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Perennial ryegrass (Lolium perenne L.) provides a cost-effective forage species for New Zealand farms. Vegetative persistence (maintained herbage growth and survival without reseeding) is an important trait for decreasing costs of pasture establishment. Breeding for vegetative persistence is difficult because of a deficiency of long-term trials to observe the complex interactions between plant genotype and environment. Over time in a long-term trial, a shift in the genetic mean of a cultivar could occur as plants with genetically enhanced persistence traits survive. This study aimed to identify a shift in the genetic mean of two cultivars sown in a long-term trial in Hawkes Bay, New Zealand. Plots of 1 m rows were assessed in a trial for 13 months to compare changes in additive genetic variation ( σ a 2 ), narrow-sense heritability ( h n 2 ), and trait associations of half-sib (HS) populations generated from "Persistent" plants and commercially bought seed of "Original" cultivars Grasslands Samson and Commando. Significant (P < 0.05) σ a 2 and high levels of h n 2 for some populations were identified for scores of herbage growth, leaf width, plant habit and aftermath heading. This study found genetic shifts over time were cultivar specific. Traits that were different between Persistent and Original populations were previously associated with decreased pasture intake. Trait associations and cluster analysis identified HS families that could be used for developing enhanced persistence. [ABSTRACT FROM AUTHOR]

Water shortage is the primary limiting factor for crop production and long-term agricultural sustainability of the North China Plain. Forage cultivation emerged recently in this region. A flyer-year field experiment studies were conducted at Yucheng Integrated Experiment Station to quantify the water requirement and water use efficiency of seven forage varieties under climate variability, that is five annuals, i.e., ryegrass (Secale cereale L.), triticale (×Triticosecale Wittmack), sorghum hybrid sudangrass (Sorghum biolor × Sorghum Sudanense c.v.), ensilage corn (Zea mays L.), prince's feather (Amaranthus paniculatus L.) and two perennials alfalfa (Medicago saliva L.) and cup plant (Silphium perfoliatum L.). Average ET for five annual varieties ranged from 333 to 371 mm, significantly lower than that of the perennial varieties. El of alfalfa is 789 mm, which is higher than that of cup plant. Ryegrass and triticale need 1.5 to 2.0 mm water per day, while others 2.9-4.4 mm. Ensilage corn and Sorghum hybrid sudangrass performed better as their irrigation demand is smaller in the dry seasons than others. Ryegrass needs 281 mm irrigation requirement, which is higher than triticale in dry years. Prince's feather is sensitive to climate change and it can be selected when rainfall is greater than 592.9 mm in the growing season. Mean WUE for prince's feather is 20 Kg ha-1 mm-1, for ensilage corn is 41 Kg ha-1 mm-1 and others is close to 26 Kg ha-1 mm-1. Our experiments indicate that excessive rain will reduce the production of alfalfae. The results of this experiment have implications for researchers and policy makers with water management strategy of forage cultivars and it also very useful in addressing climate change impact and adaptation issues. [ABSTRACT FROM AUTHOR]

Italian ryegrass ( Lolium multiflorum Lam. ssp. italicum Volkart ex Schinz et Keller) thrives well in permanent grassland in mild and moist regions of Switzerland. Ecotypes of Italian ryegrass from Swiss permanent meadows have often been used successfully as the base material of breeding programmes. However, their agronomic performance per se has never been studied in detail. Therefore, field trials were conducted to assess the potential of this semi-natural genetic resource for use in breeding. Twenty ecotype populations were collected in different geographical regions in 2003 and seed was increased. Plot trials with 20 ecotype populations were conducted 2005–2007 at three locations, supplemented by row trials at two additional locations, and including four currently recommended cultivars as controls. Average performance in terms of yield, vigour and resistance to snow mould of ecotypes was superior to the cultivars. Depending on the characteristic, between three and 16 of the 20 ecotypes performed significantly better than the cultivars mean. However, resistance against crown rust of all ecotypes was significantly poorer than that of the cultivars. Correlation and regression analysis showed that more eastern and more northern collecting sites harboured better performing ecotypes. However, the most consistent site related factor favouring performance of the ecotypes in terms of yield, vigour, snow mould and Xanthomonas resistance was a low abundance of species which are typical of Arrhenatheretum type meadows. Data from the plot trials were related to results obtained with spaced plants at a single site, either in a seedling nursery or in the greenhouse. Resistance against crown rust was extremely well predicted by spaced plant observations. Xanthomonas resistance observed after artificial inoculation in the greenhouse was also significantly, but less closely correlated with field observations. An early date of ear emergence as observed on spaced plants was associated with high annual yield in the plot trials. It is concluded that in intensively managed habitats, natural selection has resulted in ecotype populations of Italian ryegrass which are highly promising for use in breeding. Individual plant selection for resistance can be expected to efficiently reduce their high susceptibility to crown rust. [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]

The hypothesis that plant species diversity and genetic variation of the host species decrease the severity of plant diseases is supported by studies of agricultural systems, but experimental evidence from more complex systems is scarce. In an experiment with grassland communities of varying species richness (1, 2, 4, 8, 16, and 60 species) and functional group richness (1, 2, 3, and 4 functional groups), we used different cultivars of Lolium perenne (perennial ryegrass) to study effects of biodiversity and cultivar identity on the occurrence and severity of foliar fungal diseases caused by Puccinia coronata (crown rust) and P. graminis (stem rust). Cultivar monocultures of perennial ryegrass revealed strong differences in pathogen susceptibility among these cultivars. Disease intensity caused by both rust fungi decreased significantly with growing species richness of species mixtures. The response to the diversity gradient was related to the decreased density and size of the host individuals with increasing species richness. The occurrence of other grass species known to be possible hosts of the pathogens in the experimental mixtures did not promote disease intensity in L. perenne, indicating that there was a high host specificity of pathogen strains. Differences in pathogen susceptibility among perennial ryegrass cultivars persisted independent of diversity treatment, host density and host individual size, but resulted in a cultivar-specific pattern of changes in pathogen infestation across the species-richness gradient. Our study provided evidence that within-species variation in pathogen susceptibility and competitive interactions of the host species with the environment, as caused by species diversity treatments, are key determinants of the occurrence and severity of fungal diseases. [ABSTRACT FROM AUTHOR]

Perennial ryegrass ( Lolium perenne L.) is the most important grass species for temperate grassland agriculture. The level and distribution of genetic variation in gene bank ecotype collections is still largely unknown but of great interest for the planning of breeding programs. The objectives of this study were to (i) assess the molecular diversity of Polish ecotypes of perennial ryegrass, and (ii) compare the relationship between this group and German ecotypes and European cultivars investigated previously. A total number of 166 polymorphic marker bands were detected among the 171 individual plants of the 9 Polish ecotypes. In a joint analysis with 9 Polish and 22 German ecotypes, and 22 European cultivars 172 polymorphic RAPD markers could be found. Genetic distance among the Polish ecotypes ranged from 0.31 to 0.51, while for all 53 populations a broader range was detected (0.25–0.67). An analysis of molecular variance (AMOVA) revealed a much larger variation within populations (71%) than among them (29%). The Polish ecotypes contained the highest within population variation (74%). The largest among group difference (15%) was found between the Polish ecotypes versus all other accessions. We conclude that the Polish ecotypes represent a valuable genetic resource for enlarging the genetic variation in the West European germplasm pool of perennial ryegrass. [ABSTRACT FROM AUTHOR]

Two diploid (Belramo and Glen), one tetraploid (Rosalin) and one tetraploid hybrid (Lolium×boucheanumKunth) (AberExcel) intermediate-heading perennial ryegrass (Lolium perenneL.) varieties were sown in boxes (85×44×14 cm) to create micro-swards. Once established, these were defoliated at approximately 21-day intervals before being offered to individual yearling Simmental × Holstein beef heifers in short-term tests. Bite mass measured in these tests was compared with bite mass for groups of similar heifers which were rotationally stocked on the same four varieties. The boxes were weighed (± 0.1 g) before and after a period during which the heifers were allowed to take approximately 50 bites. The micro-sward methodology was developed in, 2002 and bite masses for Belramo, Glen, Rosalin and AberExcel, respectively, were 0.44, 0.46, 0.49 and 0.50 g DM bite-1 compared with 0.48, 0.49, 0.50 and 0.50 g DM bite-1 measured for rotationally stocked cattle. In 2003, the values for bite mass were 0.40, 0.41, 0.41 and 0.43 g DM bite-1 measured using sward boxes and 0.31, 0.41, 0.34 and 0.37 g DM bite-1 for rotationally stocked cattle. Whilst the rankings were similar within ploidy for the two assessment methods, there were no significant differences between the varieties. The micro-sward methodology provides a rapid, low-cost assessment method with a low seed requirement to screen for intake traits during breeding programmes and during variety evaluation. Now there is a need to develop further this methodology in order to allow small-scale simulation of other defoliation regimes, for example continuous stocking. [ABSTRACT FROM AUTHOR]

Fifteen intermediate-heading varieties of perennial ryegrass were continuously-stocked with sheep during two years and sward surface height was maintained in the range of 4 to 5 cm. Large differences in daily dry matter intake ewe-1 were observed between the varieties suggesting that there is considerable scope for breeding improved varieties for grazing. Compared with the mean in each year, the ranges in values were proportionately 0.81 to 1.24 in 1998 and 0.80 to 1.19 in 1999. Highest intakes were measured for sheep grazing 2 tetraploid hybrid varieties which also had markedly higher liveweight gains ewe-1 and ha-1 compared with those grazing the 9 diploid and 4 tetraploid varieties examined. Daily intakes were not correlated with eating time but were correlated with intake rate min-1 eating (r = 0.73 and 0.88 in 1998 and 1999, respectively). Animals appeared unable to compensate fully for low intake rate by increasing eating time. Intake rates were not correlated with green leaf mass, the number of grass tillers m-2 or water soluble carbohydrate concentrations in grass snips from the grazed horizon. High intake rates were achieved not only by sheep grazing highly-tillered diploid varieties but also by those grazing tetraploid hybrids with fewer tillers m-2. Other plant morphological and chemical attributes need to be explored to determine what factors might influence the intake characteristics of varieties destined for grazing so that new target traits can be identified and improved methods can be developed to screen rapidly for these traits during breeding programmes and during variety evaluation. [ABSTRACT FROM AUTHOR]

Lolium species (considered the ideal grasses for European agriculture) are not sufficiently robust to meet many of the environmental challenges that face extensive agriculture in less favoured areas. Fortunately, adaptations to abiotic and biotic stresses exist amongst Festuca species related closely to Lolium. The complex of species has an enormous wealth of genetic variability and potentiality for genetic exchange, thus offering unique opportunities for the production of versatile hybrid varieties with new combinations of useful characters suited to modern grassland farming. The attributes of Lolium and Festuca can be combined into a single genotype by amphiploidy or alternatively, a limited number of characters can be selectively introgressed from Festuca into Lolium or vice versa. Androgenesis of the interspecific hybrids can generate genotypes combining characters that may not be recovered by sexual backcrossing. Genomic in situ hybridization (GISH) can differentially `paint' the chromosomes of Lolium and Festuca and identify Lolium-Festuca recombinant chromosomes. GISH is valuable in the analysis of amphiploids, introgressions and androgenic genotypes and can be used to physically map introgressed traits. Introgression mapping is a powerful new approach to the mapping of traits and arises from a fusion of physical and genetic mapping. For example, in a diploid Lolium introgression genotype with only one introgressed Festuca segment, the gene(s) for any Festuca derived trait expressed by the plant must be located within the segment. Using GISH and molecular markers, a dense but highly localised map of the Festuca segment is made in isolation of the Lolium genome – this may simplify QTL analysis. [ABSTRACT FROM AUTHOR]