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As plantas de cobertura podem desenvolver diferentes mecanismos para absorver e solubilizar o fósforo proveniente do solo, especialmente em ambientes com baixa disponibilidade, melhorando também o aproveitamento do P aplicado via fertilizante. Assim, o objetivo deste trabalho foi de avaliar as alterações na disponibilidade e nas frações que o P se encontra no solo, e nos atributos químicos do solo, sob cultivos de plantas de cobertura no inverno, associadas ao efeito residual da adubação fosfatada solúvel e de baixa solubilidade aplicada no cultivo de verão. O experimento foi conduzido com seis plantas de cobertura (ervilhaca - Vicia sativa, tremoço branco - Lupinus albus, nabo forrageiro - Raphanus sativus, azevém - Lolium multiflorum, aveia preta - Avena strigosa, trevo branco - Trifolium repens) mais o pousio e duas fontes de fertilizantes fosfatados (Fosfato Natural - FN e Superfosfato Simples - SPS) mais o controle (sem P), com o cultivo de milho no verão, durante três anos. O delineamento utilizado foi o de blocos casualizados com parcelas subdivididas, em esquema fatorial 7 x 3, com três repetições. As fontes de fertilizantes fosfatados constituíram as parcelas e as espécies de plantas de cobertura, as subparcelas. Após o cultivo das plantas de cobertura, no primeiro e terceiro ano, foram coletadas amostras de solo nas camadas de 0-5, 5-10 e 10-20 cm, para análise das frações de P no solo, através da técnica de fracionamento, e dos atributos químicos do solo (pH, acidez potencial, cálcio, magnésio e potássio). Os resultados do fracionamento de P mostraram que, tanto as frações lábeis quanto as frações de menor labilidade não foram ou foram pouco influenciadas pelas plantas de cobertura, durante os três anos de cultivo. A aplicação de fertilizantes fosfatados promoveu acúmulo de P no solo, principalmente, nas frações de baixa labilidade. Observou-se também que, ao longo do tempo, independente do tratamento, ocorreu aumento dos teores de P no solo nas formas lábeis e não-lábeis, e diminuição das formas moderadamente lábeis, em todas as camadas. De modo geral, não foi observado efeito significativo das plantas de cobertura sobre os atributos químicos do solo no presente estudo. / The cover crops can develop different mechanisms to uptake and solubilize soil phosphorus, especially in environments with low availability, also improving the use of P from fertilizers. Thus, the aim of this study was to evaluate changes in P availability and P fractions in soil, and soil chemical attributes, under cultivation of winter cover crop, associated with the residual effect of high and low solubility phosphate fertilization applied in the summer crop. The experiment was composed of six cover crops (vetch - Vicia sativa, white lupin - Lupinus albus, radish - Raphanus sativus, ryegrass - Lolium multiflorum, black oat - Avena strigosa, white clover - Trifolium repens) plus a fallow, and two sources of phosphate fertilizers (Rock Phosphate-FN and Simple Superphosphate-SPS) plus a control without P, with the cultivation of maize in summer for three consecutive years. The experimental design used was a split plot distributed in randomized blocks, in a factorial scheme of 7 x 3 with three replications. Phosphate fertilizer sources constituted the plot and cover crop species was the subplot. After the cultivation of cover crops in the first and third year, soil samples were collected in layers of 0-5, 5-10 and 10-20 cm, for analysis of P fractions in the soil, through the technique of fractionation, and chemical attributes of the soil (pH, potential acidity, calcium, magnesium and potassium). The results of the P fractionation showed that both labile and lower lability fractions were not or little influenced by cover crops during the three years of cultivation. The application of phosphate fertilizers promoted accumulation of P in the soil, especially in less labile fractions. Also it was observed that, over time, regardless of treatment, the levels of P in soil in the labile and non-labile fractions increased, and moderately labile fractions decreased, in all the depth layers. Generally, it was not observed significant effect of cover crops on the chemical soil attributes on this study.

O fósforo (P) é limitante tanto na produtividade da cana-de-açúcar (Saccharum officinarum L.) quanto na atividade da microbiota do solo. Em solos de regiões tropicais, devido à elevada saturação por óxidos de ferro e alumínio, o P se encontra normalmente indisponível às plantas. Portanto, o manejo da adubação de P, baseado no uso de microrganismos capazes de promover uma melhor ciclagem do P, se faz necessário. Assim, o objetivo do estudo foi avaliar as mudanças na microbiota do solo e na produtividade da cana-de-açúcar, em condições de campo, em resposta ao manejo orgânico associado à inoculação de bactérias solubilizadoras de fosfato (BSF). Para tanto, foi utilizado um composto, obtido previamente por meio da compostagem de subprodutos da indústria sucroenergética (torta de filtro e cinzas), enriquecido com fosfatos de rocha (fosfato de Araxá-FA ou fosfato de Bayóvar-FB). No campo foram estabelecidos sete tratamentos, sendo um destes o tratamento controle, adubado com superfosfato triplo. Seis tratamentos compreendiam áreas adubadas com composto, sendo duas com composto que continha FA, duas com FB e duas somente com composto sem enriquecimento com P (C). A metade dessas áreas recebeu também inoculação com BSF, contendo os tratamentos FA+I, FB+I e C+I. A inoculação foi feita com Bacillus simplex BACBR04, Bacillus sp. BACBR06 e Rhizobium sp. RIZBR0. As avaliações foram realizadas durante o primeiro ano de cultivo (cana planta) em dois períodos (aos seis e 12 meses). As mudanças na microbiota foram acessadas por meio da atividade das enzimas fosfatases (ácida e alcalina), fitases e β-glucosidase. Mudanças na estrutura da comunidade bacteriana e fúngica foram acessadas por meio do T-RFLP. A abundância dos genes 16S RNAr, phoD (relacionado à solubilização de P) e ITS foram avaliadas por meio de PCR quantitativo. A atividade das fosfatases e β-glucosidase aumentaram com a inoculação na cana adubada com composto enriquecido com fosfato de Araxá (FA+I) e também no solo adubado com composto sem enriquecimento (C+I). Nos tratamentos FA+I e C+I houve incremento do fósforo disponível e aumento de 10% na produtividade, em relação ao tratamento controle (M). As comunidades bacteriana e fúngica do tratamento C+I se estruturaram de forma distinta em relação ao tratamento controle (M). Nos solos inoculados houve menor abundância do gene ITS aos seis meses, enquanto que, para o gene 16S RNAr, os solos inoculados apresentaram menor abundância no período de 12 meses. Verificou-se que o consórcio bacteriano inoculado, associado com a aplicação de composto, superou, no primeiro ano de cultivo, o manejo rotineiramente utilizado em cana-de-açúcar (adubação com superfosfato triplo). É possível que haja efeito residual no decorrer dos ciclos da cana-de-açúcar, o que ainda reforçaria a importância do manejo orgânico associado à inoculação com BSF. / Phosphorus (P) is limiting both the yield of sugarcane (Saccharum officinarum L.) and the activity of the soil microbiota. In tropical soils, due to the high saturation of iron and aluminum oxides, P is normally unavailable to plants. Therefore, the management of P fertilization, based on the use of microorganisms that promote better P cycling is necessary. Thus, the objective of this study was to evaluate changes in the soil microbiota and in sugarcane yield under field conditions, in response to the organic management associated with the inoculation of phosphate solubilizing bacteria (PSB). In our field experiment, our fertilizer was an organic compost, previously obtained by the composting process of by-products of the sugarcane industry (filter cake and ashes), enriched with rock phosphates (Araxá phosphate-AP or Bayóvar phosphate-BP). Seven treatments were established in the field, one of which was the control treatment, fertilized with triple superphosphate. Six treatments comprised compost fertilized areas, two with compost containing AP, two with BP, and two only with compost, and without any enrichment with P (C). Half of these areas were also inoculated with PSB, containing the treatments AP+I, BP+I and C+I. Field inoculation was done with Bacillus simplex BACBR04, Bacillus sp. BACBR06 and Rhizobium sp. RIZBR0. We performed evaluations during the first year of cultivation at two periods (at six and twelve months after planting). We accessed the changes in the microbiota through the activity of acid and alkaline phosphatases, phytases and β-glucosidase. Changes in bacterial and fungal community structure were accessed through T-RFLP. We evaluated the abundance of the 16S RNAr, phoD (related to P solubilization) and ITS genes by quantitative PCR. The phosphatases and β-glucosidase activity increased with the inoculation in sugarcane fertilized with compost and enriched with Araxá phosphate (AP+I) and in the soil fertilized with compost, but without any enrichment (C+I). In these treatments (AP+I and C+I), we found an increase in available phosphorus and a 10% increase in productivity, in relation to the control treatment (M). The bacterial and fungal communities of the treatments C+I presented a different structure in relation to the control treatment (M). In the soils that received bacterial inoculations, there was a lower abundance of the ITS gene at six months, whereas for the 16S RNAr gene the inoculated soils presented lower abundance at 12 months. We verified that the inoculated bacterial consortium, associated with the application of compost, overcame the conventional management in sugarcane (triple superphosphate fertilizer) in the first year of cultivation. In addition, it is possible residual effect during the sugarcane cycles, which would further reinforce the importance of organic management associated with BSF inoculation.

As plantas de cobertura podem desenvolver diferentes mecanismos para absorver e solubilizar o fósforo proveniente do solo, especialmente em ambientes com baixa disponibilidade, melhorando também o aproveitamento do P aplicado via fertilizante. Assim, o objetivo deste trabalho foi de avaliar as alterações na disponibilidade e nas frações que o P se encontra no solo, e nos atributos químicos do solo, sob cultivos de plantas de cobertura no inverno, associadas ao efeito residual da adubação fosfatada solúvel e de baixa solubilidade aplicada no cultivo de verão. O experimento foi conduzido com seis plantas de cobertura (ervilhaca - Vicia sativa, tremoço branco - Lupinus albus, nabo forrageiro - Raphanus sativus, azevém - Lolium multiflorum, aveia preta - Avena strigosa, trevo branco - Trifolium repens) mais o pousio e duas fontes de fertilizantes fosfatados (Fosfato Natural - FN e Superfosfato Simples - SPS) mais o controle (sem P), com o cultivo de milho no verão, durante três anos. O delineamento utilizado foi o de blocos casualizados com parcelas subdivididas, em esquema fatorial 7 x 3, com três repetições. As fontes de fertilizantes fosfatados constituíram as parcelas e as espécies de plantas de cobertura, as subparcelas. Após o cultivo das plantas de cobertura, no primeiro e terceiro ano, foram coletadas amostras de solo nas camadas de 0-5, 5-10 e 10-20 cm, para análise das frações de P no solo, através da técnica de fracionamento, e dos atributos químicos do solo (pH, acidez potencial, cálcio, magnésio e potássio). Os resultados do fracionamento de P mostraram que, tanto as frações lábeis quanto as frações de menor labilidade não foram ou foram pouco influenciadas pelas plantas de cobertura, durante os três anos de cultivo. A aplicação de fertilizantes fosfatados promoveu acúmulo de P no solo, principalmente, nas frações de baixa labilidade. Observou-se também que, ao longo do tempo, independente do tratamento, ocorreu aumento dos teores de P no solo nas formas lábeis e não-lábeis, e diminuição das formas moderadamente lábeis, em todas as camadas. De modo geral, não foi observado efeito significativo das plantas de cobertura sobre os atributos químicos do solo no presente estudo. / The cover crops can develop different mechanisms to uptake and solubilize soil phosphorus, especially in environments with low availability, also improving the use of P from fertilizers. Thus, the aim of this study was to evaluate changes in P availability and P fractions in soil, and soil chemical attributes, under cultivation of winter cover crop, associated with the residual effect of high and low solubility phosphate fertilization applied in the summer crop. The experiment was composed of six cover crops (vetch - Vicia sativa, white lupin - Lupinus albus, radish - Raphanus sativus, ryegrass - Lolium multiflorum, black oat - Avena strigosa, white clover - Trifolium repens) plus a fallow, and two sources of phosphate fertilizers (Rock Phosphate-FN and Simple Superphosphate-SPS) plus a control without P, with the cultivation of maize in summer for three consecutive years. The experimental design used was a split plot distributed in randomized blocks, in a factorial scheme of 7 x 3 with three replications. Phosphate fertilizer sources constituted the plot and cover crop species was the subplot. After the cultivation of cover crops in the first and third year, soil samples were collected in layers of 0-5, 5-10 and 10-20 cm, for analysis of P fractions in the soil, through the technique of fractionation, and chemical attributes of the soil (pH, potential acidity, calcium, magnesium and potassium). The results of the P fractionation showed that both labile and lower lability fractions were not or little influenced by cover crops during the three years of cultivation. The application of phosphate fertilizers promoted accumulation of P in the soil, especially in less labile fractions. Also it was observed that, over time, regardless of treatment, the levels of P in soil in the labile and non-labile fractions increased, and moderately labile fractions decreased, in all the depth layers. Generally, it was not observed significant effect of cover crops on the chemical soil attributes on this study.

Cowpea (Vigna ungiculata L. Walp) is a major food and fodder legume in poor countries, particularly Sub-Saharan Africa countries. It is generally produced in sandy, acid soils, deficient in phosphorus (P) which severely limits its production. Because processed phosphate fertilizers are expensive and poorly available to farmers, rock phosphate is viewed as a cheap alternative phosphate source. The present study evaluated 696 U.S Core Collection and IITA cowpea accessions for adaptation to low soil P environments and for response to rock phosphate application. Subsequently, organic acid exudation by selected cowpea genotypes as a mechanism for P acquisition from Fe-oxide and Ca bound P was investigated. A low P soil from Nacogdoches pine forest was used to grow plants. There were two P treatments: 0 and 300 mg P/kg of soil as Tahoua (Niger) rock phosphate. At harvest, plant height, shoot and root dry weights were determined and total biomass and shoot-to-root ratios were computed. Shoot P contents of 100 selected accessions were measured. Sixteen accessions reflecting the wide array of responses observed were selected for the organic acid study. Plants were grown in a growth chamber hydroponically with no P and +P nutrient solutions for 3 weeks. Organic acids were collected in a CaCl2-KCl solution. The nature and quantity of the collected organic acids was determined. Cowpea accessions were significantly different in their ability to adapt to Pdeficiency stress and to acquire P from rock phosphate. The parameters most effective in separating the accessions were shoot mass and total biomass. This data will be potentially useful in the selection of cowpea germplasm for (1) adaptation to West African soils of low P fertility, and (2) ability to utilize P from poorly soluble rock phosphate. The predominant organic acid exuded by cowpea roots was a tricarboxylic acid not yet identified. There was surprisingly more exudation of this acid under +P than under –P conditions. Exudation was more highly correlated to roots than to shoots.

Orientador: Eliana Gertrudes de Macedo Lemos / Banca: Claudia Barros Monteiro Vitorello / Banca: Roberto Alves de Oliveira / Resumo: A cultura da cana-de-açúcar (Saccharum spp.) apresenta grande importância econômica para o Brasil. Dessa forma, para propiciar boas condições de desenvolvimento e produtividade, deve-se dar grande importância ao suprimento de fósforo. Bactérias solubilizadoras de fósforo (BSF) vêm sendo utilizadas como biofertilizantes comerciais, trazendo benefícios à agricultura. A seleção de bactérias com capacidade de solubilização do fósforo pode ser feita através de caracterizações genotípicas. Os objetivos deste trabalho foram isolar e caracterizar bactérias solubilizadoras de fosfato provenientes de solos sob cultivo de cana-de-açúcar por meio do sequenciamento do gene 16S rRNA e da região BOX-A1R. Além disso, foi realizada avaliação da atividade microbiana sobre a solubilização das fontes de fosfato até 168 horas. O sequenciamento permitiu identificar gêneros como Burkholderia e Enterobacteriaceae, conhecidos quanto à solubilização. Os isolados identificados como Arthrobacter e Labrys apresentam capacidade para biodegradação de compostos tóxicos ao ambiente. O fosfato de cálcio foi a fonte mais solubilizada. Os isolados Burkholderia sp. (A5I55), Candidatus B. verschuerenii (A9IG), Enterobacter sp. (USC8) e E. hormaechei subsp. steigerwaltii (USC7) apresentaram resultados semelhantes a B. ferrariae. As bactérias-padrão obtiveram os melhores resultados para a solubilização das fontes fosfatadas. Candidatus B. verschuerenii (A9IG) e Burkholderia sp. (A3I14) e B. gladioli (A6I8) apresentaram os melhores valores para solubilização das rochas fosfatadas. Além disso, foi detectada a produção de AIA pelos isolados do gênero Enterobacter (USC7 e USC8) Labrys portucalensis (A5I42) e Burkholderia sp. (A5I55).Assim estes isolados poderiam ser indicados em testes para solubilização em culturas de campo. / Abstract: The culture of sugarcane (Saccharum spp.) has a great economic importance to Brazil. Thus, providing good conditions for development and productivity should be given great importance to phosphorus supply. Phosphate solubilizing bacteria - PSB, have been used as biofertilizers, bringing benefits to agriculture. Selection of phosphorus solubilizing bacteria can be done by genetic characterization. The aim of this work is to isolate and characterize PSB from sugarcane productive soils through the sequencing of 16S rRNA gene and BOX-A 1R genomic regions. Furthermore, the microbial activity of phosphate source was assessment until 168 hours. The sequencing has identified genus as Burkhloderia and Enterobacteriaceae, known as PSB. The isolates identified as Arthrobacter and Labrys have the capacity to biodegradation of toxic compounds in the environment. The calcium phosphate was the source more soluble. Isolates Burkholderia sp. (A5I55), Candidatus B. verschuerenii (A9IG), Enterobacter sp. (USC8) and E. hormaechei subsp. steigerwaltii (USC7) showed results similar to B. ferrariae. The bacteria-standards showed the best results for phosphates sources solubilization. Candidatus B. verschuerenii (A9IG) and Burkholderia sp. (A3I14) and B. gladioli showed the best values for solubilization of rock phosphate. Furthermore, the production of AIA was detected by Enterobacter (USC7 and USC8), Labrys portucalensins (A5I42) and Burkholderia sp. (A5I55). Therefore these isolates could be recommended for phosphorus solubilization tests and auxin producing in fieldcrops. / Mestre

Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-11-06T18:47:31Z No. of bitstreams: 2 Dissertação - Ricardo Neves Guimarães - 2013.pdf: 1524566 bytes, checksum: 408d84e38687163bef38e1381e097f44 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2014-11-06T18:47:51Z (GMT) No. of bitstreams: 2 Dissertação - Ricardo Neves Guimarães - 2013.pdf: 1524566 bytes, checksum: 408d84e38687163bef38e1381e097f44 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-11-06T18:47:51Z (GMT). No. of bitstreams: 2 Dissertação - Ricardo Neves Guimarães - 2013.pdf: 1524566 bytes, checksum: 408d84e38687163bef38e1381e097f44 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-03-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Produce biofertilizers enriched with natural phosphates may increase the solubility of phosphorus minimizing the dependence of acidulated phosphate fertilizers. The objective of this research was to evaluate the bioavailability of nutrients due to the processes of composting and vermicomposting. The experimental design was completely randomized in a factorial 4 x 3 with 5 repetitions , the factors being the sources of P ( 1 - ammoniated superphosphate , 2 - rock phosphate Itafós 3 - Araxá rock phosphate and 4 - thermophosphate Yoorin ) and the method of incorporating phosphorus sources with the organic fraction : 1 - worm compost with addition of P sources at the beginning of the process of vermicomposting ( VPI ) 2 - worm compost with addition of P sources at the end of vermicomposting process ( VPF ) and 3 - Compound earthworms with no addition of P sources at the beginning of the composting process ( CP ) . Were evaluated: weight of earthworms , microbial biomass dry weight, total carbon , N, C / N ratio , pH, Q water , citric acid, total S, K, Ca , Mg . In addition to percentage of N, P, water, citric acid, total S and Ca is left in place in relation to the start of the research. The results indicate that the source acidulated super simple at a dose of 6 kg -1 is not indicated for the processes of composting and vermicomposting. In vermicomposting, the rock phosphate Itafós secured higher values of C-BM. The compost was effective in providing nutrients. Addition of phosphorus sources after the vermicomposting process increased the solubility of phosphorus in citric acid and water for phosphates and Araxá Itafós . / Produzir organominerais enriquecidos com fosfatos naturais pode elevar a solubilidade do fósforo minimizando a dependência de fertilizantes fosfatados acidulados. Objetivou-se com esta pesquisa avaliar a biodisponibilização de nutrientes decorrente dos processos da compostagem e vermicompostagem. O delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 4 x 3 com 5 repetições, sendo os fatores as fontes de P (1- superfosfato simples amoniado, 2- fosfato natural de Itafós, 3- fosfato natural de Araxá e 4 - termofosfato Yoorin) e o modo de incorporação das fontes de P com a fração orgânica: 1- Vermicomposto com adição das fontes de P no início do processo da vermicompostagem (VPI), 2 - Vermicomposto com adição das fontes de P no final do processo de vermicompostagem (VPF) e 3 - Composto sem minhocas com adição das fontes de P no início do processo da compostagem (CP). Foram avaliados: peso das minhocas, biomassa microbiana, massa seca, carbono total, N, relação C/N, pH, P em água, ácido cítrico, total, S, K,Ca, Mg. Além de porcentagem de N, P em água, ácido cítrico, total, S e Ca que sobrou em relação ao colocado no início da pesquisa. Os resultados obtidos indicam que a fonte acidulada super simples na dose de 6 kg -1 não é indicada para os processos de compostagem e vermicompostagem. Nos vermicompostos, o fosfato natural de Itafós garantiu maiores valores de C-BM. A compostagem foi eficiente na disponibilização de nutrientes. Adição das fontes de fósforo após o processo de vermicompostagem elevou a solubilidade de fósforo em ácido cítrico e em água para os fosfatos naturais de Araxá e Itafós.

O fósforo (P) é limitante tanto na produtividade da cana-de-açúcar (Saccharum officinarum L.) quanto na atividade da microbiota do solo. Em solos de regiões tropicais, devido à elevada saturação por óxidos de ferro e alumínio, o P se encontra normalmente indisponível às plantas. Portanto, o manejo da adubação de P, baseado no uso de microrganismos capazes de promover uma melhor ciclagem do P, se faz necessário. Assim, o objetivo do estudo foi avaliar as mudanças na microbiota do solo e na produtividade da cana-de-açúcar, em condições de campo, em resposta ao manejo orgânico associado à inoculação de bactérias solubilizadoras de fosfato (BSF). Para tanto, foi utilizado um composto, obtido previamente por meio da compostagem de subprodutos da indústria sucroenergética (torta de filtro e cinzas), enriquecido com fosfatos de rocha (fosfato de Araxá-FA ou fosfato de Bayóvar-FB). No campo foram estabelecidos sete tratamentos, sendo um destes o tratamento controle, adubado com superfosfato triplo. Seis tratamentos compreendiam áreas adubadas com composto, sendo duas com composto que continha FA, duas com FB e duas somente com composto sem enriquecimento com P (C). A metade dessas áreas recebeu também inoculação com BSF, contendo os tratamentos FA+I, FB+I e C+I. A inoculação foi feita com Bacillus simplex BACBR04, Bacillus sp. BACBR06 e Rhizobium sp. RIZBR0. As avaliações foram realizadas durante o primeiro ano de cultivo (cana planta) em dois períodos (aos seis e 12 meses). As mudanças na microbiota foram acessadas por meio da atividade das enzimas fosfatases (ácida e alcalina), fitases e β-glucosidase. Mudanças na estrutura da comunidade bacteriana e fúngica foram acessadas por meio do T-RFLP. A abundância dos genes 16S RNAr, phoD (relacionado à solubilização de P) e ITS foram avaliadas por meio de PCR quantitativo. A atividade das fosfatases e β-glucosidase aumentaram com a inoculação na cana adubada com composto enriquecido com fosfato de Araxá (FA+I) e também no solo adubado com composto sem enriquecimento (C+I). Nos tratamentos FA+I e C+I houve incremento do fósforo disponível e aumento de 10% na produtividade, em relação ao tratamento controle (M). As comunidades bacteriana e fúngica do tratamento C+I se estruturaram de forma distinta em relação ao tratamento controle (M). Nos solos inoculados houve menor abundância do gene ITS aos seis meses, enquanto que, para o gene 16S RNAr, os solos inoculados apresentaram menor abundância no período de 12 meses. Verificou-se que o consórcio bacteriano inoculado, associado com a aplicação de composto, superou, no primeiro ano de cultivo, o manejo rotineiramente utilizado em cana-de-açúcar (adubação com superfosfato triplo). É possível que haja efeito residual no decorrer dos ciclos da cana-de-açúcar, o que ainda reforçaria a importância do manejo orgânico associado à inoculação com BSF. / Phosphorus (P) is limiting both the yield of sugarcane (Saccharum officinarum L.) and the activity of the soil microbiota. In tropical soils, due to the high saturation of iron and aluminum oxides, P is normally unavailable to plants. Therefore, the management of P fertilization, based on the use of microorganisms that promote better P cycling is necessary. Thus, the objective of this study was to evaluate changes in the soil microbiota and in sugarcane yield under field conditions, in response to the organic management associated with the inoculation of phosphate solubilizing bacteria (PSB). In our field experiment, our fertilizer was an organic compost, previously obtained by the composting process of by-products of the sugarcane industry (filter cake and ashes), enriched with rock phosphates (Araxá phosphate-AP or Bayóvar phosphate-BP). Seven treatments were established in the field, one of which was the control treatment, fertilized with triple superphosphate. Six treatments comprised compost fertilized areas, two with compost containing AP, two with BP, and two only with compost, and without any enrichment with P (C). Half of these areas were also inoculated with PSB, containing the treatments AP+I, BP+I and C+I. Field inoculation was done with Bacillus simplex BACBR04, Bacillus sp. BACBR06 and Rhizobium sp. RIZBR0. We performed evaluations during the first year of cultivation at two periods (at six and twelve months after planting). We accessed the changes in the microbiota through the activity of acid and alkaline phosphatases, phytases and β-glucosidase. Changes in bacterial and fungal community structure were accessed through T-RFLP. We evaluated the abundance of the 16S RNAr, phoD (related to P solubilization) and ITS genes by quantitative PCR. The phosphatases and β-glucosidase activity increased with the inoculation in sugarcane fertilized with compost and enriched with Araxá phosphate (AP+I) and in the soil fertilized with compost, but without any enrichment (C+I). In these treatments (AP+I and C+I), we found an increase in available phosphorus and a 10% increase in productivity, in relation to the control treatment (M). The bacterial and fungal communities of the treatments C+I presented a different structure in relation to the control treatment (M). In the soils that received bacterial inoculations, there was a lower abundance of the ITS gene at six months, whereas for the 16S RNAr gene the inoculated soils presented lower abundance at 12 months. We verified that the inoculated bacterial consortium, associated with the application of compost, overcame the conventional management in sugarcane (triple superphosphate fertilizer) in the first year of cultivation. In addition, it is possible residual effect during the sugarcane cycles, which would further reinforce the importance of organic management associated with BSF inoculation.

Travail réalisé en cotutelle avec l'université du Littoral côte d'opale, France / Afin de réduire l’usage des fertilisants chimiques et leurs empreintes environnementales, la production de bioinoculants à base de bactéries rhizosphériques solubilisatrices de Phosphore (PSB) est une biotechnologie prometteuse. Lorsque celle-ci est associée à l’apport de phosphate de roche (RP), elle pourrait constituer une alternative écoresponsable d’amélioration de la fertilité des sols rhizosphériques, notamment à travers l’augmentation du phosphore (P) biodisponible. Pour répondre à cet enjeu environnemental majeur, il est indispensable d’étudier la biodiversité microbienne des sols en interaction avec le RP. Ainsi, ce travail de thèse a pour objectif de caractériser, d’un point de vue taxonomique, les communautés bactériennes et fongiques associées aux compartiments racinaires et rhizosphériques de plantes natives d’environnements singuliers, peu explorés, que sont d’anciens sites miniers riches en RP. Le séquençage Illumina MiSeq d’amplicons de gènes ribosomiques des différents groupes microbiens et l’assignation taxonomique des séquences regroupées en ASV, nous ont permis de mettre en évidence des valeurs de richesse et de diversité microbiennes comparables malgré la différence des teneurs en RP et en P des sols étudiés. De même, une grande similarité entre les profils des communautés a été identifiée à haut niveau taxonomique, avec une prévalence marquée des phyla Actinobacteriota et Ascomycota, et de l’ordre Glomerales pour les communautés de champignons mycorhiziens arbusculaires (CMA). À un niveau taxonomique plus bas, un core microbien de 26 ASV mycorhiziennes, persistantes à travers le gradient de RP et de P, a également été mis en évidence. Toutefois, l’analyse statistique des données environnementales nous a permis d’identifier des ASV indicatrices des habitats enrichis versus non enrichis en RP, pour chaque communauté microbienne étudiée. La synthèse de ces résultats originaux montre une influence mineure des teneurs en RP et en P sur le profil des communautés microbiennes des sites étudiés et questionne la signification écologique de la prévalence de certains taxa en lien avec l’histoire minière du site, sa restauration écologique et sa résilience, ainsi que les stratégies de vie et les attributs fonctionnels des taxa dominants. Par ailleurs, une collection de PSB a été réalisée à partir d’isolats racinaires issus des sites miniers étudiés, ou à partir d’isolats issus de spores et d’hyphes mycorhiziens piégés au contact d’apports en RP déposés dans la rhizosphère de plantes d’intérêt agronomique. Ces PSB racinaires ou hyphosphériques, testés par ailleurs pour plusieurs traits additionnels promoteurs de la croissance des plantes, ont été assignés à trois phyla : Proteobacteria, Firmicutes et, dans une moindre mesure, Actinobacteria ; Bacillus et Pseudomonas étaient les genres prédominants. Enfin, à partir de ces isolats, deux consortia bactériens avec différent traits promoteurs de la croissance des plantes (PGP), ont été constitués et testés seuls ou en combinaison avec l’apport de RP et/ou l’ajout d’un inoculum mycorhizien à base de Rhizophagus irregularis, sur la croissance de la tomate, espèce d’intérêt agronomique. Une augmentation du taux de germination, un accroissement de la hauteur des jeunes plantules et des modifications au niveau du système racinaire des plants adultes, en particulier des variations de la densité du tissu racinaire, ont été observés en réponse à l’inoculation simple par les consortia ou à leur interaction double ou tripartite avec le RP et/ou le CMA. Le profil taxonomique du microbiote natif avant et après apport des inoculants et du RP a été caractérisé. En conclusion, l’ensemble de nos travaux s’appuyant sur l’analyse des données environnementales, combinées aux données de laboratoire sur l’inoculation de plantes par des isolats bactériens, notamment d’origine minière, soulignent l’intérêt mais aussi la complexité de l’élaboration d’inoculants microbiens promoteurs de la croissance des plantes, solubilisateurs de P. / In order to reduce the use of chemical fertilizers and their environmental footprint, the production of bioinoculants based on phosphorus solubilizing rhizospheric bacteria (PSB) is a promising biotechnology. When combined with rock phosphate (RP), it could be an eco-responsible alternative to improve rhizospheric soil fertility, especially by increasing bioavailable phosphorus (P). To address this major environmental issue, studying soil microbial biodiversity and its interactions with RP is required. Thus, the objective of this thesis is to characterize, from a taxonomic point of view, the bacterial and fungal communities associated with the root and rhizospheric compartments of native plants in singular, little explored environments, located in former mining sites rich in RP. Illumina MiSeq sequencing of ribosomal gene amplicons of the different microbial groups, then taxonomic assignment of the sequences grouped in ASV, allowed us to highlight comparable microbial richness and diversity indexes of soils despite their differences in RP and P contents. As well, a high degree of similarity between the community profiles was identified at a high taxonomic level, with a marked prevalence of the phyla Actinobacteriota and Ascomycota, and of the order Glomerales for the arbuscular mycorrhizal fungi (AMF) community. At a lower taxonomic level, a microbial core of 26 mycorrhizal ASV, persistent across the RP and P gradient, was also documented. However, statistical analysis of the environmental data allowed us to identify indicator ASV for PR-enriched versus non-rich habitats for each microbial community studied. All together, these original results contributed to rule on a minor influence of RP and P levels on the microbial community’s profiles across the studied sites, and raised the questions of the ecological significance of the prevalence of certain taxa regarding the site’s mining history, its ecological restoration, as well as the life strategies and functional attributes of the dominant taxa. In addition, a collection of PSB was made from mine site root isolates, or from isolates associated with spores and mycorrhizal hyphae trapped in contact with PR inputs deposited in the rhizosphere of agronomic plants. These root or hyphospheric PSB, tested elsewhere for several additional plant growth-promoting traits, were assigned to three phyla: Proteobacteria, Firmicutes, and, to a lesser extent, Actinobacteria; Bacillus and Pseudomonas were the predominant genera. Finally, from these isolates, two bacterial consortia with different plant growth promoting (PGP) traits were constituted and tested, alone or in combination with RP inputs and/or a mycorrhizal inoculum based on Rhizophagus irregularis, on the growth of tomato, a species with an agronomic interest. An increase in germination rate or height of young seedlings, and changes in the root system of adult plants, particularly changes in root tissue density, were observed in response to single inoculation by the consortia or to their dual or tripartite interaction with RP and/or AMF. The taxonomic profile of the native microbiota before and after inoculants and RP input was characterized. In conclusion, our work based on the analysis of environmental data, combined with laboratory data from plant inoculation experiments by bacterial isolates, especially of mining origin, underlines the interest but also the complexity of the development of microbial inoculants promoting plant growth, solubilizers of P.

Made available in DSpace on 2014-06-11T19:26:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-19Bitstream added on 2014-06-13T19:33:25Z : No. of bitstreams: 1 inui_rn_me_jabo.pdf: 573335 bytes, checksum: 56d99ae5d640b68032476e6b74cf679f (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A cultura da cana-de-açúcar (Saccharum spp.) apresenta grande importância econômica para o Brasil. Dessa forma, para propiciar boas condições de desenvolvimento e produtividade, deve-se dar grande importância ao suprimento de fósforo. Bactérias solubilizadoras de fósforo (BSF) vêm sendo utilizadas como biofertilizantes comerciais, trazendo benefícios à agricultura. A seleção de bactérias com capacidade de solubilização do fósforo pode ser feita através de caracterizações genotípicas. Os objetivos deste trabalho foram isolar e caracterizar bactérias solubilizadoras de fosfato provenientes de solos sob cultivo de cana-de-açúcar por meio do sequenciamento do gene 16S rRNA e da região BOX-A1R. Além disso, foi realizada avaliação da atividade microbiana sobre a solubilização das fontes de fosfato até 168 horas. O sequenciamento permitiu identificar gêneros como Burkholderia e Enterobacteriaceae, conhecidos quanto à solubilização. Os isolados identificados como Arthrobacter e Labrys apresentam capacidade para biodegradação de compostos tóxicos ao ambiente. O fosfato de cálcio foi a fonte mais solubilizada. Os isolados Burkholderia sp. (A5I55), Candidatus B. verschuerenii (A9IG), Enterobacter sp. (USC8) e E. hormaechei subsp. steigerwaltii (USC7) apresentaram resultados semelhantes a B. ferrariae. As bactérias-padrão obtiveram os melhores resultados para a solubilização das fontes fosfatadas. Candidatus B. verschuerenii (A9IG) e Burkholderia sp. (A3I14) e B. gladioli (A6I8) apresentaram os melhores valores para solubilização das rochas fosfatadas. Além disso, foi detectada a produção de AIA pelos isolados do gênero Enterobacter (USC7 e USC8) Labrys portucalensis (A5I42) e Burkholderia sp. (A5I55).Assim estes isolados poderiam ser indicados em testes para solubilização em culturas de campo. / The culture of sugarcane (Saccharum spp.) has a great economic importance to Brazil. Thus, providing good conditions for development and productivity should be given great importance to phosphorus supply. Phosphate solubilizing bacteria - PSB, have been used as biofertilizers, bringing benefits to agriculture. Selection of phosphorus solubilizing bacteria can be done by genetic characterization. The aim of this work is to isolate and characterize PSB from sugarcane productive soils through the sequencing of 16S rRNA gene and BOX-A 1R genomic regions. Furthermore, the microbial activity of phosphate source was assessment until 168 hours. The sequencing has identified genus as Burkhloderia and Enterobacteriaceae, known as PSB. The isolates identified as Arthrobacter and Labrys have the capacity to biodegradation of toxic compounds in the environment. The calcium phosphate was the source more soluble. Isolates Burkholderia sp. (A5I55), Candidatus B. verschuerenii (A9IG), Enterobacter sp. (USC8) and E. hormaechei subsp. steigerwaltii (USC7) showed results similar to B. ferrariae. The bacteria-standards showed the best results for phosphates sources solubilization. Candidatus B. verschuerenii (A9IG) and Burkholderia sp. (A3I14) and B. gladioli showed the best values for solubilization of rock phosphate. Furthermore, the production of AIA was detected by Enterobacter (USC7 and USC8), Labrys portucalensins (A5I42) and Burkholderia sp. (A5I55). Therefore these isolates could be recommended for phosphorus solubilization tests and auxin producing in fieldcrops.