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

Aims: An Italian ryegrass cultivar (Lolium multiflorum Lam. cv. Bb2067), selected and bred for increased leaf magnesium (Mg) concentration in the 1970s, reduced the incidence of hypomagnesaemia in sheep under experimental grazings. Here, we report evidence from archival experiments showing that cv. Bb2067 had consistently greater Mg concentrations at multiple sites. We also aimed to quantify variation in leaf Mg concentration among modern perennial ryegrass (Lolium perenne L.), hybrid ryegrass (Lolium perenne × multiflorum), and tall fescue (Festuca arundinacea Shreb.) cultivars. Methods: Data are reported from unpublished 1980s field-plot experiments for cv. Bb2067 and contemporaneous reference cultivars, sown at two UK locations in 1983 and 1984, and from 397 cultivars of modern forage grass in 13 UK-based breeding experiments sampled in spring 2013. Results: Across sites, years and cuts, cv. Bb2067 had a consistently greater leaf Mg concentration and lower potassium (K) concentration and forage tetany index (FTI) than reference cultivars in the 1980s experiments. Seasonal variation in leaf Mg and K concentrations and FTI were observed in the 1980s experiments, with K concentrations being generally greatest and Mg concentrations smallest in spring. Among modern forage grasses, there was large variation in leaf Mg concentration (up to 6.3-fold) and FTI (up to 2.1-fold), both within and between species, which varied independently of yield. Among a subset of hybrid ryegrass cultivars, there is evidence that the high Mg trait is already present in some modern breeding lines, albeit previously unreported. Conclusions: The variation in leaf Mg concentration and FTI among old and new cultivars shows there is considerable potential to breed forages with improved mineral quality to improve livestock health, potentially without compromising yield or other nutritional traits. [ABSTRACT FROM AUTHOR]

To increase ruminant production efficiency, the environmental impact of growing forage must be reduced, through lowering system inputs and increasing crop resilience to extreme weather. Here we examined the role of red clover (cv. AberClaret) in minimising nitrogen (N) requirements, alongside two novel grass varieties, (1) a festulolium (cv. AberNiche), developed for drought tolerance, with potential for deep-rooting, and (2) a ryegrass hybrid (cv. AberEcho), developed for high-sugar content, which may enhance ruminant N-uptake in-vivo. Field trials were conducted at two UK sites, growing festulolium and ryegrass ± red clover (at 29% of the seed mix weight) at a range of N fertilisation rates (0 – 600 kg N ha−1) for 2 years (six harvests). We assessed sward performance (N offtake, herbage quality, and grass N use efficiency), rooting depth and N transfer from clover to grasses using 15N natural abundance. Across both sites and years, dry matter yield and herbage-N content were overall greater from the swards that included clover. Dry matter yields from festulolium were not greater than from ryegrass under the drought conditions experienced in 2018, despite its greater root mass. Agronomic efficiency of fertiliser N was similar between grasses (19 – 22%), however the festulolium more effectively used endogenous soil N than the ryegrass. Inclusion of clover in the sward affected forage quality, with increased crude protein and metabolisable energy content and reduced sugar and fibre (NDF) content. Among the grass types, metabolisable energy was greater and NDF content less for ryegrass than for festulolium. A strong reliance on biological N fixation (80 – 94%) for clover was observed, however, N transfer from clover to the neighbouring grass was not evident from the ẟ15N signatures. We conclude that red clover is a viable fertiliser-N replacement strategy in short-term leys, and that grass varieties with improved herbage quality may provide a better option for optimising sward performance than drought tolerant grass varieties. • Festulolium gave no yield advantage over a ryegrass hybrid under drought conditions. • Ryegrass hybrid provided higher quality feed without compromising yield. • Herbage yields were greater when red clover was included within the sward. • Inclusion of red clover with grass increased sward N and metabolisable energy content. • Including red clover in grass swards replaced the need for N fertilization. [ABSTRACT FROM AUTHOR]

Four grass species typically found in semi-natural pastures in the UK were sown individually in boxes (85 × 44 × 14 cm) to create micro-swards. Yorkshire fog ( Holcus lanatus L.); creeping bent ( Agrostis stolonifera L. cv Kromi); rough meadow-grass ( Poa trivialis L.); and perennial ryegrass ( Lolium perenne L. cv Glen) were offered to yearling Simmental × Holstein steers in short-term tests to characterize bite mass in relation to morphological traits of the grass species. Boxes were weighed (±0.1 g) before and after a 5 min period during which the steers were allowed to take ~50 bites. Perennial ryegrass had the greatest sward surface height (17.7 cm vs. mean 12.7 cm for the other species). Extended tiller length was greatest for ryegrass (17.3 cm) and least for rough meadow-grass (13.5 cm). Leaf length was greatest for ryegrass (6.5 cm) and Yorkshire fog (7.0 cm) and least for creeping bent (4.0 cm). Sward DM% was lowest for ryegrass (19.7%) and highest for creeping bent and rough meadow-grass (mean 23.2%). Number of bites taken from the boxes did not differ between grass species (mean 32.7 bites). Mean dry matter bite mass was greatest for perennial ryegrass (0.50 vs. mean 0.37 g DM bite−1 for the other species). Regression analyses indicated that the best sward variables for predicting mean DM bite mass were sward DM% ( F prob. = 0.066) and sward surface height ( F prob. = 0.086). While morphological characteristics affected bite mass, more is yet to be learned about other factors that may affect intake characteristics of forage species to improve economic and environmental sustainability. [ABSTRACT FROM AUTHOR]

Perennial ryegrass and perennial ryegrass/white clover permanent dairy pastures are compared with respect to productivity, environmental impact and financial costs in nitrate vulnerable zones (NVZ) in the UK. With appropriate management, and utilisation of recommended perennial ryegrass and white clover cultivars, white clover is likely to stabilise at around 20% of total dry matter production in a mixed pasture. Plant dry matter production and milk production from a perennial ryegrass/white clover pasture are likely to be similar to that from a perennial ryegrass pasture receiving 200 kg N ha−1 annum−1 and around 70% of that obtained with perennial ryegrass supplied with 350–400 kg N ha−1 annum−1. Nitrate, phosphorus and methane losses from the system and decreases in biodiversity relative to a grazed indigenous sward are likely to be similar for a perennial ryegrass/white clover pasture and a perennial ryegrass pasture receiving 200 kg N ha−1 annum−1: nitrate leachate from both systems is likely to comply with European legislation. Greenhouse gas emissions resulting from nitrogen (N) fertiliser production would be avoided with the perennial ryegrass/white clover pasture. Within NVZ stocking rate restrictions, white clover can provide the N required by a pasture at a lower financial cost than that incurred by the application of N fertiliser. [ABSTRACT FROM AUTHOR]

Resistance to the cyclohexanedione (CHD) herbicide sethoxydim was investigated in two UK Lolium multiflorum populations, Yorks A2 and PYL. Resistance screening experiments demonstrated a qualitative difference in the responses of the two populations to sethoxydim, suggesting that the molecular basis of resistance between them was different. After treatment, Yorks A2 plants were either alive (78% of sample tested) or dead (22% tested) but plants of the PYL population showed two further intermediate categories of response. The level of acetyl-CoA carboxylase (ACCase) insensitivity directly correlated with the degree of resistance at the whole plant level, indicating that the molecular basis of resistance is associated with differences in ACCase sensitivity in each population. Direct sequencing of the carboxyl transferase domain of the ACCase gene showed that an Ile-418-Leu substitution in the L. multiflorum chloroplastic ACCase (GenBank accession number ) confers resistance to sethoxydim in Yorks A2. This corresponds to amino acid residue 1781 in the Alopecurus myosuroides full ACCase sequence. This is the first report of this mutation in this L. multiflorum, which has also been reported in four other grass-weeds, including L. rigidum. However, no amino acid substitutions were found to be specifically associated with the resistant phenotypes in the PYL population and the molecular basis of resistance in this population remains to be resolved. [ABSTRACT FROM AUTHOR]

Eight multiparous Holstein–Friesian dairy cows in late lactation were used to investigate the potential of using perennial ryegrass with a high concentration of water-soluble carbohydrate (WSC) to increase the efficiency of milk production. After a pretreatment period on a common pasture, the cows were each given ad libitum access to one of two varieties of zero-grazed grass continuously for 3 weeks. Treatments were: high sugar (HS), an experimental perennial ryegrass variety bred to contain high concentrations of WSC; or control, a standard variety of perennial ryegrass (cv. AberElan) containing typical concentrations of WSC. The two grass varieties were matched in terms of heading date. All animals also received 4 kg day–1 standard dairy concentrate. Grass dry matter (DM) intake was not significantly different between treatments (11·6 vs. 10·7 kg DM day–1 ; s.e.d. 0·95 for HS and control diets respectively), although DM digestibility was higher on the HS diet (0·71 vs. 0·64 g g–1 DM; s.e.d. 0·23; P < 0·01) leading to higher digestible DM intakes for that diet. Milk yield from animals offered the HS diet was higher (15·3 vs. 12·6 kg day–1 ; s.e.d. 0·87; P < 0·05) and, although milk constituent concentrations were unaffected by treatment, milk protein yields were significantly increased on the HS diet. The partitioning of feed N was significantly affected by diet, with more N from the HS diet being used for milk production (0·30 vs. 0·23 g milk N g–1 feed N; s.e.d. 0·012; P < 0·01) and less being excreted in urine (0·25 vs. 0·35; s.e.d. 0·020; P < 0·01). In a separate experiment, using the same grasses harvested earlier in the season, the fractional rate of DM degradation, measured by in situ and gas production techniques, was higher for the HS grass than for the control.... [ABSTRACT FROM AUTHOR]

Perennial (Lolium perenne L.) and annual (L. multiflorum) ryegrass are important species for landscape (e.g., turf) and agricultural (e.g., pasture systems) uses. Abiotic stresses limit the survival, growth, and/or appearance of these species. The synthesis and accumulation of quaternary ammonium compounds (QACs) such as glycinebetaine (GB) are an adaptive response to abiotic environmental stresses in some species. Both L. perenne and L. multiflorum are GB-accumulating species, and exogenous application of GB may enhance growth under less-than-optimal environmental conditions. We tested the effects of exogenous application of GB on growth and water relations of annual and perennial ryegrass growing under temperatures at the lower limits of their optimal growth. Osmotic stress resulted in increased GB accumulation in L. perenne, but exposure to cold temperatures did not result in increased GB accumulation in either species. Both species accumulated higher concentrations of GB in leaf and stem tissues when exogenous GB was supplied, regardless of growing temperature. Exogenous GB did contribute to lower osmotic potential in both species, but did not affect relative water content, although succulence was higher in some cases. Overall, exogenous GB did not affect growth under optimal growing temperatures, but did enhance growth of L. perenne growing under low temperatures. [ABSTRACT FROM AUTHOR]

Forage plants underpin the livestock industry. Selective breeding, including polyploidization, where genome size is increased by whole genome duplication, changes the productivity and stress tolerance of new varieties. We conducted a growth chamber experiment to investigate the likely responses of Lolium perenne L. to drought, testing four diploid and four tetraploid varieties. We simulated projected spring and summer temperatures for the South-West of England in 2080, applying three projected rainfall scenarios, which varied in drought severity. Drought caused a reduction in productivity, but there was substantial variation between varieties (up to 82%), with the optimal variety changing depending on drought severity. Across three harvests, productivity declined by 43% and 27% (dry biomass) for the severe and likely drought scenarios, respectively. In the final harvest, tetraploids exhibited a greater biomass under severe drought, whereas diploids had a greater biomass under the current rainfall and likely drought scenarios. Longer stomata were observed in tetraploids; however, stomatal conductance was not significantly different between ploidy levels. Trait selection will be important for future drought adaptation. Local climate projections will need to be consulted when selecting L. perenne varieties to tolerate the spatially variable reductions in future rainfall. [ABSTRACT FROM AUTHOR]

In official forage grass variety trials in the UK, herbage samples are dried at 100°C or more to facilitate quick drying of the large numbers of samples that are currently needed. When assessing herbage quality, however, 80°C has been recommended as the highest temperature that can be used during drying without serious deterioration. Herbage from six perennial ryegrass varieties, which were known to show a range of variation in in vitro concentration of digestible dry matter (DMD) and water-soluble carbohydrate concentration (WSC) during the vegetative phase of growth, was dried in an oven with forced ventilation at 100°C and at 80°C before analysis. Mean DMD over all varieties was slightly lower [6 g kg-1 dry matter (DM)] and mean WSC over all varieties was considerably lower (24 g kg-1 DM) at 100°C. Varieties differed in mean DMD over both drying temperatures by 37 g kg-1 DM and in mean WSC by 63 g kg-1 DM. There was, however, no significant interaction between variety and drying temperature for either DMD or WSC. Although drying at the higher temperature underestimated both DMD and WSC, it did not significantly alter the ranking of varieties or the range among them. [ABSTRACT FROM AUTHOR]

Reports that for some years ryegrass plants at the Welsh Plant Breeding Station in Great Britain have been killed by a previously unidentified disease. Death of some plants of perennial ryegrass {Lolium perenne L.) were killed; Serious damage was confined to Italian ryegrass (L. multiflorum Lam.) and Italian X perennial ryegrass hybrids; Development of most characteristic symptoms on flowering tillers; Disease's apparent similarity with that reported from Switzerland, France and Germany on Lolium spp. and other forage grasses and recently shown to be caused by Xanthomonas graminis.