effects revealed the fact that the r2v (corrected for kinship) is much smaller than r2 (uncorrected) illustrating the necessity of removing the effect of coancestry to reduce the inflation of r2 estimates. Analysis of linkage disequilibrium revealed that the amount of SNP pairs in LD differs between sub-genomes and chromosomes and any increase in the distance among SNPs reduces the amount of SNP pairs in LD. A total of 111 and 17 marker-trait associations were identified via GLM and MLM methods for the investigated traits, respectively. Most of the significant MTAs belonged to plant height and days to anthesis. Gene ontology results revealed that 34% of MTAs were located in protein-coding regions. Most of the MTAs were located on chromosomes 1B and 1D. The MTAs for plant height and days to anthesis located within the coding regions can be utilized in genome-based breeding in tall fescue breeding programs. [ABSTRACT FROM AUTHOR]

In humid-temperate silvopastoral systems (SPS), light limitations can affect the growth and persistence of temperate forage species in the understory. Our objectives were to describe the morphogenic and structural changes expressed under tree-shading (UNDER) and under non-limiting light conditions (OPEN), and how these factors could impact growth, persistence and defoliation management practices of perennial C3 grasses of different tolerance to shade: Dactylis glomerata (tolerant), Festuca arundinacea (moderately tolerant) and Phalaris aquatica (heliophilous). The experiment was carried out in thirty-six pots. Half of them in the OPEN and the other, UNDER an experimental stand of Populus deltoides planted at a 4 m × 4 m arrangement (n = 6). There were three general shade response mechanisms determined by tree-shading: a high proportion of growing leaves per tiller, a low number of living leaves and a low leaf lifespan. The increase of the proportion of growing leaves determined the increase in the total green laminae per tiller, leading to a short term increase in light resource acquisition and growth rate. However this common response was driven by different morhogenetic mechanisms in the three species, based on increase of phyllochron, reduction of leaf lifespan or both simultaneously. However, under shading all species had similar low values of leaf lifespan and would have similar optimal defoliation frequencies. An among species trade-off between green lamina length per tiller versus density of tillers per plant was found-i.e. growing versus persisting-but was not associated with differential species shade tolerance. These results contribute to understanding the shade tolerance mechanisms behind the known suitability of the three species under deciduous trees. [ABSTRACT FROM AUTHOR]

In semi-arid and arid regions, the selection of suitable grass species with high-yield production, tolerance to drought stress, and potential for recovery from drought is of special importance. Despite extensive research in cool-season grasses, inter-species differences in post-drought recovery, persistence, survival, and summer dormancy and their relationship with drought tolerance need more investigation. In the present study, 28 diverse genotypes belonged to seven cool-season grass species, including Festuca arundinacea (tall fescue), Festuca pratensis (meadow fescue), Festuca ovina (sheep fescue), Festuca rubra (red fescue), Lolium perenne (perennial ryegrass), Lolium multiflorum (Italian ryegrass) and Lolium × hybridum were evaluated during 2016–2019 under three irrigation regimes (normal, mild, and intense drought stress). Then in the fourth year (on August 2019), irrigation was withheld at all previous irrigation regimes for two months during summer, and then species were re-irrigated to study the effect of prolonged drought conditions. A wide range of genetic diversity was detected in all the measured traits among and within species in response to different irrigation levels. Recurrent drought stress decreased forage productivity, post-drought recovery, and survival in all grass species. Among the studied species, tall fescue had higher forage production, drought tolerance, survival, recovery rate, and persistence. Sheep fescue had low forage production and recovery after drought. Drought tolerance (based on stress tolerance score, STS) was highly associated with forage yield and post-drought recovery and partially with summer dormancy under both mild and intense drought stress conditions. This indicated that selection based on higher STS would lead to choosing genotypes with better recovery after prolonged drought. Superior species and preferable genotypes for forage use from species Festuca arundinacea and for turf application from species Festuca arundinacea, Lolium perenne and Lolium × hybridum were identified across different water environments for future programs. [ABSTRACT FROM AUTHOR]

Phytoremediation is considered to be the most environmentally friendly green restoration technology for dealing with mine waste. Adding amendments can improve the substrate environment for plant growth and enhance remediation efficiency. Herbaceous plants have become the preferred species for vegetation restoration in abandoned mines because of their fast greening and simple management. After 8 weeks of pot experiments in the early stage, it was shown that the plant height and fresh weight of the plants treated with 5% conditioner and 0.5% straw (C2S2) were significantly higher than those of other treatments. Considering that, in this paper, to explore the effect of composite amendments on physicochemical properties of copper tailings repaired by herbaceous plants, the untreated copper tailings were employed as the control group, whereas copper tailings repaired by ryegrass (Lolium perenne L.), vetiver grass (Chrysopogon zizanioides L.), and tall fescue (Festuca arundinacea) with or without conditioners and straw combination into the compound amendments were taken separately as the test group. After 6 months of planting, the pH, electrical conductivity, water content, available potassium, organic matter, total nitrogen, and available phosphorus in the main physical and chemical properties of copper tailings in each experimental area were analyzed. The results showed that the electrical conductivity, organic matter, and total nitrogen content of copper tailings were improved to a certain extent by planting plants without treatment. Meanwhile, compared with the control group, all indexes of planting plants showed an upward trend after adding composite amendments. Among them, pH, water content, and available potassium content of copper tailings were enhanced more obviously. Furthermore, as discovered from the gray correlation analysis results, vetiver grass planted with composite amendments has the best comprehensive effect of improving the physicochemical properties of copper tailings, followed by tall fescue and ryegrass. [ABSTRACT FROM AUTHOR]

The host response of 17 cover crop cultivars to infection by single-species populations of Pratylenchus hippeastri, Pratylenchus vulnus and Pratylenchus penetrans, the three most common root-lesion nematode species in apple orchards in South Africa (SA), was evaluated under glasshouse conditions. Reproduction of the three Pratylenchus species was assessed 12 weeks after infection of the cover crop plants based on the reproductive potential (RF) and their (relative) susceptibility compared with the most susceptible control plant included in the experiment. Most of the cover crop cultivars (12 out of 17) were poor hosts of all three Pratylenchus species: brown mustard 'Caliente 199', white mustard 'Braco', canola/rapeseed 'Garnet', tillage radish 'Groundhog', barrel medics 'Jester', ribwort plantain 'Captain', creeping fescue (cultivar unknown), black oats 'SAIA', perennial ryegrass 'Champion blend', tall fescue 'Speedway', triticale 'Korog' and french marigold 'Naughty Marietta'. These 12 cover crop cultivars did not support reproduction of P. hippeastri, P. vulnus and P. penetrans, and have thus the potential to limit the build-up of large, damaging populations of these three root-lesion nematode species. Five out of the 17 cover crop cultivars were identified as good hosts of one or more of the three Pratylenchus species: pink serradella 'Margarita' and subterranean clover 'Aarbei Klawer' were good hosts of P. penetrans only; rye 'Duiker Max' was a good host of both P. hippeastri and P. penetrans; Indian buckwheat (cultivar unknown) and garden nasturtium 'Jewel Choice mix' were good hosts of all three Pratylenchus species. These five cover crop cultivars have thus the potential to enable the build-up of large damaging populations of either one, two or three of the root-lesion nematode species and may act as primary sources of infection of apple roots. Their use as cover crops in apple orchards infested with root-lesion nematodes should be avoided. [ABSTRACT FROM AUTHOR]

Rhizoremediation is a promising method based on the synergism between plant and rhizobacteria to remediate soil co-contaminated with heavy metals and total petroleum hydrocarbons (TPHs). A plant growth–promoting (PGP) rhizobacterium with diesel-degrading capacity and heavy metal tolerance was isolated from the rhizosphere of tall fescue (Festuca arundinacea L.), after which the effects of its inoculation on rhizoremediation performance were evaluated in heavy metal– and diesel-contaminated soil planted with tall fescue. The bacterial isolate (Novosphingobium sp. CuT1) was characterized by its indole-3-acetic acid (IAA) production, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, and siderophore productivity as PGP traits. CuT1 was able to grow on 1/10 LB-agar plates containing 5 mM of Cu or 5 mM of Pb. To evaluate the remediation effect of heavy metal– and diesel-contaminated soil by CuT1 inoculation, the experimental conditions were prepared as follows. The soil was artificially contaminated with heavy metals (Cu and Pb) at a final concentration of 500 ppm. The soil was then further contaminated with diesel at final concentrations of 0, 10,000, and 30,000 ppm. Finally, all plots were planted with tall fescue, a representative hyperaccumulating plant. Compared to the rhizoremediation performance of the co-contaminated soil (Cu + Pb + diesel) without inoculation, the bioavailable Cu concentrations in the soil and the tall fescue biomass were significantly increased in CuT1 inoculation. Additionally, the root growth of tall fescue was also promoted in CuT1 inoculation. Correlation analysis showed that Cu bioavailability and bioconcentration factor were positively correlated with CuT1 inoculation. The diesel removal efficiency showed a positive correlation with CuT1 inoculation, although the diesel removal was below 30%. CuT1 inoculation was positively correlated with IAA and dehydrogenase activity in the soil. Moreover, the dry biomass of the tall fescue's roots was highly associated with CuT1 inoculation. Collectively, our findings suggest that Novosphingobium sp. CuT1 can be utilized as an applicable bioresource to enhance rhizoremediation performance in heavy metal– and TPH-contaminated soils. [ABSTRACT FROM AUTHOR]

Phytoextraction strategy by harvesting dead leaves provides continuous phytoremediation and a great saving in disposal cost of hazardous plant residues. This strategy is entirely dependent upon the amount of cadmium (Cd) accumulated in dead leaves. However, it is unknown that whether the leaf Cd accumulation is associated with its senescence and how to regulate its Cd accumulation. This study showed that Cd was preferentially and consistently distributed to and accumulated in the senescent leaves with the new leaf emergence and the old leaf dieback under 75 μM of Cd stress in tall fescue (Festuca arundinacea Schreb.). Individual leaf monitoring from its emergence to senescence showed that Cd concentration increased exponentially with the leaf life cycle, while leaf biomass decreased gradually after 14 days of leaf emergence. The total amount of Cd accumulated in the leaf showed an exponential increase during leaf senescence, regardless of the leaf biomass loss. Our results demonstrated that leaf Cd accumulation was significantly associated with its senescence and the highest Cd accumulated in dead leaves could be contributed from the continuous Cd input during the leaf senescent process, indicating that further regulatory studies should be focused on the leaf senescence process to achieve higher Cd accumulation and phytoextraction efficiency by harvesting dead leaves. [ABSTRACT FROM AUTHOR]

Melatonin is a ubiquitous molecule having versatile physiological functions in an organism that has protective roles against biotic and abiotic stresses. Heat stress has become a serious threat to plants reported in various studies. In this study, the melatonin-induced defense mechanism of tall fescue plants under heat stress was explored in terms of physiological and biochemical responses. Heat stress (42 °C) was applied to 8-day-old tall fescue seedlings in both control-treated and 20 µM melatonin-treated plants. The results revealed that under heat stress melatonin-treated tall fescue seedlings measured the higher contents of shoot fresh weight, shoot height, chlorophyll (Chl), carotenoid, total soluble protein, and antioxidant enzyme activities (Peroxidase, POD; Catalase, CAT; Superoxide dismutase, SOD) compared to control seedlings. Oppositely, melatonin-treated tall fescue seedlings showed comparatively lower production of hydrogen peroxide (H2O2) and malondialdehyde (MDA) than control treatment. These results indicated that with application of exogenous melatonin, the damaging effects of heat stress on Chl a, Chl b, carotenoid, and protein synthesis machineries of tall fescue turf grass were reduced, and the activities of antioxidant enzymes, protein, and lipid molecules were enhanced that favored the lower production of H2O2 and MDA. Therefore, with melatonin application, antioxidant enzyme-mediated defense system of tall fescue under heat stress was positively modulated and plant's oxidative damages were alleviated evidencing the improvement of growth and physiological activities. Thus, tall fescue treated with melatonin might exhibit heat tolerance attribute. This investigation would provide a new insight for further exploration of heat tolerant mechanisms of tall fescue treated with melatonin under heat stress. [ABSTRACT FROM AUTHOR]

The pathways of chlorophyll a and b degradation were studied in the leaves of reed fescue (Festuca arundinacea) under the action of volatile organic compounds (pentane, hexane, benzene, o-xylene, butyl acetate) and benzo(a)pyrene. The activity of chlorophyllase, which removes phytol, and the degree of pheophytinization of chlorophyll a were used as markers of chlorophyll a and b destruction. A dose-dependent decrease in the content of membrane-bound chlorophyll pigments was found as a result of the action of all hydrocarbons used, which was most pronounced under the action of o-xylene one day after the treatment. The destruction of pigments containing phytol occurred by both pheophytinization and dephytolization. There was no correlation between the activity of chlorophyllase and the degree of pheophytinization. [ABSTRACT FROM AUTHOR]

The demand for rhizoremediation technology that can minimize greenhouse gas emissions while effectively removing pollutants in order to mitigate climate change has increased. The inoculation effect of N2O-reducing Pseudomonas sp. TF716 on N2O emissions and on remediation performance during the rhizoremediation of diesel-contaminated soil planted with tall fescue (Festuca arundinacea) or maize (Zea mays) was investigated. Pseudomonas sp. TF716 was isolated from the rhizosphere soil of tall fescue. The maximum N2O reduction rate of TF716 was 18.9 mmol N2O g dry cells−1 h−1, which is superior to the rates for previously reported Pseudomonas spp. When Pseudomonas sp. TF716 was added to diesel-contaminated soil planted with tall fescue, the soil N2O-reduction potential was 2.88 times higher than that of soil with no inoculation during the initial period (0–19 d), and 1.08–1.13 times higher thereafter. However, there was no enhancement in the N2O-reduction potential for the soil planted with maize following inoculation with strain TF716. In addition, TF716 inoculation did not significantly affect diesel degradation during rhizoremediation, suggesting that the activity of those microorganisms involved in diesel degradation was unaffected by TF716 treatment. Analysis of the dynamics of the bacterial genera associated with N2O reduction showed that Pseudomonas had the highest relative abundance during the rhizoremediation of diesel-contaminated soil planted with tall fescue and treated with strain TF716. Overall, these results suggest that N2O emissions during the rhizoremediation of diesel-contaminated soil using tall fescue can be reduced with the addition of Pseudomonas sp. TF716. [ABSTRACT FROM AUTHOR]

The rhizosphere is a dynamic and complex interface between plant roots and microorganisms. Owing to exudates, a web of interactions establishes among the microbial members of this micro-environment. The present study explored the impact of a bacterial consortium (Azotobacter chroococcum, Bacillus megaterium and Pseudomonas fluorescens, ABP), on the fate of a human pathogen, Listeria monocytogenes EGD-e, in soil and in the rhizospheres of Cajanus cajan and Festuca arundinacea, in addition to its plant growth promoting effect. The study further assessed the impact these bioinoculants exert on the autochthonous soil bacterial communities. Experiments in sterilised soil inoculated with bioinoculants and L. monocytogenes revealed the inhibition of L. monocytogenes by approximately 80-fold compared to that without the consortium. Subsequently, experiments were conducted in non-sterile soil microcosms planted with C. cajan and F. arundinacea, and in bulk soil. The consortium led to a significant increase in plant growth in both plants and prevented growth of L. monocytogenes. However, the presence of resident soil bacterial communities overshadowed this inhibitory effect, and a sharp decline in L. monocytogenes populations (5–6 log reduction) was recorded under non-sterile soil conditions. A shift in the soil resident bacterial communities was observed upon amendment with the bioinoculants. A significant increase of potential Plant Growth Promoting Rhizobacteria (PGPR) and biocontrol agents was observed, while the abundance of potential phytopathogens dropped. The present study opens up new avenues for the application of such a consortium given their dual benefits of plant growth promotion and restricting phytopathogens as well as human pathogen. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) has been proven to be involved in the regulation of many physiological processes in plants. Though the contribution of NO in plant response to drought has been demonstrated in numerous studies, this phenomenon remains still not fully recognized. The research presented here was performed to decipher the role of NO metabolism in drought tolerance and the ability to recover after stress cessation in two closely related species of forage grasses, important for agriculture in European temperate regions: Festuca arundinacea and F. glaucescens. In both species, two genotypes with distinct levels of drought tolerance were selected to compare their physiological reactions to simulated water deficit and further re-watering, combined with a simultaneous application of NO scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). The results clearly indicated a strong relationship between scavenging of NO in leaves and physiological response of both analyzed grass species to water deficit and re-watering. It was revealed that NO generated under drought was mainly located in mesophyll cells. In plants with reduced NO level a higher photosynthetic capacity and delay in stomatal closure under drought, were observed. Moreover, NO scavenging resulted also in the increased membrane permeability and higher accumulation of ROS in cells of analyzed plants both under drought and re-watering. This phenomena indicate that lower NO level might reduce drought tolerance and the ability of F. arundinacea and F. glaucescens to recover after stress cessation. [ABSTRACT FROM AUTHOR]

Tall fescue, a promising temperate forage grass of Himalayan region, possesses extraordinary property of rapid growth with high biomass production, but its poor digestibility due to higher lignin content limits its utilization in livestock feeding. The lignification in Tall fescue is under the control of enzymatic cascade of different regulatory enzymes. Cinnamyl alcohol dehydrogenase (CAD) is a crucial regulatory enzyme that catalyzes the last step of monolignol biosynthesis and is a potential candidate for altering the content and types of lignin, and hence increasing the digestibility of fodder crops. Hence, the present investigation was conducted on isolation, cloning and characterization of CAD gene from Tall fescue. Isolation and amplification of CAD gene resulted in an amplicon of 1521 bp. The CAD gene sequence was submitted to NCBI database with an accession number MW442831. Translation of the CAD gene sequence exhibited an ORF of 361 amino acids. The deduced CAD protein was predicted to be hydrophobic, acidic and thermally stable with molecular formula C1712H2734N460O520S23, molecular mass of 38.82 kDa, theoretical pI of 5.60 and 3 strong transmembrane helices. The CAD protein was predicted to have a dimer forming behavior with putative NAD(P) binding site between amino acids 48 and 301, putative substrate-binding site between amino acids 48 and 301, catalytic zinc-binding site between amino acids 48 and 164 and structural zinc-binding site between amino acid residue 101 and 115. A conserved 189GLGGVG194 motif is the binding site for NADP(H). The conserved motif pattern of CAD's zinc catalytic center was found to be 69GHEVVGEV(X)EVG(X)2V83. The zinc-binding site was found to be conserved between amino acid 89 and 115 and was found to be 89G(X)2VG(X)G(X)2VGXC(X)2C(X)2C(X)5QYC115. The deciphered sequence and putative protein information might be useful in subsequent research in lignin bioengineering for enhanced digestibility, biomass conversion as well as impact of lignin on cell wall mechanics. [ABSTRACT FROM AUTHOR]

Estimating soil nitrogen (N) availability is important for developing effective N fertilizer recommendations for plant growth. We examined the ability of various soil biological properties to predict soil N availability, and plant dry matter and N uptake in two greenhouse trials with sorghum-sudangrass (Sorghum bicolor (L.) Moench ssp. Drummondii) as test crop using soils (0–10 cm) from 57 tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.) pastures mostly in North Carolina and Virginia. Soil biological properties, the flush of CO2, cumulative carbon (C) mineralization, soil microbial biomass C, basal soil respiration, and plant available N were positively correlated with net N mineralization, plant dry matter, and N uptake in both the greenhouse trials. The flush of CO2, which is the measure of carbon dioxide released from dried and rewetted soil during the first 3 days of aerobic incubation, explained 77% and 72% of the variation in the plant N uptake in Greenhouse Trial 1 and 2, respectively. Total soil N and residual inorganic N in both trials and manganese in Trial 1 and particulate organic C in Trial 2 added minor contributions to explaining variation in plant N uptake. The flush of CO2 was reflective of management history and soil texture. We conclude that the flush of CO2 is a reliable predictor of soil N availability across diverse pasture soils because (a) it was highly correlated with net N mineralization, plant dry matter, and N uptake, and (b) it was less laborious and more cost-effective than other direct indicators of soil N availability. [ABSTRACT FROM AUTHOR]

Estimating soil nitrogen (N) availability is important for developing effective N fertilizer recommendations for plant growth. We examined the ability of various soil biological properties to predict soil N availability, and plant dry matter and N uptake in two greenhouse trials with sorghum-sudangrass (Sorghum bicolor (L.) Moench ssp. Drummondii) as test crop using soils (0–10 cm) from 57 tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.) pastures mostly in North Carolina and Virginia. Soil biological properties, the flush of CO2, cumulative carbon (C) mineralization, soil microbial biomass C, basal soil respiration, and plant available N were positively correlated with net N mineralization, plant dry matter, and N uptake in both the greenhouse trials. The flush of CO2, which is the measure of carbon dioxide released from dried and rewetted soil during the first 3 days of aerobic incubation, explained 77% and 72% of the variation in the plant N uptake in Greenhouse Trial 1 and 2, respectively. Total soil N and residual inorganic N in both trials and manganese in Trial 1 and particulate organic C in Trial 2 added minor contributions to explaining variation in plant N uptake. The flush of CO2 was reflective of management history and soil texture. We conclude that the flush of CO2 is a reliable predictor of soil N availability across diverse pasture soils because (a) it was highly correlated with net N mineralization, plant dry matter, and N uptake, and (b) it was less laborious and more cost-effective than other direct indicators of soil N availability. [ABSTRACT FROM AUTHOR]

Context: Vegetation quantity and quality influence the degree to which large grazers shape grassland structural heterogeneity. Invasive plants threaten the function of cross-scale interactions that exist when multi-scale effects such as fire and grazing interplay to form patterns of grassland structural heterogeneity. Objectives: We investigated how grazing pressure and time since fire at the patch scale influenced patch utilization and production as well as forage quality in experimental grassland pastures dominated by an invasive grass, tall fescue (Schedonorus arundinaceous). We also assessed the response of tall fescue utilization and production to interactive fire-and-grazing under moderate and heavy grazing pressure. Methods: We collected data on vegetation quantity and quality over two grazing seasons to evaluate the role of fire and grazing across time in shaping structural heterogeneity among patches in invaded tallgrass prairie in Iowa, USA. We anticipated greater initial patch-scale utilization in patches burned for the first time in two years than patches not burned in two years in our experimental pastures. We expected that greater utilization in recently-burned patches would reduce tall fescue production, mostly where grazing pressure was highest. Results: The contrast in the availability of live herbage between patches was half the level typical for native-dominated tallgrass prairie. Under increased grazing pressure, the interplay between fire and grazing did not result in greater broad-scale heterogeneity (among-patch heterogeneity) or an invasive grass reduction in experimental pastures. Yet, increased grazing early in the season did promote native-grass production in this invaded grassland landscape. Conclusion: Our results suggest that the dominance of tall fescue mediates the lack of structural heterogeneity induced by patch-level prescribed fire and grazing. Unlike native perennial grasses, tall fescue provides access to forage in unburned patches through its low-stature growth form. Diminished cross-scale interactions through a weak coupling of fire and focal grazing in invaded tallgrass prairie may facilitate structural homogenization of fire-dependent grassland. [ABSTRACT FROM AUTHOR]

Aims: Test the effects of root drying on biomechanical properties of fibrous roots. Methods: Tensile strength and Young's modulus of Festuca arundinacea roots were tested after full hydration and during progressive drying. Root diameter, water loss, and water content were measured for all treatments. Results: Hydrated roots showed weak relations between biomechanical properties and diameter. After only 30 min air-drying, both tensile strength and Young's modulus increased significantly in thin roots (< 1 mm) and after 60 min drying, both strength and Young's modulus showed a negative power relation with root diameter. The maximum strength and Young's modulus values recorded after 60 min drying were respectively three- and four-times greater than in hydrated roots. Strength and Young's modulus increased rapidly when water content dropped below 0.70 g g−1. These biomechanical changes were the result of root diameter shrinkage of up to 50% after 60 min drying, driven by water loss of up to 0.7 g g−1. Conclusions: Strength and Young's modulus largely increased with root drying. We suggest controlling root moisture and testing fully hydrated roots as standard protocol, given that slope instability is generally caused by heavy rainfall events and loss of matric suction. [ABSTRACT FROM AUTHOR]

The mechanisms of action of toxic organic compounds (OC) (pentane, hexane, benzene, o-xylene, butyl acetate, and benzopyrene) on the reed fescue Festuca arundinacea Schreb., which is a common plant in urban environments, were studied using pulse–amplitude modulated (PAM) fluorometry, which allowed the photochemical activity of photosystem II (PS II) to be evaluated from the parameters of the kinetic curve of chlorophyll a (Chla) fluorescence induction in vivo. A dose- and time-dependent reduction in the content of hydrophobic membrane-bound chlorophyll pigments was found along with simultaneous accumulation in the leaves of chlorophyllide (Chlde), a phytol-free product of chlorophyll degradation. It was shown that the effective quantum yield [Y(II)] of PS II photochemical reactions decreased mainly at high doses of toxic compounds while the level of photochemical fluorescence quenching (qP) did not change significantly and the coefficient of nonphotochemical quenching (qN) increased significantly to different degrees depending on the type of toxicant and the time of its exposure. A high negative correlation was observed between changes in qN, which characterized the thermal dissipation of absorbed energy, and the content of membrane-bound phytol chlorophyll pigments and carotenoids. On the other hand, changes in qN correlated positively with the content of Chlde formed during treatment with OC. The demand for thermal dissipation of absorbed energy resulting from the action of OC was proportional to the degree of destruction of the chloroplast pigment apparatus. This was confirmed by the positive correlation between qN and the content of Chlde, which possessed a photodynamic effect. Thus, parameter qN can serve as a reliable test for the damaging effect of toxic techogenic OC. [ABSTRACT FROM AUTHOR]

Background and aims: There is little information about the role of fungal endophytes on plant performance under oxygen-limited conditions. This study aimed to investigate the effect of Epichloë endophyte symbiosis on tall fescue responses to oxygen stress in a greenhouse experiment. Methods: The experiment was conducted with seven air-filled porosity levels in a sandy loam soil using genotypes (75C and 75B) of tall fescue (Festuca arundinacea) infected with and without endophytic fungus Epichlöe coenophiala (E+ and E–, respectively). Growth and physiological variables were determined to characterize plant response to oxygen-limited conditions, after nine-month application of the treatments. Results: The results showed that E+ 75B plants benefited from endophytic symbiosis in all air-filled porosity levels, showing a higher plant biomass, better water status and lower catalase and ascorbate peroxidase activity than E– 75B plants. In contrast, a reverse trend was observed for the genotype 75C. The E– plants also coped with poor aeration by forming adventitious roots at the soil surface, aerenchyma formation within the root tissue, and increased alcohol dehydrogenase activity. Conclusions: The presence of endophyte improved the genotype 75B performance under anaerobic conditions, while endophyte had an adverse effect on the performance of genotype 75C. This is probably due to incompatibility between Epichlöe endophyte and genotype 75C. Epichloë endophyte is likely to decrease the flooding-induced oxidative stress and prevented the over-accumulation of reactive oxygen species in the genotype 75B. Epichloë endophyte probably maintained oxidative conditions around the roots, and consequently, E+ plants required lower level of flooding-tolerance mechanisms. [ABSTRACT FROM AUTHOR]

The remediation of wood preservative–contaminated sites is an important issue due to the carcinogenic nature of some contaminants derived from wood preservatives (e.g., Cr+6, arsenate, and pentachlorophenol). This study evaluated the effects of fertilizer application on remediation potential of co-plantings of Salix interior Rowlee. (Salix) and Festuca arundinacea Schreb. (Festuca) in a wood preservative–spiked technosol while considering the potential contaminant and nutrient leaching. Two levels of nitrogen (N) and phosphorus (P) fertilizers, NaNO3 and NaH2PO4 (25 and 75 mg L−1), were applied to achieve three N:P ratios, i.e., 3:1 (75:25), 1:3 (25:75), and 1:1 (25:25), that were compared with a control treatment (0:0 N:P) in a mesocosm experiment. Roots of the plant supplied with 1:1 and 1:3 N:P had more than double arsenic (As) and copper (Cu) amounts (i.e., biomass × concentration) compared to the control ones. Highest As and Cu amounts in shoots were found for Salix stems and Festuca leaves in the 1:3 and 1:1 N:P treatments, respectively. Arsenic and P leaching was high in mesocosms supplied with 1:3 N:P. Contamination and nutrient leaching in the 1:1 N:P treatment did not differ from the control, except for Cu. In conclusion, 1:1 N:P treatment yielded the best results in terms of metal(loid) uptake and contaminant and nutrient leaching. In 1:1 N:P treatment, the maximum values of percent As, Cr, and Cu in Salix and Festuca aboveground were 0.18%, 0.024%, and 1.20% and 0.89%, 0.08%, and 1.78%, respectively. [ABSTRACT FROM AUTHOR]

Forage maize is the predominant crop in the intensive dairy farming regions of Europe. This crop, however, is associated with considerable nitrate leaching and decreasing soil organic matter concentrations. Catch crops installed after maize harvest can usually only be sown late in the growing season in North-West Europe to tackle these problems efficiently. Intercropping maize with grass species such as tall fescue has the potential to result in a timely developed grass sward before the winter, capable of assimilating important quantities of carbon and soil residual nitrogen and to buildup soil organic matter. Yet, the intercropped grass might compete with the maize for water and nutrients. Here, we report, for the first time, the effect of (i) herbicide combinations, (ii) tall fescue sowing density and method, (iii) tall fescue morphotype, and (iv) the maize maturity group on the functioning of forage maize intercropped with tall fescue. We assessed maize and intercropped tall fescue yields and studied the N uptake and the effect on soil residual nitrate of the intercropped grass. We found that every kg dry matter ha−1 of tall fescue aboveground dry matter, present at the end of the autumn, came at a cost of 1.4 kg dry matter ha−1 of maize dry matter yield. Herbicide treatments can regulate grass-maize competition, whereas lower sowing densities of the intercropped grass or different sowing methods of the intercropped grass had no effects. Despite the superior winter growth of the Mediterranean tall fescue morphotype compared to the continental tall fescue, the reduction in soil residual nitrate was similar for both morphotypes. We demonstrate that tall fescue intercropped in maize can be an alternative to cover crops installed after the harvest of maize, to reduce nitrate leaching, and to compensate for the soil organic matter losses associated with forage maize production. [ABSTRACT FROM AUTHOR]

Planting density can influence the biomass generation and element uptake capacity of various plants, which are two critical factors that determine the phytoremediation efficiency of plants. A series of 70 d experiments was performed to evaluate the influence of the planting density (10, 15, 20, 25, and 30 g seeds·m− 2, namely D10, D15, D20, D25, and D30, respectively) of Festuca arundinacea on the decontamination of Cd-polluted soils. The variations in the biomass yield, falling tissue (senescent and dead leaf tissues) proportion, and Cd extraction capacity of the species under different cultivation strategies were determined. The results showed that the biomass generation of the species per square meter increased as the planting density increased, reached a peak at D20, and then decreased significantly. In addition, planting density can change the proportions of different leaf types, and the highest amount of senescent and dead leaves which accumulated significantly more Cd compared with the emerging and mature leaf tissues was observed at D20. A suitable planting density can also drive the species to secrete more dissolved organic matter (DOM), especially hydrophilic fractionations in to the soil, activating more Cd. Therefore, the phytoremediation efficiency of the species was determined by the dry weight of the falling tissues, which contained more than 75% of the leaf Cd. A suitable planting density can enhance the Cd decontamination capacity of F. arundinacea, and the adjustment of the planting density is a practicable and economical method that can be performed in real fields. [ABSTRACT FROM AUTHOR]

Purpose: Precrops exhibit vigorous deep root growth, especially when grown perennially. However, their contribution to accumulate essential nutrients derived from deeper soil layers in the topsoil has not been quantified. We determined the vertical distribution of phosphorous (P) and potassium (K) affected by contrasting root systems of 3 precrops and their effects on subsequently grown spring wheat. Methods: Three precrops (lucerne, chicory and tall fescue) were grown for 1, 2 and 3 years prior to spring wheat cultivation. We measured plant available soil P and K from 0 to 30 cm to 75–105 cm of soil depth after precropping. Root growth and crop performance of spring wheat as affected by precropping were measured in two repeated trials. Results: We observed maximum 22-fold higher root-length density (RLD; cm cm− 3) of taprooted chicory compared with fibrous-rooted tall fescue in the subsoil. There were significant increases in plant available K in the topsoil by 27 mg kg− 1 over the precrop duration between 1 and 3 years. Grain yield of subsequently grown spring wheat was significantly increased by 10 % and 14 % from 1 year to 3 year-treatments of lucerne and chicory, respectively. Similarly, significant increases in P uptake (7 % and 19 %) and K uptake (21 and 14 %) of spring wheat was noted for the same treatments. Conclusions: Our data suggest that there is potential for the yield of short-season cereals to be improved by increased soil nutrient bioavailability in the topsoil derived from deeper soil layers by the deep roots of perennial precrops. [ABSTRACT FROM AUTHOR]

Endophyte-mediated salinity tolerance is largely unknown in tall fescue [Schedonorus arundinaceus (Schreb.)]. The experiment was designed to characterize growth, ion accumulation, and antioxidant metabolism of tall fescue infected by the endophyte Epichloë coenophiala to different levels of salinity stress. Endophyte-infected (E +) and endophyte-free (E−) tall fescue (cv Kentucky 31) plants were exposed to 10 d of 0 (unstressed control), 100 and 200 mM NaCl treatments in a greenhouse, respectively. Salinity stress caused reductions in plant height, leaf fresh weight (LFW), leaf dry weight (LDW), and leaf water content (LWC), and increased Na+ concentration, but E + plants had significantly higher LFW, LDW, and LWC under both NaCl treatments and lower Na+ than E− plants under 200 mM NaCl. Salinity stress decreased K+ and Mg2+ and did not alter P, and increased Ca2+ in E + plants and caused no change in Ca2+ in E− plants; however, endophyte had no effects on these elements. Chlorophyll fluorescence (Fv/Fm), malondialdehyde (MDA) concentration, and activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) remained unchanged in E + plants, but Fv/Fm was reduced and MDA level and enzyme activities were elevated in E− plants under 200 mM NaCl, where E + plants had significantly higher Fv/Fm and lower MDA, SOD, and APX activities than E− plants. Peroxidase activities increased in E + plants under 200 mM NaCl and in E− plants under both NaCl treatments. The results indicated that endophyte promoted salinity tolerance in tall fescue through maintaining higher growth and photochemical efficiency and lowering Na+ accumulation and lipid peroxidation. The significantly induced antioxidant enzyme activities and lipid peroxidation in E− plants suggested a possible enhanced oxidative injury in endophyte-free plants exposed to a high level of salinity stress. [ABSTRACT FROM AUTHOR]

Aims: Root tensile tests are often rejected if failure location is outside the middle section of samples. This study aims to identify where and why failure occurs along a root axis, and hence to revisit current approaches to test-validity. Methods: Roots from Festuca arundinacea; Lolium multiflorum; Lolium perenne were sampled from field-grown plants. Roots were tensile tested using a universal testing machine. Root samples were randomly allocated into two groups for testing. Group 1 roots were orientated with the older tissue closest to the top clamp, group 2 roots were orientated oppositely. Tensile strength, Young's modulus and failure location were recorded for each sample. Results: Lolium multiflorum roots were thinner and stronger than roots of Festuca arundinacea. Failure location in tensile tests depended significantly on tissue age with 75% of samples failing in the younger third of root tissue regardless of the root orientation in the testing frame. Only 7% of roots failed in the middle third of the sample. Conclusions: Fibrous roots tested in tension were observed to consistently fail in the younger tissue along the root axis. Exclusion of samples which fail outside the middle region of the root axis needs re-evaluation for a range of species. [ABSTRACT FROM AUTHOR]

Dust is a feature of the natural environment that can be exacerbated by anthropogenic activities. A range of physiological impacts have been attributed to dust deposition on plant leaves, including altered gas exchange and reduced photosynthetic activity—traits associated with yield and overall productivity. Substantially increased traffic along rural unpaved roads following the development of shale petroleum deposits in the Bakken region of North Dakota, USA, prompted us to investigate the effect of heavy dust exposure on economically important annual crops and perennial forage grasses. In a greenhouse study, we exposed six species of annual plants (barley Hordeum vulgare, durum wheat Triticum durum, maize Zea mays, sorghum Sorghum bicolor, lentil Lens culinaris, pinto bean Phaseolus vulgaris, sunflower Helianthus annuus) and eight species of perennial grasses (creeping bentgrass Agrostis stolonifera, crested wheatgrass Agropyron cristatum, intermediate wheatgrass Thinopyrum intermedium, tall fescue Schedonorus arundinaceus, Bermuda grass Cynodon dactylon, blue grama Bouteloua gracilis, buffalograss Bouteloua dactyloides, switchgrass Panicum virgatum) to 40 g of scoria road dust every other day for 10 and 14 days, respectively, resulting in cumulative dust exposure of 200 g/m 2 for annual plants and 280 g/m 2 for perennial grasses. Chlorophyll concentration tended to increase in all annual plants within 1–2 h of dust exposure, which remained high (along with photosynthetic yield) over the duration of the study. Stomatal conductance tended to decrease over the 2-week study period, which was expected, while leaf temperature also decreased for most species, which was contrary to previous research. Conversely, we found little evidence that high levels of dust reduce the ability of perennial grasses to recover from repeated defoliation, regardless of photosynthetic pathway or functional group. While perennial grass growth appears unaffected by the heavy dust emissions produced by traffic associated with energy extraction, the effect on annual plants is difficult to determine because dust might actually have a positive, light-scattering effect that improves plant performance. [ABSTRACT FROM AUTHOR]

The excessive application of atrazine in agriculture has resulted in serious environmental contamination. The addition of biochar could reduce the bioavailability and mobility of atrazine in soil through adsorption–desorption processes. In this study, tall fescue biochar was prepared at 500 °C, and its effect on the adsorption–desorption behavior of atrazine in red soil, brown soil, and black soil was investigated. The tall fescue biochar with the pH value of 9.64 had a developed porous structure and large specific area that contained abundant surface functional groups. The element composition of the tall fescue biochar was C (50.46%), O (15.01%), N (4.54%), H (2.56%), and S (1.47%). The adsorption process of atrazine in the three soil types with and without biochar addition was divided into a fast stage, slow stage, and equilibrium stage. A pseudo second-order kinetic model was suitable for fitting the adsorption process of atrazine, and the determination coefficient (R2) ranged from 0.985 to 0.999. The adsorption–desorption processes of atrazine were described accurately by the Freundlich model (R2 of 0.967–0.999). The adsorption capacity of the three soil types for atrazine increased significantly with the addition of biochar, whereby the equilibrium adsorption amount increased from an initial range of 3.968 to 5.902 μg g−1 to a final range of 21.397 to 21.968 μg g−1. The desorption of atrazine was also inhibited as the hysteresis coefficient (HI) increased from an initial range of 0.451 to 0.586 to a final range of 0.916 to 0.941. The adsorption capacity of the red soil improved more than did the brown soil or black soil. Moreover, spontaneous adsorption of atrazine by the biochar–soil system occurred more easily at 35 °C than at 15 °C and 25 °C. Overall, tall fescue biochar was a prospective soil amendment material. [ABSTRACT FROM AUTHOR]

Grazing in small-scale dairy systems reduces costs and enhances sustainability. However, binary pastures (BP) have low persistency, which may be increased by including more species given their flexibility to withstand different agroecological and management situations. The objective was to assess a multi-species (MS) pasture of perennial ryegrass (RG), tall fescue (TF), bromegrass (BG), red clover (RC) and white clover (WC) in comparison to a BP of perennial ryegrass (RG) – WC grazed by six Holstein dairy cows during the dry season in an on-farm double cross-over experiment, with three 14-day each experimental periods for animal variables, and a split-plot design for pasture variables at 3 cow/ha. There were differences (P < 0.05) between pastures for sward height (MS 5.0 vs. BP 4.0 ± 0.10 cm, both MS and BP) and net herbage accumulation (MS 902 vs BP 228 ± 172.4 kg DM/ha, both MS and BP) and differences (P < 0.05) for chemical composition among periods. There were differences (P < 0.01) among periods for estimated DM intake, but no differences (P > 0.05) for milk yield (mean 16.8 kg/cow/day), milk fat or protein content (mean 31.8 and 28.8 g/kg). Multi-species pastures are a viable alternative for SSDS in the highlands of central Mexico, being more resistant to harsh environment and to weed and kikuyu grass invasion. [ABSTRACT FROM AUTHOR]

Aims: An Italian ryegrass cultivar (Lolium multiflorum Lam. cv. Bb2067), selected and bred for increased leaf magnesium (Mg) concentration in the 1970s, reduced the incidence of hypomagnesaemia in sheep under experimental grazings. Here, we report evidence from archival experiments showing that cv. Bb2067 had consistently greater Mg concentrations at multiple sites. We also aimed to quantify variation in leaf Mg concentration among modern perennial ryegrass (Lolium perenne L.), hybrid ryegrass (Lolium perenne × multiflorum), and tall fescue (Festuca arundinacea Shreb.) cultivars. Methods: Data are reported from unpublished 1980s field-plot experiments for cv. Bb2067 and contemporaneous reference cultivars, sown at two UK locations in 1983 and 1984, and from 397 cultivars of modern forage grass in 13 UK-based breeding experiments sampled in spring 2013. Results: Across sites, years and cuts, cv. Bb2067 had a consistently greater leaf Mg concentration and lower potassium (K) concentration and forage tetany index (FTI) than reference cultivars in the 1980s experiments. Seasonal variation in leaf Mg and K concentrations and FTI were observed in the 1980s experiments, with K concentrations being generally greatest and Mg concentrations smallest in spring. Among modern forage grasses, there was large variation in leaf Mg concentration (up to 6.3-fold) and FTI (up to 2.1-fold), both within and between species, which varied independently of yield. Among a subset of hybrid ryegrass cultivars, there is evidence that the high Mg trait is already present in some modern breeding lines, albeit previously unreported. Conclusions: The variation in leaf Mg concentration and FTI among old and new cultivars shows there is considerable potential to breed forages with improved mineral quality to improve livestock health, potentially without compromising yield or other nutritional traits. [ABSTRACT FROM AUTHOR]

Improving micropropagation success rate is important since this technique allows the development of other biotechnological tools, such as genetic transformation, in vitro polyploidization, or endophyte inoculation. This is particularly relevant for grasses, as they are traditionally considered recalcitrant to plant tissue culture. Grasses of the subfamily Pooideae establish mutualistic associations with grass endophyte fungi of the genus Epichloë. These associations are specific, as each host species is associated with one or few Epichloë species. Lolium arundinaceum (Schreb.) Darbysh. is a perennial C3 species, native to Europe, which has become an important cool season forage crop worldwide. This grass usually establishes beneficial symbioses with E. coenophiala, but these benefits depend on both plant and fungal genetics and environmental conditions. Micropropagation protocols have been published for L. arundinaceum, but the influence of Epichloë endophytes was never examined. The aim of this manuscript was to study the effect of E. coenophiala on different micropropagation stages of L. arundinaceum and growth of the regenerated plantlets. Association with E. coenophiala (E+) increased callus induction, enhanced their proliferation, and increased shoot regeneration in L. arundinaceum. However, the biomass of plantlets regenerated from E+ seeds was lower than from non-associated seeds, both in vitro and ex vitro, and the in vitro multiplication rate also decreased. Contrary to other endophyte Epichloë-host associations with Lolium multiflorum and Bromus auleticus, the association with E. coenophiala did not improve tall fescue micropropagation. We can conclude that the effects of Epichloë endophytes on micropropagation and growth of their host differ for each endophyte-host association. [ABSTRACT FROM AUTHOR]

The study of factors influencing animal intake can provide a better understanding of the dynamics of the pasture ecosystem and serve as a basis for managing livestock in a more efficient way. We measured different sward surface heights of tall fescue in the process of short-term intake rate of sheep. There was a significant effect of sward surface height on herbage mass (P < 0.001), leaf lamina mass (P < 0.001), other species mass (P = 0.02), bite mass (P = 0.01) and short-term intake rate (P = 0.03) of sheep. There was a quadratic fit between time per bite and bite mass (P = 0.006). Multivariate analysis showed that the short-term intake rate and bite mass were positively correlated (r = 0.97), bite rate and total jaw movement rate were positively correlated but both were negatively correlated with time per bite. The sward surface height of tall fescue corresponding to the maximum short-term herbage intake rate was 22.3 cm. The underlying processes were driven by the bite mass, which was influenced by the leaf lamina bulk density and its consequences upon time per bite. This sward surface height can be adopted as a pre-grazing target for rotational stocking systems to optimize sheep nutrition on pastures. [ABSTRACT FROM AUTHOR]

Intensive grazing increases the profitability and sustainability of small-scale dairy systems by reducing feeding costs. Kikuyu grass is a subtropical species from East Africa that has similar performance compared with temperate grasses when grazed by dairy cows in these systems during the summer rainy season but reduces growth and quality at low temperatures, when temperate species may have an advantage. The objective was to evaluate intensive grazing of kikuyu pastures (KYKY) alone or in association with two varieties of endophyte-free tall fescue, TF-33 (TF33) and Cajun II (CAJN), during the summer–autumn transition period when low temperatures set in, by lactating cows in small-scale dairy farms. Pasture variables were analysed with a split-plot design for sward height, net herbage accumulation and chemical composition, in vitro digestibility of organic matter, and estimated metabolisable energy content of herbage and concentrate. Experimental design for animal variables was a 3 × 3 Latin Square repeated three times with nine Holstein cows and 14 days experimental periods. Cows received 4.65 kg DM/day of a 16% CP commercial concentrate. Milk yield and composition, live weight, and body condition score were recorded. There were no significant differences (P > 0.05) for sward height and net herbage accumulation, nor for important components of chemical composition of herbages. There were no significant differences (P > 0.05) for milk yield (19 kg/cow/day) and composition, although differences (P < 0.05) were detected for live weight and body condition score. The conclusion is that there is no advantage of associating tall fescue with kikuyu in summer–autumn transition period for small-scale dairy systems. [ABSTRACT FROM AUTHOR]

Fifty tall fescue (Festuca arundinacea Schreb.) half-sib families were screened under salinity stress during germination stage, and five tolerant and five sensitive half-sib families were selected. After studying morphological and biochemical characteristics of 10 selected families, the most salt-tolerant family was used for gene expression analysis. Real-time PCR analysis showed that the NDPK expression in plants treated by 200-mM sodium chloride has increased 36.782-fold greater than that in the control ones. The full length of encoding region of NDPK in tall fescue was obtained using the rapid amplification of cDNA ends technique. The homology comparison of DNA sequences, deduced amino acid sequences, and protein sequences were carried out using CLASTALW program in NCBI. The fragment composed of 822 nucleotides (gene's ORF was 508 nucleotides), and corresponding protein consist 168 amino acids with a predicted molecular mass of 19.4 kD. Blast search for isolated fragment showed that our sequenced fragment is highly similar to UMP/CMP kinase of Oryza sativa japonica (95%). In Blastp, the amino acid sequence of isolated fragment was similar to UMP/CMP kinase of Sorghum bicolor (95%). The results of study confirm that the NDPK is related to UMP/CMP kinase. [ABSTRACT FROM AUTHOR]

Aims: Extensive knowledge of perennial forage root systems is essential, given their critical role in below-ground C input. Methods: Root length and diameter were quantified periodically from 2016 to 2018 with minirhizotrons in a field experiment with three forage management systems: mixture of timothy (Phleum pratense L.) and tall fescue (Festuca arundinacea Schreb.) fertilized with (i) dairy cattle slurry or (ii) calcic ammonium nitrate, and (iii) mixture of timothy, tall fescue, and alfalfa (Medicago sativa L.) without N fertilization. Root biomass was measured yearly by coring. Results: Management systems with the two fertilization sources did not differ in root elongation, but the management system with alfalfa resulted in a slower root elongation after the first defoliation and a lower root mortality in the fall. Root length turnover was greater in the topsoil with dairy cattle slurry than with calcic ammonium nitrate. Fine roots dominated the surface soil and coarse roots the deeper soil layers. Conclusions: Root growth and mortality were more contrasted between systems that differed by the presence of alfalfa than by fertilizer source. As many root characteristics are drivers of soil C storage, the choice of perennial species in mixtures appears as a key management factor for sustainable farming systems. [ABSTRACT FROM AUTHOR]

Aims: Tall fescue (Festuca arundinacea) is a forage grass highly used in prairies. Cultivar SFRO Don Tomás has excellent drought and cold resistance, characteristics which are influenced by the native endophytic bacterial community. The aims of this work were to deepen the characterization of a selected group of putatively endophytic strains with different plant growth promoting (PGP) traits and to analyze the relationship between colonization and PGP abilities. Methods: PGP with single inoculations in pots containing a mixture of sterile sand and field soil and with paired inoculations in field soil cores were carried out. Colonization of plants inoculated singly or co-inoculated under gnotobiotic conditions was quantified. Confocal laser microscopy was used to visualize the colonization and infection processes of strain Streptomyces sp. UYFA156 in cultivars SFRO Don Tomás and Tacuabé. Results: Tall fescue cultivars displayed different responses to single bacterial inoculation. Inoculation with two strain pairs which included UYFA156 were successful in promoting growth in soil cores. Higher bacterial densities did not correspond to higher PGP. Strain UYFA156 was observed colonizing both fescue cultivars. Conclusions: UYFA156 is a true endophyte of tall fescue. Its PGP activity is cultivar-specific and may be related to the modulation of other endophytes. [ABSTRACT FROM AUTHOR]