Search

In the last decades, the progress in ryegrass (Lolium spp.) breeding was mainly on agronomic traits such as biomass yield, forage quality or disease resistance. However, for commercial success, a stable and high seed yield is a prerequisite for any cultivar. The realized seed yield is influenced by many different factors such as non‐optimal pollination and fertilization, seed abortion and seed shattering. While seed shattering has been largely eliminated in major cereal crops such as rice, barley or sorghum during domestication, the trait has been largely neglected in ryegrass breeding programs. The close syntenic relationship of cereal and ryegrass genomes offers the opportunity to develop breeding approaches for reducing seed shattering in the latter by transferring knowledge from the former. The objectives of this review are to (1) give an overview on the knowledge of morphology on seed shattering in cereal crops and ryegrasses, (2) compare the genetic background underlying seed shattering in different species, (3) identify putative candidate genes controlling seed shattering in ryegrasses through comparative genomic analysis and (4) give an outlook on new breeding strategies resulting in low seed shattering cultivars of ryegrasses and related forage grass species. [ABSTRACT FROM AUTHOR]

One possible approach for improving the nitrogen (N)‐use efficiency of perennial ryegrass (Lolium perenne L.) pastures and reducing environmental N losses is to select cultivars or incorporate alternative pasture species with lower shoot N concentrations. Viability of this strategy depends on herbage production not being unduly compromised. A pot experiment compared the shoot N concentration requirements of a diverse range of perennial ryegrass cultivars to achieve 90% and 99% of the herbage yield maxima achievable within a 20 day regrowth cycle. This research was undertaken to quantify if and what effect Australasian breeding programs have had on the N nutrition of perennial ryegrass. Our experiment found minimal genetic variation in the shoot N concentration requirements for vegetative perennial ryegrass swards to achieve near‐maximum herbage yields of living biomass. Across evaluated cultivars, swards achieving 90% and 99% of herbage yield maxima required minimum shoot N concentrations (on a dry matter basis) of 2.56% and 2.87%, respectively. Our experiment also evaluated the shoot N concentration requirements of modern summer‐active cocksfoot (syn. orchardgrass; Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) ecotypes. We found their shoot N concentration requirements to achieve optimal herbage growth to be similar to those of perennial ryegrass. Taken together, our results suggest that within the perennial ryegrass genome, and among similar high yielding temperate perennial grasses, there may be limited scope for selecting plants with lower shoot N concentration requirements. [ABSTRACT FROM AUTHOR]

Agricultural grass cultivars bred for increased forage yield commonly have extensive root systems. As roots are an important input of organic matter into the soil, it follows that such cultivars could lead to important increases in soil organic carbon (SOC), but this, and the mechanisms involved, are poorly understood with little empirical field evidence. We assessed the effect of two cultivars, Lolium perenne L. cv. "AberMagic" and L. perenne L. × Festuca pratensis Huds. cv. "Prior", in comparison with mixed‐species permanent pasture ("Pasture") in a field experiment on temperate alluvial soil in the southwest UK. Root and SOC stocks, and specific plant‐derived lipids as mechanistic biomarkers for shoot and root inputs of C, were measured on intact 1‐m volumetric soil cores collected on four dates in 2013–2015. Total grass yields were greater for both grass cultivars (40–43 Mg ha−1) than Pasture (39 Mg ha−1), and by 2015 root stocks in the upper 0.1 m were significantly greater by more than 4.7 Mg ha−1. At 0.1–0.3 m depth, SOC stocks (per 0.1‐m depth) were significantly greater under the two grass cultivars (24–50 Mg ha−1) compared to Pasture (18–32 Mg ha−1). In the full 1‐m profile, mean SOC stocks were 137, 133 and 110 Mg ha−1 for AberMagic, Prior and Pasture, respectively, matching root biomass distribution. Odd‐chain n‐alkane concentrations were significantly greater for shoots than roots (274 vs. 64 mg kg−1, respectively), and roots had significantly greater concentrations than shoots of even‐chain hydroxy fatty acids (1829 vs. 305 mg kg−1, respectively) and diacids (317 vs. 93 mg kg−1, respectively). This confirmed lipids as candidate biomarkers for distinguishing shoot and root inputs into the soil, with roots being the dominant source of SOC. Based on the observations of increased forage yield and SOC stock, high‐yielding forage grass cultivars can contribute to future strategies for climate‐smart agriculture in grassland‐dominated temperate regions. Highlights: Selected root traits for increased depth, density and diameter may increase SOC in grassland.The effect of two high‐yielding forage grass cultivars were assessed in a field trial.Fast‐growing, high‐yielding cultivars enhanced root and SOC stocks compared to typical pasture.Lipid biomarkers confirmed that root inputs were the predominant C input to soil. [ABSTRACT FROM AUTHOR]

The effect of soil environment on cultivars compatibility was evaluated in a cutting field experiment during two growing seasons. A factorial combination of four perennial ryegrass (Lolium perenne L.; PR) and three white clover (Trifolium repens L.; WC) cultivars were grown on deep (DSS) and shallow (SSS) soils under irrigated conditions. Measurements included herbage accumulation (HA), root attributes, leaf chlorophyll content, and interception of photosynthetic radiation. The PR–WC compatibility was affected by soil environment. In both soil sites and growing seasons, the WC + PR herbage accumulations were similar but with different PR and WC partial accumulation. In DSS, the partial PR HA was 22% less than that observed in SSS; the partial WC HA was almost twice in DSS relative to SSS. In SSS, the WC stolon growing point numbers, stolon length, and stolon biomass increased 60, 88, and 94% relative to DSS, respectively. In the same way, the mixed sward increased root biomass and root length density, which was considered as a mechanism for improving plant resources capture from the soil. At cultivar level, the PR–WC compatibility was affected mainly by WC cultivar, and the effect of PR cultivar was fairly weak. The medium‐leaved WC cultivar 'Will' showed the greatest compatibility with PR, particularly with cultivar 'Bealey'. These results are valuable when designing new management strategies for mixed sward production in marginal environments. Modern cultivars of PR have capacity for adapting to marginal environments; however, it is necessary to improve the competitive ability of WC to capture soil resources under marginal soil conditions. Core Ideas: Understanding compatibility of perennial ryegrass and white clover cultivars allows for optimized mixed sward herbage accumulation.Modern cultivars of perennial ryegrass have capacity for adapting to marginal environments.Mixed sward changes its phenotypic expression in marginal environments. [ABSTRACT FROM AUTHOR]

Forage evaluation indices are available to assist farmer decision‐making on the most appropriate ryegrass cultivars to grow. However, these indices currently take no account of any feeding value trait that reflects the interaction between the animal and the structural and morphological characteristics of the pasture. Information on the feeding value of ryegrass cultivars can be confounded by nutritive value, arising from the relationship between nutritive value and heading date. The objective of this study was to determine the milk production response of dairy cows grazing four perennial ryegrass diploid cultivars: two morphologies within two different heading dates and on three occasions during lactation across two years: late spring, summer and autumn. No consistent phenotypic effect occurred on milk production across the two years. Milk production responses were more closely aligned to energy intake. The sward structure changed physiologically from year 1 to year 2, with a reduction in the ratio of leaf to stem and subsequent increase in stem mass in year 2. Despite this, the relative difference in leaf to stem between mid‐season and late‐season heading dates remained consistent between years and had no effect on milk production. In one year, the apparent dry‐matter intake was higher but it was not possible to determine which sward structure traits or group of traits contributed to this response. We conclude that, at this time, the evidence is insufficient to support inclusion of a phenotypic trait as represented by "feeding value" in forage evaluation indices. [ABSTRACT FROM AUTHOR]

Bahiagrass (Paspalum notatum Flüggé) is the base of cow‐calf operations in Florida. Nitrogen is usually the most limiting mineral in pasture‐based systems. Various bahiagrass cultivars have been released over the years; however, an evaluation of their performance under no N fertilization has not been reported. There is some evidence that bahiagrass can associate with free‐living bacteria and fix atmospheric N2. This study investigated the performance and potential biological N2 fixation (BNF) of six bahiagrass cultivars ('Argentine', 'AU Sand Mountain', 'Pensacola', 'TifQuik', 'Tifton‐9', and 'UF‐Riata') under no N fertilization during the growing seasons of 2014, 2015, and 2016. Results showed no differences among cultivars for total herbage accumulation (2835 kg dry matter ha−1), total N aboveground (28 kg N ha−1 yr−1), and BNF (9 kg N ha−1 yr−1). Pensacola had greater crude protein than Tifton‐9 (84 vs. 78 g kg−1, respectively), whereas AU Sand Mountain had greater in vitro digestible organic matter (494 g kg−1) than other cultivars, except for Argentine. Argentine had greater root‐rhizome mass (24,914 kg organic matter ha−1) than UF‐Riata and TifQuik (15,367 and 14,682 kg organic matter ha−1, respectively). Carbon and N stocks in belowground biomass were greater in Argentine (8575 and 155 kg ha−1, respectively) than UF‐Riata (4514 and 85 kg ha−1, respectively). Root‐rhizome/shoot ratio averaged 37 across cultivars. Managing bahiagrass cultivars under no N fertilization inhibits the cultivar herbage potential; however, cultivar differences in nutritive value and root‐rhizome responses can still be detected. [ABSTRACT FROM AUTHOR]

Eight perennial ryegrass cultivars (representing the variations in ploidy, heading date and water‐soluble carbohydrates concentration) were investigated for morphology and nutritive value at three phenological stages: pre‐heading vegetative, reproductive and post‐flowering vegetative stages. Chemical compositions and digestibility of morphological components (lamina, pseudostem and reproductive stem) from each perennial ryegrass cultivar were analysed in a split‐plot design. At the vegetative stages, perennial ryegrass cultivars differed significantly in the proportions of lamina and pseudostem. Tetraploid cultivars, Base and Bealey, always had the greatest lamina proportion (51.8% and 53.2% at the pre‐heading and post‐flowering vegetative stages respectively). At the reproductive stage, the emergence of seed heads diminished the differences in morphology among cultivars. Perennial ryegrass cultivars also had distinct nutritive value throughout three phenological stages. The high‐sugar cultivar, AberMagic, had high WSC concentrations (276, 227 and 90 g/kg DM at the pre‐heading vegetative, reproductive and post‐flowering vegetative stages respectively); the intermediate‐heading cultivars, Kamo and Commando, generally had a lower organic matter digestibility in dry matter than the late‐heading cultivars at the pre‐heading vegetative (70.7% vs. 74.4%) and reproductive stage (63.9% vs. 68.2%). However, although the morphological components were different in nutritive value consistently, the differences in morphology did not account for the variation in nutritive value among perennial ryegrass cultivars. [ABSTRACT FROM AUTHOR]

First-year crops of diploid perennial ryegrass (cvs. Meridian, Bronsyn and Grasslands Impact) were sown on 1 April and 14 May 2008. Applications of trinexapac ethyl ( TE) plant growth regulator at 0, 200 and 400 g a.i. ha−1 were used to shorten stems to examine the impact of seed growth. Seed filling followed a consistent sigmoidal growth pattern with a lag phase of 127°C days, and linear duration of 390°C days. Time to 95% of final seed weight was 517°C days. Seed yield increases from TE were from higher numbers of first-grade seeds m−2, achieved by a higher rate of seed filling during the linear phase of 0·115 mg per °C day per spike. For all cultivars, the maximum stem dry weight occurred at 310-400°C days post-anthesis, which suggest the stem was a strong sink. As seeds developed, their demand for assimilate increased and they drew more from the stem. At harvest, stem weights from TE treatments were 25% heavier than at anthesis, while untreated 'Bronsyn' and 'Grasslands Impact' stems were similar to those at anthesis. Thus, stems treated with TE contributed assimilates to increase seed yield but were still a net sink with assimilates in the stem at harvest. Trinexapac ethyl rate induced an inverse relationship between seed yield and stem height. This showed that competition for assimilate between stems and growing seeds limited the seed yield. Management or genetic factors that reduce stem height are likely to increase seed yields of perennial ryegrass. [ABSTRACT FROM AUTHOR]

Grazed pastures based on ryegrass species provide most of the feed for dairy cattle in New Zealand. There are many cultivars of perennial ( Lolium perenne), annual and Italian ( L. multiflorum), and hybrid ( L. boucheanum) ryegrasses available for dairy farmers to use in pasture renewal. This study describes an index which ranks ryegrass cultivars relative to a genetic base according to the estimated economic value (EV) of seasonal dry matter ( DM) traits. A farm system model was used to derive EVs ($ ha−1 calculated as change in operating profit divided by unit change of the trait) for additional DM produced in different seasons of the year in four regions. The EV of early spring DM was consistently high across all regions, whereas EV for late spring DM was moderate to low. Genotype × environment analysis revealed significant reranking of DM yield among ryegrass cultivars across regions. Hence, separate performance values ( PVs) were calculated for two mega-environments and then combined with the corresponding season and region EV to calculate the overall EV for twenty-three perennial ryegrass and fifteen short-term ryegrass cultivars. The difference in operating profit between the highest ranked and lowest ranked perennial ryegrass cultivar ranged from $556 ha−1 to $863 ha−1 year−1 depending on region. For short-term ryegrasses used for winter feed, the corresponding range was $394 to $478 ha−1 year−1. Using PV for DM yield, it was estimated that plant improvement in perennial ryegrass has added $12-$18 ha−1 year−1 (depending on region) operating profit on dairy farms since the mid-1960s. [ABSTRACT FROM AUTHOR]

Hybrid ryegrass ( HRG) is purported to have high overwinter growth characteristics and may have a role in Irish grassland systems. In a 3-year small-plot study at Fermoy, Cork, Ireland, the dry matter ( DM) production and herbage quality of HRG cultivars in early spring were compared with diploid and tetraploid perennial ryegrass ( PRG) cultivars. Treatments comprised ryegrass cultivars × defoliation managements × defoliation heights in a 5 × 3 × 2 factorial arrangement. The cultivars were Navan (tetraploid PRG), Foxtrot (diploid PRG), Foyle (tetraploid HRG), Brutus (diploid HRG) and Belleek (tetraploid HRG). Defoliation dates were: (A) 2 February and 20 April; (B) 2 February, 3 March and 20 April; and (C): 2 February, 23 March and 20 April. Defoliation heights were 4 and 7 cm, applied across each management. The HRG cultivars yielded similarly to cv. Navan on 2 February. Cumulative spring DM production was higher in cvs. Brutus and Belleek than all other cultivars. During this period, the managements A and B had similar DM yields (2765 kg DM ha−1) but were greater than management C. Defoliating swards to 4 cm height increased DM yield compared with 7 cm height. Organic matter digestibility of grass at the silage-harvest growth stage was greater for PRG cultivars. The study indicates that early spring growth of the three HRG cultivars evaluated here was not sufficiently greater than the tetraploid PRG cv. Navan to compensate for their poorer midseason sward quality. [ABSTRACT FROM AUTHOR]

An assessment of genetic improvement in turf-type perennial ryegrass was performed at a network of six locations. A comparison was made of the turf performances of five natural populations, five forage-type cultivars used for turf seeding until the 1980s and 31 turf-type cultivars released from 1974 to 2004. Populations and cultivars were also compared in two spaced-plant experiments and in two seed-yield trials. Trait regressions on registration year of turf-type cultivars showed that breeding had been highly successful in improving the turf aesthetic merit (from +8·8 to +12·5% per decade according to seasons), wear tolerance (+5·4% per decade) and crown-rust resistance (+8·9% per decade) and in lessening the turf height increase rate (−0·43 mm day−1 per decade). Turf winter greenness had been marginally improved, whereas summer greenness and seed yield had not been significantly changed. A multivariate analysis provided evidence that turf density and fineness played a major role in the visual assessment of turf aesthetic merit and that wear tolerance was closely associated with turf density. Conflicting trait associations may have precluded improvements in turf ground-cover 3 months after sowing, turf winter greenness and turf persistency. [ABSTRACT FROM AUTHOR]

Increasing the residual water-soluble carbohydrate (WSC) concentration in silage may improve the nutritional value but impair aerobic stability. Our aim was to determine whether the residual WSC concentration and aerobic stability of low dry-matter (<135 g kg−1) perennial ryegrass silage could be manipulated through the judicious use of additive and cultivar. Seven additive treatments, including three innovative treatments, were compared across four consecutive harvests of the cultivars AberDart (bred to accumulate high concentrations of herbage WSC) and Fennema (control). The standard of fermentation of silage ensiled without additive (untreated) ranged from very bad to excellent. Application of ammonium tetraformate, at 3 and 6 L t−1, or homofermentative lactic acid bacteria (LAB) alone had an inconsistent effect on the fermentation and aerobic stability, and negligible effect on residual WSC concentration. A mixture of Lactobacillus buchneri and homofermentative LAB was not an effective silage additive, producing generally poorly fermented silage. An antimicrobial mixture of sodium benzoate, sodium propionate, sodium nitrite and hexamethylenetetramine, applied at 2·5 and 5 L t−1, frequently improved the standard of fermentation, but the effects were subject to the application rate. The high application rate was the most effective additive evaluated at improving the fermentation and increasing residual WSC concentration and consistently produced silage of excellent standard of fermentation. However, the antimicrobial mixture was not effective at protecting against aerobic instability. The effects of additive treatment were largely inconsistent across cultivars. Overall, AberDart had a negligible effect on the silage fermentation, residual WSC concentration and aerobic stability compared with Fennema. [ABSTRACT FROM AUTHOR]

B ezuidenhout SR, R einhardt CF & W hitwell MI (2012). Cover crops of oats, stooling rye and three annual ryegrass cultivars influence maize and Cyperus esculentus growth. Weed Research 52, 153-160. Summary No information is available on the effect of cover crops on weed growth in maize production in KwaZulu-Natal, South Africa. In a field experiment, the influence of two preceding cover crops, stooling rye and annual ryegrass, on the growth of maize and the weed Cyperus esculentus were compared with herbicides and weed control by hoeing. Maize emergence and early growth were delayed in the presence of physical residues of both cover crop species, especially annual ryegrass. Growth of C. esculentus was significantly inhibited in the inter-row maize planting lines by the cover crops for the first 16 days after maize emergence, but this effect had diminished by day 28. In a pot experiment, the influence of the same two cover crops on maize and C. esculentus growth was evaluated together with oats and two additional annual ryegrass cultivars. Here, the growth of maize and C. esculentus were suppressed, especially by the root residues of the annual ryegrass, in particular the cultivar Midmar. Chemical analysis of the leachate of the root residues indicated the presence of phenolic acids and benzoxazolin-2(3 H)-one. To achieve effective weed control, a weed management strategy combining the mulch retained on the soil surface, with a possible reduction in the type and amount of herbicide, should be implemented. [ABSTRACT FROM AUTHOR]

Kurokawa S, Kobayashi H & Ikeda K (2010). Genetic background of an invasive Lolium population in central Japan using chloroplast DNA and SSR markers. Weed Research 50, 245–252. To determine the genetic background of an invasive population of Lolium spp., we compared three non-coding regions of chloroplast DNA (cpDNA) and nine SSR loci of the population with those of 30 cultivars of Lolium multiflorum, Lolium perenne or their hybrid and two accessions of Lolium rigidum. For the cultivars and L. rigidum, bulked DNA was used for all analyses, due to variations within cultivars. Two of three regions in cpDNA were polymorphic among samples, generating four haplotypes (A–D). We found haplotypes A and B in L. multiflorum and L. rigidum, and haplotypes C and D only in L. perenne. All 48 individuals of the invasive population were discriminated as haplotype A, suggesting annual maternal origin. Nine loci of SSR generated 55 alleles in total in the invasive population. The presence or absence of these 55 alleles was counted for the bulked DNA of cultivars and L. rigidum. There were significant differences among species in the correspondences of alleles with those of the invasive populations. The correspondence of alleles with L. multiflorum was significantly higher than that with L. perenne or L. rigidum. These results suggested that the genetic background of the invasive population was very close to L. multiflorum. Although common traits among cultivars genetically close to the invasive population were not found, the wide variation in allele correspondence among L. multiflorum cultivars may indicate that non-invasive cultivar breeding may be possible in the future. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is a coolseason turfgrass species that can exhibit significant freezing injury in northern climatic regions. The objective of this study was to quantify major physiological and biochemical changes occurring during the cold acclimation period in four perennial ryegrass accessions varying in freezing tolerance (two freezing-tolerant accessions, TOL-1 and TOL-2, and two freezing-susceptible accessions, SUS-1 and SUS-2). Plants were subjected to a cold acclimation period of 2°C for 21 d in a controlled environment chamber. Crown tissues were harvested at 0, 7, 14, and 21 d of acclimation for determination of proline, water soluble carbohydrates (WSC), and lipid composition. Leaf photochemical efficiency (Fv/Fm) was also measured weekly before plant sampling for biochemical components. In general, proline levels increased and Fv/Fm decreased during cold acclimation; however, there were no differences in proline accumulation or FyI Fm among the accessions in response to cold acclimation. Water soluble carbohydrates significantly increased in response to 2°C, with TOL accessions (TOL-1 and TOL-2) accumulating higher WSC than SUS (SUS-1 and SUS-2) by 21 d of acclimation. There were also significant changes in major phospholipids classes at 2°C. Specifically, TOL-2 exhibited a higher ratio of membrane stabilizing lipids and unsaturated fatty acid content compared to SUS-1, SUS-2, and TOL-1 by 21 d of cold acclimation. [ABSTRACT FROM AUTHOR]

The fatty acid (FA) concentration of herbage and lipid metabolism in silage, mainly oxidation and lipolysis, of different species (perennial ryegrass, red clover and white clover) and three cultivars of white and red clover at three cutting dates in the growing season (April, July and October) were studied. FA concentration and composition was strongly affected by species and cutting date. Perennial ryegrass had lower concentrations of C16:1, C18:0, C18:1 and C18:2 than red and white clover. Within red and white clover, the effect of cultivar was small. Oxidation of C18:3 during wilting was different between species and cutting date despite similar wilting conditions. Lipolysis in silage was also influenced by cutting date, species and to some extent by cultivar. Furthermore, in some cuts silages of red and white clover displayed a lower lipolysis than silage of perennial ryegrass. On average, over the three cutting dates proportionately 0·903, 0·864 and 0·857 of the membrane lipids in perennial ryegrass, red clover and white clover were hydrolysed during ensiling. In red clover this could be due to the lipid-protecting properties of polyphenol oxidase (PPO) activity. This was not observed in perennial ryegrass or white clover. Nevertheless, differences in lipolysis in silage between cultivars of red clover were not correlated with PPO activity. [ABSTRACT FROM AUTHOR]

The effect of three spring management treatments on the vertical distribution of dry-matter (DM) yield and morphology of four cultivars of perennial ryegrass ( Fennema, Corbet, Foxtrot, Melle) in mid-season was investigated. The management treatments commenced with cuts on 15 February (Early), 1 March (Medium) and 29 March (Late), each followed by a 28-day re-growth period until the next cut and then further 21-day re-growth periods after each subsequent cut. This created four mid-season measurement periods across the management treatments at cut 3 (5 April–17 May), cut 5 (17 May–28 June), cut 6 (7 June–19 July) and cut 7 (28 June–9 August). Tiller and sheath height and their ratio, and leaf lamina length, were measured prior to the four mid-season cuts (cuts 3, 5, 6 and 7) when measurements of DM yield and proportions of leaf, stem and dead material in three herbage horizons (Lower, 0–8 cm; Middle, 8–15 cm; Upper, >15 cm) were made. There were significant responses in mid-season to the management treatments involved complex interactions between management treatment and cutting date, which modified seasonal patterns in DM yield and leaf:stem ratio. There were significantly greater tiller heights, tiller:sheath ratios and leaf lamina lengths but lower sheath heights from the Early to Late management treatments. The greatest responses in morphological characteristics occurred in the Middle horizon compared with either the Lower (predominately stem and pseudo-stem), or the Upper (predominately leafy) horizons. Distribution of DM yield between Middle and Lower horizons but not overall DM yields was significantly affected by management treatment. Morphological differences between cultivars were mostly in the Middle horizon and ranking of the cultivars was similar across the management treatments. The different responses of cultivars Fennema and Melle showed that genotype had a significant effect regardless of management. The leafiest mid-season swards were achieved by delaying initial spring defoliation in the cultivar which had the lowest stem production. [ABSTRACT FROM AUTHOR]

Thermogravimetry (TG) can be used for assessing the compositional differences in grasses that relate to dry matter digestibility (DMD) determined by pepsin–cellulase assay. This investigation developed regression models for predicting DMD of herbage grass during one growing season using TG results. The calibration samples were obtained from a field trial of eight cultivars and two breeding lines. The harvested materials from five cuts were analysed by TG to identify differences in the combustion patterns within the range of 30–600°C. The discrete results including weight loss, peak height, area, temperature, widths and residue of three decomposition peaks were regressed against the measured DMD values of the calibration samples. Similarly, continuous weight loss results of the same samples were also utilised to generate DMD models. The r2 for validation of the discrete and the best continuous models were 0.90 and 0.95, respectively, and the two calibrations were validated using independent samples from 24 plots from a trial carried out in 2004. The standard error for prediction of the 24 samples by the discrete model (4.14%) was higher than that by the continuous model (2.98%). This study has shown that DMD of grass could be predicted from the TG results. The benefit of thermal analysis is the ability to detect and show changes in composition of cell wall fractions of grasses during different cuts in a year. [ABSTRACT FROM AUTHOR]

Perennial ryegrass ( Lolium perenne L.) is one of the most valuable temperate pasture grasses in the world. Understanding seed germination in response to temperature can help determine its optimal seeding times. Germination tests for two cultivars of perennial ryegrass (cv. ‘Turfstar’ and cv. ‘Transtar’) were conducted by applying thirty-six constant and alternating temperature regimes, ranging from 5 to 40°C (16 h night/8 h day). Responses in germination rate to these temperature regimes were then used to construct a quadratic response surface, giving estimated germination rates with confidence intervals at P ≤ 0·05 for both cultivars. Optimum germination rate occurred over a range of regimes: 15/25, 20/25, 20/30 and 25/30°C. Furthermore, a wide range in diurnal alternating temperatures resulted in maximum seed germination rate for cv. ‘Transtar’, while no constant temperature regime supported maximum germination rate for cv. ‘Turfstar’. A temperature-dependent germination rate function for perennial ryegrass was developed which could be used in the future to predict location-specific optimum seeding times when national or regional monthly temperature data are available. [ABSTRACT FROM AUTHOR]

This experiment quantified the effects of: (i) heading date of perennial ryegrass, (ii) grazing frequency in spring and (iii) date of silage harvest, on the ensilability of herbages harvested for silage, and on the conservation and estimated nutritive value of the resultant silages. Replicated field plots with two perennial ryegrass mixtures (intermediate- and late-heading cultivars) were subjected to three spring-grazing regimes (no grazing, grazing in late March and grazing in both late March and late April) and were harvested on four first-cut harvest dates between 20 May and 21 June. Herbage from each of the four replicates of these 24 treatments was precision-chopped and ensiled unwilted and with no additive in laboratory silos. Herbage from the sward with the intermediate-heading cultivar had a higher ( P < 0·001) dry-matter (DM) content and buffering capacity than that from the late-heading cultivar, whereas water-soluble carbohydrate concentrations increased ( P < 0·001) with more frequent grazing in spring. Later harvesting enhanced herbage ensilability through an increased ( P < 0·001) DM content and reduced ( P < 0·001) buffering capacity and pH. Fermentation profiles of the silage were not markedly influenced by the cultivar mixture used but grazing in both late March and late April resulted in a more extensive fermentation with the acids produced increasingly dominated by lactic acid. The concentrations of acetic acid, and to a lesser extent, ethanol declined as silage harvest date was delayed. Overall, the relative effects of grass cultivar mixture were smaller than those of spring-grazing treatment or silage-harvesting date although on any given harvest date the herbage from the intermediate-heading cultivar mixture was easier to preserve as silage than herbage from the late-heading cultivar mixture. Delaying the harvesting of the late-heading swards by 8 d removed the differences related to growth stage in buffering capacity, pH and DM content. [ABSTRACT FROM AUTHOR]

Crown rust is an economically devastating disease of perennial ryegrass. Both artificial crown rust inoculations, with the possibility of several selection cycles in one year, as well as marker-assisted selection can be used for more efficient breeding of new resistant cultivars. The objective of this study was to map quantitative trait loci (QTL) for response to crown rust infection in perennial ryegrass. In order to identify relevant markers for response to crown rust infection, QTL mapping was performed on a ryegrass mapping population which was evaluated for resistance in the field for two years as well as by artificial pathogen inoculations using a detached leaf assessment. The broad sense heritability values for the field, detached leaf and combined assays were 0.42, 0.56, and 0.64, respectively, indicating a good potential for selection for crown rust resistance. A total of six QTLs were identified and mapped to linkage groups (LG) LG1, LG4 and LG5, explaining between 6.8% and 16.4% of the total phenotypic variation. [ABSTRACT FROM AUTHOR]

Systematic performance trials have been conducted in several states for more than 20 yr to evaluate agronomic performance of annual rye- grass (Lolium multiflorum Lam.). Despite development and testing of many annual ryegrass cultivars, the first improved cultivar, Gulf, has remained one of 10 to 12 cultivars recommended for planting in the southeastern USA. Our objectives were to evaluate cultivar yield performance across 12 yr at five locations, to assess cultivar yield distribution within growing seasons, and to estimate cultivar yield stability (consistency of relative performance environments). Efficacy measures were early-season yield (total before 1 March), late-season yield (total after 1 March), and total annual yield. Overall means for all cultivars and individual cultivar performance (for common years) were compared with Gulf or Marshall. Neither location effects nor cultivar × location interactions were found. Cultivar and year effects, plus cultivar × year interactions were detected (P < 0.05) for all three yield responses. Mean early season yields ranged from 2.3 to 4.6 Mg ha-1, with mean late-season yields ranging from 5.1 to 7.4 Mg ha-1. No trend existed for mean total yield relative to Gulf or Marshall to increase over time in association with availability of newer cultivars. Given large yearly fluctuation in yields, it is apparent that unpredictable environmental factors, including climate and perhaps pests, are the primary determinants of annual ryegrass performance rather than differences in yield potential among cultivars. Thus, yield stability may be an appropriate selection factor to include among the criteria for development of improved annual ryegrass cultivars. [ABSTRACT FROM AUTHOR]

Four perennial ryegrass ( Lolium perenne L.) cultivars were compared for differences in herbage production, nutritive value and herbage intake of dry matter (DM) during the summers of 2002 and 2003. Two paddocks were sown with pure stands of four cultivars in a randomized block design with three replicates. Each plot was subdivided into fourteen subplots (22 m × 6 m) which were grazed by one cow during 24 h. Twelve lactating dairy cows were assigned to one cultivar for a period of 2 weeks in a 4 × 4 Latin square experimental design; the experiment lasted 8 weeks in each year. Sward structure (sward surface height, DM yield, green leaf mass, bulk density and tiller density) and morphological characteristics were measured. The ash, neutral-detergent fibre, acid-detergent lignin, crude protein and water-soluble carbohydrate concentrations, and in vitro digestibility of the herbage were measured. The sward was also examined for infestation by crown rust ( Puccinia coronata f. sp. lolii). Herbage intake of dairy cows was estimated using the n-alkane technique. Cultivar differences for all sward structural characteristics were found except for bulk density and tiller density in 2003. Cultivars differed for proportions of pseudostem, stem (in 2003 only) and dead material. The chemical composition of the herbage was different among cultivars, with the water-soluble carbohydrate concentration showing large variation (>0·35). Cultivars differed in susceptibility to crown rust. Herbage intake differed among cultivars in 2002 (>2 kg DM) but not in 2003. Herbage intake was positively associated with sward height, DM yield and green leaf mass. Canopy morphology did not affect herbage intake. Crown rust affected herbage intake negatively. It was concluded that options for breeders to select for higher intake were limited. High-yielding cultivars and cultivars highly resistant to crown rust were positively related with a high herbage intake. [ABSTRACT FROM AUTHOR]

The relative contribution of tillers present in April and those appearing in consecutive periods in spring was assessed for perennial ryegrass cultivars in the three maturity groups (early, intermediate- and late-heading). Each group was represented by two diploid and one tetraploid cultivar each in plots in their third (2000) and fourth (2001) harvest years in three replicated blocks receiving an average of 325 kg N ha−1 and cut seven (in 2001) or eight (in 2000) times annually.‘Main’ tillers and their daughters were marked with colour-coded PVC-covered wire loops in early April as were daughters which appeared in consecutive periods between harvests, the loop colour identifying the period of origin of the tiller. Tillers were harvested at cutting height (5 cm) before the plots were harvested and the herbage from tillers with the same colour code bulked per plot. Tillers were identified retrospectively as‘reproductive’ if they had been decapitated at the previous harvest. Dry-matter yield was higher in the early than late-heading cultivars in April and early May but this was reversed in harvests in late May and June. The early heading group had a lower lamina content than the late-heading group during reproduction growth, both due to the reproductive tillers (mainly those which overwintered) having a lower leaf content and to their being fewer and smaller vegetative tillers during the reproductive phase than for the late-heading group. Turnover of tillers was high in spring due to decapitation of reproductive tillers and rapid post-flowering tillering. This was particularly pronounced in the early heading group which also had slightly more tillers marked in April which were subsequently decapitated than in the other maturity groups, i.e. 0·56 compared with 0·44 for the late-maturing group. Mean ratios of rate of death: rate of tillering for 3 years (1999–2001) for the early and late-heading groups were 0·8 and 0·4, respectively, for April–May and 1·1 and 2·4, respectively, for June indicating the different patterns in tiller turnover for the two extreme maturity groups. Information on tiller origin and contribution to yield can be used to refine tiller-based grass growth models. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenneL.) is the most important grass species for temperate grassland agriculture. The genetic relationship and distance among cultivars is largely unknown but of great interest for breeding programmes. The objectives of this study were to (i) investigate the molecular variation and structure of population cultivars, (ii) describe the relationship among cultivars in terms of the modified Rogers’ distance, and (iii) determine the minimum sample size required for characterization of cultivars ofL. perenneusing random amplified polymorphic DNA (RAPD) markers. A total of 22 ryegrass cultivars, mainly of European origin, were investigated with RAPD markers. The minimum sample size required for the characterization of cultivars was about 20 individuals per population. An analysis of molecular variance (amova) revealed a much larger genetic variation within cultivars (66%) than between them (34%). [ABSTRACT FROM AUTHOR]

Molecular diversity and genetic affinity in the Lolium/ Festuca grass complex have been assessed using simple sequence repeat (SSR) marker technology. The genotypic set was derived from three accessions of perennial ryegrass, two cultivars of Italian ryegrass, two cultivars of meadow fescue, two cultivars of tall fescue and 10 accessions from different intergeneric hybrid ( Festulolium) combinations. The majority of the genomic DNA-derived SSR primer pairs from perennial ryegrass (LPSSR) and Italian ryegrass (LMSSR) produced clear, simple and distinctive amplification products from the majority of the genotypes. The efficiency of cross-specific amplification for LPSSR markers varied from 38% in meadow fescue to 93% in two cultivars of Festulolium and from 57% in meadow fescue to 87% in Italian ryegrass for LMSSR markers. Of 40 amplified markers, 14 (35%) produced species-difference alleles in the relation to cultivars used in the present study. Thirty-five LPSSR locus-derived alleles were found to be specific to Lolium species, four to meadow fescue and six to tall fescue. For LMSSR alleles, eight were specific to Lolium species and five were only associated with Italian ryegrass, and null alleles were detected for meadow fescue in all instances. These species-difference markers could clearly identify different accessions of Festulolium. Cluster analysis separated the individual taxa and showed grouping of intergeneric hybrids based on genomic composition. The data distinguished between the species and reflected the known pedigree of the cultivars and the differences between the species. The dendrogram also distinguished between the Festulolium accessions and clearly demonstrated the relations between Festulolium hybrids and their parent species. [ABSTRACT FROM AUTHOR]

Annual ryegrass ( Lolium multiflorum Lam.) is a primary forage resource for livestock producers throughout the south-eastern USA during the winter-growing season. It is important for livestock producers to begin grazing annual ryegrass as early as possible and any management practices maximizing early season production could be beneficial. To assess the impact of seeding rate on subsequent yield, yield distribution, quality, seedling density, and end-of-season plant and tiller density, a 2-year study was initiated at four locations in Louisiana. Three annual ryegrass cultivars, varying in seed size, were established at four seeding rates based on pure live seed (PLS) rates of 400, 800, 1200 and 1600 PLS m−2. There was no advantage in total yield from increasing seeding rates beyond 800 PLS m−2. However, first-harvest yields increased from 360 to 930 kg dry matter (DM) ha−1 as seeding rate increased from 400 to 1600 PLS m−2. Crude protein and neutral-detergent fibre concentrations, and in vitro DM digestibility, were not affected by seeding rate. Seedling density and end-of-season plant numbers increased as seeding rate increased. However, stems per plant decreased as seeding rate increased, indicating compensatory tillering for the reduced plant numbers observed at the lower seeding rates. These results indicate first-harvest yield can be increased by planting at higher seeding rates but total yields are not increased. [ABSTRACT FROM AUTHOR]

Abstract Annual ryegrass (Lolium multiflorum Lam.) is grown on more than one million ha in the south-eastern USA each year. Recommended and actual seeding rates vary substantially within the region. The objective of this study was to evaluate variation in seed weight, germination, seedling vigour and seasonal yield performance among annual ryegrass cultivars. During 1997, 1998 and 1999, seed from fourteen commercial cultivars was weighed and germinated to determine numbers of pure live seed (PLS) m-2 before yield evaluation at four locations. Seed from ten cultivars was planted at 0·7 and 2·0 cm depth in a greenhouse study to evaluate relative seedling vigour. Cultivar mean single-seed weight ranged from 2·4 to 4·8 mg in 1997, 1·8 to 4·5 mg in 1998, and 2·6 to 4·6 mg in 1999. Seed germination ranged from 78·8% to 98·0% in 1997, 82·3 to 98·3% in 1998 and 77·8 to 98·3% in 1999. Seed number, PLS m-2 , ranged from 675 to 1289 in 1997, 710 to 1550 in 1998, and 717 to 1179 in 1999. Among the ten cultivars evaluated for seedling vigour, seedling weight differed between planting depths and a significant cultivar by year interaction was observed. Seedling weight was highly correlated with seed weight at each seeding depth. The effect of increasing number of PLS m-2 on subsequent yield performance, although small, was consistently negative. These results indicate that target plant populations may be obtained more economically by adjusting seeding rates for seed size differences among cultivars and seed lots of annual ryegrass. [ABSTRACT FROM AUTHOR]

Differences among annual ryegrass (Lolium multiflorum Lam.) cultivars for weight gain of grazing steers have been reported, even though plot experiments suggest that forage dry matter yield among cultivars should not be a limiting factor. Likewise, forage nutritive value differences among cultivars have not been assessed. The objectives of this research were to evaluate differences in cumulative forage yield, yield distribution, and nutritive value among 'Gulf', 'Jackson', 'Marshall', 'Rio', 'Rustmaster', and 'Surrey' annual ryegrass. Plots were harvested six times beginning in December at approximate 30-d intervals during the 1997-1998 and 1998-1999 growing seasons. Nutritive value measurements included crude protein (CP), neutral detergent fiber (NDF), in vitro true digestibility (IVTD), and digestible NDF (DNDF). There were no differences among cultivars for cumulative forage yield (P = 0.99). However, for the January harvest, Surrey and Gulf averaged 1030 (±65) kg DM ha[sup -1], whereas Marshall yielded only 672 (±79) kg DM ha[sup -1]. For the March harvest, yields of all varieties were similar and averaged 1350 (±95) kg DM ha[sup -1]. At the May harvest, Marshall and Jackson yielded 1232 (±123) kg DM ha[sup -1], whereas Gulf yielded only 929 (±74) kg DM ha[sup -1]. Crude protein concentration differed significantly among harvests with a general decrease from 260 to 120 g CP kg[sup -1] as the growing season progressed. Similar declines in nutritive value occurred for NDF, IVTD, and DNDF. Trends in yield distribution and forage quality may indicate a need for cultivar specific recommendations based on intended forage need and season of use. [ABSTRACT FROM AUTHOR]

Determines the changes of seedling root fluorescence expression in perennial ryegrass in Italy. Characteristics of ryegrass cultivar genetic purity; Identification of the fluorescence levels of cultivars; Detection of physical and genetic contamination of ryegrass.

Presents information on registered crop cultivars. Includes the Gregory peanut; Apache II tall fescue; Bandana tall fescue; Coronado Gold tall fescue; Seabreeze slender creeping red fescue; Tiffany Chewing's fescue; Sonata perennial ryegrass; Discovery hard fescue; Hiller wheat.

Sample sub-populations, each of six plants, were chosen for high, mid and low tolerance of copper from each of two naturally-occurring copper tolerant populations and from tolerant individuals selected from a cultivar of Agrostis capillaris L. The naturally-occurring ecotypes came from a closed sward community at Drws y Coed, and from an open community at Parys Mountain, both copper mines in North Wales. Clonal replicates of all plants were introduced into swards of perennial ryegrass cvs. S23 or S24, growing on normal soil at the University of Liverpool Botanic Gardens. S23 plots were cut eight times between June 1977 and July 1978, whilst S24 plots were cut 3 times during the same period. Half the experimental plots received N, P, K, fertilizer; the rest received none. Plants selected from the cultivar (selected) produced most dry matter, and with infrequent defoliation flowered freely in competition with ryegrass. Those taken from Parys Mountain mine spoil produced least dry matter and no inflorescences. Drws y Coed plants were intermediate in dry matter and inflorescence production. These results may reflect differences in population density in the habitats from which the populations were sampled. Sub-populations chosen for high, mid or low copper tolerance within the selected and Drws y Coed populations did not differ significantly in dry matter yield. By contrast under certain circumstances Parys Mountain plants with low tolerance outyielded other more tolerant plants. These results are considered with respect to growth strategies adopted by plants growing on and off copper mine sites. [ABSTRACT FROM AUTHOR]

In order to study the effects of competition on the genotypic composition of chance-hybrids in Lolium multiflorum, eight chance-hybrids were produced according to Burton (1948). inbred lines and cultivars were used as parents. The proportions of parental and hybrid components in the seeds and growing-field stands of the chance-hybrids were determined over three cuts using gel electrophoresis The realized hybrid proportions in the seeds, at a maximum of 38.3%, were considerably lower than the theoretically expected 50%. In the field stands, the hybrid proportions of the chance-hybrids derived from inbred lines increased considerably and continously over cuts, whereas those of the chance-hybrids produced from cultivars increased only slightly. A maximum hybrid tiller proportion of 76.8% was found at the third cut. Correspondingly. the total yield of the chance-hybrids produced from cultivars was only slightly higher than that of the parents The production of chance-hybrids, therefore, proved to be sensible only if inbred lines had been used as parents. [ABSTRACT FROM AUTHOR]

Fifty-three genotypes of perennial ryegrass selected from a range of cultivars and ecotypes were evaluated for their reaction to crown rust isolates collected from Western Australia, Victoria, Queensland, South Australia or New South Wales in Australia. The reactions of the clones to inoculation provided evidence for the development of a differential set of perennial ryegrass genotypes, but also demonstrated that a large number of genotypes displayed universal reactions to infection with any of the crown rust isolates. [ABSTRACT FROM AUTHOR]

The incorporation of new sophisticated phenotyping technologies within a crop improvement program allows for a plant breeding strategy that can include selections for major root traits previously inaccessible due to the challenges in their phenotype assessment. High‐throughput precision phenotyping technology is employed to evaluate root ontogeny and progressive changes to root architecture of both novel amphiploid and introgression lines of Festulolium over four consecutive months of the growing season and these compared under the same time frame to that of closely related perennial ryegrass (L. perenne) varieties. Root imaging using conventional photography and assembled multiple merged images was used to compare frequencies in root number, their distribution within 0–20 and 20–40 cm depths within soil columns, and progressive changes over time. The Festulolium hybrids had more extensive root systems in comparison with L. perenne, and this was especially evident at depth. It was shown that the acquisition of extensive root systems in Festulolium hybrids was not dependent on the presence of an entire Festuca genome. On the contrary, the most pronounced effect on root development within the four Festulolium populations studied was observed in the introgression line Bx509, where a single small genome sequence from F. arundinacea had been previously transferred onto its homoeologous site on the long arm of chromosome 3 of an otherwise complete L. perenne genome. This demonstrates that a targeted introgression‐breeding approach may be sufficient to confer a significant improvement in the root morphology in Lolium without a significant compromise to its genome integrity. The forage production of Bx509 was either higher (months 1–3) or equivalent to (month 4) that of its L. perenne parent control demonstrating that the enhanced root development achieved by the introgression line was without compromise to its agronomic performance. The manuscript describes the use of precision image capture technologies to measure root ontogeny of four diverse Festulolium populations and relevant perennial ryegrass controls. It describes changes over a 4‐month period of the growing season and root development at two soil depths. The paper relates changes in root design in terms of benefits to ecosystem services and to combat climate change. [ABSTRACT FROM AUTHOR]

The article presents a discussion on the influence of cultivar and cutting date on the fatty acid composition of perennial ryegrass. Some correct versions of experimental tables are given which shows effects of period and cultivar on dry matter content, fat concentration and proportions of fatty acids in total fat in fresh herbage of six perennial ryegrass cultivars during the sampling period of the growing season of 2000.

Features the U.S. registration of the cultivar 'Shiwasuaoba' annual ryegrass, Lolium multiflorum. Research leading to the development of Shiwasuaoba; Developers of the cultivar; Breeding program; Resistance to crown crust; Possession of several B-chromosomes.

Offers information on the registration of the cultivar Secretariat Kentucky ryegrass with the agricultrual authorities in Washington. Developer of the plant variety; Plant structure and appearance; Average annual seed yield.

Reports on the registration of the cultivar Jumbo tetraploid annual ryegrass, with the U.S. Department of Agriculture. Origins of the cultivar; Development of the breed; Average grain yield.