Growth Of Perennial Ryegrass Research Articles

Arbuscular mycorrhizal fungi and exogenous Ca2+ application synergistically enhance salt and alkali resistance in perennial ryegrass through diverse adaptive strategies

The challenge of soil salinization and alkalization, with its significant impact on crop productivity, has raised growing concerns with global population growth and enhanced environmental degradation. Although arbuscular mycorrhizal fungi (AMF) and calcium ions (Ca2+) are known to enhance plant resistance to stress, their combined effects on perennial ryegrass’ tolerance to salt and alkali stress and the underlying mechanisms remain poorly understood. This study aimed to elucidate the roles of Arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis and exogenous Ca2+ application in molecular and physiological responses to salt-alkali stress. AM symbiosis and exogenous Ca2+ application enhanced antioxidant enzyme activity and non-enzymatic components, promoting reactive oxygen species (ROS) scavenging and reducing lipid peroxidation while alleviating oxidative damage induced by salt-alkali stress. Furthermore, they enhanced osmotic balance by increasing soluble sugar content (Proportion of contribution of the osmotic adjustment were 34∼38 % in shoots and 30∼37 % in roots) under salt stress and organic acid content (Proportion of contribution of the osmotic adjustment were 32∼36 % in shoots and 37∼42 % in roots) under alkali stress. Changes in organic solute and inorganic cation-anion contents contributed to ion balance, while hormonal regulation played a role in these protective mechanisms. Moreover, the protective mechanisms involved activation of Ca2+-mediated signaling pathways, regulation of salt-alkali stress-related genes (including LpNHX1 and LpSOS1), increased ATPase activity, elevated ATP levels, enhanced Na+ extrusion, improved K+ absorption capacity, and a reduced Na+/K+ ratio, all contributing to the protection of photosynthetic pigments and the enhancement of photosynthetic efficiency. Ultimately, the combined application of exogenous Ca2+ and AMF synergistically alleviated the inhibitory effects of salt-alkali stress on perennial ryegrass growth. This finding suggested that exogenous Ca2+ may participate in the colonization of perennial ryegrass plants by R. irregularis, while AM symbiosis may activate Ca2+ pathways. Consequently, the combined treatment of AM and Ca2+ is beneficial for enhancing plant regulatory mechanisms and increasing crop yield under salt-alkali stress.

Mycorrhizal and non-mycorrhizal perennial ryegrass roots exhibit differential regulation of lipid and Ca2+ signaling pathways in response to low and high temperature stresses

Lipids and Ca2+ are involved as intermediate messengers in temperature-sensing signaling pathways. Arbuscular mycorrhizal (AM) symbiosis is a mutualistic symbiosis between fungi and terrestrial plants that helps host plants cope with adverse environmental conditions. Nonetheless, the regulatory mechanisms of lipid- and Ca2+-mediated signaling pathways in mycorrhizal plants under cold and heat stress have not been determined. The present work focused on investigating the lipid- and Ca2+-mediated signaling pathways in arbuscular mycorrhizal (AM) and non-mycorrhizal (NM) roots under temperature stress and determining the role of Ca2+ levels in AM symbiosis and temperature stress tolerance in perennial ryegrass (Lolium perenne L.) Compared with NM plants, AM symbiosis increased phosphatidic acid (PA) and Ca2+ signaling in the roots of perennial ryegrass, increasing the expression of genes associated with low temperature (LT) stress, including LpICE1, LpCBF3, LpCOR27, LpCOR47, LpIRI, and LpAFP, and high temperature (HT) stress, including LpHSFC1b, LpHSFC2b, LpsHSP17.8, LpHSP22, LpHSP70, and LpHSP90, under LT and HT conditions. These effects result in modulated antioxidant enzyme activities, reduced lipid peroxidation, and suppressed growth inhibition caused by LT and HT stresses. Furthermore, exogenous Ca2+ application enhanced AM symbiosis, leading to the upregulation of Ca2+ signaling pathway genes in roots and ultimately promoting the growth of perennial ryegrass under LT and HT stresses. These findings shed light on lipid and Ca2+ signal transduction in AM-associated plants under LT and HT stresses, emphasizing that Ca2+ enhances cold and heat tolerance in mycorrhizal plants.

Response of Pasture Grasses to Organic Fertilizer Produced from Black Soldier Fly Frass.

Livestock and dairy farmers are increasingly required to maintain productivity and profitability while mitigating the environmental harm associated with high-input agriculture. Accordingly, to reduce reliance on synthetic fertilizers, a wide range of organically derived products are being evaluated for their effects on sward growth and forage quality. This study used glasshouse experiments to investigate the responses of four grass species to a novel organic fertilizer derived from the mass production of black soldier fly larvae [Hermetia illucens, HexaFrass™, Meath, Ireland]. Although there was some variability among trials, overall our results indicate that application of HexaFrass produced increased shoot growth of Perennial Ryegrass (PRG; Lolium perenne L.), Timothy (Phleum pratense L.), and Cocksfoot (Dactylis glomerata L.) compared with growth achieved in no-fertilizer control plants. In addition to increases in shoot fresh and dry weight, shoot chlorophyll content was also positively related to the HexaFrass application rate. At nitrogen-equivalent application rates, HexaFrass resulted in lower shoot growth compared with the application of urea, suggesting that the nitrogen contained in HexaFrass may not be immediately plant-available. Of relevance to grazing or silage systems, the addition of HexaFrass resulted in increased shoot regrowth of PRG and Timothy after shoots had been cut. Based on our results, insect-frass-based fertilizers may have a role in low input, organic, and/or regenerative pasture-based livestock systems, although issues may occur due to the relatively high costs and low availability compared with other organic soil amendments such as farmyard manure and slurry.

Adding Agricultural Topsoil and Growing Perennial Ryegrass (Lolium perenne L.) Enhanced the Rehabilitation of Metal/loids Enriched Iron Ore Mine Tailings

Revegetating iron-ore mine tailings is difficult due to their poor physicochemical and microbial properties. This experiment aimed to improve tailings properties for better plant growth and rhizosphere activities. First, a pot experiment was conducted to assess the influence of topsoil amendment on the remediation of tailings collected from two sites (coded A and B) in Western Australia to promote the growth of perennial ryegrass (Lolium perenne L. cv Ausvic). Each pot was filled with pre-defined ratios of topsoil to mine tailings (0, 10, 20, 30, 50 and 100% w/w). Perennial ryegrass was harvested 60 days after sowing and analysed for plant growth, root morphological characteristics and metal uptake by shoots. Second, a study on biological attributes and an incubation study over 84 days were carried out. The addition of topsoil significantly decreased pH, but EC and total organic carbon (TOC) increased with an increased proportion of topsoil. Total concentrations of As, Co, Cr, Cu, Ni, Pb, Zn, Fe and Mn decreased with an increased ratio of topsoil in growth medium. The highest root dry biomass was observed in the treatments with 30% and 50% topsoil addition to tailings, whereas shoot dry biomass only increased with 50% topsoil. Total root length increased significantly with 50% topsoil addition to site A tailings. A significant increase in microbial biomass carbon (MBC) was found with 50% addition of topsoil compared with the control. Microbial quotient (MBC/TOC) decreased significantly with the addition of topsoil to both types of tailings. Metal contents in perennial ryegrass shoots decreased with the increasing rate of topsoil, but perennial ryegrass was an effective phytoextractor of Cu, Zn and Mn. Further, the incubation study revealed that 50% topsoil application increased cumulative respiration emissions in both A and B tailings after 42 days. Iron ore mine tailings can be improved in terms of physicochemical and biological attributes by adding topsoil. However, further investigation should be carried out to determine the speciation of metal/loids in amended iron ore tailings.

Metal uptake from iron ore mine tailings by perennial ryegrass (Lolium perenne L.) is higher after wheat straw than wheat straw biochar amendment

Background and aimsMine 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.MethodologyWe 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.ResultsThe 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.ConclusionThis study suggests wheat straw is a better amendment than biochar for the iron ore mine tailings.

Kitchen compost-derived humic acid application promotes ryegrass growth and enhances the accumulation of Cd: An analysis of the soil microenvironment and rhizosphere functional microbes

Phytoremediation is an environmentally friendly and safe approach for remediating environments contaminated with heavy metals. Humic acid (HA) has high biological activity and can effectively complex with heavy metals. However, whether HA affects available Cd storage and the Cd accumulation ability of plants by altering the soil microenvironment and the distribution of special functional microorganisms remains unclear. Here, we investigated the effects of applying kitchen compost-derived HA on the growth and Cd enrichment capacity of ryegrass (Lolium perenne L.). Additionally, the key role of HA in regulating the structure of rhizosphere soil bacterial communities was identified. HA promoted the growth of perennial ryegrass and biomass accumulation and enhanced the Cd enrichment capacity of ryegrass. The positive effect of HA on the soil microenvironment and rhizosphere bacterial community was the main factor promoting the growth of ryegrass, and this was confirmed by the significant positive correlation between the ryegrass growth index and the content of SOM, AP, AK, and AN, as well as the abundance of rhizosphere growth-promoting bacteria such as Pseudomonas, Steroidobacter, Phenylobacterium, and Caulobacter. HA passivated Cd and inhibited the translocation capacity of ryegrass. The auxiliary effect of resistant bacteria on plants drove the absorption of Cd by ryegrass. In addition, HA enhanced the remediation of Cd-contaminated soil by ryegrass under different Cd levels, which indicated that kitchen compost-derived HA could be widely used for the phytoremediation of Cd-contaminated soil. Generally, our findings will aid the development of improved approaches for the use of kitchen compost-derived HA for the remediation of Cd-contaminated soil.

Timing of fraise mowing for overseeding establishment of perennial ryegrass

AbstractOverseeding of bermudagrass (Cynodon dactylon L.) with perennial ryegrass (Lolium perenne L.) is often performed to provide green cover of dormant warm‐season turfgrass in the winter. Fraise mowing is a cultural practice that can be used to disrupt the soil surface and hasten establishment of overseeded perennial ryegrass. Research was conducted to determine the most effective timing of overseeding for perennial ryegrass establishment in Northeast Mississippi, and to compare fraise mowing with other common cultural practices performed to enhance overseeding establishment. Treatments included fraise mowing at two depths (0.3 or 0.6 inches), scalping to a height of 1 inch, or vertical mowing to a depth of 1 inch at three timings (mid‐September, mid‐October, and end‐October) prior to seeding perennial ryegrass at 435 lb pure live seed acre−1. Plots were evaluated weekly for turfgrass quality, visual perennial ryegrass cover, and total green cover with digital image analysis. Fraise mowing to a depth of 0.6 inches and scalping resulted in quicker perennial ryegrass establishment. Fraise mowing to a depth of 0.3 inches resulted in quicker perennial ryegrass establishment than both the untreated control and vertically mowed treatments. End‐October fraise mowing resulted in the slowest establishment, as growing conditions were not favorable for perennial ryegrass growth. Although the mid‐September and mid‐October treatments provided the most rapid perennial ryegrass establishment, almost all seeding timings were visually similar by March 15th of the following year. Though fraise mowing temporarily causes an undesirable playing surface, more rapid perennial ryegrass establishment is afforded by restricting bermudagrass competition.

Effects of full and deficit irrigation on the growth and quality of cool-season turfgrasses under subsurface drip irrigation

Irrigation is necessary in terms of achieving high-quality turfgrass. However, it is evident that more efficient and cost effective irrigation methods should be adapted for the sake of water conservation strategies since water consumption is high during turf irrigation. The objective of this study is to determine the effects of full and deficit irrigation with subsurface drip irrigation on growth and quality of perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinaceae Schreb) in a sub-humid climate of Turkey. Three irrigation treatments [I1 (full irrigation), I2 (mild water deficit, 75%), and I3 (moderate water deficit, 50%) were applied to the plants. Turf color and quality of each plot were rated visually, and clipping yields were collected. The amount of irrigation applied varied between 457.3 - 833.9 mm and 356.7 - 710.1 mm and seasonal crop evapotranspiration (ETa) values ranged from 578.4 to 1053.0 mm for tall fescue and 551.2 to 1044.0 mm for perennial ryegrass in 2018 and 2019, respectively. Among the species, tall fescue showed higher visual color, quality ratings and clipping yields. In cases where it does not matter for one or two weeks to be below the acceptable quality (<6) minimum annual irrigation amounts required to maintain quality was 689.1 mm for perennial ryegrass and 578.4 for tall fescue. The results have suggested that acceptable visual color and quality are sustainable in the tall fescue with mild water deficit application in regions where irrigation water is limited in sub-humid climates. Studies on water-saving strategies to turfgrass in regions where the climates varies from year to year are lacking in literature.

Development of Fast Method to Upscaling Microbial Inoculums on Two Seedling Testplants

We investigated the effect of different microbial species on the germination and growth of white mustard (Sinapis alba L.) and perennial ryegrass (Lolium perenne L.), tested for two weeks. The experiment was carried out in a cell tray, filled with sandy soil:compost (9:1) mixture. The following microorganisms were used as treatment: Enterobacter ludwigii, Bacillus megaterium, B. subtilis, Kosakonia cowanii, Pseudomonas fluorescens Hx1 bacteria and Trichorderma harzianum T-22 microscopic fungi. After two weeks, we assessed the number of germinated mustard seeds, the wet and dry weight of the mustard, the length of the mustard, the wet and dry weight and the length of the ryegrass. We measured the enzyme activity of the fluorescein diacetate hydrolysis analysis (FDA) of the soils and calculated the correlation of FDA with the parameters, tested on seedling-plants. FDA generally was positively correlated, however, the above findings could not be verified statistically. The simple and relatively fast method can be suitable for the cost-effective pre-testing of different microbes and for the pre-selection of strains that can be used in further field tests.

Exogenous Methyl Jasmonate Mediated MiRNA-mRNA Network Improves Heat Tolerance of Perennial Ryegrass

Heat stress can hinder the growth of perennial ryegrass (Lolium perenne L.). Methyl jasmonate (MeJA) applied exogenously can increase heat stress tolerance in plants; however, the regulatory mechanisms involved in heat tolerance mediated by MeJA are poorly understood in perennial ryegrass. Here, the microRNA (miRNA) expression profiles of perennial ryegrass were assessed to elucidate the regulatory pathways associated with heat tolerance induced by MeJA. Plants were subjected to four treatments, namely, control (CK), MeJA pre-treatment (T), heat stress treatment (H), and MeJA pre-treatment + heat stress (TH). According to the results, 102 miRNAs were up-regulated in all treatments, with 20, 27, and 33 miRNAs being up-regulated in the T, H, and TH treatment groups, respectively. The co-expression network analysis between the deferentially expressed miRNAs and their corresponding target genes showed that 20 miRNAs modulated 51 potential target genes. Notably, the miRNAs that targeted genes related to with regards to heat tolerance were driven by MeJA, and they were involved in four pathways: novel-m0258-5p mediated signal transduction, novel-m0350-5p mediated protein homeostasis, miR397-z, miR5658-z, and novel-m0008-5p involved in cell wall component, and miR1144-z and miR5185-z dominated chlorophyll degradation. Overall, the findings of this research paved the way for more research into the heat tolerance mechanism in perennial ryegrass and provided a theoretical foundation for developing cultivars with enhanced heat tolerance.

Arbuscular mycorrhizal symbiosis enhances perennial ryegrass growth during temperature stress through the modulation of antioxidant defense and hormone levels

Perennial ryegrass (Lolium perenne L.) refers to a vital species of grass grown extensively as a biofuel and biochemical production across temperate regions. However, both low temperature (LT) and high temperature (HT) conditions are unfavorable for the development of this species, causing reduced forage yield. Arbuscular mycorrhizal (AM) fungi are recognized for promoting host plants’ resistance to abiotic stresses via different mechanisms. However, the mechanism underlying the alleviation of plant damage induced by high-temperature stress and low-temperature stress by AM fungi remains to be elucidated so far. Therefore, the current work attempted to explore how the symbiosis with AM fungus Rhizophagus irregularis (R. irregularis) affects the antioxidant activity and hormone levels in ryegrass under LT and HT stresses and reveals the molecular mechanisms. In addition, the contents of non-enzymatic antioxidants, and hydrogen peroxide (H2O2), the activities of antioxidant enzymes, the genes encoding antioxidant enzymes, and the endogenous hormone-related genes in the perennial ryegrass inoculated with or without R. irregularis were analyzed upon exposure to LT and HT stresses. The results showed that inoculating AM plants with R. irregularis alleviated growth inhibition caused by LT and HT stress, as evidenced by significantly higher plant height, shoot and root dry weight, leaf chlorophyll and carotenoid content, net photosynthesis rate, and photochemical efficiency (Fv/Fm) in comparison to non- mycorrhizal (NM) plants under LT and HT stress. Under LT and HT conditions, AM symbiosis decreased electrolyte leakage (EL), malondialdehyde (MDA), H2O2, and abscisic acid (ABA) contents while significantly increasing the activities of our analyzed enzymes (with the exception of peroxidase (POD) in shoots and ascorbate peroxidase (APX) in roots), AsA/DHA and GSH/GSSG ratio, gibberellic acid 3 (GA3), jasmonic acid (JA) and indoleacetic acid (IAA) contents in shoots and roots. R. irregularis inoculation significantly upregulated almost all genes encoding antioxidant enzyme we tested (except for LpGPX1, LpGPX3, and LpGR in shoots, which were unaffected by AM symbiosis in 3d LT treatment) and some related genes in JA biosynthetic pathway, gibberellin synthesis as well as auxin transport and signaling while down-regulated the biosynthesis and signaling genes involved in ABA.In general, the findings suggested that AM symbiosis regulated the antioxidant defense and the hormone levels in ryegrass, which consequently alleviated the temperature stress-induced plant inhibition.

Effects of arbuscular mycorrhizal fungi on the growth and metabolism of perennial ryegrass (Lolium perenne) under salt stress

Perennial ryegrass is considered an excellent cold-season turfgrass, and salinity is an important environmental factor that affects its growth. Many studies have shown that arbuscular mycorrhizal (AM) fungi can alleviate stress responses in plants, but there have been few reports on the promotion of turfgrass growth in saline-alkali land by AM fungi. We designed an experiment to investigate the effects of different saline conditions (0%, 0.05%, 0.1% salt, w/w) on the growth and physiological metabolism of perennial ryegrass. The results showed that under 0.05% salt stress, AM fungi increased the plant height by 25.9%, the aboveground and underground dry weight by 37.1% and 55.6%, respectively; and the content of chlorophyll a in the plants by 31.0%. Inoculation with AM fungi increased the net photosynthetic rate (A), transpiration rate (E), intercellular CO2 concentration (Ci), and stomatal conductance (Gs) of perennial ryegrass, and the increase in their levels negatively correlated with increasing salt concentrations. Under 0.1% salt stress, the A, Ci, Gs, and E of perennial ryegrass inoculated with AM fungi increased by 24.6%, 23.2%, 139.1%, and 40.7%, respectively. However, inoculation with AM fungi reduced Fv/Fm and had no significant impacts on the SOD activity, MDA, proline (Pro) content, soluble sugar content, and soluble protein content of perennial ryegrass. In conclusion, AM fungi can promote the growth of perennial ryegrass under salt stress, enhance its photosynthetic capacity, and improve the ability of perennial ryegrass to resist salt stress.

Fusarium equiseti-inoculation altered rhizosphere soil microbial community, potentially driving perennial ryegrass growth and salt tolerance

Fusarium equiseti is an effective plant growth-promoting fungi that induce systemic disease resistance in plants. However, the role of F. equiseti in regulating salt stress response and the underlying mechanisms remain largely unknown. Here, we investigated the effect of F. equiseti Z7 strain on the growth and salt stress response in perennial ryegrass. Additionally, the role of Z7 in regulating the abundance, composition, and structure of native microbial communities in the rhizosphere soil was determined. We observed that Z7 could produce indole-3-acetic acid (IAA) and siderophores. Hence, Z7 inoculation further enhanced plant growth and salt tolerance in perennial ryegrass. Inoculating Z7 increased K+ and decreased Na+ in plant tissues. Z7 inoculation also enhanced soil quality by reducing soluble salt and increasing available phosphorus. Moreover, inoculating Z7 altered the compositions of bacterial and fungal communities in the rhizosphere soil. For instance, beneficial bacterial genera, such as Flavobacterium, Enterobacter, Agrobacterium, and Burkholderiales were dominantly enriched in Z7-inoculated soil. Interestingly, the relative abundance of these genera showed significantly positive correlations with the fresh weight of perennial ryegrass. Our results demonstrate that Z7 could remarkably promote plant growth and salt tolerance by regulating ion homeostasis in plant tissues and microbial communities in the rhizosphere soil. This study provides a scientific foundation for applying microbes to improve plant growth under extreme salt stress conditions.

The Effect of Molybdenum Fertilizer on the Growth of Grass–Legume Mixtures Related to Symbiotic Rhizobium

Molybdenum (Mo) is required by the enzymes involved in many metabolic processes related to plant growth and development. However, the effects of Mo addition on plant growth and beneficial microorganisms in mixed grasslands are unclear. We conducted a greenhouse experiment to examine the effects of different Mo addition levels (10 and 20 mg Mo kg−1 soil in the form of Na2MoO4) on the growth of perennial ryegrass–white clover in two low-Mo soils, as well as their symbiotic microorganisms. Our results showed that the addition of Mo had a significant impact on plant growth in limestone soil but not in yellow loam soil (p &lt; 0.05). Compared with no addition of Mo fertilizer in limestone soil, an addition of 10 mg Mo kg−1 significantly increased the plant community shoot and root biomass (p &lt; 0.05). However, this improvement was not observed with an addition of 20 mg Mo kg−1. The shoot nitrogen and phosphorus content in both soil types was unaffected by the Mo addition (p &gt; 0.05), whereas the 10 mg Mo kg−1 addition significantly increased the shoot nitrogen and phosphorus uptake in limestone soil (p &lt; 0.05). This increase in plant community productivity was primarily due to the increased growth of both species, caused by the enhanced activation of the symbiotic rhizobium. We conclude that Mo supply may promote N utilization and uptake in mixed grassland by increasing the activity of symbiotic rhizobium, resulting in a higher yield of mixed grassland, which is critical for sustainable agricultural development in low-Mo soils.

Nitrogen Application Alleviates the Adverse Effects of Defoliation Stress on Lolium perenne L. by Enhancing the Antioxidant System and Promoting Photosynthesis

Perennial grasses undergo compensatory growth after defoliation. Nitrate is the main nitrogen source for the growth of perennial ryegrass and plays a significant role in plant resistance to stress. The aim of the study was to understand the physiological mechanism of ryegrass in response to defoliation stress under different nitrate supplies and to explore possible ways to alleviate defoliation stress. We performed pot experiments where 12-week-old ryegrass plants grown in low (0.05 mM KNO3) or moderate nitrate (5 mM KNO3) conditions were defoliated and subsequently supplied with different concentrations of nitrate following defoliation treatments. During the regrowth stage, the regrowth rate, biomass, photosynthetic parameters, and the response of the antioxidant system to low or moderate nitrate supply of ryegrass were investigated. The results showed that moderate nitrate supply after defoliation increased the content of photosynthetic pigments in ryegrass and improved its photosynthetic efficiency. In addition, adding moderate nitrate after defoliation increased the activity of antioxidant enzymes and the accumulation of osmotic regulating substances, thereby enhancing plant resistance, effectively reducing the damage to plants caused by defoliation stress, and promoting plant regrowth, especially for plants grown in a low nitrate environment before defoliation. Therefore, this study showed that the addition of exogenous nitrate could counteract some of the adverse effects of defoliation stress on the growth and development of ryegrass.

HPLC-DAD-MS Identification and Quantification of Phenolic Components in Japanese Knotweed and American Pokeweed Extracts and Their Phytotoxic Effect on Seed Germination.

We performed a detailed HPLC-MSn analysis of the phenolic compounds from the extracts of two invasive alien plant species (IAPS): Japanese knotweed (Fallopia japonica (Houtt.) Ronse Decr.) and American pokeweed (Phytolacca americana L.). The major phenolic groups were hydroxycinnamic acids and flavanols in Japanese knotweed (J. knotweed) and flavonols, hydroxycinnamic acids, and stilbenes in American pokeweed (A. pokeweed). We investigated the influence of solvent type and extraction time on the extraction efficiency of the phenolic compounds. The solvent 80% methanol had a higher polyphenolic extraction efficiency than water, since 14.5 times more flavonols and 2.3 times more stilbenes were extracted from J. knotweed and 5.2 times more flavonols and 2.6 times more stilbenes were extracted from A. pokeweed. In contrast, with water, we obtained a 52% higher hydroxycinnamic acids (HCA) content from J. knotweed. Hydroxycinnamic acids were best extracted in water after 24 h, flavanols after 12 h, stilbenes between 12 and 24 h, and flavonol glycosides after 48 h of extraction. We also tested the allelopathic effect of the aqueous extract of A. pokeweed and J. knotweed on seed germination and shoot and root growth of perennial ryegrass. The results showed that the water extract of J. knotweed resulted in 38 to 48% lower seed germination of perennial ryegrass, and the extract of A. pokeweed resulted in 83 to 90% lower seed germination. The phytotoxic effect of the extract of J. knotweed and A. pokeweed was also reflected in a characteristic reduced growth of shoots and roots of perennial ryegrass. The phytotoxic action of IAPS could also be applied for beneficial purposes, since this would be an effective strategy for their control and a reduction of their spread in the environment.

Insight into the regulatory networks underlying the high lipid perennial ryegrass growth under different irradiances.

Under favourable conditions, perennial ryegrass (Lolium perenne) engineered to accumulated high lipid (HL) carbon sink in their leaves was previously shown to also enhance photosynthesis and growth. The greater aboveground biomass was found to be diminished in a dense canopy compared to spaced pots. Besides, the underlying genetic regulatory network linking between leaf lipid sinks and these physiological changes remains unknown. In this study, we demonstrated that the growth advantage was not displayed in HL Lolium grown in spaced pots under low lights. Under standard lights, analysis of differentiating transcripts in HL Lolium reveals that the plants had elevated transcripts involved in lipid metabolism, light capturing, photosynthesis, and sugar signalling while reduced expression of genes participating in sugar biosynthesis and transportation. The plants also had altered several transcripts involved in mitochondrial oxidative respiration and redox potential. Many of the above upregulated or downregulated transcript levels were found to be complemented by growing the plants under low light. Overall, this study emphasizes the importance of carbon and energy homeostatic regulatory mechanisms to overall productivity of the HL Lolium through photosynthesis, most of which are significantly impacted by low irradiances.

Influence of environmental factors on seed germination and seedling characteristics of perennial ryegrass (Lolium perenne L.)

Information regarding the germination and seedling growth behavior of a potential weed species is an important tool to manage weeds without the use of agricultural chemicals that cause harmful effects on human health and the environment. A series of experiments were directed to investigate the influence of different environmental factors (temperature, pH, NaCl, moisture stress, and seed burial depth) on germination and seedling emergence of perennial ryegrass (Lolium perenne L.) under controlled conditions. Results suggested that 25 °C is the optimum temperature for maximum germination (95%) and seedling growth of perennial ryegrass, however, a quick decline was observed at 35 °C. Seed germination was unaffected by pH levels ranging from 5 to 10. The 92% seed germination was recorded where no salt stress was applied and germination was reduced by 87% at 250 mMNaCl concentration. Seed germination was unaffected by osmotic potential ranges from 0 to − 0.4 MPa thereafter declined and completely inhibited at − 0.8 or − 1.0 MPa. No seed emerged at the soil surface or a soil depth of 6 or 7 cm and 90% emergence occurred at 1 cmsoil depth. The germination and seedlings parameters like time to initial germination, mean germination time, time taken to 50% germination and germination index, root and shoot length, and fresh and dry weight of root and shoot are significantly affected with the environmental factors. The information obtained in this study will be helpful to develop better management strategies for germination and the emergence of perennial ryegrass in areas where it has the ability to rapidly colonize.

The changing role of perennial ryegrass in dairy pastures in northern Victoria, Australia

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

A Diaporthe Fungal Endophyte From a Wild Grass Improves Growth and Salinity Tolerance of Tritordeum and Perennial Ryegrass.

Some microbiome components can provide functions that extend the capabilities of plants, increasing the environmental adaptability and performance of holobionts. Festuca rubra subsp. pruinosa is a perennial grass adapted to rocky sea cliffs, where soil and nutrients are very limited, and exposure to salinity is continuous. This study aimed to investigate if a Diaporthe fungal endophyte belonging to the core microbiome of Festuca rubra roots could improve the performance of two agricultural grasses. In a greenhouse experiment, plants of tritordeum (Triticum durum x Hordeum chilense) and perennial ryegrass (Lolium perenne) were inoculated with Diaporthe strain EB4 and subjected to two salinity conditions (0 and 200 mM NaCl). Biomass production, mineral elements, proline, hormone profiles, antioxidant capacity, and total phenolic compounds were examined in plants, and fungal functions potentially related to the promotion of plant growth were determined. The inoculation with Diaporthe promoted plant growth of both grasses, increasing leaf biomass (84% in tritordeum and 29% in perennial ryegrass), root biomass, nutrient content (N, Ca, Mg, and Fe), and the production of indole 3-acetic acid, regardless of the salinity treatment. Improved growth and nutrient uptake might occur because Diaporthe produces several extracellular enzymes capable of recycling organic nutrient pools. In addition, the fungus produced indole 3-acetic acid in vitro and modulated the production of this phytohormone in the plant. Under salinity, the activity of Diaporthe ameliorated the stress, increasing proline, nutrient uptake in roots, gibberellins, and indole 3-acetic acid, which in turn results into improved growth. Thus, this fungus can transfer to alternative hosts some advantages useful at its original habitat.