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Perennial ryegrass (Lolium perenne) is a widely cultivated forage and turf grass species. Salt stress can severely damage the growth of grass plants. The genome-wide molecular mechanisms of salt tolerance have not been well understood in perennial grass species. In this study, the salt sensitive genotype P1 (PI265351, Chile) and the salt tolerant genotype P2 (PI368892, Algeria) of perennial ryegrass were subjected to 200 mM NaCl, and transcriptomics and metabolomics analyses were performed. A total of 5,728 differentially expressed genes (DEGs) were identified through pairwise comparisons. Antioxidant enzyme encoding genes (LpSOD1, LpCAT1), ion channel gene LpCaC1 and transcription factors (LpERFs, LpHSF1 and LpMYB1) were significantly upregulated in P2, suggesting their involvement in regulating expression of salt-responsive genes for salt tolerance. Functional analysis of DEGs revealed that biosynthesis of secondary metabolites, carbohydrate metabolism and signal transduction were the main pathways in response to salt stress. Weighted gene co-expression network analysis (WGCNA) based on RNA-Seq data showed that membrane transport and ABC transporters were significantly correlated with salt tolerance-related traits. The combined transcriptomics and metabolomics analysis demonstrated that the phenylpropanoid biosynthesis pathway was a major secondary metabolic pathway in the salt response of perennial ryegrass. Especially, the tolerant genotype P2 had greater amounts of upregulated phenylpropanoids, flavonoids and anthocyanins and higher expressions of relevant genes in the pathway than the sensitive genotype P1, indicating a role of phenylpropanoid biosynthesis for perennial ryegrass to adapt to salt stress. The results provided insights into the molecular mechanisms of perennial ryegrass adaptation to salinity and laid a base for genetic improvement of salt tolerance in perennial grass species. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is a key forage species in warm temperate to subtropical regions worldwide. Climate change poses significant challenges to agriculture, particularly through drought and heat stress, which adversely affect ryegrass yield and may be further exacerbated by global warming. Despite numerous research achievements in recent years, a comprehensive bibliometric analysis of the literature on drought and heat stress in perennial ryegrass is lacking. This study provides a quantitative analysis of relevant literature published from 1994 to 2024, utilizing the Web of Science database to evaluate global research trends and priorities. The results indicate a consistent annual growth in publication output, with China and the United States being major contributors, and the journal Crop Science publishing the most papers. Keyword analysis shows that "growth," "endophytic fungi," and "yield" are most frequently used in drought stress research, while "growth," "gene," and "leaf" are common in heat stress research. Over the past 30 years, research has mainly focused on phenotype, response mechanisms, and drought and heat resistance techniques in perennial ryegrass. Endophyte have become a hot topic in drought stress research in recent years and have also gained attention in heat stress research, suggesting future research directions in this area. Furthermore, there is a need to strengthen research on the molecular mechanisms associated with drought stress in ryegrass, as well as to explore molecular responses to heat stress. The research trend shows increasing attention to the interaction between drought and heat stress, indicating it will become an important direction for future studies. The findings of this study offer valuable insights for guiding future research on perennial ryegrass under drought and heat stress conditions and provide useful information for researchers in related fields. [ABSTRACT FROM AUTHOR]

Pyroglutamic acid [(5-oxoproline (5-oxp)], a non-protein amino acid, can be converted to glutamate to regulate amino acid metabolism in plants. Its roles in plant adaptation to abiotic stresses, including heat stress, are not well understood. The objectives of this study were to determine whether exogenous application of 5-oxp could promote heat tolerance in cool-season perennial grass species and identify the major metabolic pathways that could be activated or responsive to 5-oxp for enhancing heat tolerance. Perennial ryegrass (Lolium perenne L.) plants were foliar-sprayed with 5-oxp or water (untreated control) prior to and during the exposure to heat stress (35/33 ℃, day/night temperature) or ambient temperature (25/22 ℃, day/night temperature, non-stress control) in controlled-environment growth chambers. Application of 5-oxp improved the heat tolerance of perennial ryegrass, as manifested by the chlorophyll content, photochemical efficiency, cell membrane stability, and antioxidant enzyme activities increasing by 31.2%, 25.7%, 37.2%, and 57.1-258.3%, as well as the reduction in hydrogen peroxide production by 36.8%. Metabolic profiling identified metabolites up-regulated by 5-oxp that are involved in the metabolic pathways of carbon assimilation in photosynthesis, glycolysis and the tricarboxylic acid cycle of respiration, proteinogenic amino acid metabolism, glutathione metabolism, and nucleotide metabolism for DNA or RNA synthesis and ATP generation. The up-regulation or activation of those metabolic processes could contribute to 5-oxp-mediated enhancement in the heat tolerance of perennial ryegrass. [ABSTRACT FROM AUTHOR]

For forage production to be efficient and environmentally sustainable, the extent and timing of nitrogen fertiliser applications should match the uptake and growth capabilities of a grass crop. A two‐year field experiment, comprising four diverse grass cultivars, was conducted to assess the impact of two contrasting N‐application rates on forage and root biomass (RB) production and nitrogen‐use‐efficiencies (NUEs). Replicated field plots of perennial ryegrass, tall fescue and two Festulolium (ryegrass × fescue hybrid) cultivars were compared at Low N (LN) 178 and High N (HN) 356 kg ha−1 over 2 years. HN applications increased dry matter yield (DMY) in Year 1 (p < 0.05) but not in Year 2. Ryegrass outyielded all in Year 1 but in Year 2, fescue had the highest DMY at HN (p < 0.05), but cultivars did not differ in yield at LN. Festulolium yields were consistently intermediate. Root biomass at LN in Yr1 was highest in the Festulolium (Lolium perenne × Festuca arundinacea var glaucescens) (p < 0.05). For all grasses, and in both years, mean RB and nitrogen use efficiency (NUE) and nitrogen utilisation efficiency (NutE) were higher under LN, than HN. Nitrogen uptake efficiency (NupE) was similar in all grasses in Year 1, irrespective of N treatment, but in Year 2, excepting tall fescue, was greater in grasses grown under LN. Increasing RB correlated (p < 0.05) with improved NUE and NutE, but no association was evident for NupE. Grass cultivars differed in their response to nitrogen applications. Whilst relative forage production of ryegrass and fescue contrasted over the 2 years, forage yields of Festulolium cultivars were more consistent. In conclusion, HN application depressed NUE by productive grass cultivars and correlations between RB and NUEs may indicate opportunities to help tailor grass cultivar/fertiliser combinations and achieve sustainable forage and root production. [ABSTRACT FROM AUTHOR]

Abstract Perennial ryegrass (Lolium perenne) is a widely cultivated forage and turf grass species. Salt stress can severely damage the growth of grass plants. The genome-wide molecular mechanisms of salt tolerance have not been well understood in perennial grass species. In this study, the salt sensitive genotype P1 (PI265351, Chile) and the salt tolerant genotype P2 (PI368892, Algeria) of perennial ryegrass were subjected to 200 mM NaCl, and transcriptomics and metabolomics analyses were performed. A total of 5,728 differentially expressed genes (DEGs) were identified through pairwise comparisons. Antioxidant enzyme encoding genes (LpSOD1, LpCAT1), ion channel gene LpCaC1 and transcription factors (LpERFs, LpHSF1 and LpMYB1) were significantly upregulated in P2, suggesting their involvement in regulating expression of salt-responsive genes for salt tolerance. Functional analysis of DEGs revealed that biosynthesis of secondary metabolites, carbohydrate metabolism and signal transduction were the main pathways in response to salt stress. Weighted gene co-expression network analysis (WGCNA) based on RNA-Seq data showed that membrane transport and ABC transporters were significantly correlated with salt tolerance-related traits. The combined transcriptomics and metabolomics analysis demonstrated that the phenylpropanoid biosynthesis pathway was a major secondary metabolic pathway in the salt response of perennial ryegrass. Especially, the tolerant genotype P2 had greater amounts of upregulated phenylpropanoids, flavonoids and anthocyanins and higher expressions of relevant genes in the pathway than the sensitive genotype P1, indicating a role of phenylpropanoid biosynthesis for perennial ryegrass to adapt to salt stress. The results provided insights into the molecular mechanisms of perennial ryegrass adaptation to salinity and laid a base for genetic improvement of salt tolerance in perennial grass species.

Oregon produces 70% of the world's cool-season grass seed, many species of which are susceptible to yellow dwarf viruses (YDVs). This virus complex has numerous defined virus species vectored by multiple aphid species. The diversity of YDVs associated with Oregon grass seed production has not been determined and is needed to provide insight to develop a risk prediction framework and improve management guidelines to mitigate disease severity. Commercial grass seed fields (n = 57) across the Willamette Valley and central and eastern Oregon were surveyed across 2021 and 2022 to determine the incidence and diversity of YDVs associated with crop species (perennial ryegrass, tall fescue, and Kentucky bluegrass) and the abundance and incidence of YDVs associated with aphid vectors. Virus incidence and diversity were determined using multiple previously published endpoint reverse-transcriptase multiplexes specific for YDV genera and species. Across commercial grass seed crop hosts and growing seasons, 82% of fields had at least one plant sample detection of a luteovirus-type YDV, and 65% had at least one detection of a polerovirus-type YDV. Both perennial ryegrass and tall fescue crops hosted diverse YDV populations, which was especially apparent during the spring sampling season, when similarly diverse YDV communities were found associated with alate aphids. Only polerovirus-type YDVs were detected in Kentucky bluegrass, reflecting a variable landscape compared to Oregon's western Willamette Valley. This study provides a current understanding of the spatial composition and diversity of the aphid–YDV virus–vector system in grasses grown for seed in Oregon. [Figure: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2024.

Abstract Pyroglutamic acid [(5-oxoproline (5-oxp)], a non-protein amino acid, can be converted to glutamate to regulate amino acid metabolism in plants. Its roles in plant adaptation to abiotic stresses, including heat stress, are not well understood. The objectives of this study were to determine whether exogenous application of 5-oxp could promote heat tolerance in cool-season perennial grass species and identify the major metabolic pathways that could be activated or responsive to 5-oxp for enhancing heat tolerance. Perennial ryegrass (Lolium perenne L.) plants were foliar-sprayed with 5-oxp or water (untreated control) prior to and during the exposure to heat stress (35/33 ℃, day/night temperature) or ambient temperature (25/22 ℃, day/night temperature, non-stress control) in controlled-environment growth chambers. Application of 5-oxp improved the heat tolerance of perennial ryegrass, as manifested by the chlorophyll content, photochemical efficiency, cell membrane stability, and antioxidant enzyme activities increasing by 31.2%, 25.7%, 37.2%, and 57.1-258.3%, as well as the reduction in hydrogen peroxide production by 36.8%. Metabolic profiling identified metabolites up-regulated by 5-oxp that are involved in the metabolic pathways of carbon assimilation in photosynthesis, glycolysis and the tricarboxylic acid cycle of respiration, proteinogenic amino acid metabolism, glutathione metabolism, and nucleotide metabolism for DNA or RNA synthesis and ATP generation. The up-regulation or activation of those metabolic processes could contribute to 5-oxp-mediated enhancement in the heat tolerance of perennial ryegrass.

Introducing beneficial productivity and nutritional traits into food, feed and forage crops utilising the tools of biotechnology can lead to improvements via genetic modification that cannot be achieved by traditional plant breeding. The timelines and costs are significant, and the regulatory hurdles can lead to some promising traits failing to be commercialised. These challenges mean that large commodity crops are the primary beneficiaries of biotechnology. New Zealand being primarily a grazing pastoral agricultural market and small in international terms, faces greater challenges. The species used in pastoral agriculture have relatively small seed markets and therefore limited investment for genetic improvement. The nutritional quality of feed and forages both in composition and in energy density per ha has a major influence on animal productivity and the environmental impacts of agriculture. Through government and private industry support, AgResearch has developed novel approaches to improve plant photosynthesis, energy density, and nutritional quality that has applications in crops globally. This review discusses the different challenges and solutions to improving plant nutrient density and outlines the benefits of these novel biotechnology traits in animal forage and feed crops. [ABSTRACT FROM AUTHOR]

The phospholipase Ds (PLDs) are crucial for cellular signalling and play roles in plant abiotic stress response. In this study, we identified 12 PLD genes from the genome data of perennial ryegrass (Lolium perenne), which is widely used as forage and turfgrass. Among them, LpPLDδ3 was significantly repressed by ABA treatment, and induced by drought stress and heat stress treatments. The ectopic overexpression (OE) of LpPLDδ3 in Arabidopsis enhanced plant tolerance to osmotic and heat stress as demonstrated by an increased survival rate and reduced malondialdehyde (MDA) accumulation and electrolyte leakage (EL). Arabidopsis endogenous ABA RESPONSIVE ELEMENT BINDING FACTORs (ABFs) and heat stress responsive genes were elevated in LpPLDδ3 OE lines under osmotic and heat stress treatments. Additionally, overexpression of LpPLDδ3 in perennial ryegrass protoplasts could increase heat stress tolerance and elevate expression level of heat stress responsive genes. Moreover, LpABF2 and LpABF4 depressed the LpPLDδ3 expression by directly binding to its ABRE core‐binding motif of promoter region. In summary, LpPLDδ3 was repressed by LpABF2 and LpABF4 and positively involved in perennial ryegrass osmotic and heat stress responses. Summary statement: Twelve PLDs were identified from the perennial ryegrass genome, and LpPLDδ3 was induced by drought and heat.LpPLDδ3 transgene improved stress tolerance in Arabidopsis and perennial ryegrass protoplasts.LpABF2 and LpABF4 depressed the LpPLDδ3 expression by directly binding to its promoter region. [ABSTRACT FROM AUTHOR]

Abstract Background Mixtures with birdsfoot trefoil (BFT) increase herbage intake in grazing cattle. We hypothesized that BFT spatially separated from grasses would increase preferential grazing of BFT and herbage intake compared to grass and BFT in mixed rows. Methods Binary mixtures of BFT were established with orchardgrass, meadow bromegrass, tall fescue, and perennial ryegrass in alternating and in mixed rows. Pastures were rotationally stocked with Jersey heifers, and herbage mass, intake, and preferential grazing were estimated. Results Planting BFT in alternating rows did not affect herbage mass, intake, or BFT preference. Regardless of spatial arrangement, pasture production averaged 4116 kg ha−1 per rotation, of which 32% was BFT. BFT comprised 39% of herbage intake in alternating and mixed rows, 7% greater (p = 0.001) than offered, indicating partial preference for BFT. Greatest preferential grazing of BFT was in tall fescue and orchardgrass mixtures, but less than commonly reported for legumes grown in more contrasting spatial arrangements with cool‐season grasses. Conclusions Grazing heifers showed partial preference for BFT over grass. However, the lack of an effect of spatial arrangement on herbage mass, herbage intake, and diet preference indicates that spatial arrangements greater than alternating rows may be needed to increase overall herbage intake.

Anthropogenic increase in carbon dioxide (CO2) affects plant physiology. Plant responses to elevated CO2 typically include: (1) enhanced photosynthesis and increased primary productivity due to carbon fertilization and (2) suppression of leaf transpiration due to CO2‐driven decrease in stomatal conductance. The combined effect of these responses on the total plant transpiration and on evapotranspiration (ET) has a wide range of implications on local, regional, and global hydrological cycles, and thus needs to be better understood. Here, we investigated the net effect of CO2‐driven perennial ryegrass (Lolium perenne) physiological responses on transpiration and evapotranspiration by integrating physiological and hydrological (water budget) methods, under a controlled environment. Measurements of the net photosynthetic rate, stomatal conductance, transpiration rate, leaf mass per area, aboveground biomass, and water balance components were recorded. Measured variables under elevated CO2 were compared with those of ambient CO2. As expected, our results show that elevated CO2 significantly decreases whole‐plant transpiration rates (38% lower in the final week) which is a result of lower stomatal conductance (57% lower in the final week) despite a slight increase in aboveground biomass. Additionally, there was an overall decline in evapotranspiration (ET) under elevated CO2, indicating the impact of CO2‐mediated suppression of transpiration on the overall water balance. Although studies with larger sample sizes are needed for more robust conclusions, our findings have significant implications for global environmental change. Reductions in ET from ryegrass‐dominated grasslands and pastures could increase soil moisture and groundwater recharge, potentially leading to increased surface runoff and flooding. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne) is an underutilized lignocellulosic biomass that has several benefits such as high availability, renewability, and biomass yield. The grass press-juice obtained from the mechanical pretreatment can be used for the bio-based production of chemicals. Lactic acid is a platform chemical that has attracted consideration due to its broad area of applications. For this reason, the more sustainable production of lactic acid is expected to increase. In this work, lactic acid was produced using complex medium at the bench- and reactor scale, and the results were compared to those obtained using an optimized press-juice medium. Bench-scale fermentations were carried out in a pH-control system and lactic acid production reached approximately 21.84 ± 0.95 g/L in complex medium, and 26.61 ± 1.2 g/L in press-juice medium. In the bioreactor, the production yield was 0.91 ± 0.07 g/g, corresponding to a 1.4-fold increase with respect to the complex medium with fructose. As a comparison to the traditional ensiling process, the ensiling of whole grass fractions of different varieties harvested in summer and autumn was performed. Ensiling showed variations in lactic acid yields, with a yield up to 15.2% dry mass for the late-harvested samples, surpassing typical silage yields of 6–10% dry mass. [ABSTRACT FROM AUTHOR]

Background and aims: Mine tailings often contain high concentrations of metals that may lead to serious environmental concerns. Phytoremediation by suitable plant species, coupled with organic amendments, represents an intriguing way of improving the quality of mine tailings. Methodology: We conducted a glasshouse pot study to assess the impact of biochar derived from wheat straw (BC) and wheat straw (WS) at different application rates (w/w: 0%, 1%, 2%, 5%, 10%) in enhancing physicochemical and biological attributes of iron ore mine tailings. Perennial ryegrass (Lolium perenne L.) growth and uptake of metals (Co, Cu, Fe, Mn, Zn, Cr, Ni, Pb) and As were assessed. Results: The pH(H2O) of iron mine tailings (6.62 with 0% amendment) significantly increased to 8.01 in BC 10% but decreased to 5.33 in WS 10%. However, electrical conductivity, total carbon, total nitrogen and cation exchange capacity increased significantly with application of either amendment. Improvement in physicochemical parameters of tailings by amending with WS was associated with significantly greater plant growth compared with BC amendment. Shoot As and Pb accumulation by perennial ryegrass was low (below detection limit), whereas that of Co, Cu, Fe, Mn, Zn, Cr and Ni increased with an increase in both BC and WS application. Microbial biomass carbon and respiration were enhanced more in the WS than in BC treatments. Conclusion: This study suggests wheat straw is a better amendment than biochar for the iron ore mine tailings. [ABSTRACT FROM AUTHOR]

Background: Mixtures with birdsfoot trefoil (BFT) increase herbage intake in grazing cattle. We hypothesized that BFT spatially separated from grasses would increase preferential grazing of BFT and herbage intake compared to grass and BFT in mixed rows. Methods: Binary mixtures of BFT were established with orchardgrass, meadow bromegrass, tall fescue, and perennial ryegrass in alternating and in mixed rows. Pastures were rotationally stocked with Jersey heifers, and herbage mass, intake, and preferential grazing were estimated. Results: Planting BFT in alternating rows did not affect herbage mass, intake, or BFT preference. Regardless of spatial arrangement, pasture production averaged 4116 kg ha−1 per rotation, of which 32% was BFT. BFT comprised 39% of herbage intake in alternating and mixed rows, 7% greater (p = 0.001) than offered, indicating partial preference for BFT. Greatest preferential grazing of BFT was in tall fescue and orchardgrass mixtures, but less than commonly reported for legumes grown in more contrasting spatial arrangements with cool‐season grasses. Conclusions: Grazing heifers showed partial preference for BFT over grass. However, the lack of an effect of spatial arrangement on herbage mass, herbage intake, and diet preference indicates that spatial arrangements greater than alternating rows may be needed to increase overall herbage intake. [ABSTRACT FROM AUTHOR]

Finely divided carbon char products offer a cost-effective method for the safening of herbicides in soil. In this investigation, two contrasting carbon char sources: Virgin Activated Charcoal (VAC) and Recovered Carbon Black (RCB) products were evaluated for safening of metsulfuron, sulfentrazone and pyroxasulfone herbicides in soil using sugar beet bioassay, and of rimsulfuron using perennial ryegrass bioassay. Plants were grown for seven days in WhirlPack® bags in soil with added carbon char product and added herbicide, and the root or shoot lengths were measured. The VAC was more efficacious in herbicide safening than the RCB. For the VAC, concentrations in soil (wt/wt) as low as 0.375% fully deactivated metsulfuron, sulfentrazone and pyroxasulfone, while for the RCB product a gradual degree of safening was observed, except for pyroxasulfone that was completely deactivated by both VAC and RCB. The VAC at concentrations of 3% and above fully deactivated rimsulfuron, while RCB did not. The two carbon char products examined in this study had different physical properties, of which the specific surface area (91 and 515 m2 g−1 for the RCB and VAC, respectively) and specific surface area of pores (75 and 247 m2 g−1 for RCB and VAC, respectively) showed the greatest difference. Higher surface area promoting greater sorption may explain more effective deactivation of herbicides by the VAC. To obtain the same degree of herbicide safening, more RCB would be required. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is a key forage species in warm temperate to subtropical regions worldwide. Climate change poses significant challenges to agriculture, particularly through drought and heat stress, which adversely affect ryegrass yield and may be further exacerbated by global warming. Despite numerous research achievements in recent years, a comprehensive bibliometric analysis of the literature on drought and heat stress in perennial ryegrass is lacking. This study provides a quantitative analysis of relevant literature published from 1994 to 2024, utilizing the Web of Science database to evaluate global research trends and priorities. The results indicate a consistent annual growth in publication output, with China and the United States being major contributors, and the journal Crop Science publishing the most papers. Keyword analysis shows that “growth,” “endophytic fungi,” and “yield” are most frequently used in drought stress research, while “growth,” “gene,” and “leaf” are common in heat stress research. Over the past 30 years, research has mainly focused on phenotype, response mechanisms, and drought and heat resistance techniques in perennial ryegrass. Endophyte have become a hot topic in drought stress research in recent years and have also gained attention in heat stress research, suggesting future research directions in this area. Furthermore, there is a need to strengthen research on the molecular mechanisms associated with drought stress in ryegrass, as well as to explore molecular responses to heat stress. The research trend shows increasing attention to the interaction between drought and heat stress, indicating it will become an important direction for future studies. The findings of this study offer valuable insights for guiding future research on perennial ryegrass under drought and heat stress conditions and provide useful information for researchers in related fields.

The objectives were to evaluate the nutritional characteristics of perennial ryegrass silage from pile and plastic bale wrapping system (BWS) from Southern Chile using the Cornell Net Carbohydrate and Protein System. Between 2019 and 2021, 445 pile and 435 BWS silage samples were collected from 158 dairies and analyzed by NIRS. Dry matter (DM) and crude protein were significantly lower in pile than in BWS: 35.2% vs. 42.2% and 13.3% vs. 13.9%, respectively. Lignin and aNDFom were significantly higher in pile than in BWS; 51.43% vs. 49.1%; and 4.52% vs. 3.85%, respectively. Total acids were lower in BWS (4.53%) than in pile silages (6.27%). Assuming a cow consuming 25 kg of DM from each silage, the predicted metabolizable energy and protein to produce milk were significantly higher for BWS (41.8 Mcal and 462.3 g) than pile silages (40.3 Mcal and 296.6 g), respectively. Predicted fecal N, P, and K, and CH4 yield in rumen were higher in BWS than in pile silages. It is suggested that by feeding smaller amounts of BWS silage, similar milk yield can be achieved than feeding a greater amount of pile silage, with a potential lower excretion of N, P, K, and methane to the environment.

ABSTRACT For forage production to be efficient and environmentally sustainable, the extent and timing of nitrogen fertiliser applications should match the uptake and growth capabilities of a grass crop. A two‐year field experiment, comprising four diverse grass cultivars, was conducted to assess the impact of two contrasting N‐application rates on forage and root biomass (RB) production and nitrogen‐use‐efficiencies (NUEs). Replicated field plots of perennial ryegrass, tall fescue and two Festulolium (ryegrass × fescue hybrid) cultivars were compared at Low N (LN) 178 and High N (HN) 356 kg ha−1 over 2 years. HN applications increased dry matter yield (DMY) in Year 1 (p

Perennial ryegrass (PRG; Lolium perenne) remains the backbone of grass swards in Northern Ireland due to its improved digestibility persistence, and ease of management compared with other grass species. However, innovative breeding approaches are needed that include positive environmental outcomes, as well as improved productivity in ruminants. The objective of this study was to evaluate the feasibility of root-trait screening and selection using the in situ coring method under commercial grass breeding field conditions. 108 root cores were sampled over a 2-year period from a field trial sown in autumn 2021. Root cores were washed, scanned, and analysed using the open-access root scanning platform Rhizovision. A seasonal effect was noted whereby significant differences were detected in October for root volume, network area, and surface area, but no significant differences for any root parameter were detected in April. No association was observed between root volume, network area, or surface area at the October sampling with either dry matter (DM) yield at the 4th cut (October) or annual DM yield. These results suggest that this method may be useful for identifying improved germplasm in PRG for root characteristics; however, being comparatively labour and time intensive this method may not be practicable for large-scale breeding programmes.

Opportunities exist to accelerate genetic gain in forage breeding using genome-wide selection approaches. In this study, we evaluated rapid cycle recurrent genomic selection (GS) as a means of improving genetic gain for value of annual forage yield. A small population of tetraploid half-sib families was evaluated for seasonal forage yield over two years, and the maternal parent plants were genotyped and genomic prediction models developed. The GS model for value of annual forage yield had a predictive ability of 0.23. An initial round of among-family selection based on field evaluations and within-family selection using genomic estimated breeding values was performed. This was followed by two further GS cycles. New synthetics were produced after each round of selection and were established in a field trial alongside the starting population. A positive response to selection was observed in new synthetics after two successive rounds of rapid cycle recurrent genomic selection before declining in the third round. The genetic gain for the value of annual forage yield was 2.4% from C0 SYN-1 to C1 SYN-1 and 6.4% from C1 SYN-1 to C2 SYN-1. In the case of C0 to C1, genetic gain was compounded by among-family selection based on field evaluations. The implementation of rapid cycle recurrent genomic selection offers an opportunity to increase genetic gain; however, the predictive ability is likely to decay rapidly as selection candidates become more distant from the training population.

In artificially controlled pot experiments, perennial ryegrass was mixed with other leguminous plants (white clover and alfalfa) and treated with lead, zinc and cadmium (337 mg·kg, 648 mg·kg, and 9 mg·kg, respectively) to simulate compound pollution conditions. The results showed that the concentrations of heavy metals, transport factors, and bioconcentration factors in mixed planting of ryegrass decreased compared with those in monoculture. Regardless of whether heavy metal pollution was introduced, mixed planting increased the aboveground and underground biomasses of ryegrass. The different mixed planting treatments had no significant impact on the chlorophyll concentration of ryegrass. The mowing time, mixed planting treatment, and heavy metal treatment had impacts on antioxidant and osmotic adjustment substances, and there were some interactions. The mixed planting treatment did not significantly affect glutathione concentration, cysteine concentration, or nonprotein thiol. Mixed planting generally increased the nitrogen and phosphorus concentrations of ryegrass while reducing the stoichiometric ratio of carbon, nitrogen, and phosphorus. These results suggest that the mixed planting of ryegrass with legumes promotes the growth of ryegrass in the presence of high concentrations of heavy metal pollution. However, it does not enhance the ability of ryegrass to remediate heavy metal pollution in the soil. [ABSTRACT FROM AUTHOR]

Epichloë is a genus of filamentous fungal endophytes that have co-evolved with cool-season grasses with which they form long-term, symbiotic associations. In natural ecosystems Epichloë have implications for species diversity, food web structures and fundamental ecological processes. Epichloë produce a range of secondary metabolites that can have negative effects on herbivores, be they invertebrates or vertebrates. In many managed pastoral systems, selected asexual Epichloë strains are purposefully associated with grass cultivars (termed novel endophyte-grass associations) as they confer beneficial traits that protect the host from abiotic stresses (e.g. drought) and biotic stresses (e.g. herbivory from invertebrates) while having minimal impact on the health and welfare of ruminant livestock. As well as conferring beneficial traits, agriculturally selected strains of Epichloë can also increase plant biomass and seed yield. Epichloë endophyte-technology has and continues to be a scientific, agricultural, and marketing success with selected asexual strains of Epichloë now essential components of many pasture ecosystems, within New Zealand and abroad. An estimated 90% of proprietary ryegrass now sold in New Zealand contains a selected endophyte strain while the economic impact in New Zealand of AR37 alone has been estimated at NZ$3.6 billion over 20 years. With a changing climate, agriculture will continue to experience increasing temperatures, elevated atmospheric CO2 levels and changing precipitation patterns that will likely increase the geographic range and overwintering survival rates of pests. Furthermore, plant disease outbreaks are expected to intensify due to increases in the severity of existing phytopathogens and/or invasions by new phytopathogens. Functional symbioses, such as those between temperate grasses and Epichloë, are among the most successful mechanisms by which plants can improve their ability to tolerate stress. Future research is likely to utilise targeted genetic manipulation techniques to broaden the biocontrol ability of Epichloë strains, particularly to mitigate climate related stresses. [ABSTRACT FROM AUTHOR]

Perennial ryegrass is the most widely grown temperate grass species globally as a source of forage (grazing, hay, silage) or for amenity use. It is a part of landscape, protects soil from water and wind erosion, enriches it with organic substances and improves its fertility. During the period 2015-2020 in the Institute of Forage crops (IFC) - Pleven a collection nursery was studied in field non-irrigated conditions on leached black soil, in block duplicate method, in 2 replications with a total of 19 accessions of perennial ryegrass, with 50 individual plants each (25 plants for forage and 25 plants - for seeds), including 14 varieties and 5 ecotypes, 10 tetraploid and 9 diploid, from Bulgaria (BG), Belgium (BE), and Romania (RO). The aim is to determine the vitality per year and longevity (after many years, more than 3-4) of perennial ryegrass collection accessions and to make a selection of the most vital and long - lasting genotypes. Scale of survival according to the International Classifier for the family Poaceae (Bukhteeva et al., 1985) was used - limiting factors of the environment are cold - winter, drought and high temperatures - summer. An autumn inventory of the individual plants no./% was carried out annually, as 25 plants per sample = 100%., and vitality classification as follows: Very Low - less than 1 to 20% of plants are left alive; Low - more than 21 to 50%; Medium - more than 51% to 70%; High - more than 71 to 90%; Very High - more than 90% of the plants are still alive. Computer statistical processing of the data (via Excel, at P = 0.05) included variance analyses. Data on vitality and longevity are characterized by: marginal values (min and max), arithmetic mean (x), standard deviation (SD) and coefficient of variation (CV,%). Variation was considered weak, moderate, or strong at CV values, respectively: up to 10%; > 10-20%, and > 20% (Dimova and Marinkov, 1999). When grown for fodder, the local ecotypes Sokolare, Topolovgrad and Bekovi skali are the most viable by years and the longest surviving up to 5 years, with the percentage of plants alive in the fifth year being the highest for the Sokolare ecotype. Ecotype Sokolare is strongly influenced by the method of use, which is the longest-lasting and most viable when grown for fodder - 5 years and the shortest - when grown for seeds - 3 years. All diploid varieties live up to 4 years, and only the Harmoniya variety up to 5 years, with the Bulgarian varieties Harmoniya and Strandzha being the most viable and long-lasting when grown for fodder. Harvesting once a year for seeds extends the life cycle of diploid varieties up to 5 years and for the Harmoniya variety - up to 6. The Bulgarian tetraploid varieties Tetrany, Tetramis and the Belgian varieties Floris, Melpetra and Melverde are the most durable and long-lasting. One-time harvesting per year for seeds extends the life cycle of the tetraploid varieties up to 5 years, and for the Bulgarian varieties Tetrany, Tetramis and the Belgian varieties Floris, Melpetra and Melverde - up to 6. [ABSTRACT FROM AUTHOR]

Abstract Anthropogenic increase in carbon dioxide (CO2) affects plant physiology. Plant responses to elevated CO2 typically include: (1) enhanced photosynthesis and increased primary productivity due to carbon fertilization and (2) suppression of leaf transpiration due to CO2‐driven decrease in stomatal conductance. The combined effect of these responses on the total plant transpiration and on evapotranspiration (ET) has a wide range of implications on local, regional, and global hydrological cycles, and thus needs to be better understood. Here, we investigated the net effect of CO2‐driven perennial ryegrass (Lolium perenne) physiological responses on transpiration and evapotranspiration by integrating physiological and hydrological (water budget) methods, under a controlled environment. Measurements of the net photosynthetic rate, stomatal conductance, transpiration rate, leaf mass per area, aboveground biomass, and water balance components were recorded. Measured variables under elevated CO2 were compared with those of ambient CO2. As expected, our results show that elevated CO2 significantly decreases whole‐plant transpiration rates (38% lower in the final week) which is a result of lower stomatal conductance (57% lower in the final week) despite a slight increase in aboveground biomass. Additionally, there was an overall decline in evapotranspiration (ET) under elevated CO2, indicating the impact of CO2‐mediated suppression of transpiration on the overall water balance. Although studies with larger sample sizes are needed for more robust conclusions, our findings have significant implications for global environmental change. Reductions in ET from ryegrass‐dominated grasslands and pastures could increase soil moisture and groundwater recharge, potentially leading to increased surface runoff and flooding.

ABSTRACT: 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.

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]

Drought stress, which often occurs repeatedly across the world, can cause multiple and long-term effects on plant growth. However, the repeated drought–rewatering effects on plant growth remain uncertain. This study was conducted to determine the effects of drought–rewatering cycles on aboveground growth and explore the underlying mechanisms. Perennial ryegrass plants were subjected to three watering regimes: well-watered control (W), two cycles of drought–rewatering (D2R), and one cycle of drought–rewatering (D1R). The results indicated that the D2R treatment increased the tiller number by 40.9% and accumulated 28.3% more aboveground biomass compared with W; whereas the D1R treatment reduced the tiller number by 23.9% and biomass by 42.2% compared to the W treatment. A time-course transcriptome analysis was performed using crown tissues obtained from plants under D2R and W treatments at 14, 17, 30, and 33 days (d). A total number of 2272 differentially expressed genes (DEGs) were identified. In addition, an in-depth weighted gene co-expression network analysis (WGCNA) was carried out to investigate the relationship between RNA-seq data and tiller number. The results indicated that DEGs were enriched in photosynthesis-related pathways and were further supported by chlorophyll content measurements. Moreover, tiller-development-related hub genes were identified in the D2R treatment, including F-box/LRR-repeat MAX2 homolog (D3), homeobox-leucine zipper protein HOX12-like (HOX12), and putative laccase-17 (LAC17). The consistency of RNA-seq and qRT-PCR data were validated by high Pearson's correlation coefficients ranging from 0.899 to 0.998. This study can provide a new irrigation management strategy that might increase plant biomass with less water consumption. In addition, candidate photosynthesis and hub genes in regulating tiller growth may provide new insights for drought-resistant breeding. [ABSTRACT FROM AUTHOR]

Background This study investigated the factors relating to pasture chemical and fatty acid (FA) composition that influence the milk fat percentage of spring calving, grazing dairy cows. The relationship between milk fat percentage and FA composition of the milk in these herds was also investigated. Results Milk protein percentage, milk casein percentage and cheddar cheese yield were increased in milk from HMF herds. Cows from LMF herds did not have negatively altered milk processability including rennet coagulation time (RCT), pH and ethanol stability. Crude protein, NDF, ADF, ether extract and total FA content of pasture was not different between LMF and HMF herds. Milk fat concentration of conjugated linoleic acid (CLA) t10, c12 was not different between HMF and LMF herds. Pre-grazing herbage mass and pasture content of crude protein, neutral detergent fibre (NDF) and total FA were similar between HMF and LMF herds. Pasture offered to LMF herds had a higher concentration of monounsaturated fatty acids (MUFA). A strong negative relationship (r = -0.40) was evident between milk fat percentage and pasture crude protein content for MMF herds (3.31-3.94% milk fat). Conclusions This research reports improved milk protein percentage, milk casein percentage and cheddar cheese yield from HMF herds compared to LMF herds. Milk processability was not impacted by low milk fat percentage. Pasture NDF and total fatty acid content was similar in HMF herds and LMF herds. Milk fat percentage had a strong negative association (r = -0.40) with pasture crude protein content in MMF herds (MF 3.31-3.94%). Correlation values between pasture chemical and FA composition and milk fat percentage in LMF herds and HMF herds were low, indicating that diet is not the only causative factor for variation in milk fat of grazing dairy cows. Comparison of milk fatty acid composition from herds with and without milk fat depression suggests that there may be other fatty acids apart from CLA t10, c12 that contribute to the inhibition of milk fat synthesis during milk fat depression in grazing herds. [ABSTRACT FROM AUTHOR]

The chemical composition of 21 accessions of Lolium perenne L. from the collection nursery of Institute of Forage Crops - Pleven, for three cuts each year, for the period 2017-2018, was evaluated as follows: crude protein (CP), % – according to Kjeldahl‘s method; crude fiber (CF), % – by Weende analysis; water-soluble carbohydrates (WSC) – according to Ermakov et al. Statistical processing of the data was performed, which included regression, correlation, two-factor ANOVA and cluster analyses. There is a trend in both years for the first cut to be lowest in crude protein (CP); relatively high in crude fiber (CF) and highest in water soluble carbohydrates (WSC) content. In the second and third cuts, crude protein increases; crude fiber content varies within different limits, but generally decreases; and the amount of water-soluble carbohydrates also decreases. The genotype–environment (accessions x cuts) interaction had insignificant variance in all three studied traits. In terms of CP, the maximum value was reported for the Iljo variety (18.8%) and the minimum for China (14.6%). No significant differences were observed between the check Tetrany (16.1%) and the other accessions. Only two cases of significant differences were observed for CF and WSC between accessions. The cluster analysis arranges the accessions into three groups, with the second cluster of 8 accessions being the most interesting for the selection. The analysis well differentiates the accessions regarding the optimal combination of the three traits in one genotype, as well as their ploidy level. A significant negative correlation was observed between crude protein and crude fiber content (r=-0.744). [ABSTRACT FROM AUTHOR]

Rapid identification of herbicide-resistant weeds plays a crucial role in their management. Glyphosate resistance in Lolium perenne is a growing issue in New Zealand and can be conferred by a single nucleotide polymorphism (SNP) causing amino acid substitutions at codon 106 in the 5-enolpyruvoylshikimate-3-phosphate synthase (EPSPS) gene. High-throughput molecular (HTM) methodologies that can detect such SNPs include high-resolution melting and real-time quantitative PCR probe assays. Here, we compare the effectiveness of both assays with a more labour-intense derived cleaved amplified polymorphic sequence (dCAPS) test for detecting SNPs at codon 106. The results showed that both HTM assays detected mutations at this codon, and their results were consistent with those of the dCAPS. Unlike dCAPS, however, the HTM assays over-estimated homozygosity for the glyphosate resistance allele. Nevertheless, cost-effective high-throughput detection of resistance is more important than the zygosity status when initiating an on-farm management response. In summary, both HTM assays successfully identified glyphosate resistance alleles at codon 106 in the EPSPS gene. Given that both assays are more cost-effective and can screen a larger number of samples in a timely manner compared to the dCAPS method, they can be used as quick tests for detecting glyphosate resistance in L. perenne. [ABSTRACT FROM AUTHOR]

Resistance to iodosulfuron, a herbicide targeting acetolactate synthase (ALS), was identified and characterised in a population of Lolium perenne L. from Canterbury, New Zealand. The resistant population was 264 times more resistant to iodosulfuron than a susceptible population, based on a ratio of the rate corresponding to a 50% reduction in resistant and susceptible plant survival (R/S LD50). The resistant population was also 14-times more resistant to nicosulfuron, another ALS-inhibitor of the same class. However, no resistance to imazapyr, an ALS-inhibitor from a different chemical class, was detected in the resistant population. Pre-treatment with an inhibitor of cytochrome P450 reduced the level of iodosulfuron resistance to 46-fold in the resistant population, suggesting enhanced herbicide metabolism, a non-target site mechanism, contributed to resistance of this herbicide. In addition, a proline to leucine substitution at codon 197 was detected, suggesting a target-site-based mechanism was also associated with resistance to iodosulfuron. This is the first report on the resistance mechanisms to ALS-inhibiting herbicides identified in Lolium perenne in New Zealand and highlights the importance of integrated weed management approaches to reduce the likelihood of ALS-inhibitor herbicide resistance becoming more widespread. [ABSTRACT FROM AUTHOR]

Treatment of plants with mineral-organic concentrates has developed intensively in recent years. Fertilizers containing, among others, humus, L-amino acids, vitamins, chelates and metal complexes, macro-, micro- and meso-elements, organic matter and humic acids from the top organic layer of leonardite coal have a positive effect on plant growth and quality and seed yield. An experiment was conducted between 2019 and 2022 at the University of Agriculture in Kraków, in which the impact of mineral-organic concentrate on the seed yield and quality of perennial ryegrass (Lolium perenne L.) 2N Bokser (Hodowla Roślin Grunwald Ltd. Grupa IHAR, Grunwa, Poland) was determined. As part of the experiment, plants were sprayed with a mineral-organic product in three different doses: 1.0, 2.0 and 3.0 L·ha−1. The following parameters were examined: the number of generative shoots, the length of the flag leaf, seed yield, germination capacity and the weight of one thousand seeds. It turned out that the application of the concentrate with 3 L·ha−1 and 2 L·ha−1 led to a significant increase in the number of generative shoots and in seed yield, compared to control. In addition, seed germination capacity of fertilized plants was higher, with the greatest increase after the application of 3 L·ha−1. Moreover, the average weight of one thousand seeds was significantly higher in fertilized plants, compared to the control, and the largest increase was recorded in response to the highest dose. The results indicated a positive effect of the organic-mineral concentrate on perennial ryegrass development parameters and seed quality. [ABSTRACT FROM AUTHOR]

Genome editing technologies provide a powerful tool for genetic improvement of perennial ryegrass, an important forage and turfgrass species worldwide. The sole publication for gene editing in perennial ryegrass used gene-gun for plant transformation and a dual promoter based CRISPR/Cas9 system for editing. However, their editing efficiency was low (5.9% or only one gene-edited plant produced). To test the suitability of the maize Ubiquitin 1 (ZmUbi1) promoter in gene editing of perennial ryegrass, we produced ZmUbi1 promoter:RUBY transgenic plants. We observed that ZmUbi1 promoter was active in callus tissue prior to shoot regeneration, suggesting that the promoter is suitable for Cas9 and sgRNA expression in perennial ryegrass for high-efficiency production of bi-allelic mutant plants. We then used the ZmUbi1 promoter for controlling Cas9 and sgRNA expression in perennial ryegrass. A ribozyme cleavage target site between the Cas9 and sgRNA sequences allowed production of functional Cas9 mRNA and sgRNA after transcription. Using Agrobacterium for genetic transformation, we observed a 29% efficiency for editing the PHYTOENE DESATURASE gene in perennial ryegrass. DNA sequencing analyses revealed that most pds plants contained bi-allelic mutations. These results demonstrate that the expression of a single Cas9 and sgRNA transcript unit controlled by the ZmUbi1 promoter provides a highly efficient system for production of bi-allelic mutants of perennial ryegrass and should also be applicable in other related grass species.

Background. Current molecular and genetic approaches make it possible to accelerate ryegrass breeding, simplify source material evaluation, and increase its accuracy. The efficiency of PCR-based SSR and SCoT marker techniques was studied in the context of evaluating the genetic structure of annual and perennial ryegrass accessions and defining DNA-identifying markers.Materials and methods. Genomic DNA was isolated from the aggregate sample of 30 seedlings from each of the 15 analyzed cultivars according to the modified SDS DNA extraction protocol. In total, 20 SSR and 22 SCoT markers were used to assess genetic polymorphism. Basic parameters of the markers’ informative efficiency were identified. Genetic relationships among the studied cultivars were analyzed on the basis of the Neighbor-Joining dendrogram and Bayesian model.Results. To assess the genetic polymorphism of ryegrass species and varieties, 7 SSR loci were selected, for which 110 allelic variants were identified (34 alleles were unique for individual cultivars), and 9 SCoT loci, for which 78 polymorphic amplification fragments were identified, with 28 being cultivar-specific. The dendrogram of genetic similarity and modeling in the Structure v2.3.4 program according to the results of SSR and SCoT analyses distributed the cultivars by their traits according to their species, ploidy level, origin, and similarity. Based on PCoA, carried out using summarized data of SSR and SCoT analyses, a multidimensional diagram of genetic relationships among ryegrass cultivars was constructed.Conclusions. The systems of SSR and SCoT markers appeared to be an efficient tool to reveal genetic polymorphism and identify differences among ryegrass species and cultivars. We found unique DNA profiles that can be used for genetic identification. The results of the study have practical significance in cultivar-specific identification and selection of cultivars for various purposes.

Abstract 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.

Humic acid (HA) has been used as an important component in biostimulant formulations to enhance plant tolerance to salt stress, but the mechanisms underlying are not fully understood. This study was to investigate the physiological and molecular mechanisms of HA’s impact on salt stress tolerance in perennial ryegrass (Lolium perenne L.). The two types of HA were extracted from weathered coal samples collected from Wutai County (WTH) and Jingle County (JLH) of Shanxi Province, China. The grass seedlings subjected to salt stress (250 mM NaCl) were treated with HA solutions containing 0.01% WTH (W/V) or 0.05% JLH (W/V), respectively. The HA treatments improved leaf photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) and reduced leaf oxidative injury (lower malondialdehyde content) and Pro and intercellular CO2 concentrations in salt-stressed perennial ryegrass. The HA treatments also reversed the decline in antioxidative enzymes ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activity and improved growth and anti-senescence hormones indole-3- acetic acid (IAA) and brassinosteroid (BR). The HA treatments reduced the relative expression of P5CS and its downstream products proline (Pro) and the stress defense hormones abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), and polyamines (PA). The results of this study indicate that the application of HAs may improve salt stress tolerance by regulating P5CS gene expression related to osmotic adjustment and increasing the activity of antioxidant enzymes and anti-senescence hormones in perennial ryegrass. [ABSTRACT FROM AUTHOR]

Precise information about carbohydrates and proteins in relation to their utilization in the rumen is useful for the breeding purposes of perennial ryegrass cultivars used for animal nutrition. The objective of the current study was to evaluate 20 diploid perennial ryegrass accessions from the intermediary heading stage. The ruminal kinetics of different carbohydrate and protein fractions of grasses and legumes are important for forage breeding programs. The Cornell Net Carbohydrate and Protein System (CNCPS) was used to provide such information. Accession-based variation can be observed after considering dynamic degradation processes. Variation among the 20 accessions was observed. Ruminally digested (RDC) and undigested (UDC) carbohydrate and ruminally degraded (RDP) and undegraded (UDP) protein contents, total carbohydrate and total protein contents, and carbohydrate and protein fractions for the first cut and annual averages show significant differences. Although the variation was smaller for the protein fractions, the calculated usable protein content (uCP, sum of UDP and amount of synthesized microbial protein in the rumen) in the small intestine is mainly influenced by decreasing the neutral detergent fiber (NDF) and increasing the sugar content among cultivars. Carbohydrate and protein fractionation is suitable for characterizing perennial grass accessions as it uses parameters relevant to ruminant nutrition, allowing a step forward in forage plant breeding for forage quality. To conclude, using parameters related to ruminal degradation kinetics should favor the selection of accessions with higher amounts of ruminally digested carbohydrates (RDC). The selection of accessions based on protein quality (proportion of UDP) is less favorable for achieving a higher usable protein content. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to investigate the effect of additives on the fermentation properties of ensiled mixed alfalfa and perennial ryegrass silage in the karst terrain of Southwest China. A mixture of alfalfa and perennial ryegrass was ensiled at a ratio of 3:7 using three experimental treatments: (1) CK (without additives) and distilled water (5 mL kg−1 fresh weight (FW)); (2) FA and formic acid (88%) (5 mL kg−1 FW); and (3) LAB combined with the application of Lactiplantibacillus plantarum and Lentilactobacillus buchneri (2 × 107 cfu/g FW). All samples were packed manually into polyethylene bags, and three polyethylene bags from each treatment were sampled on days 7, 15, and 45. The findings demonstrated that the pH values of all the mixed silages gradually decreased during ensiling. The lactic acid (LA) and acetic acid (AA) contents increased gradually with ensiling time and peaked after 45 days of ensiling. After 45 days of ensiling, the FA and LAB groups effectively preserved the nutrient content of the mixed silage, which presented a reduced neutral detergent fiber and acid detergent fiber content (p < 0.05) and higher water-soluble carbohydrate content (p < 0.05) than the CK group. The fermentation quality of the mixed silages in the FA and LAB groups improved, as indicated by higher (p < 0.05) LA contents and lower (p < 0.05) pH and ammoniacal nitrogen contents after 45 days of ensiling compared to those in the CK group. As fermentation progressed, the abundance of harmful microorganisms (Hafnia obesumbacterium, Enterobacteriaceae, and Sphingomonas) and beneficial microorganisms (Lactiplantibacillus and Lentilactobacillus) decreased and increased, respectively. In addition, compared to those in the CK group, the FA group had higher abundances of "lipid metabolism" and "biosynthesis of antibiotics" and lower abundances of "membrane transport". Briefly, the results of this study suggest that the incorporation of FA and LAB additives could improve the quality of fermented mixed silage, and that FA is better than LAB. This information is useful for combining forage resources to satisfy the requirements for high-protein feed and for manufacturing ruminant feed annually. [ABSTRACT FROM AUTHOR]

Effects of Calcium Ammonium Nitrate (CAN) and Stabilized Urea (SU) fertilizers were compared for herbage yield and composition and silage composition of perennial ryegrass (Lolium perenne L.) swards over a two‐year study. The aim of this experiment was to establish the likely impacts of farmers transitioning to using SU fertilizers in order to reduce the nitrogenous emissions associated with silage production as the agriculture industry moves to address the challenges of climate change. Experimental plots of 7.5 m2 area were established in a randomized block experiment comprising 4 replicates of 18 treatments in a 3 × 6 factorial design (4 × 3 × 6 = 72 plots) for each of 3 silage harvest periods in 2018, and repeated in 2019. Herbage samples and yield measurements were collected weekly for weeks 2–7 post fertilizer application, and herbage harvested after seven weeks regrowth was ensiled and silage was analysed after 100 days. There were no significance differences overall between responses of CAN and SU fertilized plots in terms of grass dry matter (DM) yield and quality parameters (acid detergent fibre (ADF), ash, buffering capacity (BC), metabolisable Energy (ME), nitrate (NO32−), nitrogen (N), or water soluble carbohydrate (WSC) or silage quality parameters (DM, volatile corrected organic dry matter (VCODM), ammonia nitrogen as a fraction of total nitrogen (NH3‐N/ Total N), pH, crude protein (CP), lactic acid (LA), acetic acid (AA), propionic acid (PA), butyric acid (BA), ethanol, propanol, ADF, ash, WSC or dry matter digestibility (DMD). Numerous significant differences between week and between cut were identified for grass quality, silage quality and grass ensilability parameters, and in the grass DM yields recorded. However, in many instances there was no associated treatment effect identified. There were no significant interactions between CAN and SU treatments and either cut, or week for nitrate concentration or yield. Variance of nitrate concentration was highest at the third cut and indicates a reduction in the nitrogen use efficiency of the 3rd cut silage harvest, potentially demonstrating a need to reduce fertilizer application recommendations for late‐season silage harvests. Overall, the results of this study support the hypothesis that replacing the currently favoured CAN fertilizer products with SU will not impact production of grass silage in Northern Ireland, meaning SU can be confidently adopted by farmers as a mitigation strategy to reduce farm nitrogenous emissions without reducing levels of sward productivity. This study recorded average annual grass silage DM yields of 15.5 and 16.1 t DM/ha from the CAN and SU fertilizer treatments respectively, which were not significantly different. In addition, the yield gain response to the application of each fertilizer type were not significantly different at 21.51 and 23.24 kg of DM produced for every kg of N applied as SU or CAN respectively, relative to control plots receiving 0 nitrogen. [ABSTRACT FROM AUTHOR]

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Epichloë festucae uses a siderophore‐mediated system to acquire iron, which is important to maintain endophyte–grass symbioses. Here we investigate the roles of the alternative iron acquisition system, reductive iron assimilation (RIA), via disruption of the fetC gene, which encodes a multicopper ferroxidase, either alone (i.e., ΔfetC) or in combination with disruption of the gene sidA, which encodes a siderophore biosynthesis enzyme (i.e., ΔfetC/ΔsidA). The phenotypic characteristics of these mutants were compared to ΔsidA and wild‐type (WT) strains during growth under axenic culture conditions (in culture) and in symbiosis with the host grass, perennial ryegrass (in planta). Under iron deficiency, the colony growth rate of ΔfetC was slightly slower than that of WT, while the growth of ΔsidA and ΔfetC/ΔsidA mutants was severely suppressed. Siderophore analyses indicated that ΔfetC mutants hyperaccumulate ferriepichloënin A (FEA) at low iron concentrations and ferricrocin and FEA at higher iron concentrations. When compared to WT, all mutant strains displayed hyperbranching hyphal structures and a reduced ratio of Epichloë DNA to total DNA in planta. Furthermore, host colonization and vertical transmission through infection of the host seed were significantly reduced in the ΔfetC/ΔsidA mutants, confirming that high‐affinity iron uptake is a critical process for Epichloë transmission. Thus, RIA and siderophore iron uptake are complementary systems required for the maintenance of iron metabolism, fungal growth, and symbiosis between E. festucae and perennial ryegrass. [ABSTRACT FROM AUTHOR]

Technological development has increased the use of chemical elements that have hitherto received scant scientific attention as environmental contaminants. Successful management of these rare trace elements (RTEs) requires elucidation of their mobility in the soil–plant system. We aimed to determine the capacity of Lolium perenne (a common pasture species) to tolerate and accumulate the RTEs Be, Ga, In, La, Ce, Nd, and Gd in a fluvial recent soil. Cadmium was used as a reference as a well-studied contaminant that is relatively mobile in the soil–plant system. Soil was spiked with 2.5–283 mg kg−1 of RTE or Cd salts, representing five, 10, 20, and 40 times their background concentrations in soil. For Be, Ce, In, and La, there was no growth reduction, even at the highest soil concentrations (76, 1132, 10.2, and 874 mg kg−1, respectively), which resulted in foliar concentrations of 7.1, 12, 0.11, and 50 mg kg−1, respectively. The maximum no-biomass reduction foliar concentrations for Cd, Gd, Nd, and Ga were 0.061, 0.1, 7.1, and 11 mg kg−1, respectively. Bioaccumulation coefficients ranged from 0.0030–0.95, and increased Ce < In < Nd ≅ Gd < La ≅ Be ≅ Ga < Cd. Beryllium and La were the RTEs most at risk of entering the food chain via L. perenne, as their toxicity thresholds were not reached in the ranges tested, and the bioaccumulation coefficient (plant/soil concentration quotient) trends indicated that uptake would continue to increase at higher soil concentrations. In contrast, In and Ce were the elements least likely to enter the food chain. Further research should repeat the experiments in different soil types or with different plant species to test the robustness of the findings. [ABSTRACT FROM AUTHOR]

ABSTRACT: This experiment investigated the variation in enteric methane production and associated gas exchange parameters, nutrient digestibility, rumen fermentation, and rumen microbiome when a range of silages based on different forage types (grass or clover), and different species within the 2 types, were fed as the sole feed to heifers. Three grass species (perennial ryegrass, festulolium, and tall fescue) and 2 clover species (red clover and white clover) were included. Perennial ryegrass was harvested at 2 maturity stages in the primary growth, white clover was harvested once in the primary growth, and 4 cuts of festulolium and tall fescue and 3 cuts of red clover were harvested during the growing season, giving 14 different silage batches in total. Sixteen Holstein heifers 16 to 21 mo old and 2 to 5 mo in pregnancy were fed the silages ad libitum as the sole feed in an incomplete crossover design. Each silage was fed to 4 heifers, except for the 2 perennial ryegrass silages, which were fed to 8 heifers; in total 64 observations. The CH4 production was measured for 3 d in respiration chambers. Heifers fed clover silages had higher dry matter intake (DMI) compared with heifers fed grass silages, and heifers fed tall fescue silages had the numerically the lowest DMI. Compared with grass silages, feeding clover silages led to higher crude protein digestibility but lower neutral detergent fiber (NDF) digestibility. Rumen pH was higher in heifers fed clover silages compared with those fed grass silages. Based on composition analysis, the rumen microbiota of the heifers clustered clearly according to forage type and species. More specifically, 7 of the 34 dominating rumen bacterial genus-level groups showed higher relative abundances for the clover silages, whereas 7 genus-level groups showed higher abundances for the grass silages. Methane yield was higher for heifers fed grass silages than for those fed clover silages when methane production was related to dry matter and digestible organic matter intake, whereas the opposite was seen when related to NDF digestion. The gross energy lost as methane (CH4 conversion factor, %) reduced from 7.5% to 6.7%, equivalent to an 11% reduction. The present study gives the outlines for choosing the optimal forage type and forage species with respect to nutrient digestibility and enteric methane emission in ruminants.

Abstract Background Tall fescue (Festuca arundinacea [Schreb.], Lolium arundinaceum [Schreb.] Darbysh) and perennial ryegrass (Lolium perenne) are important cool‐season forage and amenity grasses that have a mutualistic association with an endophytic fungus. Endophytes confer insect and drought resistance to plants but can produce mammalian toxins. Novel endophytes that do not produce mammalian toxins have been introduced to elite cultivars for commercial production. Seed companies need to maintain adequate levels of novel endophytes within the elite forage cultivars. Endophyte detection is performed using immunochemical and molecular techniques because of their speed and reliability. Early detection in seedlings is essential to evaluate the viability of the endophyte within seed lots. Methods This research aimed to identify the earliest growth stage in which immunochemical and molecular methods can detect viable endophyte in seedlings of tall fescue cultivars BarOptima (e34), Texoma MaxQII (584), and Jesup MaxQ (542), as well as the perennial ryegrass cultivar Remington (NEA2). Results Immunochemical testing detected endophytes in seedlings 14 days after germination (DAG), but the detection rate increased until 42 DAG in some cultivars tested. The molecular marker Tef1exon detected endophytes at a lower rate than the immunochemical method at 28–42 DAG. However, there was insufficient DNA to detect endophytes in 14 DAG seedlings using markers. Conclusions We conclude that the most accurate detection of viable endophytes in seedlings was 42 DAG, at which sufficient and consistent endophyte colonization occurred.

Significant greenhouse gas emissions during substrate cultivation reduces the potential environmental benefits of biogas production. This study investigates the productivity of different cropping systems and their environmental impact in terms of nitrous oxide (N2O) emissions under the environmental conditions of the coastal marsh regions (Northern Germany) with heavy clay soils, in a 2-year field trial (April 2009-March 2011). Treatments included four cropping systems (perennial ryegrass (Lolium perenne, PR) ley, continuous maize (Zea mays), a rotation (CR1) of spring wheat (Triticum aestivum), Italian ryegrass (Lolium multiflorum, IR) and maize, and a rotation (CR2) of maize, winter wheat and IR; two sources of N (nitrogen) fertilizers (calcium ammonium nitrate, and biogas residue (BR)), and three levels of N fertilizer applications (control, moderate, high). Nitrous oxide emissions were determined for the unfertilized and highly fertilized cropping systems comprising PR ley, CR1 and CR2. Cumulative annual N2O emissions varied across the treatments, ranging from 0.82 to 3.4 kg N2O-N ha−1 year−1. Under high N fertilizer applications, PR ley incurred higher N2O-N losses compared to other tested cropping systems, and IR cover crop caused relatively high N2O-N emissions in a short vegetation period. The study observed wide range of yield-scaled emissions (0.00–5.60 kg N2O-N (Mg DM)−1) for different crops, emphasizing the variability in N2O emissions linked to cropping systems. The N2O-N emission factors for the three cropping systems were found to be low to moderate for all treatments, ranging from 0.03% to 0.53% compared to IPCC default Tier 1 N2O-N EFs. The lower emissions in the study were associated with prolonged high soil moisture conditions (water filled pore space >70%.), indicated by its negative correlation with N2O-N fluxes. Low dry matter and N yield of PR and of the wheat-IR sequence after BR application compared to other crops indicated a low N use efficiency. The estimation of N2O-N emissions based on N surplus was not promising specifically for the coastal study site where high groundwater level and organic matter in the soils were the predominant drivers for N2O-N emissions.