Fescue Research Articles

Seasonal changes in body weight and condition, and pregnancy and lambing rates of sheep on endophyte-infected tall fescue in the south-eastern United States

The objective of these studies was to evaluate the seasonal maintenance of body weight (BW) and condition, signs of fescue toxicosis, and reproductive performance of straightbred and cross-bred hair sheep grazing tall fescue or bermudagrass forage. Breeds examined were St. Croix (SC), Romanov (ROM) and cross-bred ewes. BW was measured in the summer (1998–2000) and the fall (1999) on ewes grazing bermudagrass overseeded with ryegrass (BER) or tall fescue (FES) forage. Body condition score (BCS) and serum prolactin concentrations were determined in the summer (1999, 2000) and fall (1999). Pregnancy and lambing rates of a summer and fall (1999) breeding season and pregnancy rates of the spring (2000) breeding season were recorded. BW and BCS reflected seasonal differences related to the forage availability of BER and FES, seasonal variations in toxins of FES forage and breed differences. At all times, serum prolactin concentrations were reduced in ewes grazing FES pastures ( P<0.01), with the exception of the summer of 1999, where cross-bred yearling ewes maintained on FES exhibited an increase in prolactin level compared to those grazing on BER forage (forage×breed; P<0.05). Pregnancy and lambing rates were similar for forage treatments, with the exception of a reduction in reproductive rate in yearling cross-bred ewes maintained on FES in summer (1999; P<0.05). Birth and weaning weights of lambs were similar for suckling ewes maintained on BER and FES forage. These experiments demonstrated that, in contrast to cattle, BCS of SC, ROM and cross-bred ewes can be maintained in an acceptable range with either BER or FES forage. Pregnancy rate may be reduced in yearling, but not the older ewes maintained on FES forage. Birth weights and growth of lambs of mature ewes were similar for the forage treatments. It is recommended that breeding of yearling ewes occur on pastures free of endophyte-infected tall fescue.

Effect of post-harvest management on seed production of creeping red fescue, tall fescue, and Kentucky bluegrass in the Peace River region of north-western Canada

A field study in the Peace River region of northwestern Canada evaluated five post-harvest management (PHM) treatments on the seed yield and quality of four grasses, viz. Boreal creeping red fescue (Festuca rubra L. var. rubra), Safari and Tomahawk tall fescue (F. arundinacea Schreber), and Midnight Kentucky bluegrass (Poa pratensis L.). The PHM treatments were: straw removal after seed harvest plus trimming prior to winter; a single propane burn; a double propane burn; power cultivation; and diuron applied in spring. The study was conducted for 3 consecutive harvest years. The grass × harvest year × PHM interaction was not statistically significant (P ≤ 0.05) for any of 10 characteristics, viz. panicle density, time of seed maturity, seed yield (per unit land area and per individual panicle), whole-plant yield, harvest index, seed dockage, 1000-seed weight, specific seed weight, and germination capacity. The grass × harvest year interaction was statistically significant (P ≤ 0.05) for each of the 10 characteristics, primarily because of the differential response of the bluegrass as compared to the fescue grasses. The grass × PHM interaction was statistically significant (P ≤ 0.05) for seed yield of individual panicles, harvest index, seed dockage and 1000-seed weight. The PHM × harvest year interaction was statistically significant (P ≤ 0.05) for specific seed weight only. The main effect of PHM was statistically significant (P ≤ 0.05) for specific seed weight and germination capacity only. The average annual seed yield of the two tall fescue cultivars (1002 and 1171 kg ha–1 for Safari and Tomahawk) was approximately twice that of Boreal creeping red fescue (554 kg ha–1) and four times that of Midnight Kentucky bluegrass (284 kg ha–1). At this northerly latitude (55°N), the effects of any PHM treatment on the seed productivity of these grasses may be limited by the short period of environmental conditions between seed harvest and the onset of winter that are conducive to vegetative and reproductive tiller development. Key words: Post-harvest management, propane burning, mechanical and chemical rejuvenation, grass seed yield, grass seed quality

Carbon Addition Reduced Lag Time for 2,4,6-Trichlorophenol Degradation

The effect of grass root exudates and glucose on the lag time associated with 2,4,6-trichlorophenol (TCP) degradation by an unacclimated microbial inoculant and an acclimated microbial inoculant was investigated. The experimental medium was a nutrient solution containing TCP spiked with radiolabeled TCP and amended with either glucose or root exudates collected from fescue grass. Treatments containing TCP as the sole organic carbon source served as biotic controls. The acclimated microbial inoculant was not provided with TCP for 4 weeks prior to the experiment. The presence of an alternate organic carbon source reduced lag time for both the acclimated microbial inoculant and the unacclimated microbial inoculant. For the latter, three ratios of alternate organic carbon content to inoculant biomass were tested. The lag time for acclimation depended on this ratio. A lag time in excess of 11 days was observed for the biotic controls. The shortest lag time with the addition of an alternate organic carbon source was between 2 and 4 days for glucose and between 5 and 9 days for root exudates. It is proposed that the presence of a readily available, alternate organic carbon source affected lag time through promotion of microbial population growth and provision of a preferred source of carbon and energy.

Evaluation of Introduced Fescue Grass for Forage and Soil Conservation in Hilly Areas of Pakistan

Evaluation of Introduced Fescue Grass for Forage and Soil Conservation in Hilly Areas of Pakistan

Hand-Held NIR Spectrometry: Part I: An Instrument Based upon Gap-Second Derivative Theory

A hand-held near-infrared (NIR) meter (called the Gmeter), based upon gap-second derivative (GSD) theory, was designed, constructed, and performance-tested. The design incorporated narrow-band interference filters for isolating the three wavelengths required by the GSD calculations. A microprocessor was included in the design to facilitate both stand-alone and personal computer (PC) operation. The Gmeter was mounted in a caddy for making measurements within the laboratory. Performance of the Gmeter was compared with the performance of a FOSS NIRSystems Model 6500 spectrophotometer for measuring protein in soy-protein/sugar mixtures and for measuring nitrogen in fescue grass tissue. Two calibrations were developed on both instruments: (1) single-term GSD equations and (2) three-term (log 1/ R) multiple linear regression (MLR) equations. Second-derivative calibration experiments on the Model 6500 spectrophotometer formulated the basis for selecting the three filters in the Gmeter. Model 6500 data indicated that the GSD calibration [coefficient of variation (CV) = 5.14%] performed better than a three-term MLR equation (CV = 8.0%). In addition, the Gmeter performed almost as well (CV = 6.30%) as the Model 6500 (CV = 5.14%) for measuring protein in the mixtures using single-term GSD equations. An exciting extra in this study was the fact that measurements from the same three filters selected for determining protein in protein/sugar mixtures could be used for determining nitrogen (CV = 17.2%) in dry-grass tissue.

Ecotoxicological Evaluation of Three Deicers (NaCl, NaFo, CMA)—Effect on Terrestrial Organisms

The use of chemical deicers such as sodium chloride (NaCl) has increased significantly during the past three decades. Deicers induce metal corrosion and alter the physicochemical properties of soils and water. Environmental damage caused by the use of NaCl has prompted government agencies to find alternative deicers. This article presents a comparative ecotoxicological study of three deicers on soil organisms. Sodium formiate (NaFo) and calcium-magnesium acetate (CMA) are the most interesting commercially available deicers based upon their characteristics and potential toxicity. Organisms used in this study were four species of macrophytes (cress (Lepidium sativum), barley (Ordeum vulgare), red fescue grass (Festuca rubra), Kentucky bluegrass (Poa pratensis)) and an invertebrate (Eisenia fetida). Using standardized and modified methods, the relative toxicity of deicers was CMA<NaFo≅NaCl. The results demonstrate that these chemicals could have similar impacts in terrestrial environments since similar quantities of NaFo and greater amounts of CMA are necessary to achieve the same efficiency as NaCl. The toxicity of the tested substances was lower in natural composted soil than in artificial substrate (silica or OECD soil), indicating decreased environmental bioavailability. The response of the organisms changed according to endpoint, species, and soil characteristics (artificial substrate as compared to natural organic soil). The most sensitive endpoint measured was macrophyte growth with Kentucky bluegrass being the most sensitive species.

Development and characterisation of simple sequence repeat (SSR) markers for perennial ryegrass (Lolium perenne L.)

Enrichment methods were optimised in order to isolate large numbers of simple sequence repeat (SSR) markers for perennial ryegrass (Lolium perenne L.), with the aim of developing a comprehensive set of loci for trait mapping and cultivar identification. Two libraries were constructed showing greater than 50% enrichment for a variety of SSR-motif types. Sequence characterisation of 1853 clones identified 859 SSR-containing clones, of which 718 were unique. Truncation of flanking sequences limited potential primer design to 366 clones. One-hundred selected SSR primer pairs were evaluated for amplification and genetic polymorphism across a panel of diverse genotypes. The efficiency of amplification was 81%. A relatively high level of SSR polymorphism was detected (67%), with a range of 2–7 alleles per locus. Mendelian segregation of alleles detected by selected SSR-locus primer pairs was demonstrated in the F1 progeny of a pair cross. Cross-species amplification was detected in a number of related pasture and turfgrass species, with high levels of transfer to other Lolium species and members of the related genus Festuca. The identity of putative SSR ortholoci in these related species was confirmed by DNA sequence analysis. These loci constitute a valuable resource of ideal markers for the molecular breeding of ryegrasses and fescues.

Humus bacteria of Norway spruce stands: plant growth promoting properties and birch, red fescue and alder colonizing capacity

We studied the potential of the humus layer of the Norway spruce stands to supply beneficial rhizobacteria to birch (Betula pendula), alder (Alnus incana) and fescue grass (Festuca rubra), representatives of pioneer vegetation after clear-cutting of the coniferous forest. Axenically grown seedlings of these species were inoculated with the acid spruce humus, pH 3.7-5.3. Actinorhizal propagules, capable of nodulating alder, were present in high density (10(3) g(-1)) in humus of long-term limed plots, whereas plots with nitrogen fertilization contained almost none (</=10 g(-1)). The genera most frequently found in the humus were Bacillus, Paenibacillus, Arthrobacter, Nocardia, Rhodococcus and Pseudomonas, independently of prior liming or fertilization of the plots. The taxa found in the seedling roots differed from that in humus by the prevalence of the Gram-negative genera Pseudomonas, Alcaligenes and Comamonas. Enrichment cultures of the roots on nitrogen-free media yielded Paenibacillus and Rhodococcus species. Nitrogen-fixing R. erythropolis and a novel Paenibacillus, closest by full sequence of 16S rDNA to P. durus, represented new classes of nitrogen-fixing rhizosphere bacteria. In addition, nitrogen-fixing R. fascians was found in the humus. The rhizoflora and humus contained high proportions of bacteria antagonistic towards plant pathogenic Rhizoctonia sp., Botrytis cinerea and Fusarium culmorum. The antagonistic isolates also commonly produced siderophores and/or cell wall degrading enzymes.

Humus bacteria of Norway spruce stands: plant growth promoting properties and birch, red fescue and alder colonizing capacity

We studied the potential of the humus layer of the Norway spruce stands to supply beneficial rhizobacteria to birch ( Betula pendula), alder ( Alnus incana) and fescue grass ( Festuca rubra), representatives of pioneer vegetation after clear-cutting of the coniferous forest. Axenically grown seedlings of these species were inoculated with the acid spruce humus, pH 3.7–5.3. Actinorhizal propagules, capable of nodulating alder, were present in high density (10 3 g −1) in humus of long-term limed plots, whereas plots with nitrogen fertilization contained almost none (≤10 g −1). The genera most frequently found in the humus were Bacillus, Paenibacillus, Arthrobacter, Nocardia, Rhodococcus and Pseudomonas, independently of prior liming or fertilization of the plots. The taxa found in the seedling roots differed from that in humus by the prevalence of the Gram-negative genera Pseudomonas, Alcaligenes and Comamonas. Enrichment cultures of the roots on nitrogen-free media yielded Paenibacillus and Rhodococcus species. Nitrogen-fixing R. erythropolis and a novel Paenibacillus, closest by full sequence of 16S rDNA to P. durus, represented new classes of nitrogen-fixing rhizosphere bacteria. In addition, nitrogen-fixing R. fascians was found in the humus. The rhizoflora and humus contained high proportions of bacteria antagonistic towards plant pathogenic Rhizoctonia sp., Botrytis cinerea and Fusarium culmorum. The antagonistic isolates also commonly produced siderophores and/or cell wall degrading enzymes.

Biosynthetic origin and longevity in vivo of alpha-d-mannopyranosyl-(1 --> 4)-alpha-d-glucuronopyranosyl-(1 --> 2)-myo-inositol, an unusual extracellular oligosaccharide produced by cultured rose cells

A non-reducing trisaccharide, alpha-D-mannopyranosyl-(1 --> 4)-alpha-D-glucuronopyranosyl-(1 --> 2)-myo-inositol (MGI) accumulated in the spent medium of cell-suspension cultures of 'Paul's Scarlet' rose (Rosa sp.) predominantly during the period of rapid cell growth. This trisaccharide was also produced by cultures of sycamore (Acer pseudoplatanus L.) but not by those of the graminaceous monocots maize (Zea mays L.) and tall fescue grass (Festuca arundinacea Schreb.). When added to cultured Rosa cells, [(14)C]MGI was neither taken up by the cells nor bound to the cell surface and was not metabolised extracellularly. When D-[6-(14)C]glucuronic acid was fed to cultured Rosa cells, extracellular [(14)C]MGI started to appear only after a 5-h lag period, compared with a 0.5-h lag period for labelling of extracelluar polysaccharides. Furthermore, [(14)C]MGI continued to accumulate in the medium for at least 20 h after the accumulation of (14)C-polymers had ceased. These observations indicate that extracellular MGI was produced from a slowly turning-over pool of a pre-formed intermediate. Structural considerations indicate that the intermediate could be a glucuronomannan or a phytoglycolipid (glycophosphosphingolipid). No Rosa polysaccharides could be found that generated MGI in the presence of living Rosa cells. We therefore favour phytoglycolipids as the probable biosynthetic origin of MGI.

Increased responsiveness to intravenous lipopolysaccharide challenge in steers grazing endophyte-infected tall fescue compared with steers grazing endophyte-free tall fescue.

Fescue toxicosis in cattle occurs as a result of consumption of ergot alkaloids in endophyte-infected (E+, Neotyphodium coenophialum) tall fescue (Festuca arundinacea). The condition is characterized by pyrexia, decreased weight gains, rough hair coats, and decreased calving rates. The objective of this experiment was to investigate whether steers grazing E+ fescue have altered host response to lipopolysaccharide (endotoxin, LPS) challenge compared with steers grazing endophyte-free (E-) fescue. Angus steers (n=8) had continuously grazed either E+ (n=4) or E- (n=4) tall fescue grass for 8 months prior to the experiment. The E+ steers had lower body weight, depressed average daily gain, and decreased basal serum prolactin compared with the E- steers prior to LPS administration. Each steer received a single bolus i.v. injection of LPS (0.2 microgram/kg body weight; Escherichia coli; 026:B6) dissolved in sterile saline, and blood was serially collected every 30 min for 4 h and at 24 h post LPS administration. LPS increased serum tumor necrosis factor-alpha (TNF-alpha), cortisol, and haptoglobin but decreased plasma glucose and IGF-I. Importantly, however, TNF-alpha, cortisol, and IGF-I responses to LPS were greater in E+ compared with E- steers. These results indicated that animals grazing E+ fescue had altered integrated metabolic host response compared with animals grazing E- fescue. Potentially, combined exposure to E+ fescue and a bacterial LPS could have greater deleterious effects on the animal compared with exposure to only one of the two and would likely lead to increased catabolism.

Wintering Beef Cattle on Mixtures of ‘Georgia 5’ Tall Fescue and Warm-Season Perennial Grasses on Coastal Plain Soils

A persistent, perennial cool-season grass could reduce winter feed costs for beef production in the lower South. Georgia 5', is an endophyte-infested [Neotyphodium coenophialum (Morgan-Jones and Gams) Glenn, Bacon & Hanlinl tall fescue (Festuca arundinacea Schreb.) cultivar developed for improved persistence in the Coastal Plain. Two experiments were conducted to define the response of overseeded Georgia 5 to fall grazing deferment varying in starting date and duration, and to evaluate its potential contribution to winter feed for beef production. Plots of this tall fescue, overseeded on a warm-season grass pasture on upland Coastal Plain soils in 2 yr, were grazed continuously after establishment except for 60-, 90-, or 120-d fall grazing deferments beginning at 15-d intervals after 31 August. Deferments beginning mid-October or later provided benefit to Georgia 5 survival. Deferments longer than 60 d allowed greater herbage accumulation, but did not further enhance persistence. Georgia 5 tall fescue was overseeded on Coastal' bermudagrass [Cynodon dactylon (L.) Pers.] or Pensacola' bahiagrass (Paspalum notatum Fluegge var. saurae Parodi) flatwoods pastures in October of 2 yr. Continuous stocking (1.9 heifers/acre in the first and 1.2 in the second year) of pastures began in the following April. Performance of heifers grazing overseeded pastures from December to April was compared with heifers fed bermudagrass hay ad libitum and 6.8 lb/head of a ground corn-cottonseed mixture three times weekly. Tall fescue herbage mass ranged from about 200 to 600 lb dry matter/acre from December through April. Growth of hay-fed heifers was faster (P < 0.05) than non-supplemented grazing heifers (1.51 vs 0.50 lb/d) in the first year, but similar for both treatments in the second year (0.99 lb/d). Foliar cover of tall fescue was stable in bermudagrass pastures and averaged 51%. Tall fescue declined in bahiagrass pastures from 61% in spring of 1990 to 35% in spring of 1992. Minor, but transient, fescue toxicosis symptoms were observed. Georgia 5 overseeded on warm-season grass pastures can be used for winter grazing and contribute to reduced beef production costs in the lower South.

Metal retention in a thin karstic soil, Christian County, Missouri

The response of a Wilderness cherty loam series soil to repeated dosages of metals (as sewage sludge) using a two-step sequential extraction procedure was investigated. Variations in metal content between amended and control soils were related to organic matter, clay content, and clay mineralogy. Of the four metals investigated, Cu was found to accumulate in the top 20 cm of amended soils; Pb and Zn were present in even smaller amounts with respect to the control soils, and Cr concentrations were unaffected with respect to both depth and amendment. None of the metals indicated accumulation in deeper (>20 cm) parts of the soil profile. Overall, results suggest that the metals remobilize in the top 20 cm, being readily uptaken by the fescue grass growing in this lot. Precipitation of insoluble forms of metal into deeper parts of the soil profile was proven unlikely based on the distribution of metal concentrations throughout the profile.

Arbuscular mycorrhizal fungi associated with Festuca species in the Canadian High Arctic

Root and soil samples from 13 collecting sites located in the Canadian High Arctic were harvested between July 18 and 29, 1991, and surveyed for root colonization and spore populations of arbuscular mycorrhizal fungi. Grasses of the genus Festuca (Festuca brachyphylla Schult. &amp; Schult., Festuca baffinensis Polunin, and Festuca hyperborea Holmen ex Frederiksen) served as target plants. Of the 197 plant-root systems and soil rhizospheres examined, 28% were associated with arbuscular mycorrhizae. Roots of both F. brachyphylla andF. baffinensis were colonized, while none were detected in F. hyperborea root specimens. Five arbuscular mycorrhizal fungal species were extracted from indigenous soils. The most frequent and abundant species was Glomus mosseae (Nicol. &amp; Gerd.) Gerdemann &amp; Trappe, which was isolated from 8 of the 13 sites sampled. Other Glomales species in Arctic soils were Glomus macrocarpum Tul &amp; Tul., Glomus fasciculatum (Thaxter sensu Gerd.) Gerd. &amp; Trappe emend. Walker &amp; Koske, and two other unidentified Glomus species. Trap cultures of the indigenous soil with leek (Allium porrum L.) plants confirmed the identity of the species previously identified from original soil and allowed the detection of an additional species, Glomus aggregatum Schenck. &amp; Smith. The novelty of these observations and the relationship between plant mycorrhizal status, fungal species, and soil disturbance are discussed.Key words: mycorrhizae, Arctic, biodiversity, Glomus, Festuca.

The influence of the phenological phase on the fodder quality of the Festuca rubra and Agrostis capillaries species

In the Cindrel Mountains, respectively in the experimental field of the Institute of Mountainology Cristian - Sibiu, situated at the height of 1300 m, on acid brown soil, we have conducted studies regarding the way the phenological phases (bellows and earing) influence the fodder quality of the two species. We have assessed on the one hand the rough chemical composition and on the other hand, by calculus, the digestibility of organic stuff at the Festuca rubra and Agrostis capillaries species form the wild flora, analysed as whole plants.

An evaluation of rDNA variation inLoliumspecies (ryegrass)

Species of the genus Lolium are important fodder and turf grasses for agricultural and amenity use world-wide. Difficulties currently exist regarding the taxonomy of Lolium species and also in the demarcation between Lolium and the genus Festuca, with the debate focusing on the status of Festuca pratensis and its relations. The diversity in ribosomal DNA (rDNA) in Lolium was investigated. Cloned probes for rDNA, derived from the intergenic spacer (IGS-M) and transcribed regions (COD-M) of mustard (Sinapis alba) were used to investigate species relationships. Genomic DNA from seven Lolium taxa, F. pratensis, and xFestulolium braunii, were assessed for variation in rDNA by RFLP. Data support continued recognition of existing Lolium species' demarcations, and provided more taxonomic insight between allogamous Lolium taxa and F. pratensis. The COD-M and IGS-M probes grouped taxa by reproductive mode. The IGS-M probe distinguished all species as unique entities and established that hybrids, xFestulolium braunii and Lolium xboucheanum, had rDNA phenotypes that were composites of their parental species. The evolution of the ribosomal repeat unit is discussed and the potential for further rDNA taxonomic study in Lolium is considered.Key words: Lolium, variation, ribosomal, rDNA, RFLP.

Reproductive hormonal responses to ergotamine and ergonovine in cows during the luteal phase of the estrous cycle.

We conducted research to evaluate whether ergot alkaloids associated with endophyte-infected tall fescue could alter plasma concentrations of hormones important to reproductive function in cows. Six primiparous, estrous-cycling Holstein cows nursing calves received single i.v. injections of ergotamine tartrate, ergonovine maleate, or saline vehicle in a simple cross-over design. Each cow received one compound per estrous cycle, d 15 or 16 after estrus, and all compounds over three estrous cycles. Blood samples were collected at 20-min intervals for 40 min before and 240 min after treatments to assess plasma concentrations of prolactin, LH, FSH, and the response by PGF2alpha metabolite 13,14-dihydro-15-keto-prostaglandin F2alpha (PGFM). Ambient temperature and respiratory rates were measured hourly. Ambient temperature averaged 26 degrees C during data collection. Treatment x time was a significant source of variation for respiration rate and plasma concentrations of every hormone evaluated except FSH. Ergotamine elevated (P < .01) respiration rates 2 to 4 h after treatment. Ergotamine and ergonovine reduced (P < .001) plasma concentrations of prolactin for 2 to 4 h after treatment compared to concentrations before treatment. Plasma concentrations of LH were lowered (P < .01) by ergonovine during the 3rd h after treatment and by ergotamine during the 4th h after treatment. Most cows exhibited secretory PGFM responses after ergotamine and ergonovine treatments compared with an absence of a PGFM response in all cows after saline (P < or = .01). Results indicated that ergot alkaloids implicated as causative agents for fescue toxicosis can alter plasma concentrations of reproductive hormones during the late luteal phase of the estrous cycle in cows.

Post Gliphosate treatments establishment of some grasses

The sward dominated by Festuca rubra/Agrostis tenuis was treated to reduce the Nardus component and others weed by spraying with Gliphosate. Treatments were applied in the autumn of 1993. In the spring of 1994 a mixture of Phleum pratense, Fesuca rubra, Dactylis glomerata, Trifolium repens and Lotus corniculatus was oversown. Establishment of each species and botanical composition of the pasture were measured over the next three years. Nardus and weed was largely replaced by Phleum/Festuca mixture.

Population dynamics of Enchytraeidae (Oligochaeta) in different agricultural systems

Organic matter and abiotic conditions seem to influence distribution patterns of Enchytraeidae. In this study effects of changes in management practices on population dynamics of enchytraeids were determined. At two sites (in Athens and Griffin, GA) parts of a fescue (FE) field were converted into conventional tillage (CT) and no-tillage (NT) plots and changes in densities and depth distribution of enchytraeids were followed for 3 years. A site at Watkinsville, containing various soil textures and characterised by very low organic carbon content, which was converted into no-tillage 4 years earlier, was also sampled. Significant reductions in enchytraeid densities, after conversion of fescue into CT, were only found at Griffin. The management practices affected the vertical distribution of enchytraeids. In fescue and NT more enchytraeids were found in the 0–5cm than in the 5–15cm layer. In conventional tillage fields enchytraeids were more evenly distributed over the profile or more abundant in the 5–15cm layer. Management also affected the timing of population dynamics in the different plots. At two sample dates high abundances were found in CT plots only, not in any of the other plots. Enchytraeids were larger at Athens than at Griffin and Watkinsville and contained more soil particles in their gut. At Athens enchytraeids will presumably contribute more to the development of soil structure than at the other sites. We conclude that management affects vertical enchytraeid distributions in soil and changes the timing of population dynamics.

Phylogenetic analysis in the Festuca-Lolium complex using molecular markers and ITS rDNA

Molecular markers were used to investigate phylogenetic relationships among the eight species of ryegrass (Lolium) and 11 species of fescue (Festuca). RAPD and RFLP analyses were carried out on total bulked DNA from each population. Factorial analysis of a phenetic distance matrix yielded three major groups: (1) fine-leaved fescues, (2) broad-leaved fescues and (3) ryegrasses. Six non-coding regions of chloroplastic DNA were PCR-amplified, then digested by 20 restriction enzymes. Nuclear rDNA sequences, including internal transcribed spacers (ITSs) were used to estimate the average proportion of nucleotide substitutions. The correlation between substitution rate estimated from ITS sequences and that estimated from organelle DNA restriction sites was very high (0.94), and the corresponding UPGMA trees were very similar, with a slightly better resolution of the ITS tree in the Lolium genus. The time-scale inferred from substitution rates indicated that the period since divergence of the broad-leaved fescues from the fine-leaved fescues was four times as long as that since divergence of the genus Lolium from the former. Among the broad-leaved fescues, meadow fescue was closer to the Lolium group, while F. glaucescens and tall fescue were very closely related. North-African fescues were clustered together and giant fescue was the most differentiated species in this group. Our dataset was merged with ITS sequences recovered from the EMBL database, and the neighbor-joining method was used to draw a phylogenetic tree. In this tree, the tribe Poeae was clearly monophyletic, and more closely related to the Aveneae than to the Triticeae or Bromoideae. The genus Festuca appeared somewhat artificial, since Vulpia myuros and Dactylis glomerata were placed between fine-leaved and broad-leaved fescues.