A simultaneous effect of selfing and Epichloë endophyte on forage,seed yield and turf characteristics of perennial ryegrass (Lolium perenne L.)

Ryegrass (Lolium perenne L.) is a putative turf and forage plant characterized as mainly outcrossing in which the extent of self‐fertilization and its consequences has not been investigated. In this study, selfed and half‐sib family seeds were obtained from ten clonally propagated ryegrass plants among which two were endophyte‐free (EF) and eight were endophyte‐infected (EI). Then, 20 seed populations plus two commercial varieties of Speedy and Vigor were sown and evaluated in a biennial experiment for their turf and forage characteristics. Selfing caused significant inbreeding depression for plant fresh and dry weight and leaf length and width in the first year for both EI and EF genotypes. In the second year, only leaf length remained depressed among these characters. Also, for the most growth, turf and reproductive traits, EI populations showed less depression. The presence of endophyte in self‐pollinated populations made an increasing effect for the number of seed per spike and days to heading, although seed weight was reduced. Some of the populations derived from self‐pollination and infected with fungal endophyte including S9 and S10 were even superior to the two commercial varieties in terms of both seed production and turf characteristics. However, for seed‐related characteristics including number of spikes per plant, seed weight and seed yield, EF populations including Speedy and Vigor were more reproductive than EI populations. It is concluded that selfing may increase the discrimination between EI and EF ryegrass plants because endophyte infection may mitigate the negative consequences of inbreeding depression in prone populations.     

Bio‐agronomic characterization and implications on the potential use as forage of Bituminaria bituminosa and B. morisiana accessions

Perennial forage legumes may be pivotal for improving the sustainability of Mediterranean rainfed farming systems. This study summarizes the outcomes of a study aimed at characterizing morphological and agronomic traits of new germplasm of Bituminaria bituminosa and B. morisiana in Mediterranean environments. Five B. morisiana and three B. bituminosa native populations were evaluated in a small‐plot field experiment in Sardinia (Italy) and compared with seven Spanish accessions of B. bituminosa. The two Bituminaria species differed greatly in morphological traits and the beginning of the flowering stage, and remarkable variations between species were found for forage production and its seasonal distribution, seed yield and persistence. Average cumulative dry‐matter yield was higher in B. bituminosa than in B. morisiana (+7.6%; 297 vs. 276 g per plant). Average 3‐year seed production varied greatly between accessions (from 0.3 to 141 g per plant). Differences for these traits were also found between Sardinian and Spanish germplasm of B. bituminosa. Four clusters were generated by K‐means clustering. Accessions included in cluster III exhibited a positive combination of favourable forage production, high seed yield and satisfactory persistence. Nonetheless, the cluster analysis did not highlight a sharp discrimination between Bituminaria species. The overall results revealed the potential role of Sardinian accessions of B. bituminosa and B. morisiana in extending the forage season and for increased resilience of grasslands in Sardinia and other Mediterranean regions under rainfed conditions.     

Optimal defoliation management of brachiaria grass–forage peanut for balanced pasture establishment

A well‐established canopy is crucial for a stable mixed grass–legume forage pasture. The aim of this study was to assess a defoliation intensity that can ensure the establishment of mixed pasture of brachiaria grass (Brachiaria brizantha) intercropped with forage peanut (Arachis pintoi). The treatments comprised four canopy heights: 10, 20, 30 and 40 cm, maintained throughout the first 3 years of pasture establishment. Canopy structure, morphogenetic and structural characteristics were measured. A block design was used with four replicates, and seasons of the year were considered using repeated measurements over time. Light interception during the experimental period was 86.3%, 95.9%, 97.6%, and 99.1% for 10, 20, 30 and 40 cm of defoliation respectively (p < .001). Competition for light in taller canopies (at 30 and 40 cm) caused etiolation of forage peanut (greater internode, petiolate and stolon lengths). This response promoted its upward growth, leading to a lower stolon density compared with 10 and 20 cm. The treatment at 10 cm displayed a predominance of forage peanut (up to 0.614), potentially compromising community stability. Overall, the 20 cm canopy height showed a desired botanical composition (from 0.20 to 0.45 of legume in forage mass) and thus was considered an ideal defoliation intensity for establishment of mixed canopies of brachiaria grass and forage peanut.     

Hide and seek – Infection rates and alkaloid concentrations of Epichloë festucae var. lolii in Lolium perenne along a land‐use gradient in Germany

The common forage grass Lolium perenne has evolved with the systemic fungal endophyte Epichloë festucae var. lolii. The endophyte provides herbivore resistance to the grass due to defensive alkaloids, some of which are toxic to grazing livestock. In this field study, we determine whether distribution of the endophyte‐grass association changes along a land‐use intensity gradient on 87 managed grasslands in three German regions. Endophyte infections were detected in 66% of the studied sites and infection rates within infected sites ranged from 1% to 95%. Alkaloid concentrations of lolitrem B (vertebrate toxin) exceeded the toxicity thresholds in 50 (14%) of 351 infected plants and of peramine (invertebrate deterrent/toxin) in 12 (3%) of 351 plants. Infection rates and alkaloid concentrations were not significantly affected by land‐use intensity and region, but alkaloid concentrations were higher in summer compared to spring. We conclude that risks for livestock intoxication are currently low, as (i) average alkaloid concentrations per grassland were always below toxicity thresholds and as (ii) none of the grasslands was dominated by L. perenne. We suggest avoidance of grass monocultures in Europe to keep intoxication risks for livestock low; we also recommend regular examination of seeds and grasslands, as seed producers might accidentally distribute infected seeds, and as climate warming might further enhance the distribution of Epichloë endophytes in European grasslands.     

Historical land use by domestic grazing revealed by the soil seed bank: a case study from a natural semi‐arid grassland of NW Patagonia

Livestock can affect the soil seed bank through various mechanisms associated with changes in vegetation. We sampled vegetation and seed banks of Patagonian grasslands, in areas with different historical use by grazing (exclosure, moderate use and high use) to evaluate to what extent changes in vegetation are reflected in the seed bank. We also evaluated the effect of historical grazing on horizontal spatial seed distribution by sampling under shrubs and in between plant gaps. We focused the study on functional groups, and on the palatable Poa ligularis, an indicator of grassland status. In general, the proportional changes in composition and abundance of functional groups produced in grazed sectors (relative to each exclosure) were bigger for the seed bank than for the aboveground vegetation. Impacts on seed bank were led by a decrease (moderate use), or total disappearance (high use) of perennial grasses, results clearly reflected by P. ligularis. Although shrubs were represented in vegetation, they were undetected in the seed bank through germination, probably due to the lack of the conditions required for breaking seed dormancy. Intensive grazing produced homogenization in seed spatial distribution. Our work revealed a poor contribution of the seed bank to vegetation regeneration at increasing historical use by grazing. We recommend sampling the seed bank when monitoring the conservation status of grasslands to obtain consistent management guidelines.     

In vitro rumen methane output of grasses and grass silages differing in fermentation characteristics using the gas‐production technique (GPT)

The chemical composition of silage consumed by cattle can influence the subsequent rumen microbial fermentation patterns and methane (CH₄) emissions. The objectives of this study were to (i) evaluate the effect of ensilage on the in vitro rumen methane output of perennial ryegrass and (ii) relate the silage fermentation characteristics of grass silages with in vitro rumen methanogenesis. Three pre‐harvest herbage‐conditioning treatments and seven silage‐additive treatments were used in a laboratory‐scale silo experiment to produce a diversity of silage fermentation characteristics. Ensilage reduced (P < 0·01) the in vitro rumen CH₄ output (mL CH₄ g^?1 dry matter (DM) disappeared). This reflected differences in the direction of rumen fermentation (lower acetic (P < 0·05) and higher propionic (P < 0·001) acid proportions in volatile fatty acids) rather than major changes in the extent of in vitro rumen fermentation (i.e. mmol VFA g^?1 DM). The magnitude of the decrease in CH₄ output (mL g^?1 DM incubated) owing to ensilage increased as the extent of silage fermentation, and in particular the lactic acid concentration, increased. In contrast, among silages with relatively similar extents of silage fermentation (i.e. total fermentation products), an increase in the proportion of lactic acid in silage fermentation products led to a more extensive in vitro rumen fermentation and thus to a greater CH₄ output (mL g^?1 DM).     

Effects of sheep stocking on the plant community and agricultural characteristics of upland Anthoxanthum odoratum–Geranium sylvaticum meadow in northern England

In the UK, upland hay meadows (Anthoxanthum odoratum–Geranium sylvaticum grassland) with high plant biodiversity are rare and confined to submontane areas of northern England. We report results from a 5‐year experiment to test suggestions that recent biodiversity declines were attributable to increased sheep‐stocking density and a longer spring stocking period, thus delaying the shut up date for the growth of the hay crop. Longer stocking periods and higher stocking densities decreased the forage mass at 8 July, but they increased herbage N content and digestibility, reduced plant species diversity and reduced populations and seed production of Rhinanthus minor. Compared with unstocked swards, the similarity of the vegetation to Anthoxanthum odoratum–Geranium sylvaticum grassland was reduced by 16·9% when stocking with sheep continued until 27 May each year, and by 8·3% when sward heights were maintained at 3 cm compared with 5 cm. Increased mean sward height and height of R. minor were positively correlated with accumulated temperatures. Results support suggestions that recent reductions in the nature value of these grasslands might be a consequence of high stocking densities persisting until later in the spring, carried out during a 1‐year period with warmer temperatures.     

Evaluation of the GrazeIn model of grass dry‐matter intake and milk production prediction for dairy cows in temperate grass‐based production systems. 1–Sward characteristics and grazing management factors

This study evaluated the prediction accuracy of grass dry‐matter intake (GDMI) and milk yield predicted by the model GrazeIn using a database representing 522 grazing herds. The GrazeIn input variables under consideration were fill value (FV), grass energy content [Unité Fourragère Lait (UFL)], grass protein value [true protein absorbable in the small intestine when rumen fermen energy is limiting microbial protein synthesis in the rumen (PDIE)], pre‐grazing herbage mass (PGHM), daily herbage allowance (DHA) and concentrate supplementation. GrazeIn was evaluated using the relative prediction error (RPE). The mean actual GDMI and milk yields of grazing herds in the database ranged from 9·9–22·0 kg DM per cow d^?1 and 8·9–41·8 kg per cow d^?1, respectively. The accuracy of predictions for the total database estimated by RPE was 12·2 and 12·8% for GDMI and milk yield, respectively. The mean bias (predicted minus actual) for GDMI was ?0·3 kg DM per cow d^?1 and for milk yield was +0·9 kg per cow d^?1. GrazeIn predicted GDMI with a level of error <13·4% RPE for spring, summer and autumn. GrazeIn predicted milk yield in autumn (RPE = 17·6%) with a larger error in comparison with spring (RPE = 10·4%) and summer (RPE = 11·0%). Future studies should focus on the adaptation of GrazeIn to correct and improve the prediction of milk yield in autumn.