Tesi sul tema "Lolium"

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

Thesis (Ph. D.)--University of Kentucky, 2004.
Title from document title page (viewed Sept. 14, 2004). Document formatted into pages; contains ix, 97 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 86-96).

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 B
The 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

Thesis (MScAgric)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: Glyphosate remains an important herbicide in weed control. This is due to several positive attributes it has including sytemicity, wide spectrum of weed control and environmental friendliness. Its efficacy and lack of residual activity are therefore important to ensure adequate weed control without imposing hazards to the environment. Despite these favourable attributes for weed control glyphosate has its shortcomings. Evolution of resistance to glyphosate has been a major concern from 1996. However, there are other factors that reduce the maximum potential of glyphosate. Any factors that reduce glyphosate efficacy may result in the target plant being subjected to non-lethal concentrations of glyphosate. This in turn may predispose the plants to developing herbicide resistance. Some factors that may influence efficacy of glyphosate, and therefore be possibly selecting for resistance were investigated in this study. Although glyphosate is a postemergence herbicide, its efficacy is not exempt from the effect of soil and nutrients in which the weeds occur. The possibility of this occurring was investigated in a greenhouse study on ryegrass (Lolium spp.) In this study ryegrass was grown in three soils: pure sand (SS), soil from pasture paddock (PS) and soil from crop field (CS). The soils varied in nutrient composition and, although all were classified as sand, they had varying proportions of sand, loam and clay. This investigation consisted of four experiments. The first experiment was investigating the effect of growing a susceptible commercial ryegrass cultivar on PS, CS and SS soils on the efficacy of glyphosate (360 g a.i. L-1 formulation) applied at five glyphosate application rates (GAR). The GARs were 0 (0x), 67.5 (1/8x), 135 (1/4x), 270 (1/2x) and 540 (1x) g a.i. ha-1. The second experiment investigated the effect of growing a susceptible commercial ryegrass cultivar and a glyphosate resistant ryegrass biotype on PS and CS soils on the efficacy of glyphosate. The application rates were 0 (0x), 270 (1/2x), 540 (1x), 1080 (2x) and 2160 (4x) g a.i. ha-1. The third and the fourth experiments were similar to the first experiment except: The latter investigated the role of nutrient content of irrigation water (pure water or balanced nutrient solution) and; the former investigated the effect of soil activity (by covering the soil surface with cotton at the time of spraying) of glyphosate with regard to the role it plays on efficacy of glyphosate. Our findings showed that: i) soil affects the efficacy of glyphosate with more control (19% survivors) found in the PS soil compared to 50% and 62% survivors in CS and SS soils respectively, this effect may be dependent upon the species resistance as; ii) the effect in the resistant ryegrass biotype was reversed with about 95% of survivors in the PS soil compared to about 78% in CS soil; iii) efficacy of glyphosate is influenced by the soil nutrient status and the nutrient content of the irrigation water. This was shown by decrease in the control of ryegrass (100% survivors) grown in SS soil when fed with pure water compared to 45% when nutrient fed. In PS soil there was no significant effect. This was probably due to inherently higher nutrient content of the PS soil; and iv) glyphosate efficacy is influenced by the amount of glyphosate reaching the soil (absorbed through the roots). This was shown in PS soil where 1/8x GAR resulted in 93.3% survivors in covered soil compared to 60% in uncovered soil. A similar trend was also observed at 1/4x GAR. An opposite effect was shown in SS soil with 0% and 40% survival at 1/4x GAR in the covered and uncovered soil respectively. Glyphosate has been hailed as an environmentally friendly herbicide as it rapidly degrades in soil and it sorbs on metals embedded in soil matrix. However, reports in the literature have showed reduction in crop yield due to soil glyphosate residues. In these studies, glyphosate phytotoxicity was found to be dependent on certain soil characteristics and nutrient content. Following this, a greenhouse study was conducted to assess the phytotoxic activity of glyphosate on a susceptible commercial ryegrass cultivar grown in PS, CS and SS soils. Glyphosate was applied at 0 (G1), 540 (G2) and 3240 (G3) g a.i. ha-1. Ryegrass seedlings of comparable size were transplanted into the soil at intervals of two hours, three weeks and four weeks after glyphosate application referred to as TAS1, TAS2 and TAS3 respectively. Evidence of soil glyphosate activity was shown by the decrease in percentage survival with the application of glyphosate. This was significant in the SS soil where about 60% and 48% survival in G1 and G2 GAR respectively was observed compared to about 100% in the untreated control when transplanted three weeks after glyphosate application. The decrease in percentage survival was time mediated with significant effect of G2 GAR shown at TAS 1 whereas at G3 GAR the effect was significant at TAS1 and TAS 2. At TAS 3 there was no effect at all GARs. Similar trends were observed with dry mass and shoot length. Trace metals required for normal plant growth have been implicated in the reduction of glyphosate efficacy. This follows glyphosate’s original development as a metal chelator. Glyphosate-trace metal antagonism has recently sparked interest following co-application in glyphosate resistant soybeans. Molybdenum (Mo), an anion, may play a role at the physiological level on the antagonism of glyphosate. A greenhouse assay was carried out where seedlings grown from seeds (of susceptible commercial ryegrass cultivar (S biotype) and glyphosate resistant biotype (R biotype)) were grown with nutrient solutions containing 0x, 1x and 2x molybdenum (Mo) concentrations where 1x is 0.05 mg L-1 Mo. Glyphosate was applied at 0 (0x), 135 (1/4x), 270 (1/2x), 540 (1x) and 1040 (2x) g a.i. ha-1 rates. In the R biotype applying 2x Mo resulted in 0% survival in the R biotype at 1x GAR compared to 50% and 90% survival at the same GAR with 0x and 1x Mo. In terms of dry mass and shoot length the results did not show any conclusive trends.
AFRIKAANSE OPSOMMING: Glifosaat is ‘n baie belangrike onkruiddoder wat in verskeie onkruidbeheerstelsels gebruik word. Dit is as gevolg van verskeie positiewe eienskappe waaroor dit besit onder andere sistemiese werking, wye spektrum van onkruidbeheer en omgewingsvriendelike werking. Die onkruiddoder se effektiwiteit en gebrek aan residuele aktiwiteit is dus belangrik om bevredigende onkruidbeheer te bewerkstellig sonder om skade aan die omgewing te veroorsaak. Ten spyte van hierdie voordelige eienskappe het glifosaat ook tekortkominge. Vanaf 1996 is ontwikkeling van weerstand teen glifosaat in onkruide ‘n groot bron van kommer. Daar is egter ook ander faktore wat die maksimum potensiaal van glifosaat strem. Enige faktore wat die effektiwiteit van glifosaat strem mag veroorsaak dat die teikenplant aan subletale dosisse van glifosaat blootgestel word. Dit mag weer daartoe lei dat sulke plante blootgestel word aan die ontwikkeling van weerstand. Sommige faktore wat die effektiwiteit van glifosaat mag strem en dus moontlik kan lei tot seleksie vir weerstand is in hierdie studie ondersoek. Alhoewel glifosaat ‘n na-opkoms middel is kan die effektiwiteit moontlik beïnvloed word deur grondfaktore en nutriënte. Hierdie moontlikheid is ondersoek in ‘n glashuisstudie waarin raaigras (Lolium spp.) gebruik is. In hierdie studie is raaigras geplant in drie verskillende grondsoorte nl. suiwer sand (SS), grond vanaf ‘n weidingskamp (PS) en grond vanaf ‘n gewasland (CS). Die gronde het gevarieer in terme van nutriëntinhoud en alhoewel al drie gronde as sand geklassifiseer is, was daar tog verskille in fisiese eienskappe. Hierdie afdeling het uit vier eksperimente bestaan. In die eerste eksperiment is die invloed van verskillende gronde (PS, CS en SS) waarin die kommersiële raaigras kultivar geplant was op die effektiwiteit van glifosaat (360 g a.b. L-1 formulasie) teen vyf verskillende dosisse (GAR) ondersoek. Die dosisse was 0 (0x), 67.5 (1/8x), 135 (1/4x), 270 (1/2x) and 540 (1x) g a.b. ha-1. Die tweede eksperiment het die invloed van twee grondsoorte (PS en CS) waarin ‘n vatbare kommersiële raaigras kultivar en ‘n glifosaat weerstandbiedende raaigras biotipe geplant is, se invloed op die effektiwiteit van glifosaat ondersoek. Die dosisse was 0 (0x), 270 (1/2x), 540 (1x), 1080 (2x) and 2160 (4x) g a.b. ha-1. Die derde en vierde eksperimente was soortgelyk aan die eerste eksperiment behalwe dat die derde eksperiment die invloed van voeding (suiwer gedistileerde water teenoor ‘n gebalanseerde voedingsoplossing) saam met besproeiing ondersoek het. In die vierde eksperiment is die grondwerking van glifosaat wat as blaarbespuiting toegedien is ondersoek deurdat sommige potte wat gespuit is se oppervlakte met ‘n laag watte bedek is tydens die spuitproses en dadelik na spuit verwyder is teenoor die ander behandeling waar die grondoppervlakte nie bedek is nie. Die resultate het getoon dat i) grondtipe die effektiwiteit van glifosaat beïnvloed met beter beheer (19% oorlewing) in die PS grond vergeleke met 50% en 62% oorlewing in die CS en SS grondtipes respektiewelik. Hierdie effek kan moontlik beïnvloed word deur die weerstandsvlak van spesies omdat ii) die effek in die weerstandbiedende biotipe omgekeer is met ongeveer 95% oorlewing in the PS grondtipe vergeleke met 78% in die CS grondtipe; iii) effektiwiteit van glifosaat is beïnvloed deur die voedingstatus van die grond en die besproeiingswater. Dit word aangedui deur die afname in beheer van raaigras (100% oorlewing) wat in SS grond gegroei het en met suiwer gedistilleerde water besproei is vergeleke met 45% oorlewing in dieselfde grond wanneer met ‘n gebalanseerde voedingsoplossing besproei is. Plante wat in PS grond gegroei het het geen betekenisvolle verskille tussen die besproeiingsbehandelings getoon in hulle reaksie op glifosaattoediening nie, waarskynlik as gevolg van die inherente hoër nutriëntinhoud van die grond en iv) glifosaat effektiwiteit word beïnvloed deur die hoeveelheid glifosaat wat die grond bereik en deur die wortels opgeneem word. Dit is bewys in plante wat in PS grond gegroei het waar 93.3% plante oorleef het waar die grondoppervlakte bedek was teenoor 60% oorlewendes waar die grondoppervlakte nie bedek was nie indien glifosaat teen 1/8x toegedien is. ‘n Soortgelyke tendens is by die 1/4x dosis waargeneem. ‘n Teenoorgestelde effek is in SS grond waargeneem waar die oorlewingspersentasie in bedekte en onbedekte grond by 1/4x glifosaatdosis 0% en 40% onderskeidelik was. Glifosaat is aanvanklik aangeprys as ‘n omgewingsvriendelike onkruiddoder omdat dit vinnig in grond afgebreek word en omdat dit geadsorbeer word aan metale in die grondmatriks. In teenstelling hiermee is daar egter verslae in die literatuur wat dui daarop dat glifosaatresidue in die grond gewasopbrengste kan verlaag. In die gemelde studies is gevind dat fitotoksisiteit van glifosaat residue afhang van grondeienskappe en grondvrugbaarheid. Na aanleiding hiervan is ‘n glashuisstudie uitgevoer waarin die fitotoksisiteit van residuele glifosaat op ‘n kommersiële raaigraskultivar wat in PS, CS en SS gronde groei, ondersoek is. Glifosaat is op die grond in potte toegedien teen 0 (G1), 540 (G2) and 3240 (G3) g a.b. ha-1. Raaigras saailinge is daarna in die potte ingeplant twee ure, drie weke en vier weke nadat die glifosaat toegedien is. Bewys van grondaktiwiteit van glifosaat is gelewer deur die vermindering in persentasie oorlewing van die saailinge met toediening van glifosaat. Die vermindering in oorlewing was betekenisvol in die SS grond waar ongeveer 60% en 48% oorlewing van saailinge was by G2 en G3 dosisse onderskeidelik teenoor 100% oorlewing in die onbehandelde kontrole. Die afname in persentasie oorlewing is deur tyd beïnvloed deurdat die G2 dosis slegs by die twee ure behandeling betekenisvolle verlaging in oorlewing veroorsaak het terwyl die G3 dosis by die twee ure sowel as die drie weke behandeling betekenisvolle verlagings veroorsaak het. Vier weke na toediening was daar geen effek van glifosaat op die saailinge in enige van die gronde gewees nie. Soortgelyke tendense is waargeneem by die droëmassa en lengte data. Spoorelemente wat noodsaaklik is vir normale plantgroeiprosesse is al geïmpliseer in verlaging van glifosaat effektiwiteit. Dit is waarskynlik omdat glifosaat oorspronklik ontwikkel is as ‘n metaal cheleerder. Glifosaat-spoorelement antagonisme was onlangs in die nuus nadat glifosaat saam met sulke elemente toegedien is op glifosaat weerstandbiedende sojabone. Molibdeen (Mo), ’n anioon, mag ’n rol op fisiologiese vlak speel in doie effektiwiteit van glifosaat. ‘n Glashuisstudie is uitgevoer waarin saailinge van ‘n glifosaat vatbare kommersiële raaigras kultivar en ‘n glifosaat weerstandbiedende raaigras biotipe besproei is met voedingsmengsels wat 0x, 1x en 2x Mo bevat waar 1x 0.05 mg L-1 Mo is. Glifosaat is op die plante toegedien teen 0 (0x), 135 (1/4x), 270 (1/2x), 540 (1x) and 1040 (2x) g a.b. ha-1 dosisse. Die 2x Mo toediening het gelei tot 0% oorlewing in die R biotipe by 1x GAR vergeleke met 50% en 90% oorlewing by dieselfde GAR met 0x en 1x Mo. In terme van droëmateriaal en lengtegroei was daar geen konkrete tendense nie.

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.

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 continents
The 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

O azevém anual (Lolium multiflorum Lam.) é uma das forrageiras mais utilizadas no RS, sendo alternativa para o período frio do ano onde as pastagens nativas paralisam seu crescimento. No RS, há relatos informais da formação de populações localmente adaptadas, em função do seu cultivo continuado por vários anos no mesmo local sem a introdução de novas sementes. O objetivo deste trabalho foi avaliar a produção e a distribuição estacional de cultivares e populações de azevém em comparação com a cultivar comercial Comum-RS. Foram realizados dois experimentos, onde o primeiro visou a avaliação da produção de 7 populações de azevém em relação a testemunha (cultivar Comum- RS) e duas cultivares uruguaias (LE-284 e Eclipse), em Eldorado do Sul (RS) e Veranópolis (RS) em 2004. O segundo visou a avaliação da produtividade de diversas linhagens, também em relação a testemunha, em Eldorado do Sul, nos anos de 2004 e 2005. Em ambos experimentos foram realizados cortes, seguidos da coleta do material para posterior separação botânica e secagem visando a avaliação de matéria seca de folhas (MSF) e matéria seca total (MST). Em ambos experimentos ficou constatada a existência de genótipos superiores produtivamente em relação as cultivares comerciais avaliadas, especialmente a Comum-RS, indicando possibilidade de obtenção de novas cultivares.
The annual ryegrass (Lolium multiflorum Lam.) is one of the grasses more used in RS, being alternative for the cold period of the year where the native pastures paralyze their growth. In RS, there are informal reports of the formation of populations locally adapted, in function of the continuous cultivation for several years in the same place without the introduction of new seeds. The objective of this work was to evaluate the production and the seasonal distribution of the annual ryegrass population in comparison with to the commercial Comum-RS. Two experiments were accomplished, where the first sought the evaluation of the production of 7 ryegrass population in relation to witness (to cultivate Comum-RS) and two cultivate Uruguayans (LE-284 and Eclipse), in Eldorado do Sul (RS) and Veranópolis (RS) in 2004. The Second sought the evaluation of the productivity of several population, also in relation to witness, in Eldorado do Sul, in the years of 2004 and 2005. In both experiments cuts were accomplished, following by the collection of the material for subsequent botanical separation and drying seeking the evaluation of dry matter of leaves (MSF) and matter total drought (MST). In both experiments the existence of superior genotypes was verified productively in relationship cultivate them commercial evaluated, especially the Comum-RS, indicating obtaining possibility of new cultivate.

The overall aim of this thesis was, to evaluate the potential of molecular markers, specifically SNPs and microsatellites, within DUS (Distinct, Uniform and Stable) testing of Lolium species. In the current DUS testing system new candidate cultivars are compared to all existing cultivars in common knowledge which is very labour intensive and expensive. As candidates pass, they become part of the reference collection. The reference collection is reaching an unmanageable size; therefore alternative testing methods are being sought. Initially morphological data for 23 cultivars comprising of Lolium perenne, L. mutiflorum, L. hybridum and Festulolium was analysed to define the relationships between them. The species grouped together, with the hybrids linking with the Italian ryegrasses. The exception to this rule was the hybrid Foyle, which linked more closely with the perennial ryegrasses. Another exception was the perennial ryegrass Bealey that linked more closely with the Italians. These groupings were then used to evaluate how successful the molecular markers were at replicating the same relationships. Initially, cytoplasmic diversity was analysed using Single Nucleotide Polymorphisms (SNPs). SNPs were ascertained from individuals within the sample set of cultivars. Screening for these SNPs highlighted species separation, but individual cultivars could not be identified. Again, Bealey linked with the Italian ryegrass cultivars. Patterns of cytoplasmic diversity were then analysed using microsatellites. Again, the split between L. perenne and L. multiflorum was marked, with Bealey as an exception. Further investigation into the cytoplasmic diversity was carried out, specifically the 'potential for identifying Essentially Derived Varieties (EDVs). Use of markers in this way relies on a low mutation rate over the loci, which was not the case in this study. The findings of the study are discussed with respect to the utility of cytoplasmic markers as a complement to the DUS testing system, and future directions suggested.

Notre travail porte sur la compréhension des interactions entre la libération de carbone par les racines et la disponibilité en azote minéral dans la rhizosphère. Deux objectifs ont été fixés: caractériser l'effet de l'azote sur la rhizodéposition et évaluer l'impact de la rhizodéposition sur le cycle interne de l'azote dans la rhizosphère en incluant l'étude des communautés microbiennes. Nous avons travaillé sur une graminée prairiale (Lolium multiflorum), en hydroponie axénique et en sol non stérile. La rhizodéposition a été évaluée par des mesures directes, par le marquage ponctuel des photo-assimilats au 14C et par un biosenseur rapporteur de la disponibilité en carbone. La microflore a été caractérisée par sa taille, son activité et la structure de ses communautés. Relativement au cycle interne de l'azote, nous avons déterminé les teneurs en azote minéral et en azote organique dans les sols, le bilan net des transformations de l'azote, l'activité argininase et le facteur limitant (C, N) de la croissance bactérienne. Nos résultats ont permis de montrer, en hydroponie, que l'azote augmentait la quantité de carbone libérée par les racines. L'exsudation a pu être modélisée par le nombre de ramification et la teneur en carbone soluble racinaire. En sol, les résultats sont moins tranchés en raison d'une forte fourniture du sol témoin en azote minéral. Dans la rhizosphère, par rapport au sol non adhérent, la densité et l'activité bactériennes ont été augmentées. La structure des communautés n'a pas été significativement modifiée. Nous avons montré que dans la rhizosphère, l'activité argininase était augmentée, suggérant une augmentation de la minéralisation brute de l'azote. Par ailleurs, nous avons observé une tendance de moindre minéralisation nette pour le sol échantillonné au voisinage des racines. Les relations entre les rhizodépôts et la dynamique de l'azote dans la rhizosphère sont discutées
Our work focuses on the interactions between the release of carbon by roots and the nitrogen availability in the rhizosphere. Two main objectives have been established : to characterize the effect of nitrogen on rhizodeposition process and to evaluate the impact of rhizodeposition on the nitrogen internai cycle including the study of microbial communities. We worked on a meadow grass: Lolium multiflorum, grown in hydroponics or in non sterile soil. Rhizodeposition has been evaluated by direct measurements, by the labelling of photo-assimilates by 14C and by the use of a biosensor reporting on the carbon availability. Microbial biomass has been characterised through its size, its activity and the structures of its community. The internai cycle of nitrogen, was studied by the determination of the argininase activity, the balance sheet of nitrogen transformations and by evaluating the limiting factor of bacterial growth. Our results indicate, in hydroponics, that nitrogen increased the quantity of carbon released from roots. This has been modelled by the number of root branches and the root soluble carbon concentration. Ln soils results are less marked due to the high concentrations of nitrogen in our control soils. Ln the rhizosphere, compared to the non adhering soil, bacterial activity and density have been increased. Communities structure has not been modified. We have shown, that in the rhizosphere, argininase activity was increased suggesting an increase of gross mineralisation. Moreover, balance sheet of the nitrogen transformations was in favour of a decrease of nitrogen mineralisation in the soil sam pies in the vicinity of roots. The relationships between rhizodeposits and nitrogen dynamics in the the rhizosphere are discussed

L’identification des gènes ou des régions du génome responsables de la variabilité des caractères quantitatifs est généralement réalisées à partir de populations de cartographie dérivées d’hybrides F1. Cependant, ces populations sont peu variables et parfois difficiles à obtenir. Une autre approche possible est la conduite d’études d’association à l’aide de collections d’individus, construites pour représenter une grande variabilité. Cependant, ces collections sont souvent structurées, ce qui peut induire la détection de « fausses » associations entre marqueurs et caractères. Ainsi, un matériel végétal idéal pour des études d’association serait des populations multi alléliques et non structurées. C’est le cas des variétés fourragères qui sont des variétés synthétiques, obtenues après plusieurs générations successives de panmixie, à partir d’un n ombre plus ou moins grand d’individus. L’objectif de cette thèse est de tester si les variétés synthétiques peuvent être utilisées pour identifier les gènes ou les régions du génome responsables de la variabilité des caractères quantitatifs dar des études d’association
Identification of genes or of genome regions which explain variationin quantitative traits is generally obtained from QTL analyses using F1 hybrids derived populations. However, these population exhibit a low variability and are sometimes difficult to obtain. An alternative would be association studies using collections of individuals, built to be highly variable. Howevre, these collections are often structured which could lead to detection of spurious associations between markers and traits. So, an ideal plant material for association studies would be multi-allelic and unstructured populations. It is the case of perennial forage varieties which are synthetics, obtained after several panmictic multiplication generations, from a variable number of parents. The objective of this thesis was to test whether synthetic varieties could be used for association studies to identify genes or genome regions responsible for variation in quantitative traits

La diminution, en fonction du temps, du taux de phosphore soluble incorpore au sol, a ete mesuree en comparant les quantites extraites par quatre reactifs (truog, olsen, joret-hebert et dyer) a celles effectivement prelevees par une plante (ray-grass d'italie): apres une semaine, un sol acide a immobilise 40 a 50% du phosphore apporte alors qu'en sol neutre ou calcaire, cette valeur est inferieure a 25%. En presence de matieres humiques, l'augmentation de la quantite de phosphore restant en solution est de 38% en sol acide, 24% en sol neutre et 18% en sol calcaire. L'etude conductimetrique et potentiometrique de la complexation du calcium par des macromolecules fulvo-humiques de diverses origines (tourbe traitee, tourbe naturelle, compost, sol) a permis d'expliquer les phenomenes observes par la complexation des cations susceptibles d'immobiliser le phosphore (ca#2#+, fe#3#+ ou al#3#+) par les acides fulvo-humiques dont les principaux groupes fonctionnels (cooh et oh phenoliques) ont ete caracterises par leurs valeurs de pka. L'addition de matieres humiques augmente l'absorption du phosphore par des microcultures de ray-grass (22% en sol acide, 14% en sol neutre et 12% en sol calcaire). L'augmentation de la production de matiere seche, des expertations de phosphore, de la longueur et du poids des racines observee en presence de matieres humiques a faible dose (0,5&) correspond a une valeur superieure du coefficient d'utilisation du phosphore apporte

Le but de ce travail est de déterminer le cycle biogéochimique du sélénium, et plus particulièrement des sélénites, dans un environnement proche de la surface. Pour cela, nous avons réalisé des études de sorption sur différentes phases minérales en système mono et multi-phasiques. Nous avons également réalisé des expériences pour étudier le devenir du sélénium dans un système-sol_plantes_microorganismes. (i) Les expériences de sorption des sélénites sur différentes phases minérales ont validé la méthode dite des « membranes de dialyse » et ont montré qu'il n'y avait pas d'additivité des capacités de sorption dans des systèmes à plusieurs phases minérales. La présence de Si aqueux relâché par la bentonite réduit la sorption du Se sur la goethite en occupant les sites de sorption. (ii) L'étude de l'influence des substances humiques (HA, FA) sur les capacités de sorption des différentes phases minérales vis-à-vis des sélénites a montré que ces substances diminuent la sorption du Se sur la goethite. De plus, ces expériences ont montré que les HA/FA ne complexent pas le sélénium. (iii) Les expériences « rhizoplants » nous ont permis de calculer des facteurs de transfert du Se des sols vers le ray-grass. Une application de ces facteurs de transfert dans un scénario de migration et de transfert du Se à partir d'un site de stockage des déchets HAVL, a donné une dose effective annuelle vers l'Homme comprise entre2,3 x 10-6 et 5,9 x 10-6 Sv. An-1
The aim of this work is to determine the biogeochemical cycle of selenium, especially selenites, in a subsurface environment. To do so, we studied Se sorption on different mineral phases in single or multi-phase systems. We also conducted experiments to investigate the fate of selenium in a soil-plants microorganisms system. (i) Sorption experiments of selenites on different mineral phases validated the « dialysis membranes » method and showed that there was no additivity of the sorption capacity in systems composed of several minerals phases. The presence of aqueous Si released by bentonite reduced Se sorption on goethite by occupying the sorption sites. (ii) The study of the influence of humic substances (HA, FA) on the sorption capacities of different mineral phases has shown that these substances decrease Se sorption on goethite. Moreover, these experiments have shown that HA/FA do not complex selenium. (iii) « Rhizoplants experiments allowed us to calculate transfer factors of soil Se toward rye-grass. In a scenario of migration and transfer of Se from a radioactive waste disposal, the application of these transfer gave an annual effective dose to Humans comprised between 2,3 x 10-6 and 5,9 x 10-6 Sv. Y-1

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.

O crescimento das atividades urbano-industriais tem provocado um significativo aumento nas emissões de poluentes aéreos para a atmosfera. A poluição do ar, um dos principais fatores determinantes da destruição do meio ambiente, causa estresse às plantas, já que apresenta compostos altamente reativos e danosos, como os metais pesados. O uso de plantas bioindicadoras de poluição aérea é uma prática comum para o monitoramento da qualidade do ar e para o diagnóstico dos efeitos da poluição aérea na vegetação. Entre as plantas bioindicadoras mais utilizadas, destaca-se a gramínea C3 de clima temperado Lolium multiflorum ssp. italicum Beck var. Lema, que acumula metais pesados, fluoretos e enxofre quando se desenvolve na presença desses elementos químicos no ar. Além disso, esta espécie acumula frutano, um carboidrato solúvel cuja produção pode ser alterada por um número variado de perturbações ambientais. O presente trabalho foi dividido em três experimentos com os objetivos de (1) verificar a partição de carboidratos solúveis em cinco partes distintas (lâmina em alongamento, lâmina expandida, porção superior do estolho, porção inferior do estolho e raízes) de plantas de L. multiflorum; (2) analisar as relações sazonais e diurnas entre concentrações de poluentes aéreos urbanos, principalmente de dióxidos de enxofre e de nitrogênio e de material particulado, entre outros fatores ambientais, concentrações foliares de metais e mudanças no acúmulo de frutanos em plantas de Lolium multiflorum Lam ssp. italicum expostas a diferentes condições de poluição do ar na cidade de São Paulo; (3) verificar se as variações sazonais e diurnas no conteúdo de frutanos são determinadas por acúmulos foliares de enxofre e metais pesados ou por variações nas concentrações de poluentes gasosos; e (4) verificar a eficiência bioacumuladora da variedade “Lema” de Lolium multiflorum para a região tropical. Para isso, as plantas foram expostas durante períodos consecutivos de 28 dias ou 2 meses, em cada estação do ano, em Congonhas (local com altos níveis de poluentes aéreos) e em casa de vegetação com ar filtrado (local controle). Após cada exposição, a frutose total foi quantificada pelo método de antrona e os frutanos analisados qualitativamente por HPAEC-PAD. As concentrações de enxofre foram determinadas por turbidimetria, enquanto que as concentrações de metais pesados (Al, Fe, Cu, Zn, Pb, Cd e Ba) foram medidas utilizando um espectrofotômetro de absorção atômica, após digestão ácida. Os resultados mostraram que o estolho contendo as bainhas foliares de L. multiflorum acumulou mais frutanos, enquanto que as raízes acumularam os menores níveis desse carboidrato. As variações sazonais no conteúdo dos carboidratos solúveis foram marcantes no presente trabalho e pareceram estar relacionadas com as condições climáticas, mas intensificadas pelas concentrações de poluentes aéreos, especialmente de metais pesados contidos no material particulado, e acumulados nas folhas de L. multiflorum expostas em Congonhas. Já as variações diurnas foram sutis, mas suficientes para refletir as variações de irradiância, temperatura e de alguns poluentes gasosos ao longo do dia. Tanto no experimento sazonal como no diurno, os frutanos de alto peso molecular pareceram ter sido hidrolisados sendo o acúmulo de frutanos de peso molecular intermediário preferencial nas plantas dos dois locais de estudo. As interferências no conteúdo e na composição de frutanos influenciaram a produção de biomassa e a partição desta entre as partes da plantas, o que ode ter alterado a capacidade acumuladora da espécie de elementos provenientes da poluição atmosférica. Assim, o uso da variedade Lema de L. multiflorum para fins de biomonitoramento da qualidade do ar em regiões tropicais deve ser cuidadoso.
The development of urban and industrial activities has caused a significant increase in the emissions of pollutants to the atmosphere. Air pollution, one of the most destructive factors of the environment, causes stress to plants, since certain compounds such as heavy metals are very reactive and dangerous to plant cells. The utilization of bioindicator plants is an usual practice to monitor the air quality and to diagnose the effects of air pollution on vegetation. The C3 temperate grass Lolium multiflorum ssp. italicum Beck var. Lema is usually employed as bioindicator of air pollution, due to its high capacity of accumulating heavy metals, fluorine and sulfur when growing in the presence of these chemical elements in the air. This species also accumulates fructan, a soluble carbohydrate, whose production can be altered by to many environmental perturbations. In the present work three experiments were performed aiming (1) to verify the partitioning of water total carbohydrates in five different parts of plants of L. multiflorum (upper stubble; under stubble; elongating leaf, expanded leaf and roots); (2) to analyze the seasonal and the diurnal relationships between the concentrations of urban air pollutants, mainly nitrogen and sulfur dioxides and particulate material, among other environmental factors, leaf concentrations of heavy metals and changes in fructan accumulation in plants of L. multiflorum exposed to different conditions of air pollution in São Paulo city; (3) to verify if the seasonal and diurnal variations in the content of fructans are determined by leaf accumulation of sulfur and heavy metals or by variations in the concentrations of gaseous pollutants or other environmental factors; and (4) to verify the bioindicator efficiency of the variety “Lema” of Lolium multiflorum in tropical areas. Plants were consecutively exposed during 28 days or two months in each season at Congonhas (site reached by high levels of air pollutants) and at a glasshouse with filtered air (reference situation). After each exposure, fructan composition as well as leaf concentrations of total fructose and of sulfur and metals (Al, Fe, Cu, Zn, Pb, Cd and Ba) were measured. Total fructose was quantified by the anthrone method and fructan composition was analyzed by HPAEC-PAD. Sulfur concentrations were determined by the turbidimetric method, whereas metal concentrations were measured using an atomic absorption spectrophotometer, after acidic digestion. Results showed that the stubble containing the leaf sheaths of L. multiflorum accumulated the highest levels of fructans, while the roots accumulated the lowest levels. Seasonal variations in the contents of soluble carbohydrates were evident in the present work and seemed to be related with the climatic conditions but intensified by the air pollutants, especially heavy metals contained in the particulate matter, and accumulated in the leaves of L. multiflorum exposed in Congonhas. However the diurnal variations were tenuous, but reflected the variations of irradiance, temperature and of some gaseous pollutants during daytime. In the both seasonal and diurnal experiments, the fructans of high molecular weight seemed to be hydrolyzed and the accumulation of fructans of intermediary molecular weigh was significant in the plants from both sites. The changes in the content and in the composition of fructans altered the biomass production and partition among roots and shoots, which might have been disturbed their characteristic of accumulating chemical elements from air pollution in the leaves. So, the use of the variety Lema of L. multiflorum for biomonitoring purposes in tropical areas should be carefully evaluated.

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.

Some aspects of the presence of systemic endophytic fungi in agriculturally important New Zealand grasses were studied in relation to plant breeding. Seedling resistance to adult Argentine stem weevil feeding in perennial ryegrass, Italian ryegrass and tall fescue was found to be related to the presence of their respective Acremonium endophytes in the seed rather than to plant genetic resistance. In addition a study of perennial ryegrass revealed that this resistance was independent of endophyte viability. The seedling resistance conferred by the endophyte of Italian ryegrass was found to be beneficial for field establishment. This endophyte differs from that in perennial ryegrass and tall fescue in that it does not confer resistance to Argentine stem weevil on mature plants, but only on seedlings. The extent of plant genetic seedling tolerance to adult Argentine stem weevil feeding was limited to broad inter-specific differences, with tall fescue more tolerant than perennial ryegrass and both of these more tolerant than Italian ryegrass. This ranking corresponds with previous observations on feeding preference on mature plants. A study of factors affecting the concentration of endophyte mycelia in infected seed of perennial ryegrass revealed that plant genetic factors had little effect. The major factors studied were: 1) the endophyte concentration in the maternal parent plant directly influenced the endophyte concentration in the seed. 2) nitrogen fertilizer applications to a seed crop reduced the concentration of mycelia in the seed, with earlier applications having a greater effect. 3) application of the fungicide propiconazole (Tilt) to a seed crop reduced the endophyte concentration in the seed. 4) the endophyte concentration in the seed was found to directly influence the endophyte concentration in seedlings, six month old plants and that of seed harvested from a first year seed crop. As there have been no previous reports of tetraploid perennial ryegrass cultivars with endophyte an experiment was conducted to determine if these could be developed by the standard procedure of colchicine treatment. The results revealed that endophyte was retained following colchicine treatment.

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.

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.

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.

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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Ryegrass is an annual cycle weed, found in virtually all winter crops, orchards and vineyards of Southern Brazil. The species is usually controlled by glyphosate, however, continued use of the product selected resistant biotypes. The managing with acetyl Coenzime A carboxylase (ACCase) enzyme inhibiting herbicides is the main alternative to control these species, which has not been satisfactory in some places, causing suspicion of being selected biotypes that are resistant to this herbicide group. The objective of this research was to evaluate the distribution of ryegrass biotypes resistant to ACCase enzyme inhibitors herbicides in Rio Grande do Sul (RS); assess by means of dose-response curves ryegrass biotypes resistant and susceptible to the herbicide fluazifop; estimate the fitness cost of susceptible and resistant biotype to fluazifop, and to investigate the competitive ability of these biotypes among themselves and with the wheat crop. Thus, seeds of ryegrass plants that survived applications of ACCase enzyme inhibitors were collected from farms in Northern RS, comprising 80 towns. The results showed that there were ryegrass resistant biotypes to the herbicide fluazifop when applied at the maximum dose of 125g a.i.ha-1 and stage specified by the manufacturer. Ryegrass biotypes have different levels of herbicide resistance, and the biotype of ryegrass TUC 11 has low-level resistance to the herbicide fluazifop. In the assessment of competitive ability and fitness cost it was found that the susceptible ryegrass and low level resistance, in general, have similar values for these variables. Wheat cultivar FUNDACEP Horizonte, in general, showed greater competitive ability than the low level resistance biotype and equivalent to the susceptible.
O azevém é uma planta daninha de ciclo anual, encontrada em praticamente todas as lavouras de inverno, em pomares e vinhedos da região Sul do Brasil. A espécie é normalmente controlada pelo herbicida glyphosate, no entanto, o uso continuado desse produto selecionou biótipos resistentes. O manejo com herbicidas inibidores da enzima acetil Coenzima A carboxilase (ACCase) é a principal alternativa para o controle dessas espécies, o qual não tem sido satisfatório em alguns locais, provocando a suspeita de que estejam sendo selecionados biótipos resistentes a este grupo de herbicidas. Assim, o objetivo da pesquisa foi avaliar a distribuição dos biótipos de azevém resistentes aos herbicidas inibidores da enzima ACCase no Rio Grande do Sul (RS); avaliar, por meio de curvas de dose-resposta, biótipos de azevém resistente e suscetível ao herbicida fluazifop; estimar o valor adaptativo de biótipo suscetível e resistente ao fluazifop; e, investigar a habilidade competitiva desses biótipos entre si e com a cultura do trigo. Para isso, sementes de plantas de azevém que sobreviveram a aplicações de inibidores da enzima ACCase foram coletadas em lavouras na região norte do RS, totalizando 80 municípios. Os resultados demonstraram que existem biótipos de azevém resistentes ao herbicida fluazifop quando aplicado na dose máxima de 125g i.a.ha-1 e estádio indicado pelo fabricante. Os biótipos de azevém apresentam diferentes níveis de resistência ao herbicida, sendo que o biótipo de azevém TUC 11 apresenta resistência de nível baixo ao herbicida fluazifop. Na avaliação de habilidade competitiva e valor adaptativo verificou-se que os biótipos de azevém suscetível e com resistência de nível baixo, em geral, apresentam valores similares para estas variáveis. A cultura do trigo, cultivar FUNDACEP Horizonte, em geral, apresentou maior habilidade competitiva que o biótipo com nível baixo de resistência e equivalente ao suscetível.

Genótipos de azevém (Lolium multiflorum Lam.) diplóides e tetraplóides são cultivados como forrageira na produção animal, no entanto, quando sistemas de produção que envolve o plantio direto são estabelecidos após o cultivo da forrageira é comum a dessecação com o herbicida glyphosate. Portanto, é importante conhecer se existe suscetibilidade diferencial a este herbicida entre os genótipos. Desta forma, foi desenvolvida a presente pesquisa como o objetivo de avaliar o grau de tolerância dos genótipos diplóides e tetraplóides de azevém ao herbicida glyphosate em quatro estádios fenológicos de desenvolvimento. Para isso, foram instalados quatro experimentos, sendo um para cada estádio fenológico do azevém (duas folhas, quatro perfilhos, pré-florescimento e formação de grãos). Os tratamentos consistiram da combinação dos dois genótipos e seis doses do herbicida glyphosate (240; 480; 960; 1.920; 3.840 e 7.680 g e.a. ha-1), e uma testemunha sem aplicação de glyphosate, em delineamento experimental de blocos ao acaso, quatro repetições. Os parâmetros analisados foram porcentagem de controle e fitomassa seca das plantas. Os resultados foram submetidos à análise de variância e em seguida ajustados para modelo de curva de dose-resposta do tipo logística, sendo destes modelos calculados valores de controle correspondestes a 50, 80, 90 e 99%. As conclusões principais obtidas nesta pesquisa foram de que os genótipos de azevém diplóide e tetraplóide apresentam suscetibilidade diferencial ao herbicida glyphosate, sendo o genótipo tetraplóide mais tolerante ao herbicida. O grau diferencial de tolerância, medido pelo fator de tolerância (FT) diferencial entre os genótipos, expresso pelo valor médio dos quatro estádios fenológicos estudados, utilizando como base o controle de 50% das plantas pelo glyphosate foi de 1,6 vezes a dose de glyphosate no genótipo tetraplóide em relação ao genótipo diplóide. Os estádios fenológicos de desenvolvimento das plantas de ambos os genótipos estudados afetam o grau de tolerância ao glyphosate. De maneira geral, em estádios mais avançados de desenvolvimento fenológico dos dois genótipos a suscetibilidade do azevém é menor ao glyphosate, exceto para o estádio de préflorescimento, no qual a planta é mais suscetível que o estádio de quatro perfilhos, quando o parâmetro de análise é a dose necessária para controle de 50% das plantas. O parâmetro de análise de suscetibilidade fitomassa seca das plantas apresentou a mesma tendência diferencial entre os fenótipos diplóides e tetraplóides que o parâmetro porcentagem de controle visual.
Diploid and tetraploid genotypes of Italian ryegrass (Lolium multiflorum Lam.) are cultivated as forage crop for animal production, however, when cropping systems that involve no tillage is established after the forage cultivation it is common the dessecation with the herbicide glyphosate. However, it is important to know if there is differential susceptibility between the genotypes to the herbicide, in four phenological stages of development. Therefore, it was developed this research with the objective of evaluating the degree of tolerance of the diploid and tetraploid genotypes of Italian ryegrass to the herbicide glyphosate. For that, four experiments were installed being one for each of the Italian ryegrass phenological stages (two leaves, four tillers, pre-flowering, and grain formation). The treatments consisted of the combination of the two genotypes and six rates of glyphosate (240; 480; 960; 1.920; 3.840 and 7.680 g a.e. ha-1) and a check plot without glyphosate application, in randomized complete blocks design, four replications. The parameters that were analyzed were control percentage and dry biomass. Results were submitted to analysis of variance and subsequently adjusted to non linear model of logistic dose-response curves, and from these models control values were calculated at 50, 80, 90 and 99%. The main conclusions obtained in this research were that genotypes of Italian ryegrass presented differential susceptibility to the herbicide glyphosate. The differential degree of tolerance, measured by the tolerance factor (TF) between the biotypes, expressed by the mean value of the four development stages studied, using the 50% Italian ryegrass control, was 1.6 times more glyphosate rate for the tetraploid genotype compared to the diploid genotype. The phenological stages of development of both genotypes affected the tolerance degree to glyphosate. In general, the more is the advanced development stages of both biotypes, the lower is the susceptibility of Italian ryegrass to glyphosate, except for the stage of pre-flowering, in which the plant is less susceptible than the stage of four tillers, when the analyzed parameter is the rate necessary to control 50% of the plants. The parameter of analysis of susceptibility plant dry biomass presented the same tendency of differential control between the diploid and tetraploid genotypes than the visual control percentage.

Aiming to evaluate non apparent relations among individual studies and provide a set of more accurate information about supplement utilization on cool-season cultivated pastures, variables from nine experiments wich tested levels and kinds of supplements offered to beef heifers were analyzed. At first, data were stratified in two groups: with and without supplement utilization. Afterwards, supplements offered in different levels were collected in three groups, to estimate the effect of sources ( by-product , grain , ration ). Pasture was evaluated in relation to the availability, structure, chemical composition and digestibility. For animals and per unit of area, the variables analyzed were average daily gain (ADG), body condition score (BCS), back height, stocking rate and live weight gain per hectare. The addition and substitution rates and the efficiency of transformation of grass and supplement were calculated. The availability and the structure of the grass were similar for both groups. Heifers that received supplement presented greater ADG and ingested grass with lesser neutral detergent fiber detergent. At the end of the pasture utilization, the heifers that received supplement were heavier, higher and presented greater BCS. Females that received ration presented higher average daily gain than heifers that received grain or by-product (P<0,05), while the higher stocking rate were verified when the beef heifers received byproduct (P<0,05), with an increment of 45,1% in relation to the others. The live weight gain per hectare was similar between the different kinds of supplement. The utilization of grains provided better results on individual and per area performance when were given at a rate of 0,8% of live weight (LW). For by-product , grain and ration , the substitution rate were 0,8, 0,1 e 0,0 kg of dry matter (DM) of grass/kg of supplement, respectively. The efficiency of transformation of the supplement into kg of LW was similar (P>0,05) among kinds of supplement. However, when the females received ration, the efficiency of transformation of the grass was higher. The choice of the kind of supplement to use in high quality pastures should be based on the purpose of the production system. Rations provide greater increments on the individual performance while by-products provide greater stocking rate and individual performance.
Com o objetivo de avaliar relações não aparentes nos estudos individuais e providenciar um conjunto de informações mais acuradas sobre o uso de suplementos em pastagens cultivadas de clima temperado, foram analisadas em conjunto as variáveis medidas em nove experimentos, que testaram níveis e tipos de suplementos para novilhas de corte. Os dados foram inicialmente estratificados em dois grupos: com e sem o uso de suplemento. Posteriormente, os suplementos fornecidos em diferentes níveis, foram reunidos em três grupos, para estimar o efeito de fontes ( subproduto , grão , ração comercial ). O pasto foi avaliado quanto à disponibilidade, estrutura, composição química e digestibilidade. As variáveis analisadas nos animais e por unidade de área foram o ganho médio diário (GMD), escore de condição corporal (ECC), altura da cernelha, taxa de lotação e ganho de peso por área. Foram calculadas as taxas de adição e substituição, eficiência de transformação do pasto e do suplemento. A disponibilidade e a estrutura do pasto foram semelhantes para os grupos com e sem suplemento. Bezerras que receberam suplemento apresentaram maior GMD e consumiram pasto com menor teor de fibra em detergente neutro. Ao final do período de utilização da pastagem as bezerras que receberam suplemento foram mais pesadas, mais altas e apresentaram maior ECC. Fêmeas que receberam ração apresentaram maior ganho médio diário GMD que bezerras que receberam grão ou subproduto (P<0,05), enquanto as maiores taxas de lotação foram verificadas quando as bezerras receberam sub-produto (P<0,05), com acréscimo de 45,1% em relação à ração e aos grãos. O ganho de peso por área foi semelhante nos diferentes tipos de suplemento. O uso de grãos proporcionou melhores resultados no desempenho individual e por área quando fornecido na proporção de 0,8% do peso vivo (PV). As taxas de substituição foram de 0,8; 0,1 e 0,0 kg de MS do pasto/kg de suplemento, para sub-produto , grão e ração , respectivamente. A eficiência de transformação do suplemento em kg de PV foi semelhante (P>0,05) entre os tipos de suplemento. A eficiência de transformação do pasto, no entanto, foi maior quando as fêmeas receberam ração. Em pastagens de alta qualidade a escolha do tipo de suplemento depende do objetivo do sistema de produção. Rações proporcionam maiores incrementos no desempenho individual enquanto subprodutos proporcionam maiores taxas de lotação e desempenho individual.

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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This work aimed to study alternatives to chemical management of ryegrass and horseweed, taking into account environmental and biological factors at the time of application of herbicides, as well as the occurrence of resistant biotypes of these species. For that, two experiments were carried out. The first one aimed to evaluate the influence of air temperature and the phenological stage on the chemical control of ryegrass biotypes resistant and susceptible to glyphosate, being conducted in a greenhouse in a completely randomized design with four replicates and arranged in a factorial scheme 10x2x2x2. The herbicides clethodim, clodinafop-propargyl, fenoxaprop-p-etyl+clethodim, glyphosate, iodosulfuron-methyl, paraquat, paraquat+diuron, sethoxydim, and tepraloxydim were applied in glyphosate-resistant and -susceptible biotypes of ryegrass in air temperatures of 20-22 ºC and 30-34 ºC in the moment of the application and growth stages of 3-4 leaves and flowering. The weed control was assessed at 7, 14, 21, and 28 days after application, assigning the percentage from 0 to 100, corresponding to the absence of injury and death of plants, respectively. Plant height and dry weight of shoots were determined after the last evaluation of control. Data were subjected to analysis of variance and means were compared by Tukey test (p≤0.05). Paraquat and paraquat+diuron controlled ryegrass, regardless of biotype, stadium, and temperature of application. The other herbicides controlled ryegrass in the 3-4 leaf stage when applied to 20-22 °C , regardless of the biotype. Herbicides applied to 30-34 °C were not effective in controlling the resistant biotype in early stage. At flowering , tepraloxydim and fenoxaprop-p-ethyl+ clethodim provided greater control of the resistant biotype when applied at temperatures of 30-34 °C. The second experiment aimed to identify herbicides to alternative control of horseweed resistant to glyphosate, as well as the influence of the stage of plant development on the weed control. The experiment was conducted in apple orchard in an area with reports of horseweed survival after applying glyphosate. The design was a randomized block with four replicates and arranged in a factorial scheme 5x2, with the herbicides ammonium-glufosinate, bentazon, diquat, glyphosate, and glyphosate+saflufenacil that were applied into horseweeds in the pre-flowering stage and plant regrowth, 15 days after cutting plants. The weed control was evaluated at 7, 14, 21, and 28 days after application, assigning a percentage from 0 to 100, corresponding to the absence of injury and death of plants, respectively. Data were subjected to analysis of variance and means were compared by Tukey test (p≤0.05). The herbicides diquat, basagran, and glyphosate+saflufenacil were not effective in controlling horseweed in pre-flowering; ammonium-glufosinate proved to be a viable alternative to horseweed control in advanced stages. With the exception of glyphosate, all herbicide controlled the regrowing horseweed biotypes in apple orchard
Este trabalho visou estudar alternativas para o manejo químico de azevém e buva, levando em consideração fatores ambientais e biológicos no momento da aplicação dos herbicidas, bem como a ocorrência de biótipos resistentes dessas espécies. Para isso, foram realizados dois experimentos. O primeiro, teve o objetivo de avaliar a influência da temperatura do ar e do estádio fenológico no controle químico de biótipos de azevém resistente e suscetível ao glyphosate e foi conduzido em casa de vegetação, em delineamento inteiramente casualizado com quatro repetições e organizado em esquema fatorial 10x2x2x2. Os herbicidas: clethodim, clodinafop-propargyl, fenoxaprop-p-etyl+clethodim, glyphosate, iodosulfuron-methyl, paraquat, paraquat+diuron, sethoxydim e tepraloxydim foram aplicados em biótipos de azevém resistente e suscetível ao glyphosate sob temperaturas do ar de 20-22 ºC e 30-34 ºC no momento da aplicação e nos estádios de 3-4 folhas e florescimento. O controle dos biótipos foi avaliado aos 7, 14, 21 e 28 dias após a aplicação dos tratamentos, atribuindo-se o percentual de 0 a 100 que correspondeu à ausência de injúria e morte das plantas, respectivamente. A estatura de planta e a massa seca da parte aérea foram determinadas após a última avaliação de controle. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey (p≤0,05). Paraquat e paraquat+diuron controlaram azevém, independente de biótipo, estádio e temperatura de aplicação. Os demais herbicidas controlaram azevém no estádio de 3-4 folhas quando aplicados à 20-22 ºC, independente do biótipo. Herbicidas aplicados a 30-34 ºC não foram eficazes no controle do biótipo resistente em estádio inicial. No florescimento, tepraloxydim e fenoxaprop-p-ethyl+clethodim proporcionaram maior controle do biótipo resistente quando aplicado em temperatura de 30-34 °C. O segundo experimento teve o objetivo de identificar herbicidas alternativos para o controle de buva resistente ao glyphosate, bem como a influência do estádio de desenvolvimento no controle. O mesmo foi conduzido em pomar de maçã, em uma área com histórico de falha de controle de buva com glyphosate. O delineamento foi em blocos casualizados com quatro repetições e organizado em esquema fatorial 5x2, sendo que os herbicidas amônio glufosinato, bentazon, diquat, glyphosate e glyphosate+saflufenacil foram aplicados em buva no estádio de pré-florescimento e em plantas rebrotadas, 15 dias após o corte das mesmas. O controle foi avaliado aos 7, 14, 21 e 28 dias após a aplicação dos tratamentos, atribuindo-se percentual de 0 a 100, correspondente a ausência de injúria e morte das plantas, respectivamente. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey (p≤0,05). Os herbicidas, bentazon, diquat, e glyphosate+saflufenacil não foram eficientes no controle de buva em pré-florescimento; amônio glufosinato mostrou-se uma alternativa viável para o controle de buva em estádios avançados. Com exceção de glyphosate, todos os demais herbicidas controlaram biótipos de buva rebrotada em pomar de maçã

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.

La composition génétique des prairies, sous l'effet des contraintes naturelles ou anthropiques, est susceptible d'évoluer dans le temps, modifiant ansi la valeur agronomique des prairies et altérant leur pérennité. L'objectif de mon travail est d'analyser les changements génétiques et phénotypiques dans des prairies monovariétales de ray-grass anglais. L'étude a montré l'existence d'une grande variabilité de la variété étudiée, de differences significatives entre les prairies pour quelques caractères phénotypiques ainsi qu'une différenciation génétique significative (présence d'allèles nouveaux). Ceci peut être dû à une selection adaptative ou au recrutement de nouvelles plantes. Cette étude montre clairement que des changements phénotypiques et génétiques se produisent dans des prairies semées de ray-grass anglais. La part des differents mécanismes d'évolution reste encore à déterminer ainsi que l'impact d'une telle évolution sur la valeur agronomique des prairies à long terme
Grassland genetic composition is likely to change over time face natural or exploitation constraints. This may impact their agronomic value and alter their perenniality. The objective of the present research work was to assess phenotypic and genetic changes that occured in grassland sown with a single grass variety. Study showed a wide genetic variation within this variety, significant differences for several phenotypic traits among sampled grasslands and significant genetic differentiation (presence of new alleles). This may be due to adaptive selection or recruitment of new plants. This study clearly showed that phenotypic and genetic changes may occur in grasslands sown with perennial ryegrass. Contribution of various evoluton mechanisms is still to be determined as well as impact of such changes on long term agronomic value of grasslands

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.

O objetivo deste trabalho foi desenvolver e aplicar um modelo de Análise de Risco Ecológico (ARE) com vistas a classificar os riscos associados às emissões atmosféricas em áreas industriais a partir da utilização do bioindicador vegetal Lolium multiflorum e da aplicação dos princípios de análise de risco ecológico utilizado em ambientes aquáticos e solos contaminados. O trabalho foi desenvolvido no período de janeiro de 2005 a abril de 2008 no entorno da refinaria de petróleo, Alberto Pasqualini, através de duas estações amostrais situadas nos municípios de Canoas (29°55'07" S 51°10'54" O) e Esteio (29°49'16" S 51°08'09" O), Rio Grande do Sul, Brasil que possuem redes de monitoramento químico e biológico das emissões de SO2. O modelo utilizado associou as informações provenientes do efeito dos estressores, oriundos das emissões atmosféricas de compostos de enxofre, nos receptores, ou seja, o tecido do bioindicador vegetal que tende a acumular poluentes, como o enxofre, na sua parte aérea. Foram avaliados os seguintes parâmetros nos bioindicadores vegetais: concentração de enxofre acumulado nas plantas, teor de clorofila α e ganho de biomassa, classificados neste estudo como variáveis respostas. Estas foram integradas aos dados de concentração de SO2 da atmosfera, que deram origem as variáveis explicativas, unidade de potencial tóxico (UPT), unidade tóxica de exposição (UTE) e taxa de sulfatação. A partir dos dados de qualidade ambiental "guidelines" e dos histogramas de freqüência foram definidas as seguintes classes de risco: baixo, médio ou alto. A integração dos resultados obtidos das variáveis explicativas e de resposta foi realizada através de análise estatística multivariada de correspondência que demonstrou indícios de risco à vegetação do entorno da refinaria, quando estas foram submetidas a UPT maiores do que a unidade. Dos 39 meses de monitoramento, verificou-se que a estação amostral de Esteio apresentou 13% destes com valores de UPT situados na classe 3, classificação de risco alto. Na estação amostral de Canoas, 26% das UPT foram classificadas como de indícios de risco alto. Nas duas estações amostrais estudadas, foi possível medir o efeito da UPT nas variáveis biológicas, tais como aumento do acúmulo de enxofre na parte aérea das plantas, redução do teor de clorofila α e redução de ganho de biomassa. A partir do desenvolvimento deste modelo torna-se possível interpretar a significância dos riscos ecológicos associados a emissões atmosféricas industriais para toda a biota do entorno da área industrial. Este modelo servirá de base para a avaliação dos efeitos danosos da poluição atmosférica sobre a vegetação de localidades industriais com características semelhantes.
The objective of this work was to develop and apply a model Ecological Risk Analysis (ERA) to classify the risks related to the atmospheric emissions in industrial areas using the vegetable bioindicator Lolium multiflorum and the application of ecological risks analysis principles in aquatic atmospheres and contaminated soils. This work was starting from January, 2005 to March, 2008 around of Petroleum Refinery area, the name Alberto Pasqualini, in two fixed samples stations localized in Canoas (29°55'07" S 51°10'54" 0) and Esteio (29°49'16" S 51°08'09") cities, Rio Grande do Sul state, Brazil. These stations have chemical and biological SO2 emissions monitoring system. The proposed model for the ecologic risk evaluation associates the information from stressors' effects, which come from sulfur compounded gases emissions, at the receptors, that is, the vegetable bioindicator tissue accumulates pollutants (as sulfur) in the plants aerial parts. It was evaluated the following vegetable bioindicators parameters; sulfur concentration accumulated in the plants, chlorophyll a and biomass increased, classified in the study as "answers data". These "answers data" were linked to the SO2 atmosphere concentration, which generate the "consequence data"; Toxic Potential Unit (TPU), Exposure Toxic Unit (ETU) and total sulfation. Based on the environmental quality data "guidelines" and the histograms of frequency it was possible to define the following risks categories: low, medium or high. The integration between the "consequence data" and "answers data" was made using the statistics correspondence multiple variable analysis that demonstrate indications of risks for the vegetation localized around the refinery, when it was exposed an TPU higher than the unit. During the 39 months of monitoring, the Esteio sample station presented 13% of TPU values in the category 3 or high risk. In the Canoas sample station, 26% of the TPU were classified as the high risk. In these two fixed samples stations it was possible measure of TPU effects in the biological variable, as sulfur accumulation in the plants aerial parts, chlorophyll "a" reduction and biomass reduction. Based of this model analysis it will be possible to evaluate the ecological risks significance linked with industrial atmospheric emissions for all biota around the industrial area of study. This model will support others studies on dangerous effects over vegetable around industrial plants that are in similar conditions.

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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FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
O estudo de diversidade genética é importante na caracterização de populações de espécies vegetais como forrageiras. O aumento da produtividade é um objetivo constante do melhoramento das forrageiras e depende diretamente da diversidade genética existente. O Azevém (Lolium multiflorum Lam.) é uma forragem de inverno, muito utilizada para o gado devido à sua alta palatabilidade, digestibilidade e resistência ao pisoteio. A espécie é proveniente da Europa e, largamente utilizada no Sul do Brasil. Como parte do Programa de Melhoramento de Azevém da Embrapa Gado de Leite o presente trabalho teve como objetivo principal estimar a diversidade genética de 32 populações de azevém. O DNA de 628 indivíduos foi extraído, e marcadores microssatélites obtidos por amplificação cruzada foram utilizados. Um dendrograma foi gerado pelo algoritmo UPGMA, usando-se o software NTSYS, através do coeficiente de similaridade de Dice. Dentre os trinta e cinco pares de primers testados, vinte e cinco (71,5%) apresentaram amplificação cruzada em L. multiflorum, demonstrando a eficiência de utilização de marcadores desenvolvidos para espécies proximamente relacionadas. Quinze marcadores foram selecionados com base no sucesso da amplificação cruzada e maior número de polimorfismos. Os valores da matriz de coeficientes de similaridade obtidos variaram de 0,43 a 0,93. Observou-se a presença de divergência genética entre as populações, indicando que elas possuem uma ampla base genética. Este resultado está de acordo com a extensa distribuição geográfica e com o sistema alógamo de reprodução da espécie.
The genetic diversity estimation is important to characterize plant populations including forage species. The increase of productivity is a constant objective in forage breeding programs and is directly dependent of the genetic diversity. The ryegrass (Lolium multiflorum Lam.) is a winter grass, widely used for cattle due to its high palatability, digestibility and resistance to trampling. The species was introduced from Europe and is widely used in southern Brazil. As part of The Embrapa Dairy Cattle Ryegrass Breeding Program, the present work aimed to estimate the genetic diversity among 32 ryegrass populations. The DNA of 628 individuals was extracted and microsatellite markers obtained by cross amplification were used. A dendrogram was generated by UPGMA algorithm, using NTSYS software and Dice’s similarity coefficient. Among the thirty-five pairs of tested primers, twenty five (71.5%) showed cross amplification in L. multiflorum, demonstrating the efficiency of using cross amplification of microsatellite markers from related species. Fifteen markers were chosen based on the cross amplification success and the level of polymorphism. The values of similarity coefficient matrix varied from 0.43 to 0.93. Genetic divergence among the populations was observed, indicating that the populations possess a wide genetic base. This result corroborates the wide geographical distribution and the allogamous reproduction system previously reported for the species.