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Made available in DSpace on 2015-03-26T13:37:51Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1284492 bytes, checksum: 553a1e66f159f200babfafbb0bac0ccd (MD5) Previous issue date: 2013-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In vitro and greenhouse tests were carried out in order to: (i) assess the compatibility of the nematophagous fungi Pochonia chlamydosporia and Duddingtonia flagrans; (ii) evaluate the control of Meloidogyne javanica by the nematophagous fungi applied together and separately; (iii) evaluate the development of tomato plants inoculated with the nematophagous fungi and study the action of the fungi on plant nutritional status. All the compatibility tests, with the exception of an antibiosis test, indicated that P. chlamydosporia and D. flagrans are compatible to be applied toghether. An experiment in microcosm soil, in which predation of M. javanica by D. flagrans was assessed, the number of juveniles reduced in up to 72.7%. In a second assay, in microcosm soil, with different doses of the fungi applied together and separately, the application of P. chlamydosporia and D. flagrans reduced in up to 81.35% the number of juveniles when 10.000 chlamydospores of each fungus were applied per g of soil. Two experiments were conducted in a greenhouse to evaluate the effect of different concentration of P. chlamydosporia and D. flagrans in the control M. javanica and growth of tomato. The number of galls, number of eggs, height and dry weight of plants were evaluated. In both experiments the antagonists reduced the number of galls and egg production of root-knot nematode and did not affect plant height. In the first experiment, the addition of P. chlamydosporia increased plant dry matter, what was not observed in second one. An assay, in greenhouse conditions, was also carried out to evaluate growth promotion and mineral nutrients content in the tomato plants depending on the application of P. chlamydosporia and D. flagrans in combination and separated. The content of N, P, K, Ca, Mg and S and dry matter of the plants were evaluated. The two fungi increased total dry matter and mineral nutrients content in tomato plants. The combination of the two antagonists provides greater control of root-knot nematode and proved to be a promising strategy in the biological control of plant nematodes. Growth promotion and the positive effect in the nutritional status of the plants inoculated with the studied fungi indicated the great potential of these organisms for agricultural use, not only for the control of nematodes but also by its direct effect on plant growth and for providing better use of fertilizers. / Testes in vitro e em casa de vegetação foram realizados com os objetivos de: (i) avaliar a compatibilidade dos fungos nematófagos Pochonia chlamydosporia (Pc) e Duddingtonia flagrans (Df); (ii) avaliar a influência do nematoide Meloidogyne javanica e de ambos os fungos nematófagos no desenvolvimento de plantas de tomate; (iii) estudar a ação dos fungos sobre o estado nutricional das plantas. Nos ensaios de compatibilidade de Pc e Df in vitro, com exceção do teste de antibiose, todos os testes de compatibilidade dos isolados indicaram que os organismos são compatíveis. No primeiro experimento no solo em microcosmo em que foi avaliado a predação de M. javanica por Df, houve redução no número de juvenis em até 72,7%. No segundo experimento em microcosmo, em que foram avaliadas doses dos fungos em conjunto e em separado, a aplicação em conjunto dos dois organismos aumentou o controle, reduzindo em até 81,35% o número de juvenis quando 10.000 clamidósporos de cada fungo foram aplicados por g de solo. Dois experimentos foram realizados em casa de vegetação para avaliar o efeito de diferentes concentrações dos fungos nematófagos Pc e Df, isoladamente ou em mistura, no controle de M. javanica e no crescimento do tomateiro. Foram avaliadas as variáveis: número de galhas g-¹ de raiz, número de ovos g-¹ de raiz, altura e massa seca das plantas. Em ambos os experimentos observou-se o efeito dos dois antagonistas na redução do número de galhas e de ovos do nematoide das galhas. Os tratamentos não influenciaram a altura das plantas nos dois experimentos. No experimento 1, a adição de Pc aumentou a massa seca das plantas, o que não ocorreu no experimento 2. Um ensaio em casa de vegetação também foi realizado para avaliar a promoção de crescimento e aquisição de nutrientes minerais no tomateiro em função da aplicação de ambos os fungos. Após 60 dias avaliou-se a massa seca das plantas e o conteúdo de N, P, K, Ca, Mg e S. Houve efeito positivo dos dois fungos aplicados sobre a massa seca total do tomateiro e conteúdo de nutrientes minerais nas plantas. Dos resultados obtidos, conclui-se que a ação conjunta dos dois antagonistas proporciona maior controle do nematoide das galhas, mostrando-se uma estratégia promissora no controle biológico de fitonematoides. Adicionalmente, a promoção de crescimento vegetal pelos dois fungos estudados, associada à melhoria do estado nutricional das plantas, indica o potencial de uso agrícola desses organismos, não apenas para o controle de nematoides, mas também por sua ação direta no desenvolvimento do tomateiro e na economia de fertilizantes.

Es wurden Wurzelsysteme auf 1900, 2400 und 3000 m eines südecuadorianischen Bergregenwaldes untersucht. Ziel war es, ein besseres Verständnis über den Einfluss der Höhenstufe auf die Wurzelfunktionen Nährstoffaneignung und Verankerung sowie Speicherung von C und Nährstoffen in der Wurzelbiomasse zu erlangen. Auf 2400 und 3000 m nahmen die Wurzellängendichten (WLD) mit zunehmender Bodentiefe schneller ab als auf 1900 m. Die vertikale Verteilung der N-Aufnahme war ähnlich der Verteilung der WLD. Das Nährstoffaneignungsvermögen war also in größerer Meereshöhe deutlich mehr auf die organische Auflage konzentriert war als auf 1900 m. Nährstoffkonzentrationen in Blättern zeigten, dass auf 1900 m das Pflanzenwachstum nicht durch Nährstoffmangel limitiert war, während auf 2400 und 3000 m v. a. N, aber auch P, S und K das Pflanzenwachstum limitierten. Die schlechte Nährstoffversorgung der Pflanzen in großer Meereshöhe war vermutlich auf langsame Mineralisation organisch gebundener Nährstoffe und auf ein geringes Nährstoffaneignungsvermögen aus tieferen Bodenschichten zurückzuführen. Die Wurzelbiomasse war auf 3000 m höher als in niedrigerer Meereshöhe. Die Bedeutung des Wurzelsystems für die C-Speicherung stieg also mit zunehmender Höhenstufe. Auch Vorräte an N, S, K, Ca und Mg in den Wurzeln waren auf 3000 m am höchsten. Die Grobwurzelsysteme der Bäume wiesen auf allen Höhenstufen Verankerungs-fördernde Merkmale auf. Bäume auf 3000 m bildeten flachgründigere Wurzelteller als auf 1900 m. Wurzeleigenschaften, die die horizontale Ausdehnung des Wurzeltellers fördern, waren auf 3000 m häufiger oder ausgeprägter als auf 1900 m. Es wird gefolgert, dass eine gehemmte Tiefendurchwurzelung des Bodens in größerer Meereshöhe sowohl das Nährstoffaneignungsvermögen als auch auf die Verankerung der Bäume verringerte. Die hohe Biomasseallokation in die Wurzeln in größerer Meereshöhe weist darauf hin, dass Umweltbedingungen hier besondere Anforderungen an die Wurzelfunktionen stellen. / Root systems at 1900, 2400 and 3000 m of a south Ecuadorian montane forest were investigated. The aim of this study was to improve our knowledge on the impact of altitude on the root functions nutrient acquisition, anchorage and storage of C and nutrients in root biomass. At 2400 and 3000 m, the decrease of root length densities (RLD) with increasing soil depth was more pronounced than at 1900 m. The vertical distribution of N uptake was similar to the vertical distribution of RLD. Thus, the ability for nutrient uptake was more concentrated to the organic surface layer at high altitudes than at 1900 m. Foliar nutrient concentrations showed that plant growth at 1900 m was not limited by nutrient deficiency. In contrast, at 2400 and 3000 m especially N, but also P, S and K limited plant growth. The decreased nutritional status of plants at high altitudes was caused by low mineralization rates of nutrients as well as low ability for nutrient acquisition from deeper soil layers. At 3000 m, root biomass was higher than at low altitudes. Hence, the importance of root systems for C sequestration increased with increasing altitude. Similarly, pools of N, S, K, Ca and Mg were higher at 3000 m than at 1900 and 2400 m. At all altitudes, coarse root systems of trees showed traits that are supposed to improve anchorage. At 3000 m, root soil plates were more superficial than at 1900 m. Root traits that improve the horizontal extension of root soil plates were more pronounced or occurred more often at 3000 m than at 1900 m. It is concluded that impeded rooting in deeper soil layers at high altitudes decreased both the ability for nutrient acquisition and anchorage. At high altitudes, the high allocation of biomass to the root systems showed that at these sites, environmental conditions enhanced the requirements to the functions of roots.

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Background: Soil microbes are key drivers of carbon (C) and nutrient cycling in terrestrial ecosystems, and their properties are influenced by the relationship between resource demand and availability. - Aims: Our objective was to investigate patterns of microbial properties and their controls to understand whether they differ between soils derived from geochemically contrasting parent material in tropical montane forests. - Methods: We measured microbial biomass C (MBC/Soil), potential extracellular enzyme activity (pEEA), and assessed microbial investments in C and nutrient acquisition at the beginning and end of a 120-day laboratory incubation experiment using soils developed from three geochemically contrasting parent material (i.e., mafic, mixed sediment, and felsic) and three soil depths (0–70 cm). - Results: We found that MBC/Soil and pEEA were highest in soils developed from the mafic parent material. Microbial investment in C acquisition was highest in soils developed from mixed sedimentary rocks and lowest in soils developed from the felsic parent material. We propose that our findings are related to the strength of contrasting mineral-related C stabilization mechanisms and varying C quality. No predominant microbial investment in nitrogen (N) acquisition was observed, whereas investment in phosphorus (P) acquisition was highest in subsoils. We found lower microbial investment in C acquisition in subsoils indicating relatively high C availability, and that microbes in subsoils can substantially participate in C cycling and limit C storage if moisture and oxygen conditions are suitable. Geochemical soil properties and substrate quality were important controls on MBC/Soil per unit soil organic C (MBC/SOC), particularly after the exhaustion of labile and fast cycling C, that is, at the end of the incubation. - Conclusion: Although a laboratory incubation experiment cannot reflect real-world conditions, it allowed us to understand how soil properties affect microbial properties. We conclude that parent material is an important driver of microbial properties in tropical montane forests despite the advanced weathering degree of soils.