Grass and Forage Science最新文献

After the Dust Bowl in the 1930s, it was common to reseed native grasses in areas impacted by the drought to help restore grassland ecosystem structure and function. Given the forecasts of intensified drought events, reseeding may need to be employed more frequently to enhance post-drought recovery. For such reseeding efforts, it is imperative to understand the adaptability of cultivars to the environmental conditions in which they are planted, including how they interact with the soil microbiome. Here, we used a greenhouse experiment with two cultivars of the C₄ grass, Bouteloua gracilis, that were planted with soil microbial inocula extracted from either previously droughted or non-droughted soils collected from native shortgrass prairie in northeastern Colorado (USA). Our goal was to examine whether the post-drought legacy of altered soil microbial communities affected the growth and performance of two B. gracilis cultivars. We found no significant differences in relative growth rate or plant biomass, and minimal differences in the microbial community composition between the two cultivars, despite differences in microbial communities at the beginning of the experiment. These results suggest that the post-drought legacy of altered soil microbial communities does not differentially affect growth and performance of the two B. gracilis cultivars evaluated, and that these cultivars do not differ in their effects on the soil bacterial communities found under ambient versus previously droughted conditions.

Molinia caerulea (Molinia) is a native plant species that dominates large tracts of the UK uplands, with detrimental impacts on floristic diversity and related habitat value. Harvesting Molinia supports biodiversity restoration and conservation, yet there is little incentive for farmers to manage this increasingly dominant species. Our aim was to evaluate Molinia's potential as an alternative forage for feeding horses based on published nutrient analysis data. Though research is limited, chemical analysis suggests Molinia is typically comprised of high energy, low water-soluble carbohydrate (WSC), but is high in fibre, resulting in poor digestibility and low metabolisable energy provision in cattle. However, low WSC, high fibre diets are favoured for feeding domestic horses where inappropriate nutrition is typically associated with obesity and metabolic disorders. Ryegrass hay, commonly fed to horses, typically has a WSC concentration of around 180 g/kg DM, which exceeds recommended thresholds and is far greater than reported for Molinia (50–70 g/kg DM). We recommend further research to understand how this plant is degraded in the equine hindgut, using in vitro gas simulation and production experiments, to explore how Molinia is degraded in the hindgut and the extent to which it could contribute to or affect gastrointestinal health, prior to in vivo studies. Were the potential of Molinia as an equine feed proven, three-fold benefits would result: a new source of low WSC forage suitable for domestic horses susceptible to weight-related metabolic disorders; a new income stream for farmers in marginal areas; improved upland grassland biodiversity.

Heatwaves are an often-overlooked aspect of current climate change in plant research. However, projections of future scenarios show an increase in their frequency and intensity in most temperate-climate regions. The effects of heatwaves on crop and woody species are well known. In contrast, for wild herbaceous species, no overview is available. Moreover, negative or neutral effects on temperate grassland species are found in the literature, raising the complexity and diversity of responses to heatwaves. To disentangle this diversity, we review research articles on the impact of heatwaves on plant growth and survival in temperate grasslands. The mechanisms and factors mentioned in these articles are discussed to better understand this diversity of responses. We highlight the importance of the timing of a heatwave relative to phenology, as heatwaves can occur in spring, summer or early autumn. We also propose to classify plant mechanisms according to their utilisation, that is, before, during and after the heatwave, which is considered a disturbance. We emphasise the overall effects (whether positive or negative, small or large) on different molecular, physiological and whole-plant mechanisms; the resilience or tolerance after heatwaves and not only resistance during heatwaves; the interactions with abiotic factors, such as drought, but also with biotic factors as plant–plant interactions; and the effects of recurrent heatwaves, which can trigger priming effects or cumulative negative effects. Solutions for grassland management in the face of current climate change, with more frequent heatwaves in temperate-climate regions, are also explored.

The use of low ammonia emission equipment for slurry distribution has become mandatory in a number of countries. However, the effects of different application methods on dry matter (DM) yield, nitrogen (N) utilisation, botanical composition and forage quality are still debated. This study offers a comprehensive assessment of the effect of various slurry application methods on forage production. Slurry distribution equipment (broadcast; band-spread; trailing-shoe), as well as slurry consistency (unaltered or extra dilution), timing (immediately or delayed after preceding cut) and sward types (with or without legumes) were tested at two sites. Low-emission equipment significantly increased DM yield and N utilisation at one of the two sites. Slurry dilution proved positive for N utilisation and DM yield, while early application timing had marginal effects. Low-emission equipment had no effect on the proportion of legume species, and at one site, it had only irrelevant effects on the proportion of undesired species. Silage quality was not negatively affected by low-emission equipment but was indicated to be positively influenced by extra diluted slurry and early application. We conclude that the use of low-emission slurry distribution equipment can be advantageous in intensively managed grasslands in terms of N utilisation and yield. However, these positive effects are not guaranteed. Negative effects on forage quality are very unlikely with such equipment, provided that the general recommendations for silage production are followed. Slurry dilution is also advantageous, particularly when broadcast or band-spread equipment is used.

Intensification of animal production systems over the last number of decades has increased the consumption of human edible protein by livestock, leading to increased competition for and cost of human edible protein. Grassland-based agriculture supports ruminant production systems, which convert human inedible proteins (grassland) into human edible meat and dairy products with high nutrient density. Grassland-based systems have a low reliance on human edible food for production, and therefore optimizing the use of grassland to produce animal protein contributes to food security. Grassland-based systems have conversion efficiencies of 2.5 to 4 in terms of kg human edible protein produced for each 1 kg human edible protein consumed by livestock, greater than that of confinement systems (≤ 1 for each 1 kg human edible protein consumed). Managed grassland offers a range of other ecosystem services including supporting plant and animal biodiversity, water resource management (e.g., water retention, provision of flood plains, water filtration), carbon storage and sequestration, and cultural services. Grassland management, sward species selection, and supplementation are amongst the strategies that can be used to optimise grassland production and utilisation by ruminants for human edible-food production to contribute to global net food security, as well as environmental conservation and management.

Estimating fresh grass intake of grazing cows is important for effective management, but direct measurements are inherently difficult in grazing systems. Therefore, this study compared 3 methods to estimate fresh grass intake of dairy cows: automated weighing bins (Roughage Intake Control; RIC), net energy evaluation (VEM), and n-alkanes. A grazing trial was performed in 3 periods with 3 different grass-based systems: restricted zero-grazing (ZG), restricted grazing (RG), and unrestricted grazing (UG). For the VEM method, energy requirements and intake and VEM content of grass were used. For the n-alkane method, C32 and C36 were supplied to the cows, and faecal samples were collected. For ZG cows, RIC indicated a higher fresh grass DMI (9.6 kg cow⁻¹ day⁻¹) compared with VEM (9.3 kg cow⁻¹ day⁻¹) and n-alkanes (8.4 kg cow⁻¹ day⁻¹). For all groups and periods, VEM resulted in a higher DMI (11.2 kg cow⁻¹ day⁻¹) compared with n-alkanes (9.6 kg cow⁻¹ day⁻¹). Methods did not show high correlations, but differences in the estimation of DMI were relatively small. With the n-alkane method, intake is estimated via natural markers, reflecting environmental and behavioural factors for grazing cows, possibly giving a better reflection of individual variation in grazing behaviour among cows compared with VEM. Concluding, either the VEM method or the n-alkanes method may be used to estimate fresh grass DMI of individual dairy cows grazing in groups, depending on the study context.

Under the regulatory framework of the International Union for the Protection of New Varieties of Plants (UPOV) for plant variety protection, a new variety must be assessed for uniformity, as well as distinctness and stability (DUS). For cross-pollinated crops such as perennial ryegrass (Lolium perenne) and lucerne (Medicago sativa), where cultivars are heterogeneous populations, assessment of uniformity poses particular challenges. These challenges stem from the fact that such evaluations can be costly and require substantial labour and time, as they typically involve the measurement of numerous comparator characteristics across multiple individual plants representative of a candidate cultivar, often over a period exceeding 1 year. Although DUS testing is based on phenotypic characteristics, genetic markers are currently permitted for use in planning of trials, and for distinctness assessment in particular situations. However, genetic markers have not yet been employed for distinctness assessment. Similarly, under OECD Seed Schemes, marketed seed is assessed for varietal purity through the observation of plants in field plots. This study proposes a new measure of genetic heterogeneity based on genetic markers, along with a method to estimate this in pooled samples to reduce costs. The method relies on a system for estimating allele frequencies at SNPs, such as genotyping-by-sequencing or sequence capture. We demonstrate the potential of this approach with example data for perennial ryegrass. The approximation based on pooled samples provided satisfactory estimates of genetic heterogeneity compared with direct assessment based on individual plants, and proved to be sensitive to contamination of samples by other varieties.

Juncao grass (Cenchrus fungigraminus Z.X. Lin, D.M. Lin, and S.R. Lan) is a recently developed C₄ forage which has been introduced to several tropical countries supported by different aid programs. However, there is no information on the potential of forage production, nutritive value, and agronomic characteristics of this new species to support management recommendations. This research aimed to compare two cultivars of Juncao to Guatemala (Tripsacum andersonii J.R. Gray) and Elephant grass [Cenchrus purpureus (Schumach.) Morrone cv. Napier] in relation to annual forage production and nutritive value subjected to different pre-harvest canopy heights. The trial was designed using randomised blocks (n = 3) in a split-plot arrangement where pre-harvesting canopy heights (0.5, 1.0, 1.5, and 2.0 m) composed the main plots and forage species/cultivars (n = 4) as the subplots. The annual forage accumulation of Juncao green and purple was approximately double that of Elephant and Guatemala grass when averaged across 2 years, while crude protein and metabolisable energy concentration was similar to Elephant and higher than Guatemala grass. Juncao green and purple cultivars should be harvested between 1 and 2 m of pre-harvest canopy height, with shorter pre-harvest targets favouring nutritional value and taller targets promoting greater biomass production per harvest, although no increments in annual forage accumulation were observed when pre-harvesting canopy height was over 1 m. The high forage production of Juncao grass, combined with its nutritional value comparable to other tropical forage, indicates substantial potential for its adoption in cut-and-carry systems in the wet tropics.