Segui questo link per vedere altri tipi di pubblicazioni sul tema: Dactylis glomerata.
Tesi sul tema "Dactylis glomerata"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-39 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Dactylis glomerata".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Mills, Annamaria. "Understanding constraints to cocksfoot (Dactylis glomerata L.) based pasture production". Phd thesis, Lincoln University. Agriculture and Life Sciences Division, 2007. http://theses.lincoln.ac.nz/public/adt-NZLIU20070717.161658/.
Testo completoAbstract (sommario):
This research examined the mechanisms by which temperature, water availability and nitrogen (N) affect the dry matter (DM) yield potential of cocksfoot (Dactylis glomerata L.) dominant pastures. The experiment was a split plot design with main plots of fully irrigated (I) or dryland (D), sub-plots of N fertiliser at 800 kg N/ha in 2003/04; and 1600 kg N/ha in 2004/05 (+N) or 0 kg N/ha (-N). The potential environmental yield of an established 8 year old cocksfoot dominant pasture was 21.9 t DM/ha/y from I+N pastures compared with 9.8 t DM/ha by I-N pastures and 15.1 t DM/ha/y by D+N pastures. The lowest yields were from dryland pastures with no N which produced 7.5 t DM/ha/y in 2003/03 and 5.0 t DM/ha/y in 2004/05.
The effect of seasonal temperatures on the DM production, when periods of water stress were excluded, was quantified using thermal time accumulated above a base temperature of 3°C as 7.0 kg DM/°Cd/ha for N fertilised pastures and 3.3 kg DM/°Cd/ha for pastures with no N.
The 2.5 t DM/ha difference in yields of D-N pastures in 2003/04 and 2004/05 was the result of the duration, extent and timing of the water stress period. In both years the critical limiting deficit (DL) was calculated as 78 mm from the soil moisture deficit in the 0-0.8 m soil layers. Beyond DL yield decreased at a rate of 1.45%/mm in +N and N pastures, relative to fully irrigated control pastures.
Yields of D+N and D-N pastures were similar during periods of water stress with 0.4±0.1 t/DM/ha produced during the rotation ending 30/12/2003. This was less than from either the I-N (1.2 t DM/ha) or I+N (3.5 t DM/ha) pastures due to the reduction in the amount of photosynthetically active radiation intercepted by the canopies of the dryland pastures. However, in the rotation ending 2/5/2004, after autumn rain alleviated drought conditions, yield of the D+N pasture was 2.1 t DM/ha compared with 1.7 t DM/ha by I+N pastures.
The effect of N on yield was described using a nutrition index which showed that as DM yield increased N% in the herbage declined. This is a function of the ratio between metabolic and structural N requirements rather than caused by ontogeny alone. Specific leaf N was determined at two harvests and appeared constant at a given point in time (1.0-1.6 g N/m² leaf). In contrast, specific pseudostem N increased from 0.8-1.0 g N/m² pseudostem at an NNI of 0.4 in N pastures to 2.6-3.0 g N/m² pseudostem at an NNI of 1.2 in the +N pastures.
Differences between the yields of +N and N pastures were caused by differences in radiation use efficiency (RUE) as determined by the linear relationship (R²=0.76) between RUE and the nitrogen nutrition index (NNI).
In this thesis, empirical relationships for the effects of temperature, water availability and N were derived and the physiological mechanisms which underlie these descriptions were identified. These relationships provide clear and simple explanations of the effects of environmental variables on the productivity of cocksfoot based pastures which will enhance understanding of the benefits and limitations of cocksfoot, particularly in dryland farming systems.
2
Cauneau-Pigot, Anne. "Pollen allergisant de dactylis glomerata L. (Gramineae) : Biopalynologie et immunochimie". Paris 6, 1990. http://www.theses.fr/1990PA066437.
Testo completoAbstract (sommario):
Le pollen de dactylis glomerata l. Est un pollen typique des graminees par sa structure. La connaissance de l'etat biologique du pollen lors de sa liberation dans l'atmosphere est indispensable pour etablir une bonne strategie de conservation et de stockage. Leur absence d'endexine, caractere propre a cette famille, en fait des pollens de structure fragile, qui ne se conservent que quelques heures, lorsqu'ils ne sont pas traites. Apres elaboration d'un milieu optimal, des essais de germination in vitro ont ete pratiques sur les pollens frais, afin d'etablir le taux initial de fertilite. Celui-ci etant connu, diverses methodes de conservation par le froid dont la lyophilisation, sont utilisees. Le controle de la viabilite est effectue au cours du stockage, par des tests de germination in vitro. La spectrometrie x a energie dispersive, couplee a la m. E. B. , permet la detection des elements mineraux dans l'exine des pollens seches naturellement. Une etude sur les pollens frais et conserves, montre qu'il n'y a pas de perturbation significative dans la presence et la concentration des elements mineraux, par contre, on note certaines modifications pour les pollens germes. Une etude immunochimique sur differentes varietes, indique que les allergenes se conservent mieux a basse temperature (40c), que l'on obtient des reponses differentes suivant ls varietes et les annees de recolte
3
Madembo, Célestin. "Etude de la variabilité, interclonale et intergénotypique de la croissance pondérale du dactyle (Dactylis glomerata L.)". Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37599319g.
Testo completo
4
Jones, Gordon B. "Persistence and Productivity of Orchardgrass (Dactylis glomerata L.) in Hay Stands". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/74878.
Testo completoAbstract (sommario):
Persistence of perennial grass crops is essential to their profitable management. Recently, orchardgrass producers in the Mid-Atlantic have reported a reduction in the persistence and regrowth vigor of their swards. The overall objective was to evaluate which factors play a major role in controlling the persistence of orchardgrass harvested for hay in the Mid-Atlantic. A survey of orchardgrass fields, growth chamber experiment, and field experiment were conducted to that end. The objectives were to: (1) assess soil fertility, management practices, disease status, and climate in relation to producer perceived stand persistence rating, orchardgrass biomass, and soil test thresholds in orchardgrass hayfields in 4 states, (2) examine the interactions of high temperature and low cutting height on the physiology and regrowth of orchardgrass in controlled environments, and (3) evaluate yield, composition, and size/density compensation-corrected productivity of orchardgrass and orchardgrass/alfalfa mixtures harvested to four cutting heights over three years. The survey of hayfields indicated that the sward age, soil organic matter, grazing, manure application, and historical average high temperature were main determinants of stand persistence score. In the growth chamber experiment, regrowth was significantly reduced by the 35°C treatment as compared to 20°C. Low cutting height significantly reduced regrowth in the cool temperature treatment, but no effect of cutting height was detected under heat stress. In the field experiment, yields were highest from plots cut to 5 cm, but orchardgrass cover in these plots thinned through the experiment. Tiller size and density measurements indicated that cutting heights of 10 cm or greater were able to achieve and maintain optimal leaf area while productivity was reduced for the 5 cm treatment. Overall, it is apparent that excessively low cutting heights are a major cause of reduced persistence in orchardgrass swards and that high temperature stress will limit regrowth. These factors likely interact with fertility and disease status, and together cause the premature loss of orchardgrass stands. Efforts should be made to communicate the importance of increased cutting height to producers. Breeding of orchardgrass resistant to fungal pathogens and heat stress may be required to sustain an orchardgrass hay industry in the Mid-Atlantic.Ph. D.
5
Maceira, Néstor Oscar. "Signification évolutive de la polyploi͏̈die, mécanismes et conséquences : exemple de Dactylis glomerata L. (Graminacées)". Montpellier 2, 1990. http://www.theses.fr/1990MON20216.
Testo completoAbstract (sommario):
Les frequences de production de diplogametes males et femelles, consideres comme etant a l'origine de la polyphoidisation sexuelle, le comportement reproductif des individus issus de gametes normaux et de diplogametes dans des croisements entre cytotypes diploides et tetraploides et l'aptitude a la competition des diploides et des autotetraploides naturels apparents ont ete etudies dans le complexe polyploide dactylis glomerata. La formation de diplogametes a ete mise en evidence chez les neuf sous-especes diploides analysees. Les frequences moyennes de diplogametes ont ete estimees egales a 1% pour le pollen et 0,5% pour les ovules, mais pour 5% des individus les frequences de l'un ou l'autre type de diplogametes a depasse 8%. Plus de 60% des tetraploides issus de diplogametes dans des croisements interploides ont presente une fertilite normale, tandis que la plupart des triploides presentait une sterilite male totale ou partielle. Cette sterilite semble etre determinee non seulement par le niveau de ploidie des descendants mais egalement par des facteurs genetiques individuels. La comparaison des diploides et des autotetraploides naturels apparentes a mis en evidence une plus grande aptitude competitive de la part des tetraploides, dans les conditions experimentales utilisees. La coexistence de deux cytotypes en sympatrie peut etre expliquee par une separation partielle des niches et la superiorite competitive du tetraploide dans certaines conditions de l'environnement. L'ensemble de ces resultats etaie la these, deja proposee par d'autres auteurs, de l'origine sexuelle de la polyploidie chez les plantes et renforce l'idee que la formation de polyploides depend de leur aptitude a surpasser le cytotype ancestral dans certains habitats ou certaines periodes de l'annee, ainsi que de l'existence d'un isolement reproductif, au moins partiel, entre les deux cytotypes en pre
6
Gügler, Beat. "Die Konkurrenz zwischen Wiesenschwingel (Festuca pratensis Huds.) und Knaulgras (Dactylis glomerata L.) bei verschiedener Bewirtschaftung /". Zürich, 1993. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10081.
Testo completo
7
Potdar, Madhukar Vishwanathrao. "Interference in monocultures and mixtures of orchardgrass (Dactylis glomerata L.) and timothy (Phleum pratense L.)". Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27510.
Testo completoAbstract (sommario):
Interference among plants involves responses of plants to their environment as modified by the presence and/or growth of neighbouring plants. An important theme of research on plant interference is the relationship between plant population density and measures of plant growth or agricultural yield. An experiment on plant interference was performed in which plots of two important forage species, orchardgrass (Dactylis glomerata L.) and timothy (Phleum pratense L.), were grown at different total population densities and mixture proportions. Measures of plant growth and yield were taken at five separate harvests during one growing season.
The analysis of variance indicated that primary and derived measures of growth and yield generally were strongly affected by the three main experimental factors: time, total population density and mixture proportions. Best subset multiple regression analysis, using Mallow's CP criterion, helped to define which experimental factors and interactions were related closely to plant responses. Both of these analytical methods indicated that the main effects of experimental factors were often significant, while interactions among factors were less prominent. The best subset models were different in structure for different response variates, however, indicating that plant responses varied when different measures of growth were considered.
Models were developed which provided an effective description of yield-density responses in monocultures and mixtures when interference was strong. Model parameters were used to compare the relative strengths of intraspecific and interspecific interference in each species. The higher-yielding species, timothy, exerted stronger interference, both within and between species than orchardgrass. Interference was significant early in growth and intensified with increasing population density. The parameters of the yield-density models were also used to assess differential yield responses in the mixtures. Net overyielding occurred in most mixtures because overyielding in timothy was not fully offset by underyielding in orchardgrass. The greatest yield advantage occurred in mixtures containing orchardgrass and timothy in proportions of 2:1.
The dynamics of plant growth were followed using methods of plant growth analysis. Absolute growth rate, relative growth rate, unit leaf rate and crop growth rate were among the growth indices showing strong responses to interference. Interference seemed to disturb the time course of growth in a complex way. Allometric relationships between dry weight per plant and either leaf area per plant or tiller number per plant were also affected by interference. The species differed in their allometric responses, and the relationships between allometry and different treatment factors also varied.Land and Food Systems, Faculty of
Graduate
8
Wittebolle, Guy. "Influence des basses temperatures racinaires sur la croissance, le regime hydrique et la repartition des assimilats chez le dactyle (dactylis glomerata l. )". Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13028.
Testo completoAbstract (sommario):
Analyse des consequences du refroidissement des racines sur la croissance et le developpement du dactyle en phase vegetative permettant l'etude du fonctionnement de la plante entiere en rapport avec la contrainte hydrique et la nutrition minerale
9
Wittebolle, Guy. "Influence des basses températures racinaires sur la croissance, le régime hydrique et la répartition des assimilats chez le dactyle (Dactylis glomerata L.)". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376192458.
Testo completo
10
Al-Sbei, Mohammad Rateb. "Dynamique de la croissance modulaire et métamérique d'une Graminée Dactylis glomerata L : variabilité environnementale et génétique". Montpellier 2, 1988. http://www.theses.fr/1988MON20090.
Testo completoAbstract (sommario):
On aborde la cinetique modulaire et metamerique de la croissance du dactyle sous la forme d'une etude in situ de la morphogenese, de la demographie foliaire et de la production. On suit notamment la croissance et la mortalite des tolles (modules) et des feuilles (metameres). L'effet de la densite sur la morphogenese, les correlations de croissance et la production aerienne a ete evaluee. Les variabilites genetique et environnementale, ont ete comparees en termes de morphogenese sur une centaine de descendants issus de tous les croisements possibles entre trois genotypes
11
Bretagnolle, François. "Etude de quelques aspects des mecanismes de la polyploidisation et de ses consequences evolutives dans le complexe polyploide du dactyle (dactylis glomerata l. )". Paris 11, 1993. http://www.theses.fr/1993PA112447.
Testo completoAbstract (sommario):
Plusieurs aspects intervenant dans l'apparition et la colonisation des polyploides ont ete etudies dans le complexe polyploide du dactyle (dactylis glomerata l. ). A travers ce travail, nous montrons en particulier, que le succes des polyploides proviendrait plus d'effets instantanes sur la moyenne des caracteres que sur des differences de plasticite entre niveaux de ploidie
12
LEDUC-BRODARD, VIRGINIE. "Les allergenes de pollen de graminee. Etude du repertoire, purification et caracterisation des allergenes de dactylis glomerata". Paris 7, 1995. http://www.theses.fr/1995PA077220.
Testo completoAbstract (sommario):
Le repertoire des allergenes du pollen de dactylis glomerata, graminee tres bien representee en france, a ete etudie par electrophorese bidimensionnelle a haute resolution (en gradients de ph immobilises) suivie d'immuno-empreinte. Les immunoglobulines de type e de patients allergiques ont permis de detecter une centaine de taches peptidiques allant de point isoelectrique 4 a 10 et de masse moleculaire allant de 60 a 6 kda. Les allergenes majeurs, reconnus par plus de 50% des patients allergiques etudies, ont ete purifies par isoelectrofocalisation preparative suivie de chromatographie liquide d'exclusion. Des sequences en acides amines ont permis, par rt-pcr, de cloner le gene de dac g 3 et d'exprimer une proteine recombinante possedant les memes epitopes reconnus par les ige que ceux de la proteine naturelle. Des anticorps monoclonaux de souris ont ete produits contre dac g 4, un allergene majeur caracterise par un point isoelectrique basique (10,4) et une masse moleculaire de 59,2 kda. Un anticorps monoclonal a permis de purifier dac g 4 par chromatographie d'affinite et de detecter des proteines de masse moleculaire semblable dans des pollens de diverses especes de graminees. Une carte epitopique de dac g 4 a ete dressee montrant la presence d'au moins quatre epitopes differents dont trois sont non chevauchants. Les affinites de ces anticorps ont ete comparees a celles des ige humaines qui se sont revelees avoir des affinites beaucoup plus elevees
13
Berjeaud, Jean-Marc. "Etude de dac gbi : allergene glycoproteique majeur du pollen de dactyle (dactylis glomerata). application de la spectrometrie de masse a l'analyse structurale de glycanes". Toulouse 3, 1991. http://www.theses.fr/1991TOU30185.
Testo completoAbstract (sommario):
Les pollens de graminees sont responsables d'un nombre important d'allergies respiratoires, le pollen du dactyle (dactylis glomerata) se situe dans notre pays au premier rang de ce type d'affection. L'allergene glycoproteique majeur du pollen de dactyle, dac g i, a ete purifie par isoelectrofocalisation preparative et chromatographie. La partie glycanique d'une fraction allegenique heterogene dac g i:m a ete partiellement caracterisee. Elle est composee de 7 oligosaccharides de structures voisines. La glycoproteine dac g i purifiee contient 4% de sucres, les monosaccharides la composant etant semblables a ceux de deux autres allergenes dac g iv et dac g ix avec lesquels elle presente des interactions. Au cours de cette etude, les limitations de certaines methodes usuelles d'analyse de glycoproteines sont apparues. En consequence, nous nous sommes attaches a etendre les possibilites de la spectrometrie de masse, par ionisation fab, a l'analyse structurale des glycanes. Nous avons montre que le greffage de groupements hydrophobes par amination reductrice sur des oligosaccharides permet un gain important en sensibilite. Nous avons egalement montre que l'etude de la decomposition d'adduits formes entre des glycosides de methyle et des cations de metaux de transition permet de differencier les anomeres ( et ) d'un meme glycoside de methyle. Cette differenciation, jusqu'alors impossible par un spectrometrie de masse, est particulierement aisee avec le cation ag#+
14
Ardouin, Pierre Jacques. "Analyse, par la biochimie flavonique, de la structure génétique et de l'organisation évolutive d'un complexe polyploïde : Dactylis glomerata L. (Gramineae)". Lyon 1, 1985. http://www.theses.fr/1985LYO11652.
Testo completoAbstract (sommario):
Constitution du complexe polyploide (14 sous-especes diploides, 5 sous-especes tetraploides). Isolement et identification par 2 types de chromatographgie des principaux composes flavoniques (600 echantillons representatifs de 30 stations). Importante variation flavonique, organisation evolutive du complexe
15
Gauthier, Perrine. "Variation altitudinale, écologique et génétique, et recherche de la différenciation écotypique chez deux espèces végétales alpines : Lotus alpinus(D.C.) Schleicher et Dactylis glomerata L". Montpellier 3, 1997. http://www.theses.fr/1997MON30042.
Testo completoAbstract (sommario):
La differenciation genetique au sein des especes est un phenomene courant chez les vegetaux qui sont fortement dependants des conditions de leur environnement. Cette differenciation qui necessite souvent un isolement au moins partiel des populations, sera ecotypique si elle depend aussi des pressions de selection du milieu. Les conditions climatiques extremes des milieux d'altitude et leur heterogeneite generent des differenciations ecotypiques et chromosomiques. Celles-ci sont etudiees, en vanoise, chez deux especes communes des milieux d'altitude et appartenant a des complexes polyploides, le lotier alpin et le dactyle alpin. En vanoise, le lotier alpin presente deux entites chromosomiques (diploide entre 2000 et 3000 m et tetraploide entre 1800 et 2500 m) qui peuvent se trouver en parapatrie voire en sympatrie. L'origine autopolyploide du tetraploide et les flux de genes qu'il entretient avec le diploide et certains cultivars de lotier cornicule introduits dans la region, sont mis en evidence par une caracterisation genetique (caryologie, variation allozymique et de l'adn chloroplastique), morphologique et phenologique. Le dactyle alpin tetraploide prealablement decrit dans les alpes suisses et italiennes, a ete localise en vanoise ou il colonise des habitats arides, en exposition sud, sur forte pente et sur calcaire dolomitique. Une caracterisation morphologique, phenologique et allozymique, a permis de montrer l'existence de flux geniques entre les individus de cette sous-espece alpine et ceux de la sous-espece ubiquiste glomerata tres repandue dans la region. Un avantage selectif des dactyles alpins au niveau de la capacite a produire des graines dans leur milieu, mis en evidence lors de transplantations reciproques, associe a un decalage phenologique partiel, peut expliquer le maintien des deux sous-especes en tant qu'entites distinctes dans une meme regionGenetic differentiation among populations is a frequently observed phenomenon in plant species. Such differentiation often depends on the degree of isolation between populations but also, where environmental selection pressures are strong, can lead to local adaptation and the production of ecotypes. Severe climatic conditions and heterogeneity prevailing in high elevation habitats are known to induce ecotypic and chromosome differentiation. In this thesis the patterns of population differentiation have been studied in two widespread species belonging to two polyploid complexes, lotus alpinus (d. C. ) scleicher and dactylis glomerata l. In the vanoise region of the alps in the vanoise, two chromosome entities of l. Alpinus (diploid between 2000 and 3000 m and tetraploid between 1800 and 2500 m) may occur in parapaty or in sympatry. The autotetraploid origin of the alpine tetraploid and gene exchange with its related diploid and also l. Corniculatus cultivars introduced into this region have been documented based on genetic (caryology, allozymes and cpdna variation), morphological, and phenological characteristics. The alpine dactylis (d. Gl. Subsp. Reichenbachii), previously described in the swiss and italian alps was observed in the vanoise where it is confined to xeric, dolomitic south-facing alpine meadows above 2100 m. Morphological, phenological and allozyme studies indicate that gene flow occurs between individuals of this alpine entity and individuals of the subspecies glomerata, which is widely distributed in the region. A reciprocal transplant experiment showed a selective advantage to alpine dactylis which produced relatively more seeds in the severe habitat. In combination with differences in flowering time between the two subspecies, such differences in fertility may explain the maintenance of the two interfertile subspecies as distinct entities in the same region
16
Kuhn, William Robert. "Pest management of billbugs in orchardgrass grown in Virginia". Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/76916.
Testo completoAbstract (sommario):
The bluegrass billbug (Sphenophorus parvulus Gyllenhal) and hunting billbug (Sphenophorus venatus vestitus Chittenden) have become important pests of orchardgrass (Dactylis glomerata L.) grown in Virginia, causing 40 - 100% stand losses according to a 2005 survey of over 324 ha (800 ac) of orchardgrass. Their sheltered feeding habits combined with a lack of labeled insecticides for orchardgrass make billbug control extremely difficult for this crop.
Over two seasons, orchardgrass fields were surveyed for paired feeding holes caused by feeding of the billbug spring adult. Simultaneously, barrier pitfall traps, a standard method for determining the presence of billbugs in orchardgrass, were used to trap billbug adults in the fields. A comparison of these methods using a Wilcoxon sign-ranked test found no significant differences in the time when paired feeding holes were first observed in fields and when billbug adults were first trapped, showing that the methods are equally satisfactory for determining the presence of billbugs in orchardgrass.
In addition, temperature data from SkyBit E-Weather® service, which are currently used to alert growers and other interested parties of pertinent billbug activity in orchardgrass, was compared to data from a field-based weather data logger over the two seasons. A comparison of these data showed high coefficients of correlation, indicating a close relationship between these two degree-day collection methods. Therefore, the SkyBit system can continue to be used for the alert system.
A field-border application of Metarhizium anisopliae (Metschnikoff) Sorokin strain F52 (Met-52), an entomopathogenic fungus, was evaluated against billbug adults as they enter orchardgrass fields in the spring. Randomized pairs of treated and untreated plots were placed along the edge of an orchardgrass field in studies over two seasons. Plots were monitored for billbug adults using barrier pitfall traps, and billbug adults were checked for Met-52 infection. The Met-52 proved unsatisfactory for controlling billbugs in this study.
A field efficacy trial was used to evaluate several insecticides and Met-52 against billbug adults in orchardgrass over two seasons. A randomized complete block design, four insecticide treatments and an untreated control were used in each of two trials. Samples from each treatment plot were dissected and checked for billbug life stages and for injury to orchardgrass plants. In one trial, plants in the Sevin XLR Plus® treatment were found to have a significantly higher percentage of injury to the crowns than all other treatments except Mustang Max. No other significant differences were seen in this study.Master of Science in Life Sciences
17
Cruz, Pablo. "Relations de compétition dans une association luzerne-dactyle : étude des dynamiques de la croissance et des prélèvements d'azote". Paris 11, 1985. http://www.theses.fr/1985PA112210.
Testo completoAbstract (sommario):
Ce travail analyse les relations de compétition intra et interspécifiques au sein de l’association luzerne (cv Lutèce)-dactyle (cv Lutetia) et des cultures pures correspondantes. La dynamique de croissance de la biomasse aérienne et des prélèvements d’azote a été étudiée au cours des différentes repousses. Aucune amélioration de la nutrition azotée de la graminée associée par la présence de la légumineuse, n’a pu être mise en évidence. La luzerne s’est montrée fortement compétitive pour l’utilisation de l’azote minéral dans les périodes où sa vitesse de croissance est élevée. L’azote apporté sur une association est alors utilisé par l’espère qui a la plus forte croissance au moment de la mise en place de la surface foliaire. C’est la compétition pour la lumière qui détermine la capacité de réponse à l’azote. Les conséquences sur l’utilisation des associations graminées-légumineuses comme culture fourragère sont discutées. La production de l’association peut être améliorée par la fertilisation mais ceci accroît l’utilisation de l’azote minéral par la légumineuse et amplifie la dominance d’un partenaire sur l’autreThis work analyses intra and interspecific competition relations within an alfalfa (cv. Lutèce)-orchardgrass (cv. Lutetia) mixture and within corresponding pure stands. Dynamics of growth of aerial biomass and nitrogen uptake was studied along successive regrowths. We were not able to find any improvement of the grass nitrogen nutrition by the presence of the legume. Alfalfa proved strongly competitive for mineral nitrogen utilization in the periods of its rapid growth. Nitrogen given to the mixture is then actually absorbed by the species whose growth is faster at the time of leaf area establishment. Competition for light is the determining factor of the ability to respond nitrogen fertilization. Consequences on grass-legume mixtures utilization as forage crops are discus sed. The yield of the mixture can be enhanced by nitrogen fertilization, but this increases the utilization of mineral nitrogen by the legume and exaggerates the dominance of one partner on the other
18
Ghaleb, Wagdi. "Analyse de la diversité génétique de la réponse germinative à la température de populations de Lolium perenne L., Festuca arundinacea Schreb et Dactylis glomerata L". Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2273.
Testo completoAbstract (sommario):
La germination des graines est une étape importante dans le cycle biologique de la plante, car elle affecte le développement, la survie et la dynamique des populations de semis. La germination commence par l'absorption de l'eau par la graine et se termine par l'allongement de l'axe embryonnaire en dehors du tégument.Elle est influencée par des facteurs environnementaux et le patrimoine génétique de la graine. La température est l'une des factures les plus importants, car elle régule la germination de trois façons: en déterminant la capacité germinative et la vitesse de germination, en enlevant la dormance primaire et/ou secondaire, et en induisant la dormance secondaire.L'objectif de ce travail est d'analyse de la diversité génétique de la réponse germinative à la température de populations de Lolium perenne L., Festuca arundincea Schreb et Dactylis glomerata L.Dans cette étude, nous avons distingué différents types de réponses à la température, ce qui indique que de la diversité génétique existe entre les lots de chaque espèce. Ces différences dans les réponses, aux températures constantes entre 5 et 32 °C, ont été observées au niveau du pourcentage de germination maximale, de la vitesse de germination (α), lu temps de début de germination (tc) et du temps nécessaire pour attendre 95 % de germination finale (t95%). Des sélections divergentes ont été réalisées sur la capacité à germer à des températures non optimales chez des populations de Lolium perenne L. Sur une population issue de la région de Reims, il ressort un effet important de la sélection pour la capacité à germer à 10 °C qui pourrait être expliqué par la présence d'un gène majeur dominant de dormance des graines à faible température, en ségrégation au sein de la population.La comparaison des fréquences alléliques pour de nombreux marqueurs répartis sur le génome entre les individus germant et ceux ne germant pas à différentes températures a permis d'identifier de nombreux gènes potentiellement impliqués dans la capacité des individus à germer à ces températures. L'effet de ces gènes reste à être validé, par exemple par des études d'expression ou par l'étude de populations crées par sélection pour porter des allèles contrastésSeed germination is an important step in the plant's life cycle, affecting the development, survival and dynamics of seedling populations. Germination begins with the absorption of water by the seed and ends with the elongation of the embryonic axis outside the integument.It is influenced by environmental factors and the genetic heritage of the seed. Temperature is one of the most important factors, which regulates germination in three ways: by determining germination capacity and germination rate, by removing primary and/or secondary dormancy, and by inducing secondary dormancy.The objective of this work is to analyze the genetic diversity of the germinative response to temperature of populations of Lolium perenne L, Festuca arundinacea Schreb, and Dactylis glomerata L.In this study, we distinguished different types of temperature responses, indicating that genetic diversity exists between lots of each species. In this study, we distinguished different types of responses to temperature, indicating that genetic diversity exists between lots of each species. These differences in responses, at constant temperatures between 5 and 32°C, were observed in terms of maximum germination percentage, germination rate (α), germination start time (tc) and time required to reach 95 % of final germination (t95%).Divergent selections were made on the capacity to germinate at sub-optimal temperatures in populations of Lolium perenne L. In a population from the Reims region, there is an important effect of selection for the capacity to germinate at 10 °C, which could be explained by the presence of a major dominant gene for seed dormancy at low-temperature, in segregated within the population. The comparison of allelic frequencies for many markers distributed over the genome between individuals germinating and those not germinating at different temperatures has identified many genes potentially involved in the ability of individuals to germinate at these temperatures. The effect of these genes has yet to be validated, for example by expression studies or by the study of populations created by selection to carry contrasting alleles
19
Glimskär, Anders. "Growth strategies, competition and defoliation in five grassland plants /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5465-4.pdf.
Testo completo
20
Fily, Marc. "Succession post-culturale et pression de pâturage dans les Pyrénées centrales : étude à l'échelle de l'écosystème, de la communauté et d'une population de Dactylis glomerata L. prise comme modèle". Toulouse 3, 1990. http://www.theses.fr/1990TOU30132.
Testo completoAbstract (sommario):
Deux trajectoires de dynamique de la vegetation post-culturale sont etudiees dans la vallee d'oo (pyrenees centrales, altitude: 1000 m). Elles different par l'intensite du paturage qui s'y exerce depuis 3, 30 et 80 ans. Apres une revue bibliographique concernant les successions vegetales, le modele d'evolution de la vegetation qui sert de base a l'echantillonnage est presente; sa valeur comme outils de diagnostic et de prevision est illustree sur des donnees botaniques exterieures a la vallee. A l'echelle de l'ecosysteme, l'importance de la structure spatiale des couverts et la grande vitesse de recuperation de l'activite photosynthetique apres defoliation sont les principaux resultats des etudes de photosynthese apparente in situ et en milieu controle. Au niveau d'organisation communautaire: a) une analyse des relations de voisinage interspecifique montre, d'une part, une complementarite entre les legumineuses et les graminees du point de vue social et, d'autre part, une plus grande intrication des especes lors du vieillissement des peuplements; b) l'etude des variations saisonnieres et annuelles de la vegetation sur 3 ans revele une coherence entre dynamique notee sur 3 ans et sur 80 ans ainsi que l'effet stabilisateur du paturage sur la composition botanique; c) l'enregistrement de 3 performances des especes durant un an montre que biomasse et recouvrement traduisent le mieux le lien entre les pratiques agricoles et la vegetation. Bien que certains genotypes de dactylis glomerata l. Resistent mieux a la defoliation que d'autres, une etude morphometrique, a l'echelle populationnelle, ne fait pas apparaitre de differenciation au cours de la succession. De l'etude du polymorphisme enzymatique on retiendra: a) la tres grande diversite genetique en tout point de la succession; b) l'effet de fondation qui caracterise les jeunes populations; c) un deficit en heterozygotes
21
Ahmed, Lina Qadir. "Analyse de la variabilité inter- et intra-spécifique de cinq espèces prairiales en réponse à la température pendant la germination et la phase hétérotrophe initiale". Thesis, Poitiers, 2015. http://www.theses.fr/2015POIT2265/document.
Testo completoAbstract (sommario):
La germination et la croissance hétérotrophe sont des phases clés de l'établissement des plantes. Ils sont sous contrôle génétique et affectés par la température. L'objectif de cette thèse est d'analyser la variabilité inter et intra-spécifique de cinq espèces prairiales dans leurs réponses à la température pendant la germination et la croissance hétérotrophe. Trente-deux populations de Lolium perenne, Festuca arundinacea, Dactylis glomerata, Medicago sativa, et Onobrychis viciifolia ont été évalués sous huit températures constantes entre 5 et 40°C.La nouveauté de ce travail vient de la large gamme de températures et le nombre de populations évaluées. Il a été observé que, au sein des espèces, la réaction des populations à la température indique une forte variabilité et des différences significatives. La germination n'a été pas observée à 40°C pour l'une des 23 graminées, l'O. viciifolia germé peu tandis que les variétés de M. sativa ont été peu affectées. La croissance hétérotrophe des 32 populations a été affectée par la température. La croissance des axes fortement fiable ou nulle à 40°C. Les courbes de réponse du taux de croissance maximale de l'axe sont asymétriques en forme de cloche.Des interactions significatives entre la température et la population ont été détectées pour la germination et la croissance hétérotrophe. La germination des populations des sites froids est renforcée par des températures plus chaudes et limité par les plus froids et vice-versa pour les populations chaudes adaptéesGermination and heterotrophic growth are key phases for plant establishment. They are under genetic control and affected by temperature. The objective of this thesis was to analyse the inter- and intra-specific variability of five pasture species in their responses to temperature during germination and heterotrophic growth.Thirty two populations of Lolium perenne, Festuca arundinacea, Dactylis glomerata, Medicago sativa, and Onobrychis viciifolia were evaluated under eight constant temperatures between 5 and 40°C.The novelty of this work comes from the wide range of temperatures and the number of populations evaluated. It was observed that, within species, the response of populations to temperature shows high variability and significant differences. No germination was observed at 40°C for any of the 23 grasses, O. viciifolia germinated poorly while M. sativa varieties were little affected. Heterotrophic growth of the 32 populations was affected by temperature. The growths of the axes were negligible or lethal at 40°C. Response curves of maximum growth rate of the axis were asymmetric bell-shaped.Significant interactions between temperature and population were detected for germination and heterotrophic growth. Germination of populations from cold sites is enhanced by warmer temperatures and limited by colder ones and vice versa for warm-adapted populations. This study demonstrates that genetic variability does exist within the five studied species. This variability could be exploited to breed new varieties adapted to the future climate
22
Tikwayo, Sizwe Edward. "The biomass production, nutrient content and silage quality of Perennial ryegrass (Lolium perenne (L)) Cocksfoot (Dactylis glomerata (L)) and Tall fescue (Festuca arundinacea (Schreb)) varieties grown under irrigation in Alice, South Africa". Thesis, University of Fort Hare, 2016. http://hdl.handle.net/10353/1796.
Testo completoAbstract (sommario):
The study aims to evaluate the biomass production and nutrient content and silage quality of perennial ryegrass (Lolium perenne (L)), cocksfoot (Dactylis glomerata (L)) and tall fescue (Festuca arundinacea (Schreb)). Six varieties were used, two for each species. A completely randomized block designed replicated three times was conducted at University of Fort Hare Research Farm during 2014-2015 growing season. The plots were harvested at four-week interval (post emergency) for one year. Biomass yields were measured for fresh forage and dry matter yield. Duplicated samples were then dried, milled and analyzed for chemical and mineral composition (CP, NDF, ADF, and ash, Ca, P, K, Na, Mn, Cu, Zn and Fe) for only winter season. In addition the grasses were ensiled and the silage was analyzed for its fermentation parameters and nutrient content (lactic acid, pH, DM, CP, NDF, ADF, and ash, Ca, P, K, Na, Mn, Cu, Zn and Fe). Biomass results showed significant differences (P < 0.05) between season and varieties. On average Tall fescue varieties Jessup (13741.67 FM kg/ha), Alix (12007.78 FM kg/ ha) and Ryegrass varieties Samson (11597.22 FM kg/ha) and Nui (10591.67 FM kg/ha) had the highest fresh biomass yield. Similarly, Tall fescue varieties Jessup (2833.06 DM kg/ha) and Alix (2708.3 DM kg/ ha) and Ryegrass varieties Samson (2169.44 DM kg/ha) and Nui (2169.67 kg/ha) had the highest dry biomass yield. Throughout the year the average biomass yield was significantly different among species (P< 0.05). During summer and autumn Tall fescue varieties Jessup and Alix gave the highest dry matter yields of 3855.5 to 1977.8 DM kg/ha, and 3877.8 to 1900 DM kg/ha, respectively, and followed by Cocksfoot 2400 DM kg/ha. Ryegrass had the highest dry matter biomass yield in winter (2975 DM kg/ha) and the least in summer (977.75 DM kg/ha). There were no significant (P>0.05) differences on the chemical composition (CP, NDF, ADF, and ash) and mineral composition (Ca, P, K, Na, Mn, Cu, Zn and Fe) of the six varieties. The grass silage results showed significant differences (P< 0.05) among the six varieties for moisture content. Perennial ryegrass variety Nui (66.76 percent) had low moisture content than the other grass silages. The different varieties had no significant effects (P>0.05) on chemical composition (CP, NDF, ADF, and ash) and mineral composition (Ca, P, K, Na, Mn, Cu, Zn and Fe). It is concluded that the biomass production of the six varieties of three grass species was different throughout the year under irrigation hence Ryegrass and Tall fescue are recommended for dairy farmers in the region for all seasons. It can be concluded that there is no difference with respect to fermentation characteristics and nutrient content among the varieties of the grass species.
23
Bristiel, Pauline. "Variabilité intraspécifique des stratégies adaptatives à la sécheresse d’une graminée pérenne (Dactylis glomerata L.) : les compromis fonctionnels des traits aériens et souterrains peuvent-ils expliciter le compromis entre potentiel de croissance et survie au stress ?" Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT108/document.
Testo completoAbstract (sommario):
Les risques de sécheresse sévère augmentent sous l’effet du changement climatique. Mieux comprendre les stratégies adaptatives des plantes au stress hydrique est ainsi l’un des défis majeurs de la recherche écologique et agronomique. Cette thèse explore la survie à la sécheresse d’une graminée herbacée pérenne (Dactylis glomerata L.) en étudiant la variabilité intraspécifique des traits aériens et souterrains d’une quinzaine de populations natives et cultivées issues d’un gradient latitudinal allant de la Scandinavie au Maroc. Une caractérisation des populations en conditions optimales sur une année a montré une coordination phénologique des traits aériens en relation avec les limitations saisonnières de croissances liées à l’origine des populations. Le rythme de croissance au printemps et à l’automne ne discrimine pas les origines, alors que la dormance estivale des populations méditerranéennes s’oppose à la dormance hivernale des populations scandinaves. Ces résultats suggéraient l’existence d’un compromis entre survie à une déshydratation sévère (sécheresse, gel) et potentiel de croissance. Alors que ce compromis a été vérifié en été (sècheresse sévère à Montpellier) et en hiver (gel en Norvège), la survie à une déshydratation de contre-saison au printemps n’est pas corrélée au potentiel de croissance des populations. Les résultats invalident donc l’existence d’un compromis constant entre survie au stress et potentiel de croissance aérienne. Ce découplage chez le dactyle permet d’envisager la sélection artificielle, à partir de la variabilité intraspécifique existante, de variétés à la fois productives et tolérantes au stress hydrique. L’imposition d’une déshydratation édaphique sévère en pots limitant l’expansion du système racinaire a montré que les populations méditerranéennes survivent mieux que les populations tempérées ou nordiques. L’association de ces résultats avec ceux issus d’une expérimentation en longs tubes favorisant le développement potentiel des racines révèle un compromis entre les stratégies d’évitement de la déshydratation (acquisition de l’eau et maintien de la croissance) et de tolérance à la déshydratation (faible croissance et forte survie à la sécheresse) qui pourrait limiter la combinaison de stratégies adaptatives au sein d’un même phénotype. Cette thèse contribue à améliorer notre compréhension des compromis fonctionnels, peu étudiés à l’échelle intraspécifique, mais qui sous-tendent la réponse des plantes à la sécheresseDrought risk increases with climate change. Improving our understanding of the adaptive mechanisms of plants response to drought has thus become one of the major challenges of ecological and agronomical research. This work investigates the drought survival of a perennial herbaceous species (Dactylis glomerata L.) through the intraspecific variability of above and below ground traits expressed by fifteen native and cultivated populations originating from a large latitudinal gradient, from Scandinavia to Morocco. Population traits characterization across one year under optimal growth conditions showed phenological coordination of above ground traits associated with seasonal growth limitations according to the origins of the populations. The spring growth rhythm does not discriminate origins while the summer dormancy of Mediterranean population contrasts with the winter dormancy of Scandinavian populations. These results suggested a growth-dehydration stress survival trade-off. Although this trade-off was confirmed in summer (severe drought in Montpellier) and winter (severe frost in Norway), no correlation was found between an off-season (spring) drought stress survival and populations’ growth potential. The result invalidates the existence of a constant trade-off between stress survival and aerial growth potential. This apparent decoupling in cocksfoot could be considered to produce new cultivars with both high productivity and high drought tolerance, from existent intraspecific variability. A severe dehydration stress imposed on plants grown in short pots, limiting roots expansion, showed that Mediterranean populations survived better than temperate or Nordic populations. In association with a long tube experiment allowing full expression of roots development, this result revealed a functional trade-off between dehydration avoidance (water acquisition and growth maintenance) and dehydration tolerance (low growth and high drought survival) which could limit the combination of adaptive strategies in a single phenotype. This work contribute to improve our knowledge about functional trade-offs, few studied within species, that underpin plant response to drought stress
24
Lhuissier, Franck. "Les pollens biomarqueurs de la pollution atmosphérique ? Approche microscopique et biochimique". Rouen, 1998. http://www.theses.fr/1998ROUES095.
Testo completoAbstract (sommario):
Nous avons étudié les potentialités de pollens comme bioindicateurs de pollution atmosphérique. Deux espèces ont été étudiées : le bouleau (Betula verrucosa Ehrh. ) et le dactyle (Dactylis glomerata L. ). Ces deux espèces sont responsables de plus de 95% des cas d'allergies au pollen en Europe. Des échantillons de pollen ont été exposés à différentes concentrations de monoxyde d'azote marqué à l'azote 15 ou de monoxyde de carbone marqué à l'oxygène 18. Ceci nous a permis de localiser les cibles cellulaires de chaque gaz en utilisant la microscopie d'émission d'ions secondaires (SIMS). Une analyse par microscopie électronique à balayage (MEB) et à transmission (MET) a été réalisée sur les différents échantillons de pollens pour étudier les éventuelles altérations structurales et stéréostructurales. En parallèle, une analyse électrophorétique et biochimique des échantillons de pollens exposés au NOx ou au CO a été réalisée pour étudier l'effet de ces deux gaz sur le contenu protéinique et allergénique des pollens étudiés. De par sa nature radicalaire, probablement, le NO présente d'importants effets sur les deux espèces de pollens étudiés. La microscopie SIMS a révélé que le NO s'accumule dans le sporoderme et dans des inclusions cytoplasmiques comparables aux globoïdes des graines. Au contraire, le CO ne se fixe pas dans les pollens comme l'ont montré les analyses par SIMS. La MEB a révélé que le NO altère le sporoderme des deux espèces de pollens étudiés. Des fissures et des trous apparaissent rapidement et se propagent à la surface des grains. Le CO ne semble pas induire de fragilisation du sporoderme comme l'a montré la MEB, ce qui est en accord avec nos analyses SIMS. Des dosages protéiques réalisés sur les extraits de pollens exposes aux NOx ou au CO ont montré une chute du taux de protéines extractibles en fonction de la dose de gaz utilisée. Les analyses électrophorétiques ont montré que les deux gaz étudiés avaient un effet important sur les protéines des pollens étudiés, ainsi que sur la reconnaissance des allergènes par des sérums de patients allergiques. Les analyses électrophorétiques ont mis en évidence une sensibilité plus faible du pollen de dactyle. Nos analyses ont mis en évidence une certaine sensibilité des pollens étudiés aux NOx et au CO tant au niveau structural que métabolique. Néanmoins, des analyses complémentaires sont nécessaires afin de qualifier plus finement les cibles des deux gaz étudiés, notamment par l'utilisation des doses plus faibles. Une étude de terrain est actuellement en cours afin de comparer nos résultats de laboratoire à des résultats obtenus en sites urbains.
25
Mécheri, Salah. "Contribution a l'etude de la modulation de la reaction anaphylactique grace a l'utilisation de constituants purifies du pollen de dactyle". Paris 7, 1988. http://www.theses.fr/1988PA077115.
Testo completo
26
Monks, D. P. "The vegetative and reproductive development of balansa clover". Lincoln University, 2009. http://hdl.handle.net/10182/1337.
Testo completoAbstract (sommario):
The vegetative and reproductive development of balansa clover (Trifolium michelianum Savi.) were quantified in relation to the environmental drivers of each phenophase in field and controlled environments. In a grazed experiment over 6 years, balansa clover sown with cocksfoot (Dactylis glomerata) contributed 1.6 t DM/ha/year, or ~20% of the total DM production. However, grazing management for increased seed production during flowering in the establishment year strongly influenced balansa clover regeneration. The earliest closed plot (September) averaged between 2.2 and 4.3 t DM/ha/year of balansa clover across all six years. In an incubator, balansa clover required 29°Cd for germination with an optimum temperature of 14°C and a maximum of 40°C. The base temperature for germination was 0°C. A field experiment determined that 38°Cd were required for emergence with an optimum soil temperature (Topt) of 8.5°C. The time from emergence until the first leaf appeared, the phyllochron and timing of axillary leaf appearance were compared with perennial ryegrass (Lolium perenne) and white clover (Trifolium repens L.). The rate of each was found to increase linearly with temperature. The balansa clover cultivar ‘Frontier’ required 97°Cd from sowing for the first leaf to appear, had a phyllochron of 47°Cd and secondary leaves appeared after 490°Cd. For each vegetative stage, the base temperature was 2.5°C. The timing of flower appearance depended on the quantity and direction of change of the photoperiod at emergence. A balansa clover plant, cv. ‘Bolta’, which emerged on 1 December into an increasing photoperiod of 15.6 hours flowered after 574°Cd (Tbase = 2.5°Cd) or 58 days after emergence. In contrast, if the plant emerged on 16 January into a similar but decreasing photoperiod it took 1503°Cd or 227 days to flower. This length of time became progressively shorter until remaining constant after the shortest day. In contrast, ‘Frontier’ took a constant 390 and 690 °Cd in increasing and decreasing photoperiods, respectively. The time which an individual inflorescence took from pollination until seeds were physiologically mature was 250 °Cd for both ‘Bolta’ and ‘Frontier’. The re-establishment of balansa clover each year relied on a large seed set (>1000 kg/ha) in the establishment year. The continued survival of balansa clover would then depend on a similar seeding event within a 4-5 year period to maintain the seed bank. Management considerations for balansa clover persistence and survival are discussed.
27
Al-Sbei, Mohammad Rateb. "Dynamique de la croissance modulaire et métamérique d'une graminée, Dactylus glomerata L. variabilité environnementale et génétique /". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37611279n.
Testo completo
28
Ates, Serkan. "Grazing management of subterranean clover (Trifolium subterraneum L.) in South Island (New Zealand)". Diss., Lincoln University, 2009. http://hdl.handle.net/10182/1338.
Testo completoAbstract (sommario):
This study consisted of two sheep grazed dryland pasture experiments. Experiment l compared sheep production from 3-year-old cocksfoot based pastures grown in combination with white, Caucasian, subterranean or balansa clover with a ryegrass-white clover pasture and a pure lucerne forage. Sheep liveweight gain per head from each pasture treatment and the pure lucerne stand was recorded in the 2006/07 and 2007/08 seasons. The cocksfoot-subterranean clover pasture provided equal (381 kg LW/ha in 2006) or higher (476 kg LW/ha in 2007) animal production in spring and gave the highest total animal production (646 kg LW/ha) averaged across years of the five grass based pastures. However, total annual liveweight production from lucerne was higher than any grass based pasture mainly due to superior animal production during summer when lucerne provided 42-85% higher animal production than any of the grass based pastures. In Experiment 2, the effect of stocking rate (8.3 (low) and 13.9 (high) ewes + twin lambs/ha) and time of closing in spring on lamb liveweight gain, pasture production and subterranean clover seedling populations was monitored over 2 years for a dryland cocksfoot-subterranean clover and ryegrass-subterranean clover pasture in Canterbury. In both years, twin lambs grew faster (g/head/d) in spring at low (327; 385) than high (253; 285) stocking rate but total liveweight gain/ha (kg/ha/d) was greater at high (7.26; 7.91) than low (5.43; 6.38) stocking rate. Ewes also gained 0.5 and 1.5 kg/head at the low stocking rate in 2006 and 2007 respectively but lost 0.2 kg/head in 2006 and gained 0.3 kg/head at high stocking rate in 2007. Mean subterranean clover seedling populations (per m²) measured in autumn after grazing treatments in the first spring were similar at both low (2850) and high (2500) stocking rate but declined with later closing dates in spring (3850, 2950, 2100 and 1700 at 2, 4, 6, 8 weeks after first visible flower). Seedling populations measured in autumn after grazing treatments in the second spring were also unaffected by stocking rate (low 1290, high 1190) but declined with later closing dates in spring (1470, 1320 and 940 at 3, 5 and 8 weeks after first flowering, respectively). The effect of stocking rate and closing dates in spring on pasture and clover production in the following autumn was similar to the effects on seedling numbers in both years. However, clover production in the following spring was unaffected by stocking rate or closing date in the previous year at the relatively high seedling populations generated by the treatments. This was presumably due to runner growth compensating for lower plant populations in pastures that were closed later in spring. Subterranean clover runner growth in spring may not compensate in a similar manner if seedling numbers in autumn fall below 500/m². Mean annual dry matter production from cocksfoot and ryegrass pastures grown with and without annual clovers pasture production ranged from 6.4 to 12.4 t DM/ha/y but stocking rate (8.3 vs. 13.9 ewes/ha) during spring did not affect annual pasture production. Pastures overdrilled with annual clovers yielded 23-45% more dry matter production than pastures grown without annual clovers. The study confirms the important role of subterranean clover in improving pasture production and liveweight gains of sheep in dryland cocksfoot and ryegrass pastures. Lowering stocking rate from 13.9 to 8.3 ewes/ha was a less effective method of increasing seed production of subterranean clover in dryland pastures although it did lead to increased liveweight gain per head.
29
Muraki, Tomohiro. "Effects of alternative grass species on grazing preference of sheep for white clover". Diss., Lincoln University, 2008. http://hdl.handle.net/10182/1095.
Testo completoAbstract (sommario):
Despite the importance of a high white clover (Trifolium repens) content in temperate pastoral systems in terms of livestock performance and nitrogen fixation, the proportion of white clover in grass-clover pastures is often low (<20%). This thesis examined in two experiments whether the white clover content of pastures could be improved by sowing white clover with alternative grass species to diploid perennial ryegrass (Lolium perenne L.). In a pasture experiment, DM production, pasture composition and morphology of grass-clover mixtures was measured over the establishment year (January 2007 to January 2008) where white clover was sown in fine mixtures with diploid perennial ryegrass, tetraploid perennial ryegrass, timothy (Phleum pratense L.) and cocksfoot (Dactylis glomerata L.). Pastures were irrigated and rotationally grazed with on-off grazing with Coopworth ewe hoggets. Total annual DM production of pasture was more than 20% higher in tetraploid (12521 kg DM ha⁻¹) and diploid (11733 kg DM ha⁻¹) perennial ryegrass than timothy (9751 kg DM ha⁻¹) and cocksfoot (9654 kg DM ha⁻¹). However, timothy (5936 kg DM ha⁻¹) and cocksfoot (5311 kg DM ha⁻¹) had more than four times higher white clover annual DM production than tetraploid (1310 kg DM ha⁻¹) and diploid (818 kg DM ha⁻¹) ryegrass. Pasture growth rate at the first three harvests in autumn was significantly greater in tetraploid and diploid ryegrass than timothy and cocksfoot. Timothy and cocksfoot had a higher proportion of white clover than tetraploid and diploid perennial ryegrass throughout the entire year. This was due to more and larger white clover plants in timothy and cocksfoot plots. In a grazing preference experiment, the partial preference of sheep for white clover offered in combination with the same grass species as in the pasture experiment was measured in five grazing tests in May, September, October, November and December 2007. Pastures were sown in January 2007. Paired plots (grass and clover both 4.2 m x 10 m) were grazed by three Coopworth ewe hoggets between 9am and 5pm, and preference was recorded by decline in pasture mass and visual scan sampling for grazing time. Grazing preference for clover was generally low throughout these tests (e.g. average apparent DM intake from clover = 47%; average grazing time from clover = 44%). Several explanations are proposed for this low preference including a high N content and intake rate of the grass relative to the clover. No significant differences were found among the grass treatments in total grass grazing time, total clover grazing time, ruminating time, the proportion of grazing time on clover, selective coefficient for clover and DM intake percentage from clover at any date. There was no significant change in overall sward surface height (SSH) decline among grass treatments throughout all the tests except December 2007 when the overall SSH decline for cocksfoot was significantly lower than the other species. The study indicated that the rapid growth rate of perennial ryegrass in the early phase of pasture establishment, rather than differences in partial preference, was the key factor limiting white clover content in the mixed swards relative to cocksfoot and timothy pastures. It is concluded that high clover-containing pastures capable of delivering high per head performance can be established through the use of slow establishing pasture species such as timothy and cocksfoot.
30
Tonmukayakul, Nop. "Water use efficiency of six dryland pastures in Canterbury". Lincoln University, 2009. http://hdl.handle.net/10182/1498.
Testo completoAbstract (sommario):
The annual and seasonal water use efficiency of six pasture combinations were calculated from the ‘MaxClover’ Grazing Experiment at Lincoln University. Pastures have been established for six years and are grazed by best management practices for each combination. Measurements for this study are from individual plots of four replicates of ryegrass (RG)/white clover (Wc), cocksfoot (CF)/Wc; CF/balansa (Bal) clover; CF/Caucasian (Cc) clover; CF/subterranean (Sub) clover or lucerne. Water extraction measurements showed soils for all dryland pastures had a similar plant available water content of 280±19.8 mm. Dry matter measurements of yield, botanical composition and herbage quality were assessed from 1 July 2008 until 30 June 2009. Lucerne had the highest annual yield of 14260 kg DM/ha/y followed by the CF/Sub at 9390 kg DM/ha/y and the other grass based pastures at ≤ 6900 kg DM/ha/y. All pastures used about 670±24.4 mm/y of water for growth. Lucerne had the highest annual water use efficiency (WUE) of 21 kg DM/ha/mm/y of water used (total yield/total WU). The WUE of CF/Sub was the second highest at 15 kg DM/ha/mm/y, and the lowest was CF/Wc at 9 kg DM/ha/mm/y. The CF/Sub pastures had the highest total legume content of all grass based pastures at 21% and as a consequence had the highest annual nitrogen yield of 190 kg N/ha. This was lower than the monoculture of lucerne (470 kg N/ha). Ryegrass/white clover had the highest total weed component in all pastures of 61%. For dryland farmers spring is vital for animal production when soil temperatures are rising and moisture levels are high. The water use efficiency at this time is important to maximize pasture production. In spring lucerne produced 8730 kg DM/ha, which was the highest dry matter yield of all pastures. The CF/Sub produced the second highest yield of 6100 kg/DM/ha. When calculated against thermal time, CF/Sub grew 5.9 kg DM/ºCd compared with lucerne at 4.9 kg DM/ºCd. The higher DM yield from lucerne was from an extra 400 ºCd of growth. The highest seasonal WUE of all pastures occurred in the spring growing period. Linear regressions forced through the origin, showed lucerne (1/7/08-4/12/08) had a WUE of 30 kg DM/ha/mm (R2=0.98). Of the grass based pastures, CF/Sub produced 18 kg DM/ha/mm (R2=0.98) from 1/7 to 10/11/08 from 270 mm of water used. The lowest spring WUE was 13.5 kg DM/ha/mm by CF/Bal pastures which was comparable to the 14.3±1.42 kg DM/ha/mm WUE of CF/Wc, CF/Cc and RG/Wc pastures. During the spring, CF/Sub clover had the highest spring legume component of the grass based pastures at 42% and produced 120 kg N/ha. This was lower than the 288 kg N/ha from the monoculture of lucerne. Sub clover was the most successful clover which persisted with the cocksfoot. Based on the results from this study dryland farmers should be encouraged to maximize the potential of lucerne on farm, use cocksfoot as the main grass species for persistence, rather than perennial ryegrass, and use subterranean clover as the main legume species in cocksfoot based pastures. By increasing the proportion of legume grown the water use efficiency of a pasture can be improved. When pastures are nitrogen deficient the use of inorganic nitrogen may also improve pasture yields particularly in spring.
31
ŠIMÁNKOVÁ, Karolína. "Výživná hodnota vybraných odrůd srhy laločnaté (Dactylis glomerata)". Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-320598.
Testo completoAbstract (sommario):
In the Czech Republic, the grasslands constitute an important landscape element and at the same time, they are one of the basic components of horses' and ruminants' rations. Therefore, the fodder quality is important in the connection with production functions of grassland forage, especially concerning the dairy cattle. The aim of the diploma thesis was to monitor changes in the nutritional value during the vegetation and the evaluation of quality indications for selected species of Cock's-foot: three existing varieties and three varieties of the new breeding. Ash, crude protein, spectra fiber, organic matter digestibility index and relative feed value were evaluated. The changes between different phases of the vegetation were identified by raising proportion of CF, ADF and NDF in all varieties analyzed. During the aging of the cover, this process corresponded to deteriorating organic matter digestibility, decreasing relative feeding value and a decreasing tendency of nitrogen compounds. The value of CF in increasing in average from 22.6% up to 28.5%, NDF is increasing from 53.4% up to 60.5% and ADF from 29.3% up to 36.8 %. The digestibility of the organic value decreased from an average of 73.8% to 63.12%. Relative feed value decreased from an average of 114 to 91. During the vegetation, crude protein content also decreased from an average of 15.3% to 8.8%. From the analysis of results we can deduce that the varieties Vega are the best quality, vv115/10 and vv88/10, being nutritionally well balanced. The variety Zora is the worse quality. In terms of digestibility and relative feed values, the varieties of the new breeding are higher quality. These varieties are better with respect to the digestibility and relative feeding value than already existing varieties of Cock's-foot.
32
Potůčková, Lucie. "Monitoring výskytu chorob u trav". Master's thesis, 2008. http://www.nusl.cz/ntk/nusl-95289.
Testo completo
33
Stevenson, K. "Optimising grass seeding rates for improved establishment of perennial legumes in cocksfoot (Dactylis glomerata) swards". Thesis, 2018. https://eprints.utas.edu.au/29129/1/Stevenson_whole_thesis.pdf.
Testo completoAbstract (sommario):
The effect of grass seeding rate on legume establishment was investigated in the low rainfall region of the Tasmanian midlands. Three clover species, Caucasian clover, Talish clover and red clover were paired with one of two cocksfoot species, summer active cocksfoot or winter active cocksfoot, at three different grass seeding rates 1 kg/ha, 3 kg/ha and 5 kg/ha. Successful establishment was defined as the maintenance of a clover proportion of 20-45% in the sward, and was determined using plant number. Successful establishment of all three clover species was achieved for the 5 month duration of the experiment. Clover proportions within the recommended range were recorded when Talish clover or Caucasian clover was sown with either cocksfoot species at the grass seeding rate of 3 kg/ha. The same result was achieved when red clover was paired with either cocksfoot species at the grass seeding rate of 5 kg/ha. Sowing treatments that contained red clover produced a significantly (P<0.05) greater biomass, than sowing treatments that contained Talish clover or Caucasian clover. The results of a parallel experiment conducted in a glasshouse at the University of Tasmania, highlighted several key differences between the species in morphology and development rate. A faster rate of leaf emergence, larger leaf area and larger shoot length were observed on cocksfoot seedlings than observed on Talish clover and Caucasian clover seedlings. Red clover seedling were observed to develop secondary stems, this contributed to their greater biomass production and improved performance relative to that of the other clover species. Issues of poor establishment previously reported for slow growing clover species, such as Caucasian clover and Talish clover, were overcome by pairing these species with cocksfoot at a lowered grass seeding rate.
34
Nguyen, TM. "Morphological responses of cocksfoot (Dactylis glomerata L.) and tall fescue (Lolium arundinaceum Schreb.) to waterlogging stress". Thesis, 2022. https://eprints.utas.edu.au/45620/1/Nguyen_whole_thesis.pdf.
Testo completoAbstract (sommario):
Waterlogging is a seasonal constraint on low-lying cropping and pasture lands in temperate regions of south-eastern Australia during winter. It has been attributed to yield loss in both crops and pastures. The tolerance level of plants to waterlogging relates to physiological, biochemical, morphological and anatomical adaptive traits. Understanding the likely response and adaptive characteristics of particular pasture species and cultivar to waterlogging can assist in choosing appropriate cultivars for waterlogging prone areas. In this study, we investigated morphological responses of cocksfoot (Dactylis glomerata L.) and tall fescue (Lolium arundinaceum Schreb., syn. Festuca arundinacea Schreb.) grass plants under waterlogging conditions. The aims of this study were: i) to examine the morphological responses of two temperate perennial grass species: tall fescue and cocksfoot under waterlogging conditions; ii) to determine which mechanisms are involved in plant adaptation to waterlogged conditions.
Two separate pot experiments were conducted at Tasmanian Institute of Agriculture, Mt. Pleasant Laboratory, Launceston, Tasmania, Australia. The first experiment was conducted from April until October 2019 on four cultivars of tall fescue (two winter active cultivars of Mediterranean origin: cv. Resolute and cv. Temora and two summer active cultivars of Continental origin, cv. Hummer and cv. Quantum II MaxP); and four cultivars of cocksfoot (two winter active cultivars of Mediterranean, cv. Kasbah and cv. Uplands and two summer active cultivars of Continental, cv. Lazuly and cv. Porto). The 14-week-old plants were subjected to waterlogging or control conditions for 4 weeks, followed by a 4-week recovery period.
The second experiment was conducted from May to August 2020 on two summer active cultivars of Continental origin of tall fescue, cv. Hummer and cv. Quantum II MaxP; and two summer active cultivars of Continental origin of cocksfoot, cv. Lazuly and cv. Porto. The 6-week-old plants were subjected to four periods of waterlogging treatments: 7, 14, 21 and 28 days. Measured above ground parameters included plant height, number of live tillers, leaf chlorophyll content (measured by Soil Plant Analysis Development (SPAD) reading) and shoot dry matter; and below ground included root length, number of adventitious roots, the formation of aerenchyma in adventitious roots and root dry matter.
Results showed that waterlogging did not affect shoot dry matter of both grass species in both experiments but did significantly affect the development of root system. Cocksfoot appeared to be more sensitive to waterlogging than tall fescue, which was indicated in most of the variables measured such as plant height, leaf chlorophyll content (measured by SPAD reading), root length and root dry matter. Waterlogging significantly induced the formation of adventitious roots and aerenchyma in the roots of all cultivars. However, aerenchyma formed significantly faster and to a greater extent in waterlogged tall fescue plants (cv. Hummer and cv. Quantum II MaxP), compared to waterlogged cocksfoot plants (cv. Lazuly and cv. Porto). The formation of aerenchyma in adventitious roots is a possible mechanism that aided tall fescue plants overcome waterlogging stress on root length development, whereas root length of all cocksfoot cultivars (cv. Lazuly, cv. Porto, cv. Uplands and cv. Kasbah) was significantly impeded by waterlogging. Hence, the proportion of aerenchyma formed in adventitious roots appeared to be the major contributor to root survival and growth under waterlogging conditions. However, waterlogging significantly caused the reduction in root dry matter of all cultivars of tall fescue and cocksfoot examined in the second experiment, most likely attributed to younger age of plants when waterlogging was started. Further investigations on aerenchyma formation in primary roots would be interesting to assess whether the loss of primary roots under waterlogging is related to capacity for aerenchyma formation in these roots of cocksfoot and tall fescue plants.
Results of this study did not show any significant differences between the two origin types (Mediterranean and Continental types) of each species in their response to waterlogging. Therefore, it is likely that differences in response of these grasses to waterlogging depend on adaptive characteristics of individual cultivar rather than origin of the breeding material per se. Results of the first experiment showed that the Mediterranean cocksfoot cv. Kasbah, was the most sensitive cultivar to 4 weeks waterlogging in all measured variables, whereas cv. Uplands, also a Mediterranean cocksfoot cultivar, showed better tolerance to waterlogging. A variation in waterlogging responses among cultivars suggests the need for further investigation to elucidate differences in physiological and morphological mechanisms of waterlogging tolerance (e.g. aerenchyma and adventitious roots) among cultivars and pre-breeding material within species, which could then be used in grass breeding programs.
35
Mehta, Prem. "Phenotypic variation for forage yield and cell wall concentration associated with polyploidization and breeding of Dactylis glomerata L". 1990. http://catalog.hathitrust.org/api/volumes/oclc/23686499.html.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Wisconsin--Madison, 1990.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 31-35).
36
"Priming Seeds in Aqueous Smoke Solutions Improves Germination of Agropyron dasystachyum, Dactylis glomerata, Elymus angustus, Elymus junceus, and Festuca hallii". Thesis, 2014. http://hdl.handle.net/10388/ETD-2014-06-1479.
Testo completoAbstract (sommario):
Seeds of many grasses and legumes from the Canadian Prairies have dormancy which prevents the germination of viable seeds in otherwise favorable conditions. Plant-derived smoke can improve germination in dormant seeds. Seeds of eight grasses, two legumes, and Lactuca sativa were investigated for the effects of seed priming in aqueous smoke solutions on germination, seedling emergence, seedling growth, and standing crop. Aqueous smoke solutions were produced by bubbling smoke generated from the incomplete combustion of wheat straw (Triticum aestivum cv. Unity) or prairie hay (Festuca hallii) through distilled water. Seeds were primed for 24 h in darkness using serial dilutions (1/1000v/v, 1/100v/v, 1/10v/v and 1/1v/v) of the aqueous smoke solutions. After priming, seeds were dried at 20°C in darkness for 7d and placed in petri dishes containing filter paper, after which 5 mL of distilled water were applied. Seeds were incubated at 10/0°C or 25/15°C in 12h light/12h darkness or 24 h darkness for 49 d. Seeds were also primed using 1/100v/v aqueous smoke solutions of wheat straw or prairie hay and seeded in the field. Non-primed seeds and those primed in distilled water (0/1v/v) were used as controls. Within species, germination varied significantly (P≤0.05) among concentrations of aqueous solutions of smoke, smoke type, light, temperature, and their interactions. Total germination of Astragalus cicer, Trifolium ambiguum, Hesperostipa comata, Stipa viridula, and Pascopyrum smithii was not changed by priming seeds. Depending on light or temperature treatments, priming seeds of Agropyron dasystachyum, Elymus junceus, Dactylis glomerata, Elymus angustus, and Festuca hallii in aqueous smoke solutions improved germination by 16%, 20%, 32%, 49%, and 50%, respectively. Priming seeds in aqueous smoke solutions reduced the number of days to 50% germination for Trifolium ambiguum, Lactuca sativa, Festuca hallii, and Stipa viridula (2 d), Elymus junceus (3 d), Dactylis glomerata (4 d), Hesperostipa comata (10 d), and Pascopyrum smithii (15 d). Priming seeds in aqueous smoke solutions increased seedling lengths (combined hypocotyl and radicle lengths) for Elymus angustus and Hesperostipa comata by 28% and 100%, respectively, but it reduced seedling lengths of Lactuca sativa, Festuca hallii, and Trifolium ambiguum. Seedlings from seeds primed in aqueous smoke solutions generated from wheat straw were longer for Lactuca sativa (83%), Elymus angustus (52%), and Hesperostipa comata (36%) as compared with prairie hay, respectively. Priming seeds interacted with smoke type to increase seedling lengths for Pascopyrum smithii (92%), Elymus junceus (100%), and Agropyron dasystachyum (100%), but it reduced seedling lengths for Astralagus cicer (26%), Trifolium ambiguum (55%), and Dactylis glomerata (90%). Exposing seeds to aqueous smoke solutions partially substituted a light requirement for germination in Pascopyrum smithii, Festuca hallii, Hesperostipa comata, Dactylis glomerata, Agropyron dasystachyum, Stipa viridula, and Elymus junceus. Priming seeds in aqueous smoke solutions increased standing crop of Dactylis glomerata by 57%, but total seedling emergence and rate of emergence of seedlings in the field were not different (P>0.05) among priming treatments. Priming seeds in aqueous smoke solutions generated from wheat straw or prairie hay can stimulate germination in Agropyron dasystachyum, Dactylis glomerata, Elymus junceus, Elymus angustus, and, Festuca hallii.
37
BERNAS, Jaroslav. "Význam trvalých travních porostů a suchovzdornost vybraných druhů trav - ovsík vyvýšený (\kur{Arrhenatherum elatius L.}) a srha laločnatá (\kur{Dactylis glomerata L.})". Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-138347.
Testo completo
38
Mills, A. "Understanding constraints to cocksfoot (Dactylis glomerata L.) based pasture production : a thesis submitted for a degree of Doctor of Philosophy at Lincoln University, New Zealand /". Diss., 2007. http://hdl.handle.net/10182/32.
Testo completo
39
Turner, LR. "Investigating the physiology and management of cocksfoot (Dactylis glomerata L.) and prairie grass (Bromus willdenowii Kunth.) as alternative perennial grass species for the dairy industry in southern Australia". Thesis, 2006. https://eprints.utas.edu.au/22184/1/whole_TurnerLydiaRuth2006_thesis.pdf.
Testo completoAbstract (sommario):
This thesis examined the productivity and pasture herbage quality of cocksfoot (Dactylis glomerata L.) cv. 'Kara' and prairie grass (Bromus willdenowii Kunth.) cv. 'Matua', under leaf stage based defoliation management. Leaf stage (number of live leaves per tiller) is a generic measure of plant development and was used to investigate the physiology underlying the regrowth response of these species following defoliation, and to determine optimal defoliation management of cocksfoot and prairie grass plants.
A survey was undertaken of Tasmanian dairy farmers, to establish the current and potential use of perennial ryegrass (Lolium perenne L.), cocksfoot and prairie grass, and to evaluate quantitatively farmer perception of the feed quality, palatability and dry matter (DM) production of these species under dryland conditions. The survey responses confirmed that perennial ryegrass is currently the dominant perennial grass species utilised in Tasmanian dairy pastures and that the herbage quality, palatability and annual DM production of perennial ryegrass under dryland conditions is generally considered to be substantially higher than for cocksfoot and prairie grass.
An initial field study investigated the effect of defoliation management based on leaf regrowth stage on the productivity and herbage quality of perennial ryegrass, prairie grass and cocksfoot under dryland conditions. The DM yield and quality of cocksfoot and prairie grass were found to be comparable with perennial ryegrass under appropriate defoliation management. While the 2-leaf to 3-leaf regrowth stage was previously well-recognised as the most favourable defoliation interval for perennial ryegrass pastures, this study showed that a defoliation interval coinciding with regrowth of four leaves provided an optimal balance between pasture productivity and herbage quality for cocksfoot and prairie grass.
The physiology underlying the regrowth response of cocksfoot and prairie grass following defoliation was further investigated in a series of four glasshouse studies. Changes in the physiology and herbage quality of prairie grass during regrowth were examined, and results provided further evidence that the optimal defoliation interval for prairie grass is the 4-leaf stage of regrowth, as this is when increased watersoluble carbohydrate (WSC) levels in the stubble coincide with a resumption of tillering and root growth, but is prior to the reduction of herbage quality due to increased senescent and stem material.
The role of nitrogenous (N) and WSC reserves during regrowth of these species was further investigated, concluding that as with perennial ryegrass, the stubble (tiller base below 50 mm height) is the primary storage site for energy reserves and the priority sequence for allocation of WSC reserves follows the expected order of leaf growth, root growth and tillering for both species. Nitrogenous energy reserves were found to play a minor role in the regrowth of cocksfoot plants following defoliation. For prairie grass, although WSC reserves were identified as the primary contributor to plant regrowth following defoliation, there was a strong relationship between stubble N concentration and regrowth parameters. The distribution of WSC reserves within the stubble of cocksfoot and prairie grass was also determined. The pattern of WSC accumulation in the stubble of these species suggests that the previously adopted defoliation stubble height of 45-50 mm (optimal management for perennial ryegrass) is also suitable for the persistence of cocksfoot and prairie grass. However, while decreasing defoliation height to 30 mm may be acceptable for cocksfoot, prairie grass is more sensitive to defoliation severity, with defoliation below 45 mm not recommended.
Differences between four cocksfoot and four brome cultivars (including Kara and Matua) under leaf stage based defoliation management in the glasshouse were xamined. Variation between cultivars indicated that there are some improvements resulting from selection and breeding within the cocksfoot and brome genera since the commercial release of Kara and Matua. However, whether the overall value of the newer cultivars to dairy pasture systems exceeds the value of the original cultivars is yet to be determined.
The remaining potential limitations to the use of Matua and Kara in the dairy industry, as highlighted in this thesis, include slow establishment of Kara in the field, high rates of seeding for Matua, and relatively high fibre levels for both cultivars compared with perennial ryegrass. However, the overall results show that under defoliation management based on leaf stage, an optimal balance between pasture yield, persistence and herbage quality can be achieved, supporting the future use of cocksfoot and prairie grass in dryland dairy pastures of southern Australia.