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Cytochrome P450s (CYPs) play crucial roles in regulating plant growth, development, and stress tolerance. In this study, a perennial ryegrass (Lolium perenne) CYP gene, LpCYP72A15, was identified as a candidate gene regulating plant osmotic stress tolerance based on a cDNA library screening in the background of yeast ∆hog1 mutant. LpCYP72A15 is localized in the plastids, and its expression was regulated by osmotic stress and ABA treatment. Overexpressing LpCYP72A15 significantly enhanced plant drought tolerance in both Arabidopsis and perennial ryegrass. Under drought stress, the transgenic ryegrass showed significant lower reactive oxygen species (ROS) levels, higher ROS‐scavenging enzymatic activities, and higher soluble sugar contents than the wildtype plants. Transient over‐expressing the gene also enhanced survival rates of ryegrass mesophyll protoplasts under H2O2‐induced oxidative or mannitol‐enforced osmotic stresses. Taken together, LpCYP72A15 confers oxidative‐ and osmotic‐stress tolerances that positively regulates plant drought tolerance in perennial ryegrass. [ABSTRACT FROM AUTHOR]

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]

We describe an experiment where cattle urine was applied at a rate of 420 kg N ha−1, equivalent to 10 L m−2, to mesocosm swards of a high lipid genetically modified perennial ryegrass line (HME) and its wild type (WT). We measured N pools and fluxes in the plant and soil, soil microbial populations and N2O production. HME plants produced 21% greater biomass than WT (p =.02), resulting in greater N uptake (27% higher in HME, p =.05). Urine N recovery in total plant biomass during the experiment in HME and WT swards were 54.7% and 33.9% respectively. The nitrification potential of soil was significantly lower (p =.01) in HME than WT. Partial least square‐discriminant analysis using microbial gene abundance data indicated that HME and WT plant growth induced distinct microbial populations in the soil. These differences in plant soil microbial interactions between HME and WT swards resulted in significantly lower N2O emissions from the HME sward. Total N2O emissions over the 4 weeks after urine application was 38% lower (p <.03) in HME swards than in WT swards. The next step in this work is to identify the specific changes in HME traits that drive the reduction in N2O. [ABSTRACT FROM AUTHOR]

Multispecies swards, comprised of different plant functional groups have comparable production potential to high N input L. perenne swards at reduced N when legumes are included. However, information on the appropriate management of multispecies swards is limited. The effect of differing management practices on the herbage dry‐matter (DM) production and botanical composition of different sward types was investigated using a 3 × 2 × 2 factorial design plot experiment. The experiment consisted of three sward types: L. perenne‐only receiving (LP; 250 kg N ha−1 a−1); L. perenne‐Trifolium repens (LP‐TR); multispecies sward containing L. perenne, Phleum pratense, Trifolium repens, Trifolium pratense, Plantago lanceolata and Cichorium intybus (MSS). LP‐TR and MSS received 90 kg N ha−1 a−1. Harvesting of plot herbage took place every 21 or 28 days to a defoliation height of 4 or 6 cm, over two growing seasons (March to November 2020 and 2021 inclusive). Annual herbage produced by both LP and LP‐TR was not significantly affected by defoliation frequency. However, MSS produced 1923 kg DM ha−1 a−1 more herbage when harvested less frequently. Unsown species contributed significantly less to the herbage DM of MSS compared to LP and LP‐TR and remained similar in 2020 and 2021, whereas the contribution of unsown species to herbage DM increased in LP and LP‐TR from 2020 to 2021, with noxious species more associated with LP and LP‐TR than MSS. Results demonstrate the role of multispecies swards in improving the sustainability of grass‐based agricultural systems in an environment of reduced fertilizer inputs. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne) plant breeding has delivered several high performing and broadly adapted cultivar‐endophyte (Epichloë) combinations for the New Zealand pasture‐based livestock industries. However, the trends in key traits and the potential economic value being added to farm systems have not previously been addressed systematically. Rates of gain in yield, nutritive value, phenological and morphological traits, and the economic value of those traits, were estimated among and within ryegrass functional groups (heading date, ploidy) traded commercially between 1973 and 2012. Whole pasture dry matter yield improvements of c. 80 and 60 kg DM/ha per year were identified in in late‐season heading diploids and tetraploids respectively. Trends in metabolisable energy were negative within functional groups, but positive when all cultivar‐endophyte combinations were included in the analysis due to the addition of tetraploids and late‐season heading diploids from the mid‐1990s. The estimated trend in overall economic value (all cultivar‐endophyte combinations included) was $7/ha per year based on DM yield only, about half the rate of gain previously estimated using small‐plot merit testing data. The trend increased to $15/ha per year when ME was included due to the emergence of commercial tetraploids from the early 2000s onwards. Estimated economic gains were high within late‐season heading diploids and tetraploids but not mid‐season diploids. These trends suggest that, if high performing cultivar‐endophyte combinations had been adopted in New Zealand dairy systems, then pasture utilization should have increased by ~1 t DM/ha above the current industry average. Reasons for this apparent discrepancy are discussed. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (PRG, Lolium perenne L.) breeding effort in New Zealand (NZ) has increased since c. 1990, resulting in greater functional trait diversity (e.g. heading date, ploidy, and associated Epichloë endophyte strain) in commercial products. This study quantified the variation, associations and interactions in dry matter (DM) yield, nutritive value and persistence‐related traits among commercial cultivar‐endophyte combinations released between 1973 and 2012, as a basis for assessing gains in value being delivered to the pasture‐based livestock industries. Twenty‐four or 28 combinations were compared over 3 years in two trials in each of two regions: Waikato in northern NZ (dryland), and Canterbury in central eastern South Island (irrigated). Cultivar‐endophyte combinations were sown in mixtures with white clover, and pastures were intensively grazed 8–11 times per year by dairy cows. Principal Component Analysis identified 4 distinct clusters for the DM yield variables and for metabolisable energy (ME) content in each of the four trials. A broadly‐adapted group of three late‐season flowering, AR37‐infected diploids with NZ and Spanish breeding backgrounds dominated the highest‐yielding clusters. Tetraploids dominated the high ME content clusters. Interactions with region were observed throughout the data set: the strongest of these was driven by endophyte strain effects in Waikato. High‐yielding cultivar‐endophyte combinations in these trials were also generally high‐yielding in the standard cultivar merit testing system operated in New Zealand, as interpreted via the DairyNZ Forage Value Index. However, alignment was poorer for medium‐ and lower‐yielding cultivar‐endophyte combinations. Several implications for forage evaluation methods and end‐user industries are identified. [ABSTRACT FROM AUTHOR]

In the dairy region of northern Victoria, Australia, the performance of temperate perennial dairy pastures is often poor over summer due to a combination of high temperatures and limited water availability that can restrict dry matter production and plant survival. This review summarizes published and unpublished research on perennial ryegrass, mostly undertaken in the northern Victoria region over the past decade, to help determine its future role in this environment. It includes information from a series of field experiments or case studies where the effects of heat and restricted irrigation on the growth and nutritive characteristics of perennial ryegrass were examined. This research involved investigations on whether plant survival under the stressed experimental conditions could be influenced by plant genotype, irrigation, and grazing management strategies, as well as by the presence of endophyte. In conclusion, it was difficult to identify any irrigation, grazing management or plant genotype effect that consistently improved the performance of perennial ryegrass in the hot, dry summers of northern Victoria, Australia. The incidences of extreme heat events and low water availability in this region are increasing, and the role of C3 perennial grasses as major suppliers of feed for dairy cows is diminishing. A major focus for the dairy industry in this region is now to identify new farming systems and alternative species that may be better adapted to the climate environment than perennial ryegrass, as well as be capable of adapting to year‐to‐year variations in irrigation water supply. [ABSTRACT FROM AUTHOR]

As the earth's climate changes, the ability of breeders to select for traits within forage species that impart adaptability to these changes will be critical for the maintenance of grassland agricultural systems. Temperate ‐ tropical climate transition zones (between 27 and 31° N and S latitude) have proven to be ideal zones for breeding species with variable climate adaptation. Programs located in these regions have the advantage of exposure to alternating extreme warm and cold temperatures, drought and flood conditions, and a multitude of biotic pests including fungi, viruses, insects and nematodes. In this paper we will present examples of how forage breeding programs in north‐central Florida have capitalized on these distinct advantages for selection of cultivars with resiliency to changing climate variables. Breeding programs in red clover (Trifolium pratense L.) and annual ryegrass (Lolium multiflorum Lam.) will be discussed as examples for moving cool season species into warmer climates. Species attributes that contribute to climate resiliency will be identified and described. The ability to identify small changes in genetic photoperiod responses in these regions, are illustrated as an advantage when the objective is development of earlier or later maturity. Transition zones also provide suitable environments for biotic stresses, from both tropical and temperate areas, including fungal diseases, nematodes, and insects, offering desirable field environments for screening and genetic improvement. [ABSTRACT FROM AUTHOR]

Autumn closing date (CD) in intensive pasture‐based systems influences spring herbage availability. Little is known about the impact of earlier closing of swards in autumn on sward structure. A two‐year experiment was undertaken to investigate the impact of five CD on herbage production, leaf extension rate (LER), leaf senescence rates (LSR), sward free leaf lamina (FLL) content and the production and survival of tillers over winter and into spring. The five CD ranges were October 1–15 (CD1), October 16–30 (CD2), October 31––November 14 (CD3), November 15–29 (CD4), November 30–December 14 (CD5) and sward measurements were made on four measurement dates (MD): December 11 (MD1), January 6 (MD2), January 27 (MD3) and prior to spring defoliation (MD4). Thirty perennial ryegrass tillers were measured until the first defoliation in spring (average 1 March). Herbage mass was greatest in early CD and tillers had greater LER and LSR (4.6 and 4.5 mm tiller−1 day−1 respectively) compared to swards with a later CD (3.2 and 2.3 mm tiller−1 day−1 respectively). Early CD had greater parent and daughter tiller mortality than later CD (parent tiller mortality 1.1 and 0.3 ± 0.19 tillers; daughter tiller mortality 1.1 and 0.3 ± 0.27 tillers respectively). Early CD also had greater LER and LSR in daughter tillers (2.6 and 1.5 mm tiller−1 day−1, respectively) compared to late (1.5 and 0.5 mm tiller−1 day−1, respectively). Earlier closing of sward increased herbage mass in spring, however, there were negative implications, such as increased LSR and tiller mortality. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is considered the most important pasture species in temperate agriculture, with over six million hectares of sown area in Australia alone. However, perennial ryegrass has poor persistence in some environments because of low tolerance to a range of both abiotic and biotic stresses. To breed perennial ryegrass, cultivars with greater persistence and productivity may require evaluation of genotypes over a number of years. Persistence assessment in pasture breeding depends on manual ground cover estimation or counting the number of surviving plants or tillers in a known area. These methods are subjective and labour intensive, which may limit data collection in large‐scale breeding programs. With the rapid development of sensors and image processing algorithms, image‐based high‐throughput phenotyping (HTP) is becoming commonplace in the breeding of major food crops. Image‐based HTP approaches consist of the deployment of a wide range of sensors on ground‐based or airborne platforms and data analysed through image processing pipelines. Image‐based HTP shows high potential for use in pasture phenotyping in breeding programs and may be able to reduce timeframes for releasing new cultivars. Moreover, existing image‐based HTP approaches could be further developed to include precise tools for phenotyping pasture persistence traits such as pasture senescence, botanical composition, pathogen and pest resistance. In this study, we reviewed existing image‐based HTP approaches in precision agriculture and discussed their feasibility for perennial ryegrass persistence estimation in pasture breeding. Although the paper focuses on application in perennial ryegrass, the principles equally apply to other perennial forage species. [ABSTRACT FROM AUTHOR]

We evaluated Italian ryegrass (Lolium multiflorum Lam.) establishment in a factorial of grazing intensity (intense, moderate, moderate‐light, light, and no grazing, with target average sward heights of 10, 20, 30, and 40 cm in the grazed plots) and additional seeding (self‐seeding with or without additional seeding) in an integrated soybean‐beef cattle system in southern Brazil. Grazing treatments were imposed in winter (June–July) and followed by a direct‐seeded soybean crop (November). The establishment was quantified prior to the stocking periods in 2017 and 2018, corresponding to self‐seeding from 2016 and 2017. Intense grazing impaired ryegrass re‐establishment, resulting in larger individual plants (0.54 vs. 0.15 g dry matter plant−1) but lower population density (57 vs. 1,355 plants m−2) than in the other treatments. Additional broadcast ryegrass seeding did not fully compensate for the reduced natural reseeding in this treatment. The addition of seeds under intense grazing increased plant population density to values comparable to moderate grazing intensities but reduced individual plant mass, limiting herbage mass attained by the end of the pasture establishment phase. Contrastingly, the various combinations of individual plant mass and population density were sufficient to maintain herbage masses in moderate to light grazing intensities that were comparable to that in the ungrazed treatment, regardless of seed addition (63 vs. 180 g DM m−2 for intense grazing vs. the average of other treatments over the whole establishment phase). Moderate grazing, e.g., target sward heights of 20 cm or greater, is necessary to achieve a system that can sustain itself without seed addition. [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]

The objective of this study was to compare the grazing efficiency of 30 perennial ryegrass varieties, differing in ploidy and heading date. Plots were grazed by lactating dairy cows and managed under a rotational grazing system with 19 grazing events occurring over two years. Pre‐grazing and post‐grazing compressed sward heights were measured with a rising plate meter. A mixed model was used to predict the post‐grazing sward height of each variety based on year, grazing event, block and pre‐grazing sward height. Residual grazed height (RGH) was derived as the difference between the actual and predicted post‐grazing sward height and was used as the measure of grazing efficiency. Negative RGH values indicated that the actual herbage removed was greater than that predicted and so indicated a superior grazing efficiency. Varieties differed in their level of grazing efficiency (p <.001), with RGH values ranging from −0.38 to +0.34 cm. Tetraploid varieties exhibited significantly greater grazing efficiency performance than diploids (p <.001), with average RGH values of −0.13 and +0.13 cm respectively. A significant difference in grazing efficiency was found among recommended perennial ryegrass varieties that are not being recorded by mechanically harvested simulated grazing protocols. A variety reappraisal that included grazing efficiency could identify varieties capable of improving on‐farm livestock productivity from grass. [ABSTRACT FROM AUTHOR]

Field indicators of forage nutritive value could help farmers with rapid management decisions to optimize timing and intensity of grazing and meet objectives regarding animal nutrition. The objective of this research was to evaluate the likely relationships among leaf blade nutritive value, herbage mass and leaf stage of pasture regrowth under different growing seasons and residual sward heights. Experiments were performed on perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea Schreb.) pastures during spring and summer of 2016. In both pastures, three residual sward height treatments (3, 6 and 12 cm) were imposed on plots arranged in a split plot design, replicated in three blocks. Sward plots were harvested 5–6 times at intervals spaced 7–10 days apart to measure herbage mass, plant morphology, neutral detergent fibre (NDF), and the 24‐hr in vitro digestibility of NDF (NDFD) and dry matter (DMD) of leaf blades. Pastures showed strong (R2:.62 to.70), but variable, negative relationships between NDFD and herbage mass that varied with the rate at which pasture grew in each season of experimentation. Although there was a consistent NDFD decline as leaf stage of regrowth progressed (R2:.75 to.97), the NDFD also decreased as residual sward height increased, most notably in tall fescue. Additionally, findings indicate that the greater leaf length plasticity of tall fescue compared to residual sward heights may offer opportunities to manage both post‐ and pre‐grazing targets to achieve tall fescue forages with a similar high nutritive value as perennial ryegrass. However, the evaluation of this hypothesis at the farm level and its impacts on animal intake and performance warrants further careful investigations. [ABSTRACT FROM AUTHOR]

Limited persistence of perennial ryegrass (Lolium perenne L.) in dairy pastures is a significant issue in parts of New Zealand. The contribution of plant genetic background to this problem is not well understood. Temporal changes were investigated in genotypic and phenotypic composition of two perennial ryegrass cultivars (Nui SE and Alto AR37, older and newer cultivars respectively) sown as fields plots at three locations. Samples from survivor populations collected annually over 6 years from each location were established in a field nursery, analysed by simple sequence repeat (SSR) markers and assessed for vigour, leaf morphology and tiller number. SSR‐based estimates of the statistic G′ST indicated no significant (p >.05) genetic differentiation between survivor populations and plants grown from remnant seed (ex‐seed) after 5 years, and no significant change (p >.05) in within‐population genetic diversity for either cultivar at any location. SSR analysis of endophytic fungus (Epichloë festucae var. lolii) type revealed only limited ingress of off‐type ryegrass volunteers into plots at two locations. Vigour scores of survivor plants were not significantly (p >.05) different among plants collected from different locations and ex‐seed plants. Leaves on ex‐seed plants were longer (p <.001) than those on the survivor plants after four but not 6 years and may reflect a short‐term response to climatic conditions experienced in the field nursery. Our results suggest that the reported poor ryegrass persistence is not driven by changes in population genetic structure and that the sown cultivars survived and remained true to type. [ABSTRACT FROM AUTHOR]

Recent years have seen a decline in herbage production and tiller populations in New Zealand's perennial ryegrass (Lolium perenne) dairy pastures. One hypothesis is that modern genotypes are less suited to the warmer, drier weather experienced under changing climate patterns. In this study, a combination of long‐term trial data (2011–2017) and a process‐based pasture model (BASGRA) was used to explore the causes and possible mitigation of the observed production and population loss at three sites (dryland sites in Northland and Waikato and an irrigated site in Canterbury). Bayesian calibration was used to identify the model parameter sets that were consistent with the trial data and to identify differences in plant morphology and responses between sites. The model successfully simulated the observed differences in tiller numbers between the dryland sites, where populations and production declined rapidly after the second year and the irrigated site where populations and production were maintained. Analysis of the model calibrations along with preliminary scenario simulations suggests that increased tiller mortality associated with drought was the main cause of persistence failure at the dryland sites and that decreasing grazing pressure or breeding for tolerance to higher temperatures may not be successful in preventing this. [ABSTRACT FROM AUTHOR]

In perennial ryegrass breeding programmes, dry‐matter yield (DMY) of individual plots is monitored destructively at the different cuts or derived from non‐destructive canopy height measurements using devices like rising plate meters (RPM). These approaches both have constraints. Destructive sampling implies low temporal resolution, restraining the study of dry‐matter accumulation rates, while RPM measurements are influenced by the canopy structure and limit intra‐field variability identification. We present a phenotyping methodology, based on the use of an affordable RGB camera mounted on an unmanned aerial vehicle (UAV), to monitor the spatial and temporal evolution of canopy height and to estimate DMY. Weekly flights were carried out from April to October above a field comprising a diverse set of accessions. To test the capacity of UAV imagery to estimate canopy height, 8 ground control points and 28 artificial height references were placed at different locations. Accurate flights with an RMSE as low as 0.94 cm were achieved. In addition, canopy height was recorded using an RPM and destructive biomass samples were collected. Different models (linear, multiple linear, principal components, partial least squares regression and random forest) were used to predict DMY, and their performance was evaluated. The best estimations were obtained by combining variables including canopy height, vegetation indices and environmental data in a multiple linear regression (R2 = .81). All models built using UAV data obtained a lower RMSE than the one using RPM data. The approach presented is a possibility for breeders to incorporate new information in their selection process. [ABSTRACT FROM AUTHOR]

Dry matter (DM) production of multispecies swards compared to perennial ryegrass (Lolium perenne; PRG) swards under intensive grazing warrants investigation as it is relatively unknown. A 5 × 2 factorial experiment, with five sward types and two defoliation methods, was used to investigate the effect of grazing versus cutting on dry matter (DM) production of multispecies and PRG‐only swards. Five sward types were established namely: a PRG‐only sward, receiving 250 kg N ha−1 year−1 (PRG250), and a PRG‐only sward (PRG90), a two‐species sward with PRG and white clover (Trifolium repens; PRGWC), a six‐species sward (6S) and a nine‐species sward (9S), each receiving 90 kg N ha−1 year−1. Cutting plots measured 1.95 × 10 m and grazing plots measured 10 × 10 m. All plots were harvested concurrently every 21–30 days from April‐November for two years (2015 and 2016). A strip from the grazing plots was cut for DM yield determination prior to turning in cattle for grazing. There was an interaction between sward type and defoliation method (p < .01), whereby there was no effect of defoliation method on the PRG‐only swards, however, the annual DM production of PRGWC, 6S and 9S swards reduced under grazing compared to cutting (p < .001; on average 1,929 kg DM/ha lower). Multispecies swards had lower DM production under grazing compared to cutting, while the DM yield of PRG‐only swards was unaffected by defoliation method. [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]

Ryegrass (Lolium perenne L.) is a putative turf and forage plant characterized as mainly outcrossing in which the extent of self‐fertilization and its consequences has not been investigated. In this study, selfed and half‐sib family seeds were obtained from ten clonally propagated ryegrass plants among which two were endophyte‐free (EF) and eight were endophyte‐infected (EI). Then, 20 seed populations plus two commercial varieties of Speedy and Vigor were sown and evaluated in a biennial experiment for their turf and forage characteristics. Selfing caused significant inbreeding depression for plant fresh and dry weight and leaf length and width in the first year for both EI and EF genotypes. In the second year, only leaf length remained depressed among these characters. Also, for the most growth, turf and reproductive traits, EI populations showed less depression. The presence of endophyte in self‐pollinated populations made an increasing effect for the number of seed per spike and days to heading, although seed weight was reduced. Some of the populations derived from self‐pollination and infected with fungal endophyte including S9 and S10 were even superior to the two commercial varieties in terms of both seed production and turf characteristics. However, for seed‐related characteristics including number of spikes per plant, seed weight and seed yield, EF populations including Speedy and Vigor were more reproductive than EI populations. It is concluded that selfing may increase the discrimination between EI and EF ryegrass plants because endophyte infection may mitigate the negative consequences of inbreeding depression in prone populations. [ABSTRACT FROM AUTHOR]

The objective was to evaluate water‐soluble carbohydrate (WSC) and crude protein (CP) concentration of perennial ryegrass (PRG) cultivars with different genetic potential for producing WSC under two contrasting agronomic managements in temperate climate (southern Chile). A 4 × 2 factorial design was randomly allocated to 24 plots (31 m2 each, three blocks): four PRG cultivars (diploid standard cultivar, "2nSt"; tetraploid standard cultivar, "4nSt"; diploid high sugar cultivar developed in New Zealand, "2nHSNZ"; and tetraploid high sugar cultivar developed in Europe, "4nHSEU") and two agronomic managements ("favourable," defoliations at three leaves per tiller and nitrogen (N) fertilization rate of 83.3 kg N ha−1 year−1; "unfavourable," defoliations at two leaves per tiller and N fertilization rate of 250 kg N ha−1 year−1). Herbage samples were collected in early spring, spring, summer and autumn. Concentration of WSC did not differ among cultivars in spring and summer, averaging 194 and 251 g/kg DM, respectively. The cultivar 4nHSEU had the greatest WSC concentration in early spring and autumn (187 and 266 g/kg DM, respectively) and the greatest CP concentration across samplings (average 230 g/kg DM). Favourable management improved WSC concentrations in early spring and summer and decreased CP in spring, summer and autumn. Annual DM yield did not vary with cultivar or management, averaging 8.43 t/ha. Within a 12‐month study at one site in a temperate environment in southern Chile, PRG cultivars have not shown a consistent expression of the "high sugar" trait, where a genetic × environment interaction might be operating. [ABSTRACT FROM AUTHOR]

One of the challenges of modern grassland systems is to minimize nitrogen (N) fertilization without negatively affecting the forage yield. Therefore, critical N dilution curves (Nc = acW−b) have been developed in different species to improve N fertilization management. The aim of this study was to validate a critical N dilution curve for hybrid ryegrasses. Two field experiments were conducted in southern Chile. Treatments were the factorial combination of two hybrid ryegrasses (Shogun and Trojan cultivars) and seven N fertilization rates (0, 50, 100, 200, 350, 525 and 700 kg N/ha). Factors were arranged in a split‐plot design, where forage species were assigned to main plots and N rates to subplots that were randomized into four blocks. A wide range in forage yield and plant N concentration was observed (yield: 0.16 and 3.9 Mg DM/ha and N: 1.6% and 5.1%). The variations in these traits were principally explained by the N levels and harvest times. Relative yield responses of both cultivars were significantly (p < 0.001, R2 = 0.81–0.87) related to the nitrogen nutrition index (NNI) calculated with different critical N dilution curves. However, the NNI calculated with N dilution curves from annual ryegrass best described the relative yield response of hybrid ryegrass. Therefore, this validated critical N dilution curve (%Nc = 4.1W−0.38) will serve as a useful diagnosis tool for improving the N fertilization management of grazing systems for hybrid ryegrasses. [ABSTRACT FROM AUTHOR]

Eleven laboratory‐scale trials were undertaken in different years where ryegrass (Lolium perenne L.) or lucerne (Medicago sativa L.) were ensiled with different concentrations of tannin extracts (quebracho, Schinopsis balansae Engl., mimosa, Acacia mearnsii DE WILD.), and the effects on protein degradation were assessed. The dry‐matter (DM) content in grass silages ranged between 186 and 469 g/kg and in lucerne silages between 187 and 503 g/kg. Tannin extract, either quebracho or mimosa, was applied at 0–30 g/kg forage DM. Commercial additives such as Lactobacillus plantarum, formic acid or hexamine + NaNO2 were applied in two of the grass trials and in six of the lucerne trials. Eight of the trials incorporated a maximum ensiling duration of 90 or 180 days in addition to replicates which were opened and evaluated at earlier stages. All trials included silages which were assessed after at least 49 days of anaerobic storage. The crude protein (CP) fraction A (non‐protein nitrogen, NPN) as proportion of total CP, served as the main indicator for proteolysis. In ryegrass, in general, the level of proteolysis was lower than in lucerne. A correlation of DM content in silages and degree of proteolysis was only evident for ryegrass. In both forages, the degradation of true protein slowed considerably after 24 days of ensiling. True protein was conserved most with the highest level of tannin extract addition. However, in lucerne, the combination of formate with lactobacilli was equally effective up to 330 g DM/kg, and deamination was further inhibited by formic acid compared to tannin extracts. [ABSTRACT FROM AUTHOR]

Non‐systemic endophytes coexist with grasses and produce positive or negative effects for the host. In agricultural grasses, endophytes such as Epichloë spp. (formerly: Neotyphodium spp.) enhance the biometric parameters and agricultural value of grass biomass and seeds. Some endophytic fungi produce active substances that exert a negative influence on grass‐fed livestock. There is a general scarcity of studies investigating other endophytic fungi, the species composition of fungal communities, fungal species capable of colonizing different grasses and endophyte transfer between grass taxa. This study aims to fill in the existing knowledge gap by describing the relationships between fungal species and grass species. Timothy grass (Phleum pratense L.) is more readily colonized by endophytic fungi than perennial ryegrass (Lolium perenne L.), and the ratio of fungi isolated from the above species was determined at 3:1. Ecological indicators, especially diversity, were also higher in the fungal community colonizing timothy grass. The vast majority of the isolated fungi were ascomycetes. In addition, two Basidiomycota isolates and three Oomycota isolates (Phythium acanthicum) were also obtained from timothy grass. The most prevalent fungal species were Alternaria alternata, Microdochium bolleyi and Epicoccum nigrum. An analysis of minisatellite DNA regions revealed high levels of genetic polymorphism in A. alternata, whereas the remaining isolates were characterized by low levels of genetic variation or genetic homogeneity. The transfer of endophytic fungi between grass species was determined, which was one of the most important observations made in the study. The Sørensen–Dice coefficient reached 50%, which indicates that all fungal species isolated from perennial ryegrass are capable of colonizing timothy grass. [ABSTRACT FROM AUTHOR]

A complete randomized design was used to investigate the effect of increasing pasture species on herbage production, chemical composition and utilization under intensive sheep grazing. Four experimental farmlets were established, namely perennial ryegrass (Lolium perenne) only, receiving 163 kg N ha−1 year−1 (PRG); a perennial ryegrass and white clover (Trifolium repens) sward (PRGWC); a six species sward containing two grasses, two legumes and two herbs (6S); and a nine species sward containing three grasses, three legumes and three herbs (9S), each receiving 90 kg N ha−1 year−1. Ewes (12.5 ewes ha−1) and lambs rotationally grazed each farmlet from turnout post‐lambing until housing. Target pre‐grazing herbage mass (above 4 cm) was 1,200 kg dry‐matter (DM) ha−1, Target post‐grazing sward height was 4 cm for all rotations. Herbage samples were collected for DM yield, botanical and chemical composition determination at each grazing. Annual DM production of the 6S, 9S and PRG swards was similar (10.3, 9.9 and 9.9 ± 0.5 t DM ha−1, respectively) despite differences in N application. The 6S sward, however, had greater annual DM production compared to the PRGWC sward (9.1 t DM ha−1, p < 0.05). Herb proportions decreased in the 6S and 9S swards from 2015 to 2016 (p < 0.05) resulting in increased proportions of grass in these swards (p < 0.05). In conclusion, the PRGWC, 6S and 9S swards produced similar annual herbage DM from lower N inputs to PRG swards; however, maintaining the proportions of herbs is a challenge under intensive sheep grazing. [ABSTRACT FROM AUTHOR]

Increasing herbage dry‐matter (DM) production and utilization on‐farm improves efficiency and sustainability. The objective of this study was to investigate the effect of perennial ryegrass, Lolium perenne L., ploidy and white clover, Trifolium repens L., inclusion on herbage DM production and utilization in an intensive animal grazing system, with high nitrogen (N) inputs (250 kg N ha−1) and a high stocking rate (2.75 livestock units ha−1). The study was a 2 × 2 factorial design, consisting of diploid and tetraploid cultivars sown as grass‐only and grass‐white clover to give four sward treatments (diploid‐only, tetraploid‐only, diploid‐white clover, tetraploid‐white clover). These were evaluated at each grazing occasion (8–10 per year) for 3 years (2014–2016). Tetraploid‐white and grass‐white clover swards had a lower sward density (−9 and −8 kg DM cm−1, respectively) and perennial ryegrass tiller density (−820 and −1,436 tillers m−2, respectively) leading to lower postgrazing sward heights (−0.15 and −0.41 cm, respectively), and maintained a superior nutritive value when compared with diploid‐only and grass‐only swards respectively. White clover inclusion resulted in higher productivity characterized by increased herbage DM production (+1,468 kg DM ha−1), improved nutritive value and increased utilization across the three grazing seasons. Varying sward composition with perennial ryegrass ploidy led to improved nutritive value and favourable grazing characteristics in tetraploid swards. [ABSTRACT FROM AUTHOR]

The effect of winter feeding system on the periparturient performance and early milk production and metabolism of pregnant Holstein‐Friesian dairy heifers destined for a high‐output, total mixed ration (TMR)‐based system was examined. Forty‐eight, 23 ± 0.4‐month‐old, in‐calf Holstein‐Friesian heifers were assigned to one of three treatments: out‐wintered on perennial ryegrass and grass silage (G), out‐wintered on fodder beet and grass silage (F) or housed and fed grass silage and concentrate (H). The study commenced in November 2013, with heifers on treatment for 91 days, housed from 6 weeks prior to parturition and fed a dry cow TMR. Postpartum performance and metabolism were monitored for 12 weeks. Prepartum, average daily gain was lower in heifers receiving G at 0.95 kg d−1 cow−1 than F or H (1.24 and 1.11 kg d−1 cow−1 respectively). Body condition score of heifers that received G was also lower compared with treatments F or H both pre‐ and postpartum. Prepartum, plasma β‐hydroxybutyrate concentrations were lowest in animals receiving treatment H, highest in F and intermediate in G, but did not differ between treatment postpartum. Milk yield averaged 30.7 kg d−1 cow−1 and was not affected by treatment, but milk fat content was lowest in animals that received F (35.4, 37.1 and 37.9 g/kg for F, G and H respectively). The results indicate that out‐wintering in‐calf dairy heifers on fodder beet or perennial ryegrass is a viable alternative to winter housing in high‐output TMR‐based milk production systems in a temperate region. [ABSTRACT FROM AUTHOR]

Abstract: In perennial ryegrass seed production, the establishment of seed yield potential occurs until the point of anthesis. However, utilizing potential seed yield is predominately focused on processes after anthesis, namely seed set (%) and seed filling. In practice, seed yield is the product of the number of harvested seeds remaining after cleaning and average seed weight. For this study, the anthesis patterns and seed set were recorded in a diploid variety grown in seed production fields in three different Danish regions with contrasting weather conditions and investigated in 2013 and 2014. Increases in the total precipitation during anthesis reduced the anthesis synchrony and the seed set, which ranged from 50% to 66%. Under semi‐controlled environmental conditions in which the influence of precipitation was excluded, the seed set was found to be influenced by the floret position in the spikelet and ranged from 73% in the florets in basal positions to 25% in the distal florets. It is suggested that a lower number of florets per spikelet will reduce the anthesis period. These results may provide insights for breeding programmes focused on increasing seed yield. [ABSTRACT FROM AUTHOR]

Abstract: In forage grasses, vegetative and reproductive investments are major determinants of yield and persistence. A survey of the diversity of vegetative and reproductive investment traits was carried out on 213 perennial ryegrass genotypes, representing 51 natural European accessions. Plants were phenotyped for traits related to leaf elongation, tillering, reproductive investment and heading date, at two locations with markedly different climates. Strong genetic effects for all traits were found. Interactions between genotype and location were moderate. Plants showed stronger spring leaf growth, lower numbers of tillers and higher reproductive investments at Lusignan (France) than at Melle (Belgium). Plant growth rate and tillering capacity were genetically nearly independent suggesting breeding for both traits simultaneously and independently should be possible. A high genetic diversity was observed for all traits. This diversity was structured in three main clusters. One cluster comprised early‐flowering genotypes with high reproductive investments and high spring growth rates. The remaining genotypes fell into two clusters based on differences in tillering capacity. Clear links were found between traits and the climatic conditions of the region of origin of the accessions. Autumn growth rate was positively correlated with solar radiation at the region of origin in October and February. [ABSTRACT FROM AUTHOR]

Abstract: Perennial ryegrass (Lolium perenne) is an important source of protein and energy for dairy cattle. To improve the protein/energy ratio of this forage, focus is now on improving its cell wall digestibility. The in vitro assessment of the digestible fraction of the neutral detergent fibre (NDFD) is a superior method for determining the cell wall digestibility, but requires the use of ruminal fluid, which has a highly variable composition and is often not readily available. As lignin is considered the main cell wall component that impedes NDFD, we investigated whether this “subtrait” could serve as alternative breeding selection criterion to improve NDFD. Therefore, we assessed the accuracy of two lignin quantification methods: van Soest (ADL) and Klason lignin (KL). We also considered KL estimates corrected for the solubilized lignin (total lignin or TL) and non‐solubilized protein (TL'). Although the latter is considered the truest possible lignin content, it was not always the most correlated to NDFD, due to the limited accuracy of protein quantification on lignin residue. TL is most correlated to NDFD and we therefore recommend it for use in conventional breeding if NDFD determination is not a possibility. However, NDFD is still a superior selection criterion, as it combines the effect of several subtraits and not just lignin. For marker–trait association studies, a more accurate estimate of lignin content is more important than a high correlation with NDFD, but also here, TL performs best. [ABSTRACT FROM AUTHOR]

Abstract: Potassium fertilization in intensive grassland systems is particularly important on sandy soils with limited K storage capacity. A 3‐year plot experiment was conducted in south‐western Australia to determine the critical K concentration in herbage dry matter (DM) of annual and Italian ryegrass required to achieve 0.95 of the maximum yield, under best‐practice grassland management. A factorial design was employed with eight fertilizer K rates (range 0–360 kg ha−1 year−1) and two ryegrass species replicated four times, on a sandy soil site managed over 7 years to deplete mean soil Colwell K concentration to 42 mg/kg. Herbage was defoliated six times per year at the 3‐leaf stage of regrowth. Herbage DM yield, macronutrient and micronutrient concentrations were measured at each defoliation. Dry‐matter yield increased significantly (p < .001) with increasing levels of K fertilizer in all 3 years and the effect was curvilinear, while 0.95 of the maximum herbage DM yield was achieved at an annual K fertilizer application rate of 96, 96 and 79 kg/ha respectively. At these K fertilizer application levels, the mean K concentration of herbage DM over the 3 years was derived to be 11.4, 12.7 and 11.2 g/kg respectively. Sodium, magnesium and calcium concentrations of herbage DM all declined significantly (p < .001) as the K concentration increased. Grassland producers on sandy soils should target a K concentration in herbage DM of 16 g/kg for annual ryegrass and Italian ryegrass‐dominant swards to ensure K availability is not limiting herbage production. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the associative effects between fresh perennial ryegrass and fresh white clover on intake and digestion in sheep. Five proportions of ryegrass and white clover, ranging from 0 to 1 in 0·25 increments ( DM basis), were allocated to two groups of five sheep according to a replicated 5 × 5 Latin square design, and intake behaviour and digestive parameters including methane ( CH4) emissions were measured. Feeding behaviour was affected through increased forage intake when the proportion of white clover was increased, and there were positive associative effects on intake, eating time and eating rate during the main meals consumed immediately after feed was given. These effects seemed to be related to a greater motivation to eat, rather to more efficient digestion, as no difference on DM digestibility (average 766 g kg−1) was detected. There were no differences in CH4 yield (average 18·1 g kg−1 DM intake) among the treatments. The optimal proportion of white clover fed with ryegrass to optimize intake and digestion was between 0·25 and 0·50. These results indicate that mixing perennial ryegrass and white clover positively affects forage intake in sheep and their motivation to eat. [ABSTRACT FROM AUTHOR]

Three grazing experiments were carried out in late spring (early lactation), summer (mid-lactation) and autumn (late lactation) to compare the effects of perennial ryegrass cultivar or grass species, sown in binary or multispecies mixtures, on milk yield and nitrogen excretion of dairy cows. Replicated groups of multiparous Holstein Friesian × Jersey cows were offered either a control or high-sugar perennial ryegrass ( Lolium perenne) or tall fescue ( Festuca arundinacea) base grass in a binary mixture with white clover ( Trifolium repens) or in a multispecies mixture with additional legumes, bromegrass ( Bromus willdenowii) and forbs. During each 9-day experiment, botanical composition, milk production and faecal and urine composition were measured. Milk solid ( MS) yield for the control ryegrass, high-sugar ryegrass and tall fescue grass types averaged, respectively, 1.53, 1.64 and 1.70 kg MS cow−1 day−1 for a binary mixture sward, compared with 1.65, 1.54 and 1.53 kg MS cow−1 day−1 for a multispecies sward. Legume content influenced milk production more than the number of species present in a mixture. There was lower urine N concentration from a multispecies sward compared with a binary mixture. Urine N concentration of cows grazing the control ryegrass, high-sugar ryegrass and tall fescue grass types averaged, respectively, 4.6, 5.3 and 6.8 g N L−1 for a binary mixture, compared with 4.1, 3.9 and 3.9 g N L−1 for a multispecies mixture. Feeding dairy cows on multispecies swards containing forbs presents an opportunity to reduce N losses without compromising milk yield. [ABSTRACT FROM AUTHOR]

Leaf stage-dependent defoliation is linked to the plant's physiological status and may be a more suitable criterion than time-based intervals for harvesting forage grasses, but no reports of research with annual ryegrass ( Lolium multiflorum Lam. var. westerwoldicum) were found. To address this, a 2-year field study was carried out at Raymond, MS, on a Loring silt loam soil (fine-silty, mixed, thermic Typic Fragiudalfs). Forage production, morphological characteristics and nutritive value responses to defoliation based on leaf stage (2, 3 and 4 leaves per tiller) and two residual stubble heights ( RSH; 5 and 10 cm) of a tetraploid ('Maximus') vs. a diploid ('Marshall') cultivar of annual ryegrass were quantified. Forage harvested, in 2011, increased linearly as leaf stage increased from 7.3 to 8.8 Mg/ha, but during 2012 was least (7.0 Mg/ha) at 3-leaf stage and similar at the other two leaf stages (7.6 Mg/ha). Tiller density was less for Maximus (1,191 tillers/m2) than for Marshall (1,383 tillers/m2). Leaf blade proportion decreased with increasing leaf stage and was greater by 9% for Maximus than for Marshall. Generally, forage nutritive value became less desirable with increasing leaf stage. There was a dichotomy in forage harvested and nutritive value responses, but maximum forage productivity was achieved when annual ryegrass was defoliated at the 4-leaf stage interval. [ABSTRACT FROM AUTHOR]

The objectives of this study were to measure the variability in 'realized' tiller morphology and identify whether there are emergent generalizations about a tiller ideotype for productivity or survival. Morphological traits during the vegetative growth stage were measured for 2 years in the field for eight perennial ryegrass cultivars: six diploid and two tetraploid cultivars under low and high nitrogen fertilizer (50 and 225 kg N ha−1 year−1 respectively). Traits measured were lamina width, length and area; pseudo-stem length and diameter; an index of tiller shape; tiller dry weight; tiller density; and herbage mass. Almost all the traits differed significantly between cultivars and significant correlations were found between the 2 years. Principal component analysis identified that tiller morphology and dry-matter yield were independent. No trait associations indicating alternative cultivar-specific tiller morphologies were detected but cultivars differed in tiller size. The patterns of change between the 2 years indicated a possible morphological trajectory as swards age. The genetic compensatory relationship between tiller size and density had a 1:1 slope, indicative of constant yield. This implies that larger tillers would be more leafy, and higher leafiness of tetraploid over diploid cultivars was confirmed by the leaf:non-leaf ratio and tiller shape index. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of defoliation frequency (either at two- or three-leaf stage) and nitrogen (N) application rate (0, 75, 150, 300, 450 kg N ha−1 year−1) on herbage carbohydrate and crude protein ( CP) fractions, and the water-soluble carbohydrate-to-protein ratio ( WSC: CP) in perennial ryegrass swards. Crude protein fractions were analysed according to the Cornell carbohydrate and protein system. Carbohydrate fractions were analysed by ultra-high-performance liquid chromatography. Sward defoliation at two-leaf stage increased the total CP, reduced the buffer-soluble CP fractions and decreased carbohydrate fractions of herbage ( P < 0·001). The effect of defoliation frequency was less marked during early spring and autumn ( P < 0·001) than for the rest of the seasons. An increase in N application rate was negatively associated with WSC, fructans and neutral detergent fibre ( P < 0·001), and positively associated with CP and nitrate (N- NO3) contents of herbage. Nitrogen application rate did not affect CP fractions of herbage ( P > 0·05). The fluctuations in CP and WSC contents of herbage resulted in lower WSC: CP ratios during early spring and autumn (0·45:1 and 0·75:1 respectively) than in late spring (1·11:1). The herbage WSC: CP ratio was greater ( P < 0·001) at the three-leaf than the two-leaf defoliation stage and declined as the N application increased in all seasons ( P < 0·001). The results of this study indicate that CP and carbohydrate fractions of herbage can be manipulated by sward defoliation frequency and N application rate. The magnitude of these effects, however, may vary with the season. [ABSTRACT FROM AUTHOR]

Failure of perennial ryegrass swards to persist is a key issue on dairy farms in many areas of the world. This study describes an experiment conducted to test the hypothesis that high ryegrass seeding rates (>18 kg seed ha−1) reduce plant size and physical survival during the first year after sowing, with negative implications for population persistence. Four cultivars representing four functional types of perennial ryegrass were sown at five seeding rates (equivalent to 6, 12, 18, 24 and 30 kg seed ha−1) with white clover in three dairying regions of New Zealand. Plant establishment rates, size and survival were measured for the first 13 months after sowing. Herbage accumulation, botanical composition and perennial ryegrass tiller density were also monitored. Increasing seeding rate reduced plant survival in the seven weeks after sowing, reflecting likely differences in germination and very early mortality of small seedlings. Thereafter, plant survival was relatively high and consistent across seeding rates at two sites but was consistently greater in the 6 kg ha−1 treatment compared with the 24 and 30 kg ha−1 treatments at one site. Higher seeding rates also increased ryegrass tiller density and the contribution of ryegrass towards total herbage biomass but reduced the contribution of white clover. Very few cultivar × seeding rate interactions were detected for any of the measured variables. Many of the seeding rate effects dissipated by the end of the first year after sowing, indicating that high seeding rates did not predispose swards to poor persistence in the longer term, irrespective of ryegrass functional type. [ABSTRACT FROM AUTHOR]

Soil quality of tillage systems receives much attention worldwide, although few studies attempt to link soil quality to yield. Partial least-squares regression analysis is a suitable method to construct predictive models around plural, highly collinear factors, such as soil quality and its effects on yield. This study aimed at identifying the soil quality properties which best model pasture herbage yield by relating soil quality indicators with variations in yield as a result of soil disturbance caused by tillage. The study was conducted on kikuyu ( Pennisetum clandestinum) over-sown with annual ryegrass ( Lolium multiflorum) using different tillage methods. Tillage methods involved over-sowing kikuyu with ryegrass using a minimum-tillage seed drill, eradication of kikuyu with herbicide and ryegrass sown with a minimum-tillage planter, shallow and deep disturbance, and a control. Most changes in soil quality indicators as a result of soil tillage were observed shortly after tillage and occurred mostly at the 0-100 mm soil layer. Few of these effects were still visible 420 d after tillage. Microbiological indicators changed most in response to the treatments, but unlike the chemical and physical indicators, microbiological indicators have no causal link to pasture production. The contribution of individual soil quality indicators to variance in pasture productivity could not be isolated and should thus be seen as complex processes which affect yield. Although mechanisms of how some soil quality indicators affect yield is clear, more research is required to determine mechanisms of how a combination of multiple soil quality indicators affects yield. [ABSTRACT FROM AUTHOR]

Mixtures and pure stands of perennial ryegrass, tall fescue, white clover and red clover were grown in a three-cut and a five-cut system in southern Norway, at a low fertilization rate (100 kg N ha−1 year−1). The nutritional quality (annual weighted averages) of the dried forage from the two-first harvesting years was analysed. There was no significant effect of species diversity on crude protein ( CP) concentration. In the three-cut system, we found a significant species diversity effect leading to 10% higher concentrations of acid detergent fibre ( ADF), 20-22% lower concentrations of water-soluble carbohydrate ( WSC) and 4% lower net energy for lactation ( NEL) concentrations in mixtures compared with pure stands (averaged across the two-first years). In the five-cut system, similar effects were seen in the first year only. This diversity effect was associated with a reduction in WSC and NEL concentrations and an increase in ADF, NDF and CP concentrations in the grass species, and not in red clover, when grown in mixtures. This is thought to be a combined result of better N availability and more shading in the mixtures. Species diversity reduced the intra-annual variability in nutritional quality in both cutting systems. [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]

Four-species mixtures and pure stands of perennial ryegrass, tall fescue, white clover and red clover were grown in three-cut and five-cut systems at Ås, southern Norway, at a low fertilization rate (100 kg N ha−1 year−1). Over a three-year experiment, we found strong positive effects of species diversity on annual dry-matter yield and yield stability under both cutting frequencies. The overyielding in mixtures relative to pure stands was highest in the five-cut system and in the second year. Among the possible pairwise species interaction effects contributing to the diversity effect, the grass-grass interaction was the strongest, being significant in both cutting systems and in all years. The grass-legume interactions were sometimes significant, but no significant legume-legume interaction could be detected. Competitive relationships between species varied from year to year and also between cutting systems. Estimations based on species identity effects and pair-specific interactions suggested that the optimal proportions of red clover, white clover, perennial ryegrass and tall fescue in seed mixtures would have been around 0·1, 0·2, 0·4 and 0·3 in the three-cut system, and 0·1, 0·3, 0·3 and 0·3 in the five-cut system. [ABSTRACT FROM AUTHOR]

Productive pasture systems require a regular supply of mineral nitrogen (N) to replace the N removed through the export of animal products and other loss pathways such as leaching and emissions. High spatial and temporal variability of both N supply by the soil and demand by the plant means that synchronizing these is challenging, and early indicators are lacking. Optimum fertilization rates for an irrigated ryegrass pasture in Canterbury, New Zealand, were determined in a simulation study with twenty fertilization rates using the Agricultural Production Systems Simulator with a refined version of APSIM's pasture module (AgPasture). Improvements in AgPasture included ideal N concentrations for tissues of different ages (growing, mature, senescent and dead) and allowing N remobilization to occur from all tissue stages. The critical N concentration curve (the minimum N concentration required to achieve maximum aerial biomass) was tested as an early indicator for guiding N fertilization, which maximizes plant growth while avoiding unnecessary environmental impacts. Highest pasture yields were achieved with application rates of 20, 30, 140 and 160 kg N ha−1 for winter, autumn, summer and spring. These rates also minimized simulated N losses. Pasture N contents corresponding to the standing dry matter of the pastures were similar to the critical N curve in summer and spring, but lower critical N concentrations were obtained for autumn and winter. Before the critical N reference curve can be used to guide fertilization for pastures, further experimental studies, model testing and parameterization are required. It is also possible that season-specific critical N curves need to be established for pastures. [ABSTRACT FROM AUTHOR]

Perennial ryegrass ( Lolium perenne L.) evaluation trials are often conducted under simulated grazing to identify the most productive cultivars. It is unclear whether simulated grazing identifies the most productive cultivar for animal-grazed swards. Ten cultivars were established as plots and managed concurrently under simulated grazing ( SG), animal grazing ( AG) and conservation ( CON). The experiment lasted 3 years with dry-matter ( DM) off-take, digestibility, tiller density and ground-cover score recorded in all years. A good relationship existed between DM off-take under SG and CON ( R2 = 0·73). The relationship between SG and AG was strongest in year 2 and 3 ( R2 = 0·53 and 0·55 respectively). High DM production was observed in SG swards in year 1; this was weakly related to the DM production of the AG sward. Across the 3 years, the CON treatment had higher yields than either of the other two treatments and was poorly correlated to DM yield under AG, confirming that cultivars should be evaluated under a similar defoliation frequency to their intended use. Tiller density declined quickest under CON and slowest under AG. Some reranking of cultivars occurred between defoliation managements. The results show that simulated grazing is a useful indicator of DM yield performance of animal-grazed swards. [ABSTRACT FROM AUTHOR]

Six dryland pastures were established at Lincoln University, Canterbury, New Zealand, in February 2002. Production and persistence of cocksfoot pastures established with subterranean, balansa, white or Caucasian clovers, and a perennial ryegrass-white clover control and a lucerne monoculture were monitored for nine years. Total annual dry-matter (10.0-18·5 t DM ha−1) and sown legume yields from the lucerne monoculture exceeded those from the grass-based pastures in all but one year. The lowest lucerne yield (10 t ha−1 yr−1) occurred in Year 4, when spring snow caused ungrazed lucerne to lodge and senesce. Cocksfoot with subterranean clover was the most productive grass-based pasture. Yields were 8·7-13·0 t DM ha−1 annually. Subterranean clover yields were 2·4-3·7 t ha−1 in six of the nine years which represented 26-32% of total annual production. In all cocksfoot-based pastures, the contribution of sown pasture components decreased at a rate equivalent to 3·3 ± 0·05% per year ( R2 = 0·83) and sown components accounted for 65% of total yield in Year 9. In contrast, sown components represented only 13% of total yield in the ryegrass-white clover pastures in Year 9, and their contribution declined at 10·1 ± 0·9% per year ( R2 = 0·94). By Year 9, 79% of the 6.6 t ha−1 produced from the ryegrass-white clover pasture was from unsown species and 7% was dead material. For maximum production and persistence, dryland farmers on 450-780 mm yr−1 rainfall should grow lucerne or cocksfoot-subterranean clover pastures in preference to ryegrass and white clover. Inclusion of white clover as a secondary legume component to sub clover would offer opportunities to respond to unpredictable summer rainfall after sub clover has set seed. [ABSTRACT FROM AUTHOR]

Seven forage types (diploid and tetraploid perennial ryegrass, Italian ryegrass and hybrid ryegrass, a low-input mixture of perennial ryegrass, cocksfoot, timothy and meadow fescue, a mixture of perennial ryegrass and white clover, and monoculture of red clover) were sown in late July 2004. Each received one of four rates of dairy cattle slurry in three annual applications by trailing shoe, which supplied average nitrogen (N) inputs of 0·0, 114·9, 204·8 and 301·2 kg N ha−1 annum−1. Treatments were cut either three or four times annually over four years. Average dry-matter yield ( DM) response to slurry N was 15·6 kg DM kg−1 N. Lowest recovery of slurry N was in the second application each year (after first cut). The data suggest that slurry applied to Italian ryegrass, and also to swards containing legumes on soils with high phosphorus content, will produce a lower DM response to slurry N and result in a lower slurry N recovery than on swards of perennial ryegrass or cocksfoot-dominant low-input mixtures. Apparent recovery of slurry N was low at the second cut, especially when first-cut yields had been high. To maximize slurry N recovery, application to regrowths with potentially slow rates of growth or high legume content should be avoided. [ABSTRACT FROM AUTHOR]

There is increasing interest in tall fescue ( Festuca arundinacea Schreb.) in Western Europe and elsewhere, mainly because of its better drought resistance and yield potential compared with perennial ryegrass ( Lolium perenne L.). Important drawbacks of tall fescue, compared with perennial ryegrass, are its lower digestibility and voluntary intake. Mixtures of both species might combine the advantages of each, and species interactions may eventually lead to transgressive overyielding. We compared the agronomic performance of tall fescue, perennial ryegrass and tall fescue-perennial ryegrass mixtures, as pure-grass swards or in association with white clover ( Trifolium repens L.). Tall fescue-perennial ryegrass mixtures differed in the proportion and ploidy of the perennial ryegrass component. Yield, feed quality and botanical composition were measured in the 3 years after the sowing year. We found significant effects of ploidy of the ryegrass variety and of the proportion of ryegrass in the initial seed mixture on the botanical composition of the swards. Nevertheless, all swards were dominated by tall fescue at the end of the experiment. No overyielding of the mixtures compared with that of single-species swards was found, but feed quality was intermediate between that of the single-species swards. Mixed swards had better drought resistance than L. perenne and higher feeding quality than F. arundinacea swards. [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]

Increasing plant species diversity in grasslands may improve productivity and stability of yields. In a field experiment, we investigated the herbage dry-matter ( DM) yield and crude protein content of two-species swards of perennial ryegrass-white clover ( Lolium perenne L.- Trifolium repens L.) and three-species swards of ryegrass-white clover with red clover ( Trifolium pratense L.). Five different managements represented cutting, grazing and combinations thereof, with different slurry fertilization treatments in 1- to 4-year-old swards. The three-species mixture out-yielded the two-species mixture in years 1 and 2. Across all 4 years, yields were 8-10% higher in cut swards. Inclusion of red clover increased the yields of clover across the 4 years by 51% without fertilizer and by 90% when fertilized. Responses to slurry fertilization were similar in both mixtures and were mainly independent of sward age. There was a complementary effect over the season and across managements. Red clover dominated in the first and third cuts; white clover dominated in the second and fourth cuts. Red clover dominated in cut swards and white clover in grazed swards. Future prospects of the inclusion of red clover in sown swards are discussed. These may include higher nitrogen-use efficiency in ruminants, increased soil fertility and improved sward flexibility to cope with changing managements. The findings also suggest positive yield effects of alternating between cutting and grazing within the season or between years. [ABSTRACT FROM AUTHOR]