Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2016-10-04T21:00:20Z No. of bitstreams: 1 2010 - Joventino Fernandes Moreira.pdf: 3401468 bytes, checksum: 9e89bb418c26be61f0e61413f30a9f7f (MD5) / Made available in DSpace on 2016-10-04T21:00:20Z (GMT). No. of bitstreams: 1 2010 - Joventino Fernandes Moreira.pdf: 3401468 bytes, checksum: 9e89bb418c26be61f0e61413f30a9f7f (MD5) Previous issue date: 2010-02-26 / CAPES / Bio-indicators are frequently used for environmental quality studies, monitoring of degraded areas and recovery processes, because they are intimately associated to specific landscape characteristics and respond to environmental changes by alterations in vital functions. In this sense, the study of the behaviour of edaphic organisms can contribute significantly to the evaluation of the environmental quality and to strategies and processes aiming the recovery and rehabilitation of areas affected by some type of degradation. This study aimed monitoring the colonisation by the soil fauna community of areas degraded by bauxite mining activities and revegetated with a mixture of native and leguminous species in the municipality of Porto Trombetas-PA, Brazil. Material was sampled in the years 2000, 2002, 2003, 2004 and 2008, in a chronosequence of regenerated areas of bauxite waste covered or not with topsoil, and in plantings in former bauxite tailing ponds. The individuals were captured in pitfall traps and separated in the Laboratory of Soil Fauna of the Embrapa Agrobiologia Research Centre. The evaluated parameters were abundance, richness, Shannon index, Pielou?s equitability index and the colonization patterns of fauna groups. The soil fauna profiles were obtained by nonmetric multidimensional scaling (NMS) ordination, and the response of soil fauna community was evaluated using principal response curves (PRC). The results showed that the time from planting and the nutrient availability were determining factors during the environmental recovery of the system, especially in the bauxite waste areas revegetated in 1984, 1992 and 1994, and in the tailing pond areas that received higher amounts of fertilizers. In these areas, the vegetation development caused a better colonization and structuring of the soil fauna community, increasing its diversity and reestablishing the ecological processes. / Bioindicadores s?o frequentemente utilizados para estudos de avalia??o da qualidade ambiental, como no monitoramento de ?reas degradadas e de processos de recupera??o, uma vez que est?o intimamente associados a caracter?sticas espec?ficas da paisagem e respondem ?s mudan?as ambientais por meio de altera??es na composi??o e estrutura das comunidades. Neste sentido, o estudo do comportamento de organismos ed?ficos pode contribuir significativamente para a avalia??o da qualidade ambiental assim como de estrat?gias e processos destinados ? recupera??o e reabilita??o de ?reas que sofreram algum tipo de degrada??o. Este trabalho teve por objetivo acompanhar a coloniza??o da comunidade da fauna ed?fica em ?reas degradadas pela minera??o de bauxita e revegetadas com a mistura de esp?cies nativas e leguminosas arb?reas e arbustivas em Porto Trombetas-PA. As amostragens foram feitas nos anos 2000, 2002, 2003, 2004 e 2008 em reflorestamentos de diferentes idades plantados sobre material est?ril com e sem cobertura de solo superficial e em plantios em tanque de rejeito da lavagem da bauxita. Os indiv?duos foram capturados em armadilhas do tipo ?pitfall? e triados no Laborat?rio de Fauna de Solo da Embrapa Agrobiologia. Os par?metros usados para avalia??o foram: a abund?ncia, a riqueza, o ?ndice de diversidade Shannon, o ?ndice de Equabilidade de Pielou e o padr?o de coloniza??o dos indiv?duos da fauna do solo. Os perfis da fauna do solo foram obtidos pelo ordenamento multivariado atrav?s da t?cnica de escalonamento multidimensional n?o m?trico (NMS) e a resposta da comunidade de fauna ed?fica ?s varia??es ambientais foram avaliadas por meio de curvas de respostas principais (PRC). Os resultados mostraram que a idade do plantio e a disponibilidade de nutrientes foram fatores determinantes na recomposi??o da comunidade de fauna de solo, a qual foi maior nos reflorestamentos de 1984, 1992 e 1994 no est?ril e nas ?reas do tanque de rejeito que receberam maiores quantidades de fertilizantes. Nessas ?reas, o desenvolvimento da vegeta??o levou ? maior coloniza??o e a melhor estrutura??o da comunidade de fauna ed?fica, aumentando a sua diversidade e o restabelecimento de processos ecol?gicos.

En raison de leur capacité à former une symbiose avec des bactéries du sol appelées Rhizobium, ces bactéries fixent l’azote atmosphérique et leurs plantes-hôtes n’ont donc pas besoin de fertilisant azoté, les légumineuses jouent un rôle important dans l'agriculture. En outre, certaines souches de Rhizobium ont la capacité de solubiliser le phosphate, fournissant ainsi du phosphore assimilable aux plantes hôtes. Une aptitude à lutter contre certains agents pathogènes a aussi été démontrée dans plusieurs études. La présente étude évalue l’efficacité symbiotique de rhizobiums tunisiens, leur capacité à solubiliser le phosphate, et leur aptitude à lutter contre la verticilliose ainsi que d’autres champignons pathogènes chez Medicago truncatula. Trente-six isolats de rhizobiums prélevés sur des nodules racinaires de M. truncatula provenant de différentes régions de Tunisie ont été obtenus pour ce travail. Environ 60% de ces isolats étaient capables de solubiliser le phosphate in vitro. Dans une seconde étape, trois rhizobiums solubilisant le phosphate et un isolat incapable de solubiliser le phosphate in vitro ont été utilisés pour des essais en phytotron afin de voir l’effet de la présence des rhizobiums sur les paramètres de croissance des plantes en présence de phosphate inorganique sous forme de CaHPO4 et rocheux sous forme brute. Les résultats de l’essai montrent que les plantes de la lignée A17 traitées au CaHPO4, ont tendance à produire plus de nodules et de biomasse aérienne que la lignée F83005.5 et que la forme du phosphate utilisé, soluble ou non soluble, affecte les paramètres étudiés. L'inoculation de quatre lignées de M. truncatula avec 16 isolats de rhizobium sélectionnés auparavant a montré une interaction significative entre les isolats et les lignées pour la symbiose visible par la formation de nodules. Tous les isolats de rhizobium testés ont augmenté la biomasse aérienne des plantes, réduit la biomasse racinaire et entraîné une teneur plus élevée en azote mais l’effet dépendait de l’isolat de rhizobium et de la lignée de M. truncatula utilisés. Enfin, ces isolats ont été testés pour leur capacité à protéger des plantes de M. truncatula contre une maladie racinaire, la verticilliose. Des activités antagonistes in vitro contre divers champignons pathogènes dont Verticillium et Fusarium ont également été recherchées permettant d’identifier un isolat efficace pour la lutte biologique. Les résultats de cette étude suggèrent que des isolats de rhizobium sélectionnés pourraient être utilisés comme biofertilisants dans les sols pauvres pour réduire l'utilisation d'engrais chimiques azotés et phosphorés mais pas pour lutter contre la verticilliose. / Because of their ability to form a symbiosis with soil bacteria called Rhizobium, legumes play an important role in agriculture. These bacteria fix atmospheric nitrogen; hence their host plants do not need nitrogen fertilizers. In addition, some strains of Rhizobium have the ability to solubilize phosphate, thus providing phosphorus to host plants. An ability to control certain pathogens has also been demonstrated in several studies. The present study evaluates the symbiotic efficiency of Tunisian rhizobia, their ability to solubilize phosphate, and their ability to control Verticillium wilt and other pathogenic fungi in Medicago truncatula. Thirty-six rhizobial isolates were obtained from root nodules of M. truncatula from different parts of Tunisia were used in this work. About 60% of these isolates were able to solubilize phosphate in vitro. In a second step, three phosphate solubilizing rhizobia and one isolate unable to solubilize phosphate in vitro were used for phytotron assays to see the effect of the presence of rhizobia on plant growth parameters in the presence of soluble and insoluble forms of phosphate. The results of the experiment show that A17 plants treated with CaHPO4, tend to produce more nodules and shoot biomass than F83005.5 and that the phosphate form used, soluble or non-soluble, affects parameters studied. Inoculation of four M. truncatula lines with 16 previously selected rhizobial isolates showed significant interaction between isolates and lines for symbiotic abilities as visualised by nodule formation. All rhizobial isolates tested increased above-ground biomass, reduced root biomass, and increased nitrogen content with strains effects of plant genotype and bacterial isolate. Finallly, these isolates were tested for their ability to protect M. truncatula plants against Verticillium wilt, and to inhibit the growth of pathogenic fungi such as Verticillium and Fusarium in vitro. However, no isolate could be identified as effective for biological control. The results of this study suggest that selected rhizobial isolates could be used as biofertilizers in poor soils to reduce the use of nitrogen and phosphorus fertilizers but not to control Verticillium wilt.