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The objective of this study was to quantify the farm gate nitrogen (N) offset potential of perennial ryegrass (Lolium perenne L.; PRG) white clover (Trifolium repens L.; WC) swards by comparing the herbage and milk production from dairy farmlets that were simulations of full farming systems. A study was established where 120 cows were randomly assigned to 4 farmlets of 10.9 ha (stocking rate: 2.75 cow/ha), composed of 20 paddocks each. Cows were fed 526 kg of DM of concentrate on average each year. The 4 grazing treatments were PRG-only at 150 or 250 kg of N/ha and PRG-WC at 150 or 250 kg of N/ha. Cows remained in their treatment group for an entire grazing season and were re-randomized as they calved across treatments each year. As cows calved in the spring as standard practice in Ireland, they were rotationally grazed from early February both day and night (weather permitting) to mid-November, to a target postgrazing sward height of 4.0 cm. Mean sward WC content was 18.1% and 15.4% for the 150 and 250 kg of N/ha PRG-WC treatments, respectively over the 3-yr period. When WC was included, lowering the N rate did not reduce pregrazing yield, pregrazing height, or herbage removed, but those factors decreased significantly when WC was absent. Total annual herbage DM production was 13,771, 15,242, 14,721, and 15,667 kg of DM/ha for PRG-only swards receiving 150 or 250 kg of N/ha and PRG-WC swards receiving 150 or 250 kg of N/ha, respectively. In addition, when WC was present, compressed postgrazing sward heights were lower (4.10 vs. 4.21 cm) and herbage allowance (approximately 17 kg/cow feed allocation per cow per day) higher than the high-N control (+ 0.7 kg of DM/cow per day). There was a significant increase in milk production, both per cow and per hectare, when WC was included in PRG swards. Over the 3-yr study, cows grazing PRG-WC had greater milk (+304 kg) and milk solids (+31 kg of fat + protein) yields than cows grazing PRG-only swards. This significant increase in milk production suggests that the inclusion of WC in grazing systems can be effectively used to increase milk production per cow and per hectare and help offset nitrogen use. This result shows the potential to increase farm gate N use efficiency and reduce the N surplus compared with PRG-dominant sward grazing systems receiving 250 kg of N/ha, without negatively affecting milk solids yield or herbage production, thus increasing farm profit by €478/ha. [ABSTRACT FROM AUTHOR]

Background: Drought resistance is a complex characteristic closely related to the severity and duration of stress. Perennial ryegrass (Lolium perenne L.) has no distinct drought tolerance but often encounters drought stress seasonally. Although the response of perennial ryegrass to either extreme or moderate drought stress has been investigated, a comprehensive understanding of perennial ryegrass response to both conditions of drought stress is currently lacking. Results: In this study, we investigated the genetic variation in drought resistance in 18 perennial ryegrass varieties under both extreme and moderate drought conditions. The performance of these varieties exhibited obvious diversity, and the survival of perennial ryegrass under severe stress was not equal to good growth under moderate drought stress. 'Sopin', with superior performance under both stress conditions, was the best-performing variety. Transcriptome, physiological, and molecular analyses revealed that 'Sopin' adapted to drought stress through multiple sophisticated mechanisms. Under stress conditions, starch and sugar metabolic enzymes were highly expressed, while CslA was expressed at low levels in 'Sopin', promoting starch degradation and soluble sugar accumulation. The expression and activity of superoxide dismutase were significantly higher in 'Sopin', while the activity of peroxidase was lower, allowing for 'Sopin' to maintain a better balance between maintaining ROS signal transduction and alleviating oxidative damage. Furthermore, drought stress-related transcriptional and posttranscriptional regulatory mechanisms, including the upregulation of transcription factors, kinases, and E3 ubiquitin ligases, facilitate abscisic acid and stress signal transduction. Conclusion: Our study provides insights into the resistance of perennial ryegrass to both extreme and moderate droughts and the underlying mechanisms by which perennial ryegrass adapts to drought conditions. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is a commonly grown pasture species in temperate agriculture, mainly serving as a primary energy source for dairy cows. However, its limited persistence often leads to missed production potential and early resowing, especially in countries that experience summer drought, e.g., Australia and New Zealand. Therefore, understanding the factors influencing perennial ryegrass pasture persistence is crucial for sustainable land management and climate resilience in pasture-based animal production systems. Significant gaps in knowledge exist regarding the factors influencing pasture persistence, as the number of conducted studies in this area remains limited. This study aimed to investigate the factors influencing the expression of persistence in perennial ryegrass populations using airborne and ground-based sensors. A field experiment was conducted in the southwest region of Victoria, Australia, involving ten commercial perennial ryegrass cultivar–endophyte combinations in two different populations. Persistence was evaluated using sensor-based and conventional pasture measurements over two consecutive autumns. The results revealed significant fixed effects of cultivar, endophyte, and environment and their interactions on persistence traits of perennial ryegrass. Cultivars Alto, Samson, and One50 exhibited high levels of persistence when infected with novel endophyte strains. Furthermore, prolonged environmental stresses were found to drive directional selection within pasture populations. The findings emphasise the importance of selecting appropriate cultivar–endophyte combinations and early detection of signs of poor persistence to optimise sward longevity and financial returns from pasture-based animal production systems. This study fills a knowledge gap regarding the factors influencing pasture persistence and provides valuable insights for sustainable pasture management strategies. [ABSTRACT FROM AUTHOR]

Perennial ryegrass is an important turf and forage grass in temperate regions worldwide. Limited genetic gains have been made with current breeding strategies compared with other grass crops, such as rice and maize, which benefit from Filial 1 (F1) hybrid breeding. One of the largest constraints on hybrid breeding in ryegrass is self‐incompatibility preventing inbreeding, as homozygous parental lines are required to develop hybrids with maximal hybrid vigour. Obligate outcrossing in ryegrass has resulted in cultivars with high levels of heterozygosity, lacking trait uniformity across the population. A naturally occurring self‐fertile (SF) locus that overcomes the self‐incompatibility system has been identified in a European perennial ryegrass population. This study crossed the SF locus into an elite cultivar, producing a self‐compatible population that was inbred for several generations. Genotyping‐by‐sequencing (GBS) was used to assess the population structure and degree of inbreeding in the self‐compatible population. Phenotypic analysis indicated that increased homozygosity did not necessarily affect growth and performance. This study concludes that self‐compatible ryegrass is a promising tool for hybrid breeding and agronomic improvement of perennial ryegrass. [ABSTRACT FROM AUTHOR]

In summer 2018, brown stripe symptoms were observed on leaf blades of perennial ryegrass (Lolium perenne L.) used as a turfgrass in an athletic field in Saitama Prefecture, Japan. Bacterial ooze exuded from lesions, from which a pathogenic bacterium was isolated. Inoculation of blades of perennial ryegrass with the isolates reproduced the same symptoms. Pathogenicity and bacteriological properties of the isolates were almost identical to those of Acidovorax avenae, and the identification was supported by phylogenetic analysis. This is the first report of the brown stripe on perennial ryegrass caused by A. avenae (= A. avenae subsp. avenae) in Japan. [ABSTRACT FROM AUTHOR]

α-Ketoglutarate (AKG) is a key intermediate metabolite in the tricarboxylic acid cycle of respiration and a precursor for glutamate, playing important roles in regulating plant growth and stress tolerance. The objectives of this study were to examine effects of AKG on heat tolerance characterized by leaf senescence in a cool-season grass species by foliar application and to determine major metabolites and associated metabolic pathways regulated by AKG for its effects on heat tolerance. Perennial ryegrass (Lolium perenne L.) plants were exposed to heat stress (35/30 °C, day/night) or optimal temperature (25/20 °C, day/night, non-stress control) in controlled-environment growth chambers. The solution containing AKG (5 mM) was applied to leaves by spraying 7 d prior to the initiation of heat stress and every 7 d during the heat stress period. Exogenous application of AKG enhanced heat tolerance in perennial ryegrass, as manifested by significant increases in leaf chlorophyll content, photochemical efficiency, and membrane stability, as well as activities of antioxidant enzymes for H 2 O 2 scavenging in AKG-treated plants relative to untreated control plants exposed to heat stress. Metabolic profiling and pathway analysis demonstrated that exogenous AKG application enhanced metabolite accumulation in four major metabolic pathways, including antioxidant metabolism, amino acid metabolism, glycolysis and tricarboxylic acid cycle of respiration, and pyrimidine metabolism, contributing to AKG-improved heat tolerance in perennial ryegrass. • α-Ketoglutarate (AKG) enhanced heat tolerance in perennial ryegrass. • AKG suppressed heat-induced leaf senescence. • AKG regulated the metabolism of antioxidant, amino acids, pyrimidine, glycolysis, and TCA cycle of respiration. [ABSTRACT FROM AUTHOR]

The productivity of perennial ryegrass (Lolium perenne L.) is constrained by summer water deficit. We hypothesised that selection for desirable water relations traits might partially mitigate this constraint. Genotypes of a 1970s, and two recent ryegrass cultivars were grown in 55 cm tall pots for three months and exposed to moisture deficit for four weeks, then 66 plants were assessed for shoot (SDW) and root (RDW) dry weight, leaf elongation rate (LER), specific water use (SWU), leaf osmotic potential (OP), OP change, leaf relative water content (RWC), and gravimetric soil moisture. Among the 66 genotypes, SWU ranged from 935 ± 19 to 1754 ± 74 g H2O g–1 DM. In principal component (PC) analysis, PC1 indicated greater growth and lower SWU from greater soil water extraction as the common trait association among genotypes tested and ANOVA of PC scores indicated that recent cultivars outperformed the 1970s cultivar. PC2 indicated water saving by decreased LER and SDW, with increased RDW indicative of summer dormancy. PC3 associated more negative OP with improved SWU and RWC. This experiment demonstrates not only genotypic diversity for SWU but also diversity in trait associations determining SWU, which should be considered when investigating SWU, both in ecology and agronomy research. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effects of cultivar, nitrogen (N) rate, and biostimulant application on the chemical composition of the aboveground biomass of perennial ryegrass (Lolium perenne L.). A small-area field experiment was established in the Agricultural Experiment Station in Tomaszkowo (53°42′40.8″ N 20°26′04.7″ E, north-eastern Poland). The experiment had a split-plot design with three replications, and the experimental variables were as follows: (i) perennial ryegrass cultivar: Bajka and Baronka, (ii) N fertilizer rate: 0, 120, 240 kg N ha−1, (iii) application of biostimulants: Blatt Boden-Foliar (BB-F) and Blatt Boden-Foliar + Blatt Boden-Multical (BB-F + BB-M). This study demonstrated that the tetraploid cultivar Baronka had a more desirable chemical composition than the diploid cultivar Bajka. The biomass of cv. Baronka had a higher content of CP, CF, and K, and it was characterized by higher leaf greenness (SPAD) values. Nitrogen fertilization considerably increased the content of CP, P, and K, and leaf greenness (SPAD) values in both cultivars, and the noted increase was higher when N was applied at 240 kg ha−1. The N fertilizer rate of 120 kg ha−1 led to a significant decrease in the average Ca content of plants, whereas the N fertilizer rate of 240 kg ha−1 had no significant effect on Ca concentration. The tested biostimulants significantly affected the chemical composition of perennial ryegrass biomass, and their influence was greater when they were applied in combination. The foliar application of Blatt Boden-Foliar and Blatt Boden-Multical increased the content of CP, P, and chlorophyll in perennial ryegrass leaves, whereas it decreased the accumulation of CF, K, and Ca in plants. The analyzed biostimulants had a positive effect on the chemical composition of perennial ryegrass biomass. This is an important practical consideration because high-quality green fodder for livestock can be produced while minimizing the use of mineral fertilizers and adverse environmental impacts. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne) is a widely used cool season turfgrass with outstanding turf quality and grazing tolerance. High temperature is the key factor restricting the distribution of perennial ryegrass in temperate and sub-tropic regions. In this study, we found that one HEAT SHCOK TRANSCRIPTION FACOTR (HSF) class A gene from perennial ryegrass, LpHSFA3 , was highly induced by heat stress. LpHSFA3 is localized in nucleus and functions as a transcription factor. Ectopic overexpression of LpHSFA3 in Arabidopsis improved thermotolerance and rescued heat sensitive deficiency of athsfa3 mutant. Overexpression of LpHSFA3 in perennial ryegrass enhanced heat tolerance and increased survival rate in summer season as evidenced by decreased EL and MDA, increased number of green leaves and total chlorophyll content. LpHSFA3 binds to the HSE region in LpHSFA2a promoter to constitutively activate the expression of LpHSFA2a and downstream heat stress responsive genes. Ectopic overexpression of LpHSFA2a consequently rescued thermal sensitivity of athsfa3 mutant and enhanced thermotolerance of athsfa2 mutant. Perennial ryegrass protoplasts with overexpression of LpHSFA3 and LpHSFA2a exhibited induction of similar subsets of heat responsive genes. These results indicated that transcription factor LpHSFA3 functions as positive regulator of LpHSFA2a to improve thermotolerance of perennial ryegrass, providing further evidence to understand the regulatory networks of plant heat stress response. • LpHSFA3 and LpHSFA2a were significantly induced by heat stresss. • LpHSFA3 improves plant heat tolerance and survival rate in summer season. • LpHSFA3 directly activates the expression of LpHSFA2a. • LpHSFA2a enhances plant heat tolerance. [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]

The aim of this study was to determine and compare the sensitivity of new high yield Bulgarian varieties of perennial ryegrass (Lolium perenne L.) - Harmoniya, Tetrany and Tetramis to glyphosate in laboratory conditions. The effect of three doses of glyphosate - 360, 720 and 1440 g a.i./ha applied in the growth stage tillering (BBCH - 22-23) on perennial ryegrass on the dynamics of plant growth and formed fresh biomass in g per plant was studied. Genotypic differences were observed between the studied varieties of perennial ryegrass to glyphosate. With a relatively high sensitivity to glyphosate conditionally can be determined diploid variety Harmoniya in which the depression coefficients (B) on the dynamics of growth and accumulation of fresh biomass are in the range from -5.7 to - 4.7, while for tetraploids Tetrany (B) (average) is in the range of -3.3 to -3.9 and for Tetramis (B) (average) is within limits from -3.2 to -3.9, they have relatively high tolerance to glyphosate and can be used as components in future programs. [ABSTRACT FROM AUTHOR]

Despite the progress made in DNA sequencing over the last decade, reconstructing telomere-to-telomere genome assemblies of large and repeat-rich eukaryotic genomes is still difficult. More accurate basecalls or longer reads could address this issue, but no current sequencing platform can provide both simultaneously. Perennial ryegrass (Lolium perenne L.) is an example of an important species for which the lack of a reference genome assembly hindered a swift adoption of genomics-based methods into breeding programs. To fill this gap, we optimized the Oxford Nanopore Technologies' sequencing protocol, obtaining sequencing reads with an N50 of 62 kb—a very high value for a plant sample. The assembly of such reads produced a highly complete (2.3 of 2.7 Gb), correct (QV 45), and contiguous (contig N50 and N90 11.74 and 3.34 Mb, respectively) genome assembly. We show how read length was key in determining the assembly contiguity. Sequence annotation revealed the dominance of transposable elements and repeated sequences (81.6% of the assembly) and identified 38,868 protein coding genes. Almost 90% of the bases could be anchored to seven pseudomolecules, providing the first high-quality haploid reference assembly for perennial ryegrass. This protocol will enable producing longer Oxford Nanopore Technology reads for more plant samples and ushering forage grasses into modern genomics-assisted breeding programs. [ABSTRACT FROM AUTHOR]

To reveal the structural characteristics and physicochemical properties of perennial ryegrass lignin, sequential alkali extractions or double ball-milling and enzymatic hydrolysis on the basis of ultrasonic and hydrothermal pretreatments were proposed in this study. Results revealed that sequential alkali extractions released 89.4% of original lignin from the ryegrass cell walls and 0.75–4.16% of associated carbohydrates as compared to the double ball-milling and enzymatic hydrolysis (96.0% and 18.39%). It was observed that the two types of lignin prepared were SGH-type and had different amounts of p -coumarates and ferulates, and primarily consisted of β-O-4 ′ linkages combined with minor amounts of β-β ′ and β-5 ′ linkages. Besides, alkali-soluble lignins exhibited relatively fewer β-O-4 ′ linkages, higher S/G ratios and H-type units, and abundant phenolic OH groups as compared to the double enzymatic lignin. Overall, the deeper investigation of the lignin structure of ryegrass will provide useful information for the efficient utilization of lignin macromolecules in biorefineries. • Structural characteristic of perennial ryegrass lignin was elucidated in detail. • Two types of lignin prepared by different integrated treatments were SGH-type. • Two types of lignin prepared mainly consisted of β-O-4 ′, β-β ′, and β-5 ′ linkages. • Alkali-soluble lignins had higher purity as compared to double enzymatic lignin. [ABSTRACT FROM AUTHOR]

The type-B response regulator (ARR) family members represent the elements of two-component regulatory systems and play crucial roles in the cytokinin signaling, plant growth, and stress responses. The objective of this study was to characterize type-B ARR genes from perennial ryegrass, and to investigate their roles in regulating to salt tolerance. Twelve type-B ARRs , namely LpARR1 - 12 , were identified in perennial ryegrass. They were clustered into three subgroups and were unevenly distributed on chromosomes. The stress responsive elements (SREs) and hormone responsive elements (HREs) were identified in LpARRs promoters and the transcription of LpARRs genes were responsive to various abiotic stress (heat, salt, and osmotic) and hormonal (cytokinin, ABA, and ethylene) treatments. LpARR10 was strong induced by salt stress, therefore it was selected for function analysis. Overexpressing LpARR10 in Arabidopsis led to a significant improvement in salt tolerance. The LpARR10 -overexpressing (LpARR10 -OE) lines exhibited lower levels of Na+ content compared to WT plants, and the expression levels of SOS1 and SOS3 were significantly higher in the LpARR10 -OE lines. Results of yeast auto-transactivation and plant cell transcriptional activity assays shows LpARR10 is a nucleus localized transcriptional activator and directly bind and transactivated the promoter of SOS1 and SOS3. Together, LpARR10 enhances salt tolerance may via trans-activating SOS1 / SOS3 in Arabidopsis. Knowledge gained in this study will facilitate further functional analysis of LpARRs for molecular breeding of ryegrass and other related grass species. • Overexpressing LpARR10 resulted in a reduction in Na+ content compared to WT plants. • The LpARR10 -OE lines exhibited significantly higher expression levels of SOS1 and SOS3. • LpARR10 acts as a transcriptional activator and positively regulates salt tolerance by up-regulating the expressions of SOS1 and SOS3. [ABSTRACT FROM AUTHOR]

Genotype-by-environment interaction (G×E) is commonly observed in perennial ryegrass species and significantly impacts dry matter yield (DMY) performance across environments. Variation in DMY of perennial ryegrass cultivars and their distinct responses to different environments directly influence the profitability of the Australian dairy industry. In this study, we implemented a separate two-way factor analytic strategy to fit multi-environment-multi-harvest data collected from 18 trials spanning 14 years to account for the G×E effects across complex pasture environments in south-eastern Australia to achieve accurate DMY predictions. Three mega-environments were identified, and the seasonal and environmental DMYs of 126 cultivars or breeding lines (defined by a combination of varieties and endophytes) were predicted. Statistical differences in DMY performance and crossover G×E effects in cultivar rankings were observed among the three mega-environments. Several high-yielding cultivars specific to each mega-environment were also identified. The analysis demonstrated the importance of accounting for G×E effects when predicting the DMY of perennial ryegrass and highlighted the potential for identifying high-yielding cultivars specific to mega-environments. The research rationalizes implementing an appropriate independent pasture trialling system to generate necessary data for the dairy industry and could further facilitate dairy farmers to select suitable cultivars based on their specific environments and perennial ryegrass breeders when accounting for the genetic relationship of cultivars. • G×E impacts perennial ryegrass cultivar rankings and breeding strategies. • Factor analytic model is a robust tool for analysing G×E. • Analysing G×E provides accurate DMY prediction and facilitates identifying high-yielding cultivars. • Identified 3 mega-environments and predicted DMYs for 126 cultivars. • Appling an independent trialling system is necessary to identify environmental-specific cultivars. [ABSTRACT FROM AUTHOR]

• Genome-wide identification and comprehensive analysis of NAC gene family. • LpNAC genes expression analysis under various abiotic stress. • Candidate function gene identification based on phylogenetic analysis. NAC is one of the largest family of plant-specific transcription factors, and it plays important roles in plant development and stress responses. The study identified 72 LpNACs genes from the perennial ryegrass genome database. Gene length, MW and pI of NAC family transcription factors varied, but the gene structure and motifs were relatively conserved in bioinformatics analysis. Phylogenetic analyses of perennial ryegrass, rice and Arabidopsis were performed to study the evolutionary and functional relationships in various species. The expression of LpNAC genes that respond to various abiotic stresses including high salinity, ABA, high temperature, polyethylene glycol (PEG) and heavy metal was comprehensively analyzed. The present study provides a basic understanding of the NAC gene family in perennial ryegrass for further abiotic stress studies and improvements in breeding. [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 aim of this field study was to evaluate genotype x year interaction for spike length, 1000 seed weight, seed number per g and hectoliter mass in perennial ryegrass, using eight divergent genotypes across two growing seasons. Interaction was evaluated using AMMI (Additive Main Effects and Multiplicative Interaction) model. All traits schowed additive (genotype, year) and non additive (genotype x year interaction) variation. On the basis od AMMI1 biplot genotype G4 showed most stability for all examined traits, so it can be recommended for sowing in different environmental conditions. Also, the genotype G4 could be used in the creation of new local varieties of perennial ryegrass. [ABSTRACT FROM AUTHOR]

The 'Grazing Utilization' sub-index within the Pasture Profit Index identifies perennial ryegrass varieties with high grazing efficiency. Grazing efficiency is assessed in plot trials conducted over a number of years. The objective of this study was to investigate the repeatability of variety grazing efficiency. Correlations were derived between variety performance in separate evaluation years and between variety performances in separate trials. Grazing efficiency was found to be moderately repeatable, with correlation values ranging from 0.47 to 0.86 between years and ranging from 0.51 to 0.84 between trials. The results will provide commercial seed companies with increased confidence when developing variety mixes intended for intensive grazing. Farmers will benefit from improved variety selection and animal performance from their farms. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (PRG) is an important forage grown on dairy farms in temperate regions globally, including south-eastern Australia. A forage value index (FVI) providing information on the seasonal production of commercially available PRG cultivars is currently available. Despite the importance of the nutritive value of pasture in dairy farm systems, the nutritive characteristics of PRG cultivars are not currently included in the FVI as they are not routinely measured in cultivar evaluation trials. This study investigated differences between cultivar functional groups (diploid and tetraploid). It also examined differences between individual cultivars within seasons at four locations in south-eastern Australia and examined how trial location affects cultivar ranking. Samples were collected from existing cultivar evaluation trials over a 3-year period and analysed for nutritive characteristics. There were differences (p < 0.05) between diploids and tetraploids for metabolisable energy (ME) and neutral detergent fibre (NDF) in each season at each location with a few exceptions in summer and autumn. Crude protein (CP) differed between functional groups in some seasons at some sites. Spearman rank correlations within season were strong for ME between trial locations (r = 0.78–0.96), moderate to high for NDF (0.51–0.86) and variable for CP (−0.69–0.56). These findings provide guidance on methods for implementing nutritive value testing in cultivar evaluation trials and support the imminent inclusion of ME in the Australian FVI. The ranking of cultivars for ME was more consistent across trial sites compared to NDF and CP, suggesting the latter two traits, in particular CP, are more sensitive to environmental influences. Based on these results, we do not recommend the inclusion of CP as an individual trait in the Australian FVI. A significantly larger dataset and further research on the genotype by environment interactions would be needed to reconsider this. The addition of ME in the Australian FVI will lead to better cultivar choices by farmers and could lead to more targeted perennial ryegrass breeding programs. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine genetic variability, heritability and correlation of seed yield components and seed yield of progenies of autochthonous populations and cultivars of perennial ryegrass, and that on the basis of these results distinguish genotypes that would be later used in the creation of new local cultivars of perennial ryegrass. Research was carried out on experimental fields and laboratories of the Agricultural Institute of Republic of Srpska in Banja Luka in 2007. and 2008., on 6 natural populations of perennial ryegrass collected in Bosnia and Herzegovina and two cultivars, Maja and Calibra as standard. Following parameters were analyzed: number of generative tillers per plant, time of flowering, spike length, number of spikelets per spike, seed yield per spike and plant and 1000 seed weight. Analysis of the results of the number of generative tillers per plant indicates a statistically significant difference in the studied populations and cultivars of perennial ryegrass. The highest average number of tillers per plant was found in the cultivar Maja (193.8), and the least number was detected in population Dragočaj (78.9), so statistical differences were highly significant. The longest period to beginning of flowering was determined in cultivar Calibra (56.5 days) and the shortest in population Laminci (43 days). The average length of spike of perennial ryegrass in the studied population was 22.78 cm and was significantly lower than cultivar Maja. Statistically significant differences between populations and variety Maja in the number of spikelets per spike were detected. The average seed yield per spike of studied populations was in level with cultivar Maja and 37.5% higher compared with variety Calibra. In the studied populations of perennial ryegrass seed yield ranged from 5.21 g (Dragočaj population) to 15.40 g (Kupres population). Weight of 1000 seeds was highest in the variety Calibra (2.60 g) and lowest in population Maglajani (1.94 g). Proportion of genetic to phenotypic variance for time of flowering, the number of generative tillers, seed yield per spike and plant and 1000 seed weight indicate that the variability of these traits in this collection of genotypes, largely derived from plant genotype. In this investigation, the presence of a highly significant positive genetic correlation was found between time of flowering and spike length (0.98), time of flowering and 1000 seed weight (0.97), number of generative tillers and seed yield per plant (0.91) and spike length and 1000 seed weight (0.98). [ABSTRACT FROM AUTHOR]

Abstract: Dielectric spectroscopy (DS) is routinely used in yeast and mammalian fermentations to quantitatively monitor viable biomass through the inherent capacitance of live cells; however, the use of DS to monitor the enzymatic break down of lignocellulosic biomass has not been reported. The aim of the current study was to examine the application of DS in monitoring the enzymatic saccharification of high sugar perennial ryegrass (HS-PRG) fibre and to relate the data to changes in chemical composition. DS was capable of both monitoring the on-line decrease in PRG fibre capacitance (C =580kHz) during enzymatic hydrolysis, together with the subsequent increase in conductivity (G =580kHz) resulting from the production of organic acids during microbial growth. Analysis of the fibre fractions revealed >50% of HS-PRG lignocellulose had undergone enzymatic hydrolysis. These data demonstrated the utility of DS biomass probes for on-line monitoring of simultaneous saccharification and fermentation (SSF). [Copyright &y& Elsevier]

The plant growth regulator trinexapac-ethyl (TE) is widely used to enhance ryegrass seed yields by reducing lodging (i.e. delaying collapse of the crop). However, lodging data are usually a single evaluation related to TE rate for a particular date of measurement. In eight field trials with varying rates of TE, weekly lodging assessments were made from full head emergence and days to 50% lodging were determined. In all trials, dynamic assessment of TE treatment showed there was a strong positive correlation (R 2 = 0.82) between the number of days to 50% lodging and seed yield. Nil TE reached 50% lodging in 7 days compared with 33 days for TE treatments of 400 g ha-1. On average, one days' delay in reaching 50% lodging increased seed yield by 24 kg ha-1 (response range 16-33 kg ha-1). The data indicate that TE rate per se is less important than the rate required to delay the date that 50% lodging is reached. The seed yield response was linear for delayed lodging from full head emergence to harvest, suggesting that the highest yields are achieved if the crop is not more than 50% lodged at harvest. [ABSTRACT FROM AUTHOR]

The effects of one cycle of selection for adventitious root system shape (i.e. percentage of total root mass in successive depth increments) were investigated in progeny of four perennial ryegrass pools with contrasting rooting patterns: (1) low surface (0-10 cm) root mass and roots to 1 m; (2) high surface root mass and roots to 1 m; (3) high root mass 10-20 cm and roots to 1 m; (4) high surface root mass, shallow rooting. Ten half-sib families were selected from each of the root type progenies, and five seeds from each family were sown and raised as stock plants. Tiller cuttings of each plant were planted into individual 1 m deep root screening tubes of sand and irrigated with nutrient solution After 115 days, the shoots were cut off, the sand/root column cut into 10 cm increments and the roots washed free of sand. The shoots and root samples were oven-dried and weighed. The four root shape progeny groups did not differ significantly for shoot or root dry weight (DW), or root/shoot DW ratio. Root type 2 (high surface root mass and roots to 1 m) progeny had a significantly higher percentage of total root mass between 0 and 10 cm than did root type 1 (low surface root mass and roots to 1 m) but none of the other differences were significant for percentage roots 0-10 cm. The root type 2 progeny had a lower percentage of total root DW between 10 and 20 cm than all the other root types, none of which differed and had a significantly lower percentage of root DW 20-30 cm than types 1 and 4 but did not differ at this depth from type 3 progeny. The probability of root type 4 (high surface root mass, shallow rooting) plants having roots at 1 m depth was 0.67; this was significantly lower than for the other selections, none of which varied significantly. These results indicate that it should be possible to change root system shape in perennial ryegrass using conventional breeding techniques. [ABSTRACT FROM AUTHOR]

The leaf regrowth stage of perennial ryegrass (Lolium perenne L.) is an effective and generic measure to determine the optimum time for defoliation and reflects important physiological processes. Previous research suggests that uptake of phosphorus (P) fertiliser by perennial ryegrass during regrowth may vary with leaf development stage, however little research has been undertaken in this area. The current study aimed to characterise P uptake with sequential leaf development, in order to provide knowledge which could be used to improve the efficiency of P fertiliser uptake. A glasshouse study was used to investigate the uptake of P by ryegrass grown in soil with optimum P fertility. Results showed a positive linear relationship between the 10-leaf stage increments (ranging from 0 to 4 leaves) and both the change in P content in leaves and P uptake by the whole plant (leaves, tiller bases and roots) (P < 0.001 for both relationships and R² = 0.58 and 0.48 respectively). The linear relationship showed that an increasing amount of P was removed from the soil as the regrowth cycle progressed and, although P uptake was greatest at the 4-leaf stage of regrowth, the optimum time of defoliation for perennial ryegrass is between the 2-leaf and 3-leaf stages of regrowth. This suggests that the greatest uptake of P by the plant can be enabled by providing adequate soil P availability prior to the optimum 2-leaf to 3-leaf defoliation interval. [ABSTRACT FROM AUTHOR]

Gibberellins are plant hormones that activate dormant enzyme systems. Applied to pasture, they can stimulate out-of-season growth or accelerate growth through reserve mobilisation, leaf and stem elongation, and promotion of flowering. When evaluating gibberellin as a potential pasture production stimulant, historical investigations frequently used rates ranging from 25-700 g/ha of active ingredient. Responses were found to be uneconomic, and there were often side effects including a decrease in tillering, decreased root mass, and a yield depression subsequent to the initial response. With gibberellic acid now available from China at comparatively cheaper prices than applied historically, and emerging understanding that application rates as low as 5-10 g/ha active ingredient can produce more cost-effective responses, possibly with reduced side effects, there is renewed interest in gibberellin use to increase winter and spring pasture production or manipulate seasonality of production. a rationale for delivery of extension advice is presented. [ABSTRACT FROM AUTHOR]

Root and shoot dry weights (DW), and root DW depth distribution were determined for wild type perennial ryegrass, breeding lines and cultivars. The plants were grown in 1 m deep tubes of sand culture in a glasshouse experiment. There were significant differences in shoot DW among accessions in the wild types but not within the bred material, and the wild types had more accessions with low shoot DW. Root DW varied significantly among accessions in both the bred material and the wild types. There were significant differences in root/shoot DW ratios among accessions, and between pools in the breeding lines, but no differences within the wild types. Root/ shoot ratios in the wild types had a much narrower and generally higher range of values than those in the bred lines. The percentage of root DW in the top 10 cm of sand did not vary significantly in the bred lines but it did in the wild types. Variation was recorded in root DW depth distribution at both the accession and genotype levels. We concluded that selection for merit based on shoot performance does not necessarily result in large root systems, and better plant performance might result from an increase in root system size in perennial ryegrass. [ABSTRACT FROM AUTHOR]

With global warming, high temperature stress has become a main threat to the growth of cool-season turfgrasses, including perennial ryegrass. As one of the conserved plant microRNA families, miR408s are known to play roles in various abiotic stresses, including cold, drought, salinity, and oxidative stress, but no report, thus far, was found for heat. Here, perennial ryegrass plants overexpressing rice Os-miR408 were used to investigate the role of miR408 in plant heat tolerance. Both wild type (WT) and miR408 transgenic perennial ryegrass plants (TG) were subjected to short-term heat stress at 38 °C for 72 h (experiment 1) or at 42 °C for 48 h (experiment 2), and then let recover for 7 days at optimum temperature. Morphological changes and physiological parameters, including antioxidative responses of TG and WT plants, were compared. The results showed that miR408 downregulated the expression of two putative target genes, PLASTOCYANIN and LAC3. Additionally, overexpression of Os-miR408 improved thermo-tolerance of perennial ryegrass, demonstrated by lower leaf lipid peroxidation and electrolyte leakage, and higher relative water content after both 38 and 42 °C heat stresses. In addition, the enhanced thermotolerance of TG plants could be associated with its morphological changes (e.g., narrower leaves, smaller tiller angles) and elevated antioxidative capacity. This study is the first that experimentally reported a positive role of miR408 in plant tolerance to heat stress, which provided useful information for further understanding the mechanism by which miR408 improved plant high-temperature tolerance, and offered a potential genetic resource for breeding heat-resistant cool-season turfgrass in the future. [ABSTRACT FROM AUTHOR]

• Toxicity threshold for ryegrass staggers is lowered the longer perennial ryegrass is fed. • Sub-chronic (>60 day) threshold for lolitrem B is 1554 µg/kg in Angus beef cattle. • Lolitrem B accumulates in fat tissue in a dose- and time-responsive manner. Lolitrem B is a potent tremorgen responsible for the syndrome known as "ryegrass staggers" in livestock consuming perennial ryegrass (Lolium perenne) infected with the endophyte fungus Epichloë festucae var. lolii. We evaluated clinical signs in cattle continuously fed endophyte-infected perennial ryegrass straw at four concentrations of lolitrem B (LB)/ergovaline (EV) (groups: I-2256/638, II-1554/373, III-1012/259 or IV-<300/0 µg/kg LB/EV, n =5-6 steers/group) over 64 days to establish a sub-chronic threshold of toxicity for this mycotoxin; animals were supplemented with 1 kg grain mix/day. Most animals in groups I and II developed clinical signs consistent with ryegrass staggers by day 64; thus, it is recommended that a threshold level of 1554 µg/kg LB should not be exceeded for extended feeding regimens using endophyte-infected perennial ryegrass feed material alone. This toxicity threshold is lower than that observed with shorter feeding periods, i.e. 1800–2000 µg/kg LB when fed for less than 30 days. No clinical signs associated with ergovaline toxicosis (i.e. decreased weekly weight gain) were observed. As adipose tissue appears to be the main compartment where LB is deposited, the concentration of LB and its metabolic derivatives in fat samples was determined at 37 and 64 days. Lolitrem B and three previously defined metabolites bioaccumulated in a dose- and time-dependent manner throughout the feeding experiment in fat tissue, at levels similar to those found in past research. Ratios of metabolites to LB were consistent across time points and dose groups, indicating that the enzyme(s) responsible for LB metabolism were not saturated. In summary, LB toxicity thresholds are dependent upon specificities of the dietary program including the duration feed material is fed, and should be considered when formulating safe livestock feeding regimens. [Display omitted] [ABSTRACT FROM AUTHOR]

Perennial ryegrass is widely used for overseeding dormant bermudagrass on golf courses and sports fields in Southeastern United States to provide green color and improved playability. Late spring and summer persistence of perennial ryegrass may decrease the quality of the bermudagrass turf and reduce its winter hardiness. To help solve this problem, we developed a strategy to activate a pro-herbicide within the transgenic perennial ryegrass plants and to cause self elimination of the plants. An E. coli argE gene was introduced into perennial ryegrass by the biolistic method, which resulted in four independently transformed green plants. The mRNA of argE gene was detected in three of the plants by RT-PCR. Perennial ryegrass plants expressing the argE transgene were selectively controlled upon application of a pro-herbicide, N-acetyl- l-phosphinothricin (or N-acetyl-PPT), since the N-acetylornithinase encoded by argE gene is able to convert N-acetyl-PPT to the herbicide phosphinothricin (PPT). The non-transgenic bermudagrass plants were unaffected by the treatment. This approach provides a means to selectively remove a group of transgenic plants without affecting other plants growing with them. [ABSTRACT FROM AUTHOR]

Plots of five intermediate-heading varieties of perennial ryegrass (Lolium perenne L.) [AberDove, Belramo and Glen (diploid); Twins (tetraploid); and AberExcel (tetraploid hybrid)i were continuously stocked with sheep to maintain a target sward surface height of 4050 mm. Daily dry matter (DM) intake was significantly different (F-value = 0032) between the varieties, with the tetraploid hybrid AberExcel having the highest values for daily DM intake and intake rate during eating. Amongst the diploid varieties, intake rate tended to be higher for sheep grazing Glen. The varieties comprised a wide range in potential growth habit, from the relatively prostrate, highly tillered Glen to the more-erect AberExcel and there were differences between them in the vertical distribution of leaves within the sward canopy. The leaves of AberExcel weighed 16 mg DM cm-2 leaf area in contrast to the other varieties (4·3-5·3 mg DM cm-2 leaf area) resulting in a high leaf area index (LAI) in relation to the green leaf mass. Intake rate was not significantly correlated with extended tiller and sheath tube lengths, partition of herbage mass, number of tillers per square metre or LAI. However, canonical variates analysis showed that there were significant differences between the varieties for the morphological and chemical factors examined. Other factors also need to be explored to explain these differences in ingestive behaviour in order to identify plant traits that are correlated with herbage intake rate. These are needed for varieties destined for grazing use, both during the breeding programme and their subsequent evaluation. [ABSTRACT FROM AUTHOR]

Bermudagrass (Cynodon app.) turf is often overseeded with a cool-season species such as perennial ryegrass (Lolium perenne L.) to provide an improved winter surface for activities such as golf or athletic events. Perennial ryegrass can become a persistent weed in overseeded turf due to the heat and disease tolerance of improved cultivars. Intermediate ryegrass is a relatively new turfgrass that is a hybrid between perennial and annual ryegrass (L. multiflorum Lam.). Very little information is available on intermediate ryegrass as an overseeding turf. Greenhouse, field, and growth chamber studies were designed to compare two cultivars of intermediate ryegrass (`Transist' and `Froghair') with three cultivars of perennial ryegrass (`Jiffie', `Racer', and `Calypso II') and two cultivars of annual ryegrass (`Gulf' and 'TAM-90'). In a greenhouse study, the perennial ryegrass cultivars had finer leaf texture (2.9-3.2 mm), shorter collar height (24.7-57.0 mm), and lower weight/tiller (29-39 mg) than the intermediate and annual cultivars. In the field studies, the intermediate cultivar Transist exhibited improved turfgrass quality (6.1-7.1) over the annual cultivars (4.5-5.8) and the other intermediate cultivar Froghair (5.4-5.7). However, neither of the intermediate cultivars had quality equal to the perennial ryegrass cultivars (7.0-7.9). The perennial ryegrass cultivars exhibited slow transition back to the bermudagrass compared to the annual and intermediate ryegrass cultivars. In the growth chamber study, the annual and intermediate cultivars all showed increased high-temperature stress under increasing temperatures compared to the perennial cultivars, which did not show stress until air temperature exceeded 40°C. Collectively, these studies indicate that the intermediate ryegrass cultivar Transist may have promise as an overseeding turfgrass due to its improved quality compared to annual types and a lack of heat tolerance relative to perennial... [ABSTRACT FROM AUTHOR]

Accumulating herbage mass to facilitate the extension of the grazing season in autumn is commonly practised. The objective of the current study was to investigate the effect of accumulating varying target herbage masses (THM) in autumn and imposing different defoliation dates (DD), on herbage mass, sward quality and water-soluble carbohydrates in autumn and the subsequent spring. A 4 × 3 factorial split plot design was assigned with four THM (Low ≈ 500 kg·DM·ha−1, Medium ≈ 1500 kg·DM·ha−1, High ≈ 2000 kg·DM·ha−1 and Very high ≈ 3000 kg·DM·ha−1) and three DD (DD1—15 October, DD2—7 November and DD3—21 November), across two years. Measurements were carried out at each DD and in spring. Differences in sward quality were found between each THM on different DD. Sward quality reduced from DD2 to DD3 in the high THM (−13 g·kg−1 DM CP, p < 0.001). The very high THM had the lowest sward quality from DD1 (206 g·kg−1 DM CP, p < 0.001 and 787 g·kg−1 DM DMD, p < 0.05). This study has identified the defoliation date of THM in autumn as key to improving autumn management strategies for increased utilisation and sward quality. [ABSTRACT FROM AUTHOR]

• Mixtures of perennial ryegrass varieties did not exhibit significant agronomic benefits. • Mixtures did not enhance grazing efficiency. • Mixture performance can be accurately predicted based on monoculture evaluations. • Inferior varieties within mixtures dilute the agronomic potential of superior varieties. Perennial ryegrass varieties are evaluated in monoculture plots, but in practice are typically sown as combinations of three or more varieties. Monoculture performance is used a predictor of mixture performance, but is questionable, particularly for grazing efficiency traits that interact with the grazing animal. Two field experiments were carried out to examine the production, grazing efficiency and nutritive quality traits of varieties sown in monoculture, and their binary, ternary and quaternary mixtures. Both studies contained two diploid and two tetraploid varieties comprising of only Late heading varieties in Study 1 and combinations of Late and Intermediate heading varieties in Study 2, all managed under cattle grazing with 16 grazing events taking place over two years. Synergistic effects, defined as a higher performance above that of the component variety mean (based on their respective component monoculture performance), were observed within some mixtures for certain traits although these rarely exceeded that of the best component monocultures. Performance differences attributable to ploidy in monoculture were expressed in the mixtures but differences in the spread of heading date within a mixture had few effects. Differences in grazing efficiency between varieties were also expressed within mixtures but with no consistent evidence of a synergistic enhancement of the cattle's willingness or ability to graze sward mixtures more effectively. Mixture performance values were within the range of the component varieties for most traits, indicating that monoculture evaluation can be used as a reliable indicator of the performance of perennial ryegrass mixtures. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effects of cultivar, nitrogen (N) rate and harvest time on the content of water-soluble carbohydrates (WSC), crude protein (CP) and the WSC:CP ratio in the aboveground biomass of perennial ryegrass (Lolium perenne L.). A small-area field experiment was conducted in the Agricultural Experiment Station in Tomaszkowo (53°42′40.8″ N 20°26′04.7″ E, north-eastern Poland). Data were presented for three years of full utilization (2013–2015). The experimental factors were as follows: (i) perennial ryegrass cultivar: Bajka and Baronka, (ii) N rate (kg ha−1): 0, 120, and 240, and (iii) harvest time: 8.00–10.00 a.m., 12.00–2.00 p.m., and 4.00–6.00 p.m. The tetraploid cultivar Baronka had higher WSC content and lower CP content on a dry matter (DM) basis than the diploid cultivar Bajka (by approx. 3% on average). An increase in N fertilizer rate to 240 kg ha−1 contributed to a decrease in WSC concentrations by 23% in cv. Bajka and by 19% in cv. Baronka, and to an increase in the CP content of aboveground biomass by 32% and 23%, respectively. Both cultivars accumulated significantly higher WSC amounts when biomass was harvested at noon and in the afternoon than in the morning. The CP content of biomass was also affected by harvest time, and it was higher in cv. Bajka when harvesting was carried out at 12.00–2.00 p.m. and 4.00–6.00 p.m., and in cv. Baronka when harvesting was carried out at 4.00–6.00 p.m. The WSC:CP ratio in the biomass of the analyzed cultivars was within the optimal range for ruminants, and it was higher in cv. Baronka (1:1.11). Nitrogen applied at 240 kg ha−1 had a negative influence on the WSC:CP ratio, decreasing its value by around 36% (relative to the rate of 120 kg N ha−1) and around 35% (relative to the unfertilized treatment). In both perennial ryegrass cultivars, biomass harvested in the morning was characterized by the lowest WSC:CP ratio. [ABSTRACT FROM AUTHOR]