Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / The species Eragrostis pilosa and Eragrostis plana has been found in lowland environment promoting interference by competing with the rice (Oryza sativa). Eragrostis are exotic plants to the floodplain environment and usually develops in deep soils and well drained as the highlands. The characterization of the species and the study of their biology in different environments is needed to understand the process of adaptation of these species in these poorly drained environments in order to develop an efficient management of these. In this sense the present study at Masters level, aims to assess the phenotypic behavior and the anatomical and morphological alterations of these plants when subjected to three soil moisture conditions (50% soil water capacity, 100% soil water capacity and Flooding). The study was conducted in 2014/2015 season in greenhouse using seeds of Eragrostis pilosa and Eragrostis plana access derived from rice producing areas of Itaqui/ Rio Grande do Sul Brazil.The results showed that each species showed different responses to treatments which have been submitted. For E. plana there was a reduction in tillering, less formation of panicles and reduction of aerenchymas of the plants when exposed to flooding. As for the plants E. pilosa, the responses to treatment flooding were observed with reduced tillering, with consequent reduction in the formation of panicles per plant, changes in the development of the flag leaf, reduction in dry weight root, and shoot and increasing the vegetative cycle of plants. The two species showed formation aerenchyma the roots and stems and adventitious roots on the soil surface when subjected to treatments of 100% of soil water capacity and flooding, in response to hypoxic stress. For chlorophyll parameters, the responses were similar in both species, by reducing the amount of chlorophyll, reflecting the low electron transport capability. The flooding affect the development of plants evaluated, which infers that the management of the rice crop water plays an important role in the management of invasive plants. / As espécies Eragrostis pilosa e Eragrostis plana tem sido encontradas em ambientes de terras baixas promovendo interferência por competição com a cultura do arroz (Oryza sativa). Eragrostis são plantas exóticas ao ambiente várzea e, normalmente, se desenvolvem em solos profundos e bem drenados como as terras altas. A caracterização das espécies e o estudo da sua biologia em diferentes ambientes é necessário para entender o processo de adaptação destas espécies nestes ambientes mal drenados como forma de desenvolver um manejo eficiente destas. Neste sentido o presente trabalho tem por objetivo avaliar o comportamento do crescimento e desenvolvimento destas plantas quando submetidas a três condições de umidade do solo, uma simulando ambiente natural dessas plantas com umidade reduzida de 50% da capacidade de retenção de água do solo (CRA) e outros dois tratamentos simulando ambiente de terras baixas com maior umidade do solo, um com 100% da CRA, simulando ambientes mal drenados de várzea, e outro com lâmina de água de 10 cm simulando a lavoura de arroz irrigado. Foram analisadas as alterações morfológicas-anatomicas dos acessos através com medições de parâmetros morfológicos, alterações anatômicas com a quantificação da formação de mecanismos adaptativos ao meio hipóxico, ainda foram quantificados os pigmentos fotossintéticos e realizada a avaliação da capacidade de transporte de elétrons pela cadeia transportadora da fotossíntese. O estudo foi desenvolvido no ano de 2014/2015 em ambiente controlado de casa de vegetação, utilizando-se sementes de acessos de Eragrostis pilosa e Eragrostis plana oriundos de áreas de produção de arroz de Itaqui/RS. Os resultados permitem concluir que cada espécie apresentou respostas diferentes para os tratamentos os quais foram submetidas. Para E. plana houve a redução no perfilhamento, menor formação de panículas e redução do volume da parte aérea das plantas quando submetidas a lâmina de água. Já para as plantas de E. pilosa, as respostas ao tratamento de lâmina de água foram evidenciadas com a redução do perfilhamento, com consequente redução na formação de panículas por planta, alterações no desenvolvimento da folha bandeira, na redução de massa seca de raiz e parte aérea e no aumento do ciclo vegetativo das plantas. As duas espécies estudadas apresentaram formação de aerênquimas nas raízes e colmos e raízes adventícias na superfície do solo quando submetidas aos tratamentos de 100% da CRA e lâmina de água, como resposta ao estresse hipóxico. Para os parâmetros de clorofila, as respostas foram semelhantes para as duas espécies, com a redução da quantidade de clorofila a e clorofila total, refletindo na baixa capacidade de transporte de elétrons. A lâmina de água interferiu negativamente o desenvolvimento das plantas avaliadas, o que infere que o manejo da água da lavoura de arroz cumpre importante papel no manejo das plantas invasoras.

Exposure to Poaceae airborne pollen (PAP) has been shown to induce allergic reactions in individuals sensitive to PAP. Patient care for individuals sensitive to PAP can be aided by knowledge of PAP profiles. Air samples were collected using a Rotorod M40 rotation impact sampler from February 2005 to September 2017. Air samples were collected daily, excluding weekends and winter months, and are expressed in grains per cubic meter (g/m3). Light microscopy at 400x magnification was used to analyze samples. Pollen was classified according to the classifications provided by the American Academy of Allergy Asthma and Immunology and the National Allergy Bureau. Detection of PAP onset averaged on day 84 (March 25th); end day averaged on day 285 (October 12th); average duration was 202 days; average peak level onset was on day 146 (May 26th) and the average peak level was 135 g/m3. Average number of days during Poaceae season with 1 to 19 g/m^3 detected was 95; with 20 to 39 g/m^3 was 7; with 40 to 59 g/m^3 was 4; and with 60 g/m^3 or more was 2. Day of onset of PAP trended to be 1.6 days earlier in the year over the course of our data collection, with R2= 0.3476. Poaceae airborne pollen in Johnson City, Tennessee was noticeable for almost 7 months out of the year. We can assume the riskiest months of the year are from March to October with the highest risk period being the end of May.

Depuis l’apparition de la vie sur terre, les pressions de sélection liées aux interactions biotiques et abiotiques ont généré une forte diversité des formes de vie. Ainsi, chaque espèce eucaryote coévolue avec sa communauté microbienne associée. Dans le cas des plantes, la diversité génétique se traduit au niveau de multiples traits phénotypiques (exsudation de substrats carbonés, architecture racinaire, densité et aération du sol, acidification, etc.) susceptibles d’influer sur les interactions avec les populations microbiennes du sol, et donc sur la composition et le fonctionnement de la communauté microbienne rhizosphérique. Notre hypothèse est que les différences entre communautés bactériennes rhizosphériques sont proportionnelles aux distances évolutives entre partenaires végétaux. L’objectif de cette thèse était donc de déterminer l’importance, dans le cas des Poacées et notamment du maïs, de l’histoire évolutive de la plante dans la capacité de sélection des communautés bactériennes de la rhizosphère. Les analyses faites à l’aide d’une puce à ADN taxonomique 16S indiquent que la composition de la communauté rhizobactérienne dépend du groupe génétique de maïs mais n’est pas liée aux marqueurs microsatellites de diversité du maïs. Par contre, à l’échelle des Poacées, une corrélation a été trouvée entre la phylogénie végétale et la composition de la communauté bactérienne (voire la prévalence de taxons bactériens particuliers). Cette corrélation n’était pas significative quand l’étude était limitée à l’effectif, le niveau de transcription de nifH ou la diversité du groupe fonctionnel des bactéries fixatrices d’azote. En conclusion, l’histoire évolutive du partenaire végétal à l’échelle des Poacées (mais pas à celle du maïs) est un facteur conditionnant les interactions avec les groupes bactériens taxonomiques (mais pas nécessairement fonctionnels) de la rhizosphère / Since the emergence of life on earth, the selection pressures related to biotic and abiotic interactions generated a high diversity of life forms. Thus, each eukaryotic species co-evolved with its associated microbial community. In the case of plants, genetic diversity is reflected in many phenotypic traits (exudation of carbon substrates, root architecture, soil density, aeration, acidification, etc.), and may influence interactions with soil microbial populations and hence the composition and functioning of the rhizosphere microbial community. Our hypothesis is that the differences between rhizosphere bacterial communities are proportional to evolutionary distances between plants partners. The objective of this thesis was to determine the importance, in the case of Poaceae and in particular of maize, of the evolutionary history of plant in the selection of bacterial communities in the rhizosphere. Analyses performed using a 16S taxonomic microarray indicated that the composition of the rhizobacterial community depends on the genetic group of maize but is not linked to microsatellite diversity of maize. Conversely, across the Poaceae, a correlation was found between plant phylogeny and the composition of the bacterial community (and the prevalence of specific bacterial taxa). This correlation was not significant when the study was limited to the size, the level of transcription or nifH diversity of the functional group of nitrogen-fixing bacteria. In conclusion, the evolutionary history of the plant partner across the Poaceae (but not maize) is a factor conditioning interactions with bacterial taxonomic groups (but not necessarily functional groups) in the rhizosphere

Made available in DSpace on 2016-02-26T14:53:15Z (GMT). No. of bitstreams: 1 MarcelaMarcelinoDuarte.pdf: 1274052 bytes, checksum: b5ce76c20accecbe1f4d7eaa128750c6 (MD5) Previous issue date: 2009-03-13 / The aims of this work were to evaluate the effect of different population levels of the green belly stink bug D. melacanthus on corn and wheat plants and also to estimate the damage level of this pest for both crops. The experiments were carried out in an experimental area of Embrapa Western Region Agriculture in Dourados, Mato Grosso do Sul State. Corn was sown in February 2006 and wheat in May 2007. In the corn trial, experimental units were iron cages of 1 m length, 0.9 m width and 0.9 m height that had five corn plants. In the wheat trial, the experimental unit was a wood cage with 160 plants distributed in three rows of 1.12m length and 0.2 m between them. At the moment when the wheat plants showed three leaves they were submitted to different infestation levels of D. melacanthus (0, 2, 4, 6, and 8 bugs/cage) for a period of 15 days. In the corn trial, plants were submitted to the same infestation levels at the moment when showed one leaf (V1) and the period of infestation was 10 days. For both experiments, the experimental design was a completely randomized block with five replicates. Experiments were carried out until harvest and the following measurements were done: number of corn grains row in the ears, ear weight, weight of 100 corn seeds, corn grain yield, ear number, weight of 100 wheat seeds and wheat grain yield. All these measurements were submitted to variance analysis and averages compared by Tukey test at 5%. For determination of the economic threshold level of this pest for both crops, grain yield data were submitted to regression analysis. The cost to control the stink bug on corn and wheat crops was considered in the calculation of the damage level. For the corn crop, number of corn grains row in the ears and the weight of 100 seeds were not significantly influenced by different population densities of the stink bug. For wheat, ear number and the weight of 100 seeds were not significantly different for the different infestation levels of the stink bug. The economic threshold levels were 0.58 and 1 bug/m2 for corn and wheat crops, respectively / O objetivo desse trabalho foi de avaliar o efeito de diferentes níveis populacionais do percevejo barriga-verde Dichelops melacanthus nas plantas de milho e de trigo, visando estimar o Nível de Dano (ND) dessa praga para essas culturas. Os experimentos foram conduzidos em campo na área experimental da Embrapa Agropecuária Oeste em Dourados, MS. O milho foi semeado em fevereiro de 2006 e o trigo em maio de 2007. No ensaio com milho, as unidades experimentais consistiram de uma gaiola em armação de ferro de 1,0 m de comprimento por 0,90 m de largura e 0,90 m de altura, a qual continha cinco plantas de milho. No ensaio com trigo a unidades experimentais consistiram de uma gaiola de madeira que abrangia 160 plantas distribuídas em três fileiras, espaçadas de 0,20 m por 1,12 m de comprimento. Quando as plantas de trigo apresentaram três folhas estas foram submetidas a diferentes níveis populacionais de D. melacanthus (0, 2, 4, 6 e 8 percevejos/gaiola) por um período de infestação de 15 dias. No ensaio de milho, quando as plantas apresentavam uma folha (V1), foram submetidas aos mesmos níveis populacionais do percevejo utilizados no experimento de trigo durante um período de infestação de 10 dias. Ambos os ensaios foram conduzidos no delineamento de blocos casualizados com cinco repetições. Os experimentos foram conduzidos até a colheita para determinação das seguintes variáveis: número de fileiras de grãos nas espigas, peso da espiga, peso de cem sementes e rendimento de grãos do milho e número de espigas, peso de cem sementes e rendimento de grãos do trigo, sendo estas os dados obtidos submetidos à análise de variância e as médias dos tratamentos comparadas pelo teste de Tukey a 5% de significância. Para determinação do NDE da praga nas duas culturas, os valores de rendimento de grãos foram submetidos à análise de regressão. Para o cálculo do nível de dano considerou-se o custo de controle do percevejo na cultura do milho e do trigo. No milho os valores de número de fileiras de grãos por espiga e o peso de cem sementes não foram significativamente influenciados pelas diferentes densidades populacionais do percevejo. No trigo o número de espigas e peso de cem sementes não diferiram estatisticamente entre as diferentes densidades populacionais do percevejo. O NDE encontrado para a cultura do milho foi de 0,58 percevejo/m² e para a cultura do trigo ficou em torno de 1,0 percevejo/m²

La chlordécone (CLD) est un insecticide organochloré qui a été utilisé principalement aux Antilles pour lutter contre le charançon du bananier (Cosmopolites sordidus). Sa faible dégradabilité dans le sol et sa dispersion dans les bassins versants entraînent une contamination durable des sols agricoles et des écosystèmes environnants. Cela pose un problème d’exposition pour l’Homme par la consommation de végétaux contaminés et pour l’environnement par le transfert de la molécule dans les chaînes alimentaires (bioamplification). Pour l’Homme, les principaux végétaux à risque sont les légumes-racines, en contact direct avec la CLD dans le sol, mais aussi les autres légumes car des résidus de CLD sont retrouvés dans les parties aériennes, tiges ou feuilles. Ce travail de thèse a porté sur le transfert sol-plante de la CLD, d’une part dans les tubercules des légumes-racines pour appréhender le risque sanitaire et d’autre part dans les graminées pour le risque environnemental. La lipophilie de la CLD joue un rôle majeur dans son transfert dans les plantes. La CLD a une affinité particulière pour les tissus lipophiles, notamment le périderme subérifié des tubercules et les parois cellulaires incrustées de lignine des vaisseaux du xylème. En outre, le transfert est dépendant de l’architecture de la plante, de sa physiologie et de l’histologie de ses organes. Nous avons mis en évidence deux voies de contamination des plantes par la CLD : l’absorption racinaire et l’adsorption sur le périderme des tubercules. Ces phénomènes sont suivis de la translocation de la molécule vers les tissus internes du tubercule par diffusion et vers la partie aérienne de la plante par évapotranspiration via les faisceaux vasculaires du xylème. Dans le cas des tubercules, nous avons distingué la part de contamination apportée par l’absorption racinaire de celle due à l’adsorption péridermique. Chez le radis, il a été montré que le phénomène prépondérant était la diffusion trans-péridermique. Une analyse du risque de contamination de tubercules couramment consommés aux Antilles (patate douce, dachine, igname) a été réalisée en se basant notamment sur l’architecture de la plante et l’histologie des tissus mis en place lors de la tubérisation. Concernant les graminées, la capacité de transfert de la CLD dans la partie aérienne de la plante a été étudiée chez plusieurs graminées usuelles. Le potentiel de contamination de la plante dépend de ses caractéristiques physiologiques (métabolisme) et de son cycle de vie (pérennité). Ces caractéristiques pourraient permettre d’orienter le choix de certaines graminées pour la phytoremédiation de la CLD. / Chlordecone (CLD) is an organochlorine insecticide mainly used in French West Indies to struggle against banana weevil (Cosmopolites sordidus). Its low degradability into soils and its spreading in catchment basins cause a sustainable contamination of agricultural soils and surrounding ecosystems. This leads to a human exposure risk, by food consumption of contaminated vegetables, and to an environmental risk by transfer of CLD in food chains. Main hazardous vegetables for human health are root-vegetables that are directly in contact of soil but also other vegetables because CLD residues are found in aerial parts of plant, leaves and shoots. The environmental risk seems to be the biomagnification of contamination in trophic chains due partly by consumption of contaminated plants. This work focused on the CLD soil-plant transfer, on the one hand in tubers of edible-roots for knowing the health risk and on the other hand in grasses for environmental risk. The CLD lipophilicity plays a major role in its transfer to plants. CLD exhibits a certain affinity for lipophilic tissues particularly for the suberised periderm of tubers and the xylem cell walls that are thickened by lignin. In addition, transfer depends on plant architecture, physiology and organ histology. Two ways of CLD plant contamination were highlighted: roots absorption and adsorption onto tuber periderm. These mechanisms are followed by CLD translocation towards internal tissues of tuber by diffusion and to above-ground parts of the plant within the transpiration stream occurring in vascular xylem vessels. For tubers, we distinguished between the contamination brought by roots absorption and the one brought by peridermic adsorption. In radish, the trans-peridermic diffusion was showed as the major way of contamination. A risk analysis mainly based on plant morphology and tissue histology set up during tuberization process was realized. For grasses, CLD transfer ability to aerial part of plant was studied in several usual gramineae (yam, sweet popato, dasheen). Plant contamination potential is mainly determined by its physiological traits (metabolism) and its life cycle (perenniality). These features could drive the choice of some gramineae to perform CLD phytoremediation.

Submitted by Maria Beatriz Vieira (mbeatriz.vieira@gmail.com) on 2017-03-29T15:17:23Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) dissertacao_tuane_araldi_da_silva.pdf: 1228072 bytes, checksum: 53d0b042633ad80a28404e1dc2bc54db (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-05T17:53:17Z (GMT) No. of bitstreams: 2 dissertacao_tuane_araldi_da_silva.pdf: 1228072 bytes, checksum: 53d0b042633ad80a28404e1dc2bc54db (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-05T17:54:30Z (GMT) No. of bitstreams: 2 dissertacao_tuane_araldi_da_silva.pdf: 1228072 bytes, checksum: 53d0b042633ad80a28404e1dc2bc54db (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-04-05T17:54:42Z (GMT). No. of bitstreams: 2 dissertacao_tuane_araldi_da_silva.pdf: 1228072 bytes, checksum: 53d0b042633ad80a28404e1dc2bc54db (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-02-27 / Sem bolsa / Os trabalhos foram realizados no Laboratório de Fisiologia de Sementes - UFPel, nos anos de 2012 a 2014 e objetivaram avaliar o efeito de diferentes concentrações de extratos vegetais sobre aspectos fisiológicos de sementes e plântulas de alface e trigo. Nos capítulos 1 e 2 foram utilizados extratos de folhas de buva (Conyza bonariensis) e azevém (Lolium multiflorum)nas concentrações 0; 2; 4; 6 e 8% e como espécie alvo foram utilizadas sementes de alface. No capítulo 3, a espécie alvo foi trigo e o extrato aquoso utilizado foi de folhas de Lolium multiflorum nas concentrações 0; 2; 4; 6 e 8%. Foram avaliados a germinação, a primeira contagem de germinação, o índice de velocidade de germinação, o comprimento de parte aérea e de raiz primária, a massa seca total de plântulas, a condutividade elétrica, a atividade das enzimas superóxido-dismutase (SOD), catalase (CAT) e ascorbarto-peroxidase (APX), peroxidação lipídica, peróxido de hidrogênio, emergência de plântulas, área foliar, comprimento de parte aérea e de raiz e massa seca total das plântulas emergidas. No capítulo 1, verificou-se que as maiores concentrações do extrato aquoso de buva proporcionaram maior inibição da germinação e do crescimento inicial de plântulas de alface. Houve aumento da condutividade elétrica em sementes de alface, níveis de peróxido de hidrogênio, da peroxidação lipídica e atividade das enzimas superóxido-dismutase, catalase, ascorbato-peroxidase. No capítulo 2 verificou-se que o extrato aquoso de folhas de azevém afetou negativamente a primeira contagem de germinação, o índice de velocidade de germinação e o crescimento de plântulas de alface. O aumento da concentração do extrato proporcionou a elevação na atividade das enzimas antioxidantes, sendo resultados mais pronunciados, observados nas concentrações de 6 e 8%. No capítulo 3, o índice de velocidade de germinação de sementes de trigo foi reduzido de forma marcante na concentração 8% do extrato de azevém. As concentrações mais altas do extrato resultaram nos maiores teores de peróxido de hidrogênio, peroxidação lipídica e atividades das enzimas superóxido-dismutase, catalase e ascorbato-peroxidase. / The works was carried out at the Seed Laboratory of Physiology - UFPel in the years 2012 to 2014 and aimed to evaluate the effect of different concentrations of plant extracts on physiological aspects of seeds and lettuce and wheat seedlings. In chapters 1 and 2 leaf extracts were used horseweed (Conyza bonariensis) and ryegrass (Lolium multiflorum) at concentrations of 0; 2; 4; 6 to 8% as the target species and lettuce seeds were used. In Chapter 3, the target species was wheat and the aqueous extract was of Lolium multiflorum leaves at concentrations of 0; 2; 4; 6 to 8%. We evaluated the germination, the first count, the germination rate index, shoot length and primary root, total seedling dry weight, electrical conductivity, the activity of superoxide dismutase (SOD), catalase (CAT) and ascorbarto-peroxidase (APX), lipid peroxidation, hydrogen peroxide, seedling emergence, leaf area, shoot and root length and total dry mass of emerged seedlings. In Chapter 1, it was found that higher concentrations of the aqueous extract showed higher horseweed inhibition of germination and initial growth of lettuce seedlings. There was an increase of the electrical conductivity lettuce seeds, hydrogen peroxide levels, lipid peroxidation and activity of superoxide dismutase, catalase, ascorbate peroxidase. In Chapter 2 it was found that the aqueous extract of ryegrass leaves negatively affected the first count, the germination speed index and the growth of lettuce seedlings. The increase of the extract concentration resulted in higher in antioxidant enzyme activity, being more pronounced results observed at concentrations of 6 to 8%. In Chapter 3, the wheat seed germination speed was reduced markedly in concentration 8% of ryegrass extract. Higher concentrations of the extract produced the highest yields of hydrogen peroxide, lipid peroxidation and activities of superoxide dismutase, catalase and ascorbate peroxidase.

Depuis l'apparition de la vie sur terre, les pressions de sélection liées aux interactions biotiques et abiotiques ont généré une forte diversité des formes de vie. Ainsi, chaque espèce eucaryote coévolue avec sa communauté microbienne associée. Dans le cas des plantes, la diversité génétique se traduit au niveau de multiples traits phénotypiques (exsudation de substrats carbonés, architecture racinaire, densité et aération du sol, acidification, etc.) susceptibles d'influer sur les interactions avec les populations microbiennes du sol, et donc sur la composition et le fonctionnement de la communauté microbienne rhizosphérique. Notre hypothèse est que les différences entre communautés bactériennes rhizosphériques sont proportionnelles aux distances évolutives entre partenaires végétaux. L'objectif de cette thèse était donc de déterminer l'importance, dans le cas des Poacées et notamment du maïs, de l'histoire évolutive de la plante dans la capacité de sélection des communautés bactériennes de la rhizosphère. Les analyses faites à l'aide d'une puce à ADN taxonomique 16S indiquent que la composition de la communauté rhizobactérienne dépend du groupe génétique de maïs mais n'est pas liée aux marqueurs microsatellites de diversité du maïs. Par contre, à l'échelle des Poacées, une corrélation a été trouvée entre la phylogénie végétale et la composition de la communauté bactérienne (voire la prévalence de taxons bactériens particuliers). Cette corrélation n'était pas significative quand l'étude était limitée à l'effectif, le niveau de transcription de nifH ou la diversité du groupe fonctionnel des bactéries fixatrices d'azote. En conclusion, l'histoire évolutive du partenaire végétal à l'échelle des Poacées (mais pas à celle du maïs) est un facteur conditionnant les interactions avec les groupes bactériens taxonomiques (mais pas nécessairement fonctionnels) de la rhizosphère

Les formations herbacées actuellement dominantes en zone intertropicale sont mal discriminées par les marqueurs de végétation courants. Ainsi, la modélisation de la végétation et les reconstitutions des climats passés dans ces zones sont limitées. Les phytolithes sont des particules d'opale formées par précipitation de silice amorphe entre et/ou dans les cellules de nombreuses plantes vivantes, couramment utilisés pour tracer la dynamique des formations herbacées. Cependant, les calibrations entre assemblages phytolithiques, végétation et climat sont rares. Cette thèse établit des fonctions de transfert entre indices phytolithiques, caractéristiques des formations herbacées intertropicales actuelles, et contraintes bio-climatiques, en vue de pouvoir intégrer les données phytolithiques à la méthode de biomisation pollinique permettant des reconstitutions de végétation. Ceci permettra d'améliorer et de valider certains modèles prédictifs de végétation. En Afrique de l'Ouest, l'indice Iph permet de différencier les savanes à graminées basses des savanes à graminées hautes. Une fonction de transfert, établie pour estimer l'évapotranspiration (AET/PET), offre de bons résultats, comparables et complémentaires aux estimations fournies par la biomisation pollinique. L'indice Ic étudié sur un gradient altitudinal en Afrique de l'Est estime correctement la proportion des sous-familles graminéennes Pooideae et Panicoideae en zone intertropicale soit, potentiellement, la domination des Poaceae en C4/C3, jusqu'alors difficilement enregistrée. Pour la première fois un marqueur de végétation, l'indice D/P, est calibré de façon quantitative en terme de LAI le long d'un transect forêt-savane. Finalement, une analyse discriminante utilisant la totalité des assemblages permet de définir six biomes phytolithiques. Ces biomes intégrés à la méthode de biomisation pollinique, offriront des reconstructions paléo-environnementales plus précises, notamment les transitions désert/savane/forêt.

Subtribe Alopecurinae (Poeae, Poaceae) sensu lato‘s seven genera share interesting morphological similarities (dense spicate panicles and one-flowered spikelets) that were widely thought to have a common origin. However, recent molecular evidence for three of the genera has suggested that the subtribe may be polyphyletic. To test this, five DNA regions were sequenced and analyzed using phylogenetic methods. Results confirm that Alopecurinae s.l. as presently treated is polyphyletic and should be dissolved. Additionally, the genus Cornucopiae may be just another Alopecurus. Limnas and Pseudophleum are not closely allied to Alopecurus or each other, and are even further from Phleum. Phleum is a distinct lineage that is not closely allied to any other included Alopecurinae genus. Evidence for revising infrageneric classifications of Alopecurus and Phleum is presented, as is evidence for separating A. magellanicus into two or more subspecies.

Subtribe Alopecurinae (Poeae, Poaceae) sensu lato‘s seven genera share interesting morphological similarities (dense spicate panicles and one-flowered spikelets) that were widely thought to have a common origin. However, recent molecular evidence for three of the genera has suggested that the subtribe may be polyphyletic. To test this, five DNA regions were sequenced and analyzed using phylogenetic methods. Results confirm that Alopecurinae s.l. as presently treated is polyphyletic and should be dissolved. Additionally, the genus Cornucopiae may be just another Alopecurus. Limnas and Pseudophleum are not closely allied to Alopecurus or each other, and are even further from Phleum. Phleum is a distinct lineage that is not closely allied to any other included Alopecurinae genus. Evidence for revising infrageneric classifications of Alopecurus and Phleum is presented, as is evidence for separating A. magellanicus into two or more subspecies.