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1
Liu, Jianyang. "Morphological and genetic variation within perennial ryegrass (Lolium perenne l.)." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1127245394.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xiii, 123 p.; also includes graphics (some col.). Includes bibliographical references (p. 99-107). Available online via OhioLINK's ETD Center
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Will, Jacqueline Ann Kennedy. "Genome analysis in Lolium." Thesis, Aberystwyth University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.344086.
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Chen, Caifu. "Molecular genome characterization and introgression in Lolium perenne and Festuca species /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9809676.
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Cao, Mingshu. "Molecular cytogenetic analysis of genomes between Festuca mairei and Lolium perenne /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3012953.
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Barrett, S. K. "Growth regulators in Lolium perenne grown for seed." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378463.
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Huang, Ji-Wei. "Wear tolerance in perennial ryegrass (Lolium perenne L.)." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389474.
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Meharg, Andrew Alexander. "Factors affecting rhizosphere carbon-flow in Lolium perenne." Thesis, University of Aberdeen, 1989. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU031803.
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The dynamics of root carbon have been studied on a limited number of plants under a limited range of environmental conditions. This is particularly true of temperate pasture grasses. It was proposed to investigate rhizosphere carbon flow within Lolium perenne, to determine environmental factors affecting root exudation and root respiration. A number of microcosms were designed in which ryegrass could be pulse labelled with 14C-CO2, and the fate of the label determined within a plant-soil system. A wide range of factors were found to affect the distribution of carbon within the plant and soil under laboratory conditions. These factors include plant stage of development, micro-organisms, temperature, soil pH, soil water stress and soil anaerobism. A field experiment was carried out to estimate rhizosphere carbon flow under 'natural' conditions and to determine if the laboratory studies could be related to field conditions. Results showed that rhizosphere carbon flow varied greatly depending on environmental conditions. It was proposed that the major loss of newly photoassimilated carbon was dominated by root respiration rather than by root exudation. Inoculation with micro-organisms affected carbon loss from plant roots as exudates. The pattern of carbon distribution within the plant and rhizosphere varied greatly depending on the inoculant.
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Kavanová, Monika. "Leaf growth regulation in Lolium perenne under nutrient stress." [S.l.] : [s.n.], 2006. http://mediatum2.ub.tum.de/doc/613553/document.pdf.
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Manzanares, Chloé. "Genetics of self-incompatibility in perennial ryegrass (Lolium perenne L.)." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4280/.
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Self-incompatibility (SI) prevents pollination by “self” pollen and promotes outbreeding. SI is a widespread mechanism among angiosperms. Grass SI is known to be controlled by two loci, S and Z, mapped in linkage group 1 and 2 respectively but the mechanism remains elusive. SI in perennial ryegrass (Lolium perenne L.) is studied at the gene level for the S-locus. Using a fine-mapping approach, followed by the sequencing of the genomic S-locus region and the transcripts from pollen and stigma, the project identified four stigma S-candidate genes and potentially six pollen S-candidate genes. Moreover, using closely linked markers, the allelic diversity in a breeding population was assessed for both S and Z. This assay demonstrated that allelic diversity is maintained in a half-sib family recurrent selection programme and that even if the SI genes are unknown, it is possible to predict their genotypes. Finally, self-compatibility has been reported in many grasses. Using self-compatible perennial ryegrass populations, two additional loci, F and T, have been investigated, by a mapping approach as well as observation of self-pollination under the microscope. For both loci, a distortion segregation was observed on linkage group 3 (F) and 5 (T) and initial marker recombination maps were created.
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Bushoven, John T. "The role of nitrate and carbohydrates in modulating the partitioning of nitrate assimilation between leaves and roots in perennial ryegrass (Lolium perenne L.) /." View online ; access limited to URI, 2003. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3112113.
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Kraus, Edwin. "Yield and respiration of populations of Lolium perenne as affected by plant growth conditions = Opbrengst en ademhaling van populaties van Lolium perenne onder verschillende kweek kondities /." [S.l. : s.n.], 1995. http://www.gbv.de/dms/bs/toc/189735295.pdf.
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Raikar, Sanjeev Vencu. "Protoplast fusion of Lolium perenne and Lotus corniculatus for gene introgression." Phd thesis, Lincoln University. Bio-Protection and Ecology Division, 2007. http://theses.lincoln.ac.nz/public/adt-NZLIU20080214.105406/.
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Protoplast fusion of Lolium perenne and Lotus corniculatus for gene introgression
by Sanjeev V. Raikar
Lolium perenne is one of the most important forage crops globally and in New Zealand. Lotus corniculatus is a dicotyledonous forage that contains valuable traits such as high levels of condensed tannins, increased digestibility, and high nitrogen fixing abilities. However, conventional breeding between these two forage crops is impossible due to their markedly different taxonomic origin. Protoplast fusion (somatic hybridisation) provides an opportunity for gene introgression between these two species. This thesis describes the somatic hybridisation, the regeneration and the molecular analysis of the putative somatic hybrid plants obtained between L. perenne and L. corniculatus.
Callus and cell suspensions of different cultivars of L. perenne were established from immature embryos and plants were regenerated from the callus. Of the 10 cultivars screened, cultivars Bronsyn and Canon had the highest percentage of callus induction at 36% each on 5 mg/L 2,4-D. Removal of the palea and lemma which form the seed coat was found to increase callus induction ability of the embryos. Plant regeneration from the callus was achieved when the callus was plated on LS medium supplemented with plant growth regulators at different concentrations. Variable responses to shoot regeneration was observed between the different cultivars with the cv Kingston having the lowest frequency of shoot formation (12%).
Different factors affecting the protoplast isolation of L. perenne were investigated. The highest protoplast yield of 10×106 g-1FW was obtained when cell suspensions were used as the tissue source, with enzyme combination A (Cellulase Onozuka RS 2%, Macerozyme R-10 1%, Driselase 0.5%, Pectolyase 0.2%), for 6 h incubation period in 0.6 M mannitol. Development of microcolonies was only achieved when protoplasts were plated on nitrocellulose membrane with a L. perenne feeder layer on PEL medium. All the shoots regenerated from the protoplast-derived calli were albino shoots.
The highest protoplast yield (7×106 g-1FW) of L. corniculatus was achieved from cotyledons also with enzyme combination A (Cellulase Onozuka RS 2%, Macerozyme R-10 1%, Driselase 0.5%, Pectolyase 0.2%), for 6 h incubation period in 0.6 M mannitol. The highest plating efficiency for L. corniculatus of 1.57 % was achieved when protoplasts were plated on nitrocellulose membrane with a L. perenne feeder layer on PEL medium. The highest frequency of shoot regeneration (46%) was achieved when calli were plated on LS medium with NAA (0.1 mg/L) and BA (0.1 mg/L).
Protoplast fusion between L. perenne and L. corniculatus was performed using the asymmetric somatic hybridisation technique using PEG as the fusogen. L. perenne protoplasts were treated with 0.1 mM IOA for 15 min and L. corniculatus protoplasts were treated with UV at 0.15 J/cm2 for 10 min. Various parameters affecting the fusion percentage were investigated. Successful fusions were obtained when the fusions were conducted on a plastic surface with 35% PEG (3350 MW) for 25 min duration, followed by 100 mM calcium chloride treatment for 25 min. A total of 14 putative fusion colonies were recovered. Shoots were regenerated from 8 fusion colonies. Unexpectedly, the regenerated putative hybrid plants resembled L. corniculatus plants.
The flow cytometric profile of the putative somatic hybrids resembled that of L. corniculatus. Molecular analysis using SD-AFLP, SCARs and Lolium specific chloroplast microsatellite markers suggest that the putative somatic hybrids could be L. corniculatus escapes from the asymmetric protoplast fusion process. This thesis details a novel Whole Genome Amplification technique for plants using Strand Displacement Amplification technique.
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Raikar, S. V. "Protoplast fusion of Lolium perenne and Lotus corniculatus for gene introgression." Diss., Lincoln University, 2007. http://hdl.handle.net/10182/301.
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Lolium perenne is one of the most important forage crops globally and in New Zealand. Lotus corniculatus is a dicotyledonous forage that contains valuable traits such as high levels of condensed tannins, increased digestibility, and high nitrogen fixing abilities. However, conventional breeding between these two forage crops is impossible due to their markedly different taxonomic origin. Protoplast fusion (somatic hybridisation) provides an opportunity for gene introgression between these two species. This thesis describes the somatic hybridisation, the regeneration and the molecular analysis of the putative somatic hybrid plants obtained between L. perenne and L. corniculatus. Callus and cell suspensions of different cultivars of L. perenne were established from immature embryos and plants were regenerated from the callus. Of the 10 cultivars screened, cultivars Bronsyn and Canon had the highest percentage of callus induction at 36% each on 5 mg/L 2,4-D. Removal of the palea and lemma which form the seed coat was found to increase callus induction ability of the embryos. Plant regeneration from the callus was achieved when the callus was plated on LS medium supplemented with plant growth regulators at different concentrations. Variable responses to shoot regeneration was observed between the different cultivars with the cv Kingston having the lowest frequency of shoot formation (12%). Different factors affecting the protoplast isolation of L. perenne were investigated. The highest protoplast yield of 10×10⁶ g⁻¹FW was obtained when cell suspensions were used as the tissue source, with enzyme combination 'A' (Cellulase Onozuka RS 2%, Macerozyme R-10 1%, Driselase 0.5%, Pectolyase 0.2%), for 6 h incubation period in 0.6 M mannitol. Development of microcolonies was only achieved when protoplasts were plated on nitrocellulose membrane with a L. perenne feeder layer on PEL medium. All the shoots regenerated from the protoplast-derived calli were albino shoots. The highest protoplast yield (7×10⁶ g⁻¹FW) of L. corniculatus was achieved from cotyledons also with enzyme combination 'A' (Cellulase Onozuka RS 2%, Macerozyme R-10 1%, Driselase 0.5%, Pectolyase 0.2%), for 6 h incubation period in 0.6 M mannitol. The highest plating efficiency for L. corniculatus of 1.57 % was achieved when protoplasts were plated on nitrocellulose membrane with a L. perenne feeder layer on PEL medium. The highest frequency of shoot regeneration (46%) was achieved when calli were plated on LS medium with NAA (0.1 mg/L) and BA (0.1 mg/L). Protoplast fusion between L. perenne and L. corniculatus was performed using the asymmetric somatic hybridisation technique using PEG as the fusogen. L. perenne protoplasts were treated with 0.1 mM IOA for 15 min and L. corniculatus protoplasts were treated with UV at 0.15 J/cm² for 10 min. Various parameters affecting the fusion percentage were investigated. Successful fusions were obtained when the fusions were conducted on a plastic surface with 35% PEG (3350 MW) for 25 min duration, followed by 100 mM calcium chloride treatment for 25 min. A total of 14 putative fusion colonies were recovered. Shoots were regenerated from 8 fusion colonies. Unexpectedly, the regenerated putative hybrid plants resembled L. corniculatus plants. The flow cytometric profile of the putative somatic hybrids resembled that of L. corniculatus. Molecular analysis using SD-AFLP, SCARs and Lolium specific chloroplast microsatellite markers suggest that the putative somatic hybrids could be L. corniculatus escapes from the asymmetric protoplast fusion process. This thesis details a novel Whole Genome Amplification technique for plants using Strand Displacement Amplification technique.
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Jupp, A. P. "Some effects of severe drought on the roots of Lolium perenne." Thesis, University of Bristol, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375027.
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Yang, Bicheng. "Investigations of self-incompatibility (SI) in perennial ryegrass (Lolium perenne L.)." Thesis, University of Birmingham, 2009. http://etheses.bham.ac.uk//id/eprint/1097/.
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Perennial ryegrass (Lolium perenne L.) is one of the most economically and environmentally important grass species for the temperate zone. It maintains effective self-incompatibility (SI), which promotes outbreeding as well as limits the efficient production of inbred lines and hybrids. SI in L. perenne is controlled by the S and Z loci, mapping to linkage groups 1 and 2, respectively. None of the gene products has been identified so far. Comparative mapping has identified regions on rice chromosomes 5 (R5) and 4 with synteny to regions of L. perenne genome containing the S and Z loci, respectively. Markers were developed from the syntenic rice genomic region to refine the S and Z maps. The closest flanking markers had a map distance of 2 cM from S and 0.2 cM from Z. SI cDNA libraries were developed from in-vitro pollinated stigma subtracted with unpollinated stigma to identify SI components and SI response related genes. Through a BLAST search, candidates identified from the SI libraries that were orthologous to sequences on the S and Z flanking regions on rice R4 and R5 were the prime candidate SI genes. Altogether ten SI candidate genes were identified with incompatible response associated differentially expression pattern: a rapid increase in expression within two minutes after pollen-stigma contact and reaching a maximum between 2-10 minutes, implying their roles in the SI response. Attempts were carried out to determine the linkage relationships between the identified candidates and the S or Z loci. Large fine scale mapping populations were developed individually for the S and Z loci to generate high resolution maps of S and Z towards map-based cloning. Tightly linked markers were identified mapping at a distance of 1.4 cM from S and 0.9 cM from Z. The studies performed in this project have implications on both the underlying genetic control and the associated biochemical responses involved in L. perenne SI. The closely linked markers for S or Z could be applied in future marker assisted selection breeding programmes and map-based cloning.
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Foito, Alexandre. "A metabolomics-based approach to study abiotic stress in Lolium perenne." Thesis, University of Dundee, 2010. https://discovery.dundee.ac.uk/en/studentTheses/897810b2-4b52-43a8-a687-d21fef3a6d1e.
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In the United Kingdom and Ireland, a major percentage of fertilized agricultural area is devoted to grasslands, which helps to support the associated milk and beef production industries. In temperate grasslands, perennial ryegrass (L. perenne) is the major forage grass and this species is particularly suitable as a forage grass due to its high yield and digestibility, when compared with other species. However, perennial ryegrass is not well adapted to abiotic stress conditions which are likely to occur in its natural environment. Some of the abiotic stress factors which have significant impacts on plant growth and development include water and nutrient availability. Therefore, this project set out to unravel some of the mechanisms involved in the adaptation of perennial ryegrass to limited water, phosphorous and nitrogen. In order to understand the metabolic mechanisms acting in response to these stresses, metabolite profiling was performed using GC-MS. Furthermore, for the water- and phosphorous-limitation studies this approach was complemented with transcript analysis.In order to study water-limitation a hydroponics system supplemented with polyethyleneglycol (PEG) was used to induce water-limitation for a period of one-week. A clear difference in the metabolic profiles of the leaves of plants grown under water stress was observed. Differences were principally due to a reduction in fatty acid levels in the more water stress-susceptible genotype Cashel and an increase in sugars and compatible solutes in the drought-tolerant PI 462336 genotype. Sugars exhibiting a significant increase included, raffinose, trehalose, glucose, fructose and maltose. Raffinose was identified as the metabolite exhibiting the largest accumulation under water-stress in the more tolerant genotype and may represent a target for engineering superior drought tolerance or form the basis of marker-assisted breeding in perennial ryegrass. The metabolomics approach was combined with a transcriptomics approach in the water stress tolerant genotype PI 462336 which identified genes in perennial ryegrass that were regulated by this stress.The characterization of the response to phosphorus-limitation was performed in a hydroponics system containing two solutions with different levels of phosphorus. Samples were collected from the roots and leaves of two genotypes 24 hours after being exposed to stress. Internal phosphate concentrations were reduced and significant alterations were detected in the metabolome and transcriptome of two perennial ryegrass genotypes. Results indicated a replacement of phospholipids with sulfolipids in response to P deficiency and that this occurs at the very early stages of P deficiency in perennial ryegrass. Additionally, the results suggested the role of glycolytic bypasses and the re-allocation of carbohydrates in response to P deficiency The characterization of the metabolic response of L. perenne leaves to different levels of nitrogen supply was performed for seven different genotypes with variability in the regrowth response rate to nitrogen supply in a hydroponics system. This facilitated the identification of common mechanisms of response between genotypes to nitrogen. The metabolic response observed included modifications of the lipid metabolism, as well as alterations of secondary aromatic metabolite precursors in plants exposed to nitrogendeficit. In contrast, plants grown in a nitrogen saturated media appeared to modify to some extent the metabolism of ascorbate. Additionally, it was found that amino acid levels increased with increasing concentrations of nitrogen supplied. This study suggested that the involvement of secondary metabolism, together with lipid and ascorbate metabolism, is of crucial importance in the early-adaptation of perennial ryegrass plants to different levels of nitrogen supply.
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GUERRAND, DAVID. "Etude des voies de synthese des fructanes chez lolium perenne l." Caen, 1997. http://www.theses.fr/1997CAEN2036.
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Chez les poacees, la synthese des fructanes serait catalysee par plusieurs enzymes vacuolaires dont la sst, consideree comme etant l'enzyme cle du metabolisme des fructanes. La sst catalyse la synthese d'un trisaccharide, le 1-kestotriose, a partir de deux molecules de saccharose, et n'a pas encore ete purifiee a l'homogeneite chez les poacees. Chez les especes du genre lolium, ce modele ne permet pas de rendre compte de la synthese de l'ensemble des fructanes detectes in vivo, et notamment des fructanes de masse moleculaire elevee. Une voie enzymatique additionnelle, associee a la fraction proteique insoluble et appelee phleine sucrase, catalyserait la synthese des fructanes de masse moleculaire elevee. Ce travail montre qu'au cours de la repousse consecutive a une coupe la fraction enzymatique soluble totale catalyse la synthese in vitro de la majorite des fructanes detectes in vivo. La fraction insoluble catalyse au cours de la meme periode la synthese de 1-kestotriose uniquement. L'hypothese de l'existence d'une isoforme insoluble de la sst a ete emise et la purification de la sst a ete envisagee. Dans des conditions favorisant l'accumulation des fructanes dans les parties aeriennes de lolium perenne, l'activite sst est multipliee par 3 dans les gaines foliaires et par 1,5 dans les bases des feuilles en croissance. L'emploi d'inhibiteurs des syntheses proteiques suggere que cette augmentation est due a a la synthese de novo de l'enzyme ou de facteurs proteiques controlant son activite. Une approche originale a ete developpee pour purifier la sst : comparaison par electrophorese bidimensionnelle des profils proteiques des tissus foliaires, suivie de la restauration des activites enzymatiques. Trois proteines de masse moleculaire proche de 80 kda ont ete mises en evidence dans les gaines et dans les bases des feuilles en croissance. Leur intensite augmente lorsque les plantes accumulent des fructanes et une d'entre elles catalyse la synthese in vitro de 1-kestotriose en presence de saccharose. Il pourrait s'agir d'une sst.
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Nurjaya, I. Gusti Made Oka. "Studies on the competitive ability of white clover (Trifolium repens L.) in mixtures with perennial ryegrass (Lolium perenne L.) : the importance of non-structural carbohydrate reserves and plant traits /." Title page, contents and summary only, 1996. http://web4.library.adelaide.edu.au/theses/09APSP/09apspi11.pdf.
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Bazely, Dawn. "Foraging behaviour of sheep (Ovis aries L.) grazing on swards of perennial ryegrass (Lolium perenne L.)." Thesis, University of Oxford, 1988. http://ora.ox.ac.uk/objects/uuid:d48c2508-a774-43b4-805b-9470971bd236.
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The grazing behaviour and diet selection of a vertebrate herbivore, the domestic sheep (ovis aries L.), feeding in patchy perennial ryegrass (Lolium perenne L.) monocultures was investigated. Heterogeneity or patchiness was created by manipulating (1) the nutritional content of ryegrass, (2) parameters of sward structure e.g. sward height, pseudostem and lamina length, and tiller density, and (3) brightness of ryegrass relative to the background sward. Patches were either fertilised turves transplanted into paddock swards or were created in situ by local fertilisation, trimming etc. The background sward was low in nitrogen (<1.0%N dry weight) compared with average ryegrass leys found on farms in British lowland areas. Sheep preferred to graze in transplanted patches of ryegrass. These patches were structurally similar to the background sward, but were higher in nitrogen content and digestibility as a result of fertilisation. Thus, sheep actively selected more nutritious ryegrass. There was a significant quantitative relationship between brightness and the nitrogen and water soluble carbohydrate content of ryegrass. Darker green ryegrass had a higher nitrogen content and lower water soluble carbohydrate content than lighter green ryegrass. It is suggested that sheep learned to use brightness as a cue in intra-specific forage selection. They had a high preference for short, dark green patches of similar height to the lighter green, background sward. Sheep also preferred to graze in tall patches of ryegrass (>10 cm taller than the background sward) regardless of their nutritional content or brightness relative to the background sward. It is likely that sheep use a multiplicity of physical cues associated with perennial ryegrass in diet selection. The interaction between structural and sward parameters and nutrition content of forage in influencing diet selection requires further investigation. In further experiments, an optimal foraging model, the marginal value theorem was used to make predictions about the behaviour of sheep grazing in monocultures containing highly preferred transplanted patches of tall, fertilised ryegrass. By manipulating the cost of travel between these good ryegrass patches and by detailed measurements of intake within patches by individual sheep, I was able to make quantitative predictions about the time spent grazing in each patch. Travel time and costs were increased by moving good patches further apart and by hobbling sheep to slow down their speed of movement. As predicted by the marginal value theorem, average time spent in a patch was positively correlated with average travel time between patches. For two sheep, the predicted and observed times spent in patches were statistically similar at low travel times, while at higher travel times, observed times were greater than predicted. For a third sheep, all observed times were greater than predicted. Thus overall, there was not a good quantitative fit between the model and the observed behaviour. While incorporation of the difference in the energetic cost of travel relative to that of grazing in a good patch into the model resulted in an increase in predicted optimal patch residence times, the fit between predicted and observed values was not significantly improved. Reasons for this difference between observed and predicted patch residence times are discussed. However, these experiments demonstrated that patch-use foraging models may be more useful than prey models in investigating grazing behaviour of vertebrate herbivores, and that travel time between patches of forage is a previously unidentified constraint of sheep grazing behaviour.
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Wiltshire, J. J. J. "The use of the growth regulator triapenthenol in seed crops of Lolium perenne L." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233613.
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Damrongkool, Prapassorn. "Sequence and distribution of the Neotyphodium lolli peptide synthetase gene lpsA." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=2927.
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Thesis (Ph. D.)--West Virginia University, 2003.Title from document title page. Document formatted into pages; contains ix, 134 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.
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Tomaszewski, Celine. "Fine mapping of biomass yield quantitative trait loci in Lolium perenne L." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/10827.
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Biomass yield is a complex quantitative trait controlled by many environmental and genetic factors. Therefore its study relies on QTL mapping. In a precursor study, a genetic map of L. perenne was constructed on an inbred-derived F2 population and three major biomass QTL have been found on linkage groups (LGs) 2, 3 and 7. In this study, a fine map of the QTL positions was developed by mapping additional ryegrass specific SSR, rice Sequence Tagged Site and Diversity Array Technology markers. A total of 153 markers were added to the existing map leading to a map density of 3.5 cM. The QTL positions were recalculated for dry weight, fresh weight, dry matter and leaf width and in accordance to the preliminary analysis biomass QTL were localized on LGs 2, 3 and 7 but despite the fine map the QTL intervals were not reduced. In order to analyze the QTL regions, the screening of a L. perenne BAC library was performed using the markers flanking the QTL and several clones were isolated. After analysis using the AFLP fingerprinting method, five clones were send for full sequencing to perform a gene prediction and annotation using the Ab initio approach. The annotation revealed for one of the gene structures predicted homology to the lg1- like gene and four other showed homology to regions flanking genes of interest suggesting the possible presence of the genes within the biomass QTL region. The four genes were: L. perenne heading date (Hd1) gene, Avena strigosa beta-amyrin synthase (Sad1) and cytochrome P450 CYP51H10 (Sad2) genes and Lolium multiflorum gene for cold responsive protein.
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Lowes, Wendy. "A molecular analysis of the factors affecting frost tolerance in Lolium perenne." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299054.
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Devereaux, Alissa Corrine. "Transformation and overexpression of a MnSOD gene in perennial ryegrass (Lolium perenne L.)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61891.pdf.
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Xu, Xiangming. "The genetic assessment of inbred lines and their hybrids in Lolium perenne L." Thesis, Aberystwyth University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283766.
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Morgan, Sarah Ann. "Relationships between fatty acids, lipids and other characteristics of perennial ryegrass (Lolium perenne)." Thesis, Aberystwyth University, 2015. http://hdl.handle.net/2160/faf97ebd-42b4-447d-bda5-71d41d14c031.
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Production and consumption of ruminant products is partly being held accountable for the increasing global challenges of human health and climate change. Also, increasing demand for food, feed and fuel is placing growing pressure on land availability. One area under investigation in response to these challenges is fatty acid content of forages. This thesis sets out to investigate the variation and relationships between fatty acids, lipids, chlorophyll and other nutritional aspects of perennial ryegrass. Additionally, it will investigate alternative methods to predict fatty acids in forage. The core experiment involved twenty-four genotypes from two perennial ryegrass populations. Fatty acids were found to increase in leaf material during a growing season. Genotype differences in fatty acid content and composition were found which were broadly consistent across the growing season. Fatty acids correlated positively with crude protein but negatively with water-soluble carbohydrates. A positive and consistent relationship was found between chlorophyll and fatty acids across the growing season. The use of a chlorophyll meter to estimate fatty acid content did not perform very well, due to poor relationships with in vitro chlorophyll, however near-infrared reflectance and Fourier-transform mid-infrared spectroscopy had acceptable prediction accuracies for use as a screening tool. The accuracies of these prediction methods could be improved with further development using larger datasets. Investigation of the lipid composition revealed that galactolipid proportion was the main contributor to increased total fatty acid content in the high FA genotypes. While phospholipid proportion was minimally affected and neutral lipid negatively affected by increased total fatty acid content. Further work is needed to determine the underlying genetic control of fatty acid and lipid synthesis in perennial ryegrass. Additionally, a great deal more research is needed to establish environmental and genetic effects on lipid composition of forages.
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Alcántara, Mondragón Viridiana. "Evaluación de una pradera de ryegrass perene (Lolium perenne) bajo pastoreo continuo por corderos en crecimiento y finalización en Primavera-Verano." Tesis de Licenciatura, Universidad Autónoma del Estado de México, 2017. http://hdl.handle.net/20.500.11799/68549.
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La población humana mundial sigue aumentando con gran rapidez, en México para 2017 hay una población de 123.5 millones, y, de igual manera, se incrementa la demanda de productos pecuarios como la leche, carne y huevo; de tal forma que las empresas dedicadas a la agricultura y ganadería coinciden en la necesidad de lograr una mayor eficiencia productiva y rentabilidad económica; el caso de la ovinocultura no es la excepción; empero, esta actividad tiene la opción de producir a base de forrajes usados en condiciones de pastoreo, lo cual le permite disminuir los costos de producción, resultando esto en una gran ventaja sobre otras empresas como la avícola y porcina (Church et al., 2002).
El manejo agronómico de la pradera, así como el pastoreo animal, son aspectos fundamentales para explotar el potencial genético de las diferentes especies de gramíneas de clima templado como es el caso del ryegrass (Lolium perenne); sin embargo, en muchas ocasiones su desconocimiento ocasiona el fracaso de los sistemas de producción animal en pradera (Núñez et al., 1995).
Ofrecer y suministrar un forraje de buena calidad puede significar una mayor rentabilidad en la empresa ganadera; hay parámetros que determinan la calidad de los pastos, uno de ellos es su composición química, la cual se estima al practicar un análisis químico proximal del forraje, determinando el contenido de cenizas, fibra ácido detergente (FAD), fibra neutro detergente (FND), proteína cruda (PC), fibra cruda (FC), extracto etéreo (EE), extracto libre de nitrógeno (ELN), además del contenido de calcio, (Ca), fósforo (P), potasio (K), magnesio (Mg), y de los microelementos como manganeso (Mn), zinc (Zn), cobre (Cu), selenio (Se) y hierro (Fe) (Mc Donald et al., 1995).
La fracción de un alimento que, después de ser ingerida y digerida, no aparece en las heces fecales, debido a su desintegración y absorción, se denomina fracción digerida o digestible (Fondevila y Barrios, 2001).
La digestibilidad de la materia orgánica es un factor de suma importancia para determinar el valor nutritivo de un forraje, esa digestibilidad se modifica a medida que las plantas maduran con disminución de la proteína y aumento de la fracción fibrosa a base de los carbohidratos estructurales (Mc Donald et al., 1995). La digestibilidad de los forrajes puede variar dependiendo de factores asociados a los animales, y también según la especie vegetal, su edad y manejo agronómico (Bogdan, 1997).
El grado de digestibilidad de las plantas completas y de sus fracciones puede precisarse a través de métodos in vitro, uno de ellos es el método por producción de gas (Theodorou et al., 1994), en el cual el gas producido provee datos útiles sobre la digestión de las fracciones solubles e insolubles del alimento.
La evaluación de la pradera permite determinar la calidad nutritiva del forraje para aprovechar al máximo el material disponible a ser proporcionado a los animales en las mejores condiciones para su óptima producción (Duthil, 1989; Church et al., 2002).
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Renner, Christine Joan. "Interactive effects of sulphur dioxide, nitrogen dioxide and the winter environment on Lolium perenne." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254029.
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Bababe, B. "Soil hydraulic conductivity and its influence on water status of Lolium perenne, L. seedlings." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376253.
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Canunayon, Meraluna. "Identification of QTL for leaf senescence related traits in perennial ryegrass (Lolium perenne L.)." Thesis, Aberystwyth University, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.704755.
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Hesse, Uljana. "Untersuchungen zur Endophytbesiedelung von Gräserökotypen und zu Symbioseeffekten durch Neotyphodium lolii in Lolium perenne-Genotypen hinsichtlich Stresstoleranz und Ertragsmerkmale." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965087298.
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Zbib, Nasrallah. "Toxicité de la fétuque élevée et du ray-grass anglais endophytés sur ovins." Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0101/document.
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Les associations symbiotiques entre différentes espèces de champignon du genre Epichloë et des plantes fourragères sont à l’origine de la production de mycotoxines responsables, dans certains pays, de toxicoses du bétail et de pertes économiques. Le développement de d’E. coenophiala dans la fétuque, qui est associé à la production d’ergovaline, est responsable de « fescue foot disease » alors que la présence d’E. festucae var. lolii dans le ray-grass anglais, qui est accompagnée d’une production de lolitrem B, est responsable du « ryegrass staggers » et de la production d’ergovaline, dont les effets toxiques associés à la présence de lolitrème B sont mal documentés. Mon travail de thèse a consisté à explorer les effets de la distribution de différents fourrages de fétuque et ray-grass endophytés toxinogènes produits dans des conditions agricoles françaises, sur la santé et la production animale et les mécanismes d’action de l’ergovaline et du lolitrème BThe symbiotic associations between different varieties of fungi of the Epichloë kind and forages are responsible for the production of mycotoxins which are responsible of toxicoses in livestock and economic losses in some countries. The development of E. coenophiala in tall fescue, which is associated with the production of ergovaline, is responsible for « fescue foot disease » while the presence of E. festucae var. lolii in ryegrass, which is accompanied by the production of lolitrem B, is responsible for the « ryegrass staggers ». and the production of ergovaline, whose the toxic effects associated in the presence of lolitrem B are poorly documented. My thesis was to explore the effects of the distribution of different toxic forages of endophyte-infected tall fescue or ryegrass produced in French agricultural conditions on health and animal production and the mechanisms of action of ergovaline and lolitrem B
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Migault, Vincent. "Insertion de la morphogenèse racinaire dans L grass, un modèle structure-fonction de graminées fourragères." Thesis, Poitiers, 2015. http://www.theses.fr/2015POIT2254/document.
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Un modèle de morphogenèse aérienne de graminées fourragères, nommé L grass, a été développé lors de travaux précédents. Le but de la thèse est de proposer une méthode d'insertion de la morphogenèse racinaire dans ce modèle afin de tenir compte de l'impact des ressources telluriques sur la structure et le fonctionnement de la plante.Un simulateur de plante entière de ray-grass anglais (Lolium perenne L.) incorporant (i) des règles d'autorégulation de l'architecture aérienne, (ii) le développement architecturé du système racinaire, (iii) des processus de coordination entre les parties aérienne et racinaire et (iv) un système d'allocation du carbone a été développé. La nature autorégulée du modèle lui permet de reproduire les réponses à l'intensité d'une défoliation et à la compétition pour la lumière sans nécessiter de contrôle central. Le couplage du modèle avec un modèle de sol permet de simuler le développement de la plante subissant différents scénarios d'apport en eau sans nécessiter de consignes morphogénétiques données a priori.La représentation architecturée du système racinaire présente quelques limites, principalement en termes de ressources informatiques, pour les simulations de peuplements. Afin de pallier ces limites, un modèle continu de dynamique de densités racinaires a aussi été incorporé pour simuler l'enracinement. Les comparaisons entre les deux modèles de système racinaire ont montré l'intérêt indéniable des modèles de densités racinaires notamment pour les études à l'échelle d'un couvert végétalA model of the shoot morphogenesis of forage grasses, called L-grass, was developed in previous studies. The aim of this thesis is to propose a method for introducing root morphogenesis in the current model so the effect of telluric resources availability can be taken into account for shaping plant form and functioning.A simulator of perennial ryegrass (Lolium perenne L.) whole plant, which includes (i) the rules of shoot architecture self-regulation,(ii) the architectural development of the root system, (iii) the coordination processes between shoot and root parts and (iv) a system of allocation of carbon, was developed. The self-adaptable character of the model allows the reproduction of the responses to the intensity of defoliation and the competition for sunlight without the need of any central control. The coupling of the model with a soil model enables to recreate the development of the plant undergoing different scenarios of water supply with no requirement of previously established morphogenetic guidelines.The architectural representation of the root system presents some shortcomings, mainly regarding the need in computing power when simulating plant populations. In order to overcome these limitations, a continuous model of the dynamics of root densities has been also incorporated to simulate plant rooting. The comparison between both models of root systems has shown the undeniable interest of modeling root density, especially for the studies at the vegetation cover level
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Murphy, P. M. "Genetic variation in crown rust (Puccinia coronata) and its interactions with perennial ryegrass (Lolium perenne)." Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273155.
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Carlile, Eloise. "Studies on genes and methods for transforming the nucleus and plastids of Lolium perenne L." Thesis, University of Manchester, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687415.
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Lolium perenne L. (perennial ryegrass) is the most widely used turf and forage grass grown in temperate climates throughout the world, commonly found on sports grounds, and in cattle and sheep farming systems. The introduction of new cultivars of L. perenne with improved agricultural performance has relied on traditional breeding methods. Nuclear and plastid transformation provides an alternative approach to obtain plants with desired phenotypes, some of which would be difficult to achieve by classical breeding.
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Podkówka, Lucyna. "Wartość pokarmowa oraz ocena przydatności do zakiszania zielonek z Phleum pratense, Lolium perenne i Festulolium." Rozprawa doktorska, [Nakł.aut.], 2001. http://dlibra.utp.edu.pl/Content/270.
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Ansell, Kevin J. "How does increased COâ†2 concentration effect leaf photosynthesis at low temperatures in Lolium perenne." Thesis, University of Essex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394185.
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Putta, Karthik. "Physical mapping of EPSPS gene copies in glyphosate resistant Italian ryegrass (Lolium perenne ssp. multiflorum)." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/36183.
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Master of ScienceDepartment of Agronomy
Randall S. Currie
Mithila Jugulam
Italian ryegrass (Lolium perenne L. ssp. multiflorum (Lam.) Husnot), one of the problem weeds of the US, evolved resistance to multiple herbicides including glyphosate due to selection in Arkansas (AR). Glyphosate is a 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) inhibitor and amplification of EPSPS gene, the molecular target of glyphosate confers resistance to this herbicide in several weed species, including Italian ryegrass from AR. The objective of this study was to determine the expression of EPSPS gene and protein as well as distribution of EPSPS copies on the genome of glyphosate-resistant Italian ryegrass (ARR) using a known susceptible Italian ryegrass (ARS) from AR. EPSPS gene copies and expression of ARR and ARS were determined using quantitative PCR with appropriate endogenous controls. EPSPS protein expression was determined using Western blot analysis. Fluorescence in situ hybridization (FISH) was performed on somatic metaphase chromosomes to determine the location of EPSPS copies. Based on qPCR analysis, ARR plants showed a wide range of 12 to 118 EPSPS copies compared to a single copy in ARS. EPSPS gene expression correlated with the gene copy number in both ARR and ARS. Individuals with high EPSPS copies showed high protein expression in Western blot analysis. FISH analysis showed presence of brighter EPSPS signals, distributed randomly throughout the genome of ARR individuals compared to a faint signal in ARS plants. Random distribution of EPSPS copies was previously reported in glyphosate-resistant Palmer amaranth. Overall, the results of this study will help understand the origin and mechanism of EPSPS gene amplification in Italian ryegrass.
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Reinholz, Johannes. "Analytische Untersuchungen zu den Alkaloiden Lolitrem B und Paxillin von Neotyphodium lolii und Lolium perenne, in vivo und in vitro." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961553723.
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Repussard, Céline. "Etude des facteurs de production d’alcaloïdes toxiques par des Epichloë endophytes de graminées fourragères dans le Sud de la France." Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0104/document.
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Les associations symbiotiques Epichloë- graminées fourragères les plus étudiées concernent le ray grass anglais (Lolium perenne) avec Epichloë festucae var. lolii et la fétuque élevée (L. arundinaceum) avec E. coenophiala. Ces champignons peuvent synthétiser des alcaloïdes toxiques pour le bétail tels que l’ergovaline et le lolitrème B. Mon travail de thèse a consisté à explorer les facteurs en lien avec la production de mycotoxines dans les graminées. Pour cela différentes études ont été conduites sur la fétuque et le ray grass afin de révéler i) la présence de souches endophytées toxinogènes dans le Sud Ouest de la France et ii) l’influence des conditions climatiques françaises sur la synthèse d’ergovaline et de lolitrème B dans des variétés fourragères connues pour être responsables de cas de toxicité sur d’autres continentsThe most studied symbiotic associations Epichloë- cool seasons grasses concern perennial ryegrass (Lolium perenne) with Epichloë festucae var. lolii and tall fescue (L. arundinaceum) with E. coenophiala. These fungi can synthesize alkaloids that could be toxic to livestock such as ergovaline and lolitrem B. My thesis work was to explore the factors related to the production of mycotoxins in grasses. Different studies have been conducted on tall fescue and perennial ryegrass to reveal i) the presence of endophyte-infected toxigenic strains in the South West of France and ii) the influence of environmental conditions of Saint-Affrique (Aveyron) on the synthesis of ergovaline and lolitrem B in forage varieties known to be responsible for toxicity on other continents
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Monnet, Fabien. "Tolerance a un exces de zinc et activite photosynthetique de lolium perenne infecte ou non par neotyphodium lolii; epuration des eaux residuaires urbaines associee a la production de plantes horticoles (doctorat environnement,biologie et physiologie vegetale)." Clermont-Ferrand 1, 2001. http://www.theses.fr/2001CLF1MM24.
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Araneda, Calderón Mariana Alejandra. "Comparación estacional del almacenaje de carbono total y carbono orgánico en tres cultivares de ballica perenne (Lolium perenne L.) y su relación con la fotosínteis." Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/150860.
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Memoria para optar al Título Profesional de Ingeniera AgrónomaLas emisiones de dióxido de carbono (CO2) pueden conducir a un aumento de la temperatura ambiental global e influir en el cambio climático, lo cual se ha convertido en un problema de discusión global. Los céspedes urbanos pueden mitigar estos efectos, ya que capturan el CO2 mediante el almacenamiento de carbono en los sustratos y la vegetación. El objetivo del presente estudio fue comparar estacionalmente la habilidad de secuestro de carbono y los parámetros fotosintéticos de tres cultivares de ballica perenne (Lolium perenne L.): ‘Derby Xtreme’, ‘Nobility’ y ‘Premier II’ y un suelo desnudo en la zona central de Chile. Se realizaron dos muestreos de suelo de los tres cultivares a tres profundidades (0–10, 10–20 y 20–30 cm), en la primavera de 2011 y en el otoño de 2012.
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Butler, Tony. "Physiological effects of drought on perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea Schreb.)." Lincoln University, 2008. http://hdl.handle.net/10182/1098.
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The Canterbury plains are frequently exposed to summer drought and climate predictions forecast that the severity and frequency of summer drought will increase. The most commonly used pasture grass, perennial ryegrass (Lolium perenne L.), is drought sensitive. One possible method to maintain sward dry matter (DM) production under water stress is to use an alternative grass species such as tall fescue (Festuca arundinacea Schreb.). The objective of this research was to compare summer DM production of monoculture swards of perennial ryegrass and tall fescue under various seasonal drought regimes to study physiological and biochemical drought responses of each species. Data were collected over a period of two-summer seasons, Season One (2006-2007) and Season Two (2007-2008) in an automated rain shelter at Lincoln, Canterbury. Drought treatments included exposure of plants to a spring or autumn drought or a four-weekly "irrigated" drought regime. DM yields of the two species were similar under each watering regime. The control treatment, under non-limiting conditions, has the highest accumulated yield in both Season One and Two for ryegrass (17.1 and 15.7 t DM ha⁻¹) and tall fescue (18.8 and 16.0 t DM ⁻¹) respectively. Spring and autumn drought treatments were similar for the two species in accumulated yield in either season, however the exposure to drought stress returned yields lower than the control. Consistently, the lowest-yielding treatment was the four-weekly irrigated drought, which resulted in an average yield across species in Season One of 10.1 t DM ha⁻¹ and 8.35 t DM ha⁻¹ in Season Two. Growth rates of the swards were calculated using accumulated DM production against accumulated thermal time using a base temperature of 3°C for both species. The control treatments showed a strong linear relationship for both species in both seasons, though Season Two showed a period of approximately 390 °Cd of no growth. Spring growth was similar for all treatments until October when both the spring drought and four-weekly irrigated treatment deviated from the control as water stress commenced. Growth also ceased under autumn drought later in the season. The physiological drought responses between species and among treatments differed. Tall fescue under control conditions had the highest photosynthesis rates of 20.5 µmol CO₂ m⁻² s⁻¹,or 22% higher than ryegrass, whereas the four-weekly irrigated treatment showed no inter-species differences. Differences were also found for other gas exchange parameters. Physiological water use efficiency (phys WUE) in ryegrass was 15% greater than tall fescue in Season Two. Photosynthesis and gas exchange rates against leaf water potential showed declining gas flow in both species across all treatments in response to drying soil conditions and across all irrigation treatments. The osmo-protectant proline was 22% higher in concentration in ryegrass than in tall fescue in Season Two and increased in drought stressed treatments in both seasons. Water stress was found to reduce total chlorophyll concentrations in all treatments and in tall fescue, while little change occurred in the chlorophyll a:b ratio. In conclusion, the findings from this thesis suggest similar DM responses for the two species under drought. The findings suggests that tall fescue performs more as a "water user" under drought conditions, compared with perennial ryegrass, which is more a "water saver." Resonses to the changing environment to a point, before "shuttting up shop" through lower stomatal conductance.
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Mellon, R. M. "The development of thermogravinetric tools for assessing herbage quality of perennial rye grass (Lolium perenne L.)." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.579753.
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The aim of this study was to evaluate herbage quality of perennial ryegrass Lolium perenne using thermogravimetry. Both Dynamic and isothermal thermal analyses were investigated over a range of heating rates to first establish any association between thermal profiles and dry matter digestibility values. The results suggested thermal methods could be used to predict dry matter digestibility (in vitro DMD) and identified the best experimental protocols for further study. Further investigations were carried out to predict DMD values using discrete and continuous TG weight loss data streams by multivariate analysis. This approach enabled the successful modelling and prediction of DMD. Further studies were undertaken to investigate the application of the technique to predict digestible organic matter in the dry matter (in vivo DOMD) and Metabolisable energy values (ME). The results were again positive and indicated potential for the application of thermal methods and for further investigation. Thermal combustion and pyrolysis techniques were employed to study the key fibre fractions associated with neutral detergent fibre, acid detergent fibre and lignin to establish their relationship with thermal profiles. The results indicated that there was potential to further develop the method to predict the fibre fractions.
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Hamill, M. E. "Development of new characteristics for identification and classification of cultivars of perennial ryegrass (Lolium perenne L.)." Thesis, Queen's University Belfast, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373531.
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Silva, Jose Carlos Sousa. "The response of Lolium perenne L. S23 to light and temperature studied from experiment and modelling." Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/12937.
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The growth of Lolium perenne S23 was studied under different conditions of temperature and shade in laboratory and in garden plots. Data on plant and leaf dry weight were used to establish simple growth models. In the laboratory three light intensities (330, 165 and 85 μmol m-2s-1) were combined with temperature regimes of 10/10, 15/10, 15/15, 20/10, 20/15 and 20/20 oC in a 16h-photoperiod. Harvests were made when each of the first three leaves were fully expanded. In garden plots light quantity, light quality, R:FR ratio, temperature and total rainfall were monitored with seedlings grown in natural light (control), two artificial shade conditions (50 and 25% from total light) or two natural shade conditions effected by use of young poplar trees. Harvests were made at 5 day intervals per experiments conducted in June, July 1992 and August, September and October 1991. As expected significant effects of both light and temperature were found on total plant dry weight and on leaf dry weight. Increasing shade decreased plant weight at the same developmental stage, but tended to increase leaf length. These effects became progressively larger at successive harvests. Light also affected leaf cell number. Variation was largest in leaf three at 20/20 0C in high light and decreased with shade and temperature. In field experiments the influence of temperature was greater than that of shade on plant and leaf dry weight, leaf length and number of leaves coinciding in the main with laboratory findings. In contrast, cell number was more variable with no clear effect of shade on final cell number per leaf.
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Erley, Gunda Schulte auf'em. "Die Stickstoff- und Kohlenstoffallokation von Gräsern mit unterschiedlicher Wachstumsdynamik (Lolium Perenne L. und Festuca rubra L.)." Bonn : Rheinische Friedrich-Wilhelms-Universität, Institut für Pflanzenbau, Lehrstuhl für Allgemeinen Pflanzenbau, 2001. http://hss.ulb.uni-bonn.de:90/ulb_bonn/diss_online/landw_fak/2001/schulte_auf_m_erley_gunda/0200.pdf.
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Care, Debbie Anne. "Effect of some external factors on root hair demography in Trifolium repens L. and Lolium perenne L." Thesis, University of Auckland, 1999. http://wwwlib.umi.com/dissertations/fullcit/9940677.
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Light microscopy, low ionic strength solution culture and image analysis methods were used to make detailed measurements on root hair populations of different genotypes of white clover (Trifolium repens L.) and ryegrass (Lolium perenne L.). A model of root hair population structure was developed and validated that will facilitate research on root hairs of these species. Diagrams were drawn of the root hair length and frequency on entire root systems. The distributions of root hairs on these diagrams often differed from textbook diagrams of root hairs because root hair length and frequency varied considerably along the root axis. The key issue examined was the response at species, population and genotype levels of root hair populations perturbed by aluminium and phosphate, and the implications of these responses for our understanding of the strategies adopted by plants growing in stressful environments. Demographic growth analysis gave the best understanding of the mechanisms of root hair population response to genetic variability, resource depletion and environmental perturbation. Root hair length seemed to be controlled by the individual root hair. However the number of root hairs appeared to be controlled by the root. Therefore it is the root that controls the distribution of the hairs on the root, and how this distribution is modified by perturbation. Root hair populations were shown to have strategies that were similar to their shoot system growth strategies-guerrilla for clover, phalangeal for ryegrass. The root and root hair systems, and shoot systems also demonstrated similar characteristics when the r and K strategy model was applied. At an ecosystem level, clover and ryegrass occupied the same orthogonal in the CSR (competitive-stress-ruderal) model. Therefore at a larger scale, these plants are able to coexist, but they do this by having different strategies at a species level.Subscription resource available via Digital Dissertations only.
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Swieter, Anita [Verfasser], and Sylvia [Akademischer Betreuer] Moenickes. "Modellgestützte Bestimmung des optimalen Schnittzeitpunkts von Lolium perenne-Sorten für die Biogasproduktion / Anita Swieter ; Betreuer: Sylvia Moenickes." Braunschweig : Technische Universität Braunschweig, 2015. http://d-nb.info/1175819840/34.
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Crowe, Samuel Richard. "The response of Lolium perenne and Holcus lanatus to shading in relation to a silvopastoral agroforestry system." Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333809.
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