Made available in DSpace on 2014-06-11T19:23:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-09Bitstream added on 2014-06-13T18:50:27Z : No. of bitstreams: 1 silva_efl_me_jabo.pdf: 383641 bytes, checksum: 59b012609413039433f00a07564e3f1e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este estudo teve como objetivo avaliar o efeito de doses crescentes de lodo de esgoto (LE), aplicadas por treze anos em Latossolo Vermelho eutroférrico, nos atributos biológicos e bioquímicos, nos teores de elementos-traço do solo e no acúmulo destes pelas plantas daninhas. O experimento foi conduzido em condições de campo, em Jaboticabal-SP, utilizando-se delineamento em blocos casualizados com quatro doses de LE (0, 5, 10 e 20 Mg ha-1, base seca) e cinco repetições. As amostras de solo (0 a 10 cm), plantas daninhas e resíduos culturais foram coletadas em outubro de 2010, 130 dias após a colheita do milho. Os valores do carbono da biomassa microbiana não variaram em função das doses de LE, porém os valores de respiração basal e quociente metabólico foram maiores nas doses 10 e 20 Mg ha-1. Para o quociente microbiano, o menor valor foi observado na dose 0 Mg ha-1 de LE. Os teores totais de Cd e Cr no solo não variaram em função das doses de LE. De forma contrária, os teores totais de Ni e Pb no solo aumentaram proporcionalmente até a dose 10 Mg ha-1. A atividade das enzimas desidrogenase, arilsulfatase, celulase e urease não variou. Porém a atividade hidrolítica do diacetato de fluoresceína (FDA) e da fosfatase ácida foram maiores na dose 20 Mg ha-1. Em relação às plantas daninhas e a palha do milho a adição de LE por longo período causou efeitos semelhantes nos valores da produção de matéria seca e nos teores totais de Cd, Cr, Ni e Pb. Entretanto, os teores acumulados de Cd, Ni e Pb na parte aérea dos grupos de planta daninha aumentaram até a dose 10 Mg ha-1 diferindo da testemunha. O LE causou atividade biológica negativa no solo nas doses 10 e 20 Mg ha-1. A atividade foi indicada pelos aumentos na respiração basal, na atividade hidrolítica do FDA e na atividade da fosfatase ácida. Entretanto, o aumento do quociente metabólico e a diminuição do quociente microbiano indicaram estar havendo estresse / This study aimed to evaluate the effect of increasing doses of sewage sludge (SS), applied for thirteen years in Oxisol in biological and biochemical attributes, the levels of trace elements in soil and accumulation of weed. The experiment was conducted under field conditions in Jaboticabal, using a randomized block design with four doses of SS (0, 5, 10 and 20 Mg ha-1, dry basis) and five replicates. Soil samples (0-10 cm), weeds and crop residues were collected in October 2010, 130 days after the corn harvest. The values of microbial biomass carbon did not vary with the doses of SS, but the values of basal respiration and metabolic quotient were higher in doses 10 and 20 Mg ha-1. For the microbial quotient, the lowest value was observed at the dose 0 Mg ha-1 SS. Total concentrations of Cd and Cr in the soil did not vary with the doses of LE. Conversely, the total concentration of Ni and Pb in soil increased proportionally to the dose of 10 Mg ha-1. The activity of enzymes dehydrogenase, arylsulfatase, cellulase and urease did not change. However, the hydrolytic activity of the fluorescein diacetate (FDA) and acid phosphatase were higher in the dose 20 Mg ha-1. In relation to weeds and straw corn, adding SS for a long period caused similar effects on the values of dry matter production and total contents of Cd, Cr, Ni and Pb. However, the accumulated contents of Cd, Ni and Pb in the aerial part of the weed groups increased until the dose of 10 Mg ha-1 differed from the control. The SS has caused negative biological activity in soil at doses 10 and 20 Mg ha-1. The activity was indicated by increases in respiration, FDA hydrolytic activity and acid phosphatase activity. However, the increase metabolic quotient and decrease of the ratio having indicated that microbial stress

Orientador: Wanderley Jose de Melo / Coorientador: Gabriel Maurício Peruca de Melo / Banca: Ademir Sérgio Ferreira de Araújo / Banca: Ely Nahas / Resumo: Este estudo teve como objetivo avaliar o efeito de doses crescentes de lodo de esgoto (LE), aplicadas por treze anos em Latossolo Vermelho eutroférrico, nos atributos biológicos e bioquímicos, nos teores de elementos-traço do solo e no acúmulo destes pelas plantas daninhas. O experimento foi conduzido em condições de campo, em Jaboticabal-SP, utilizando-se delineamento em blocos casualizados com quatro doses de LE (0, 5, 10 e 20 Mg ha-1, base seca) e cinco repetições. As amostras de solo (0 a 10 cm), plantas daninhas e resíduos culturais foram coletadas em outubro de 2010, 130 dias após a colheita do milho. Os valores do carbono da biomassa microbiana não variaram em função das doses de LE, porém os valores de respiração basal e quociente metabólico foram maiores nas doses 10 e 20 Mg ha-1. Para o quociente microbiano, o menor valor foi observado na dose 0 Mg ha-1 de LE. Os teores totais de Cd e Cr no solo não variaram em função das doses de LE. De forma contrária, os teores totais de Ni e Pb no solo aumentaram proporcionalmente até a dose 10 Mg ha-1. A atividade das enzimas desidrogenase, arilsulfatase, celulase e urease não variou. Porém a atividade hidrolítica do diacetato de fluoresceína (FDA) e da fosfatase ácida foram maiores na dose 20 Mg ha-1. Em relação às plantas daninhas e a palha do milho a adição de LE por longo período causou efeitos semelhantes nos valores da produção de matéria seca e nos teores totais de Cd, Cr, Ni e Pb. Entretanto, os teores acumulados de Cd, Ni e Pb na parte aérea dos grupos de planta daninha aumentaram até a dose 10 Mg ha-1 diferindo da testemunha. O LE causou atividade biológica negativa no solo nas doses 10 e 20 Mg ha-1. A atividade foi indicada pelos aumentos na respiração basal, na atividade hidrolítica do FDA e na atividade da fosfatase ácida. Entretanto, o aumento do quociente metabólico e a diminuição do quociente microbiano indicaram estar havendo estresse / Abstract: This study aimed to evaluate the effect of increasing doses of sewage sludge (SS), applied for thirteen years in Oxisol in biological and biochemical attributes, the levels of trace elements in soil and accumulation of weed. The experiment was conducted under field conditions in Jaboticabal, using a randomized block design with four doses of SS (0, 5, 10 and 20 Mg ha-1, dry basis) and five replicates. Soil samples (0-10 cm), weeds and crop residues were collected in October 2010, 130 days after the corn harvest. The values of microbial biomass carbon did not vary with the doses of SS, but the values of basal respiration and metabolic quotient were higher in doses 10 and 20 Mg ha-1. For the microbial quotient, the lowest value was observed at the dose 0 Mg ha-1 SS. Total concentrations of Cd and Cr in the soil did not vary with the doses of LE. Conversely, the total concentration of Ni and Pb in soil increased proportionally to the dose of 10 Mg ha-1. The activity of enzymes dehydrogenase, arylsulfatase, cellulase and urease did not change. However, the hydrolytic activity of the fluorescein diacetate (FDA) and acid phosphatase were higher in the dose 20 Mg ha-1. In relation to weeds and straw corn, adding SS for a long period caused similar effects on the values of dry matter production and total contents of Cd, Cr, Ni and Pb. However, the accumulated contents of Cd, Ni and Pb in the aerial part of the weed groups increased until the dose of 10 Mg ha-1 differed from the control. The SS has caused negative biological activity in soil at doses 10 and 20 Mg ha-1. The activity was indicated by increases in respiration, FDA hydrolytic activity and acid phosphatase activity. However, the increase metabolic quotient and decrease of the ratio having indicated that microbial stress / Mestre

Currently, 74% of cotton acres in the United States are planted with glyphosatetolerant varieties. The average glyphosate-tolerant cotton crop is treated with glyphosate 2.1 times each year in addition to other herbicides, insecticides, and fungicides. The primary objectives of this research were to: 1) describe the influence of glyphosate and pesticides commonly applied at or near the time of cotton planting on soil microbial activity and biomass; 2) study the effect of glyphosate on fluometuron degradation; 3) evaluate the response of Rhizoctonia solani to glyphosate and fluometuron; 4) study changes in glyphosate metabolism that occur as a result of repeated glyphosate applications; and 5) define shifts in the soil microbial community. Additionally, methods for accelerated solvent extraction (ASE) of fluometuron from soils were developed. In one experiment, the addition of glyphosate reduced C-mineralization in soils treated with fluometuron, aldicarb, or mefenoxam + PCNB formulations. However, in a second experiment, C-mineralization increased when glyphosate was applied with fluometuron relative to fluometuron applied alone. Accelerated solvent extraction was used in experiments which demonstrated that application of glyphosate with fluometuron increased the rate of fluometuron degradation in soil relative to fluometuron alone. When glyphosate was added to minimal medium, degradation of fluometuron by R. solani was reduced and less fungal biomass was produced. The total amount of 14C-glyphosate mineralized was reduced when glyphosate was applied 5 times relative to 1, 2, 3, or 4 times. Incorporation of 14Cglyphosate residues into soil microbial biomass was greater following five glyphosate applications than one application 3 and 7 days after application (DAA). Soil fatty acid methyl ester (FAME) profiles were altered by five glyphosate applications relative to one application. Additionally, FAMEs common to gram-negative bacteria were present in higher concentrations following five applications relative to 1, 2, 3, or 4 applications both 7 and 14 DAA. These studies indicated that: 1) glyphosate altered the soil microbial response to other pesticides; 2) fluometuron-degrading microorganisms in soil responded differently to glyphosate; 3) changes in the dissipation or distribution of glyphosate following repeated glyphosate applications were associated with changes in the structural diversity of the soil microbial community.

Les modèles disponibles prévoient que le changement climatique entrainera de plus longues périodes de sécheresse et/ou une diminution globale des précipitations en région méditerranéenne. Ces changements affecteront probablement la composition des communautés, la biodiversité et les processus écosystémiques. Cependant, les effets de la biodiversité, des changements de précipitations et de leurs interactions sur le fonctionnement des écosystèmes restent mal connus. Dans cette thèse, j’ai cherché à quantifier le rôle de la diversité des plantes dans la réponse d’un écosystème de garrigue méditerranéenne à une diminution de la disponibilité en eau, avec un intérêt particulier pour les processus souterrains, tels que le fonctionnement de la communauté microbienne du sol et les réponses fonctionnelles des racines.Afin d’étudier les conséquences d’une sécheresse sévère répétée sur la croissance végétale, et particulièrement racinaire, j’ai mis en place une expérience en rhizotrons, en conditions semi-contrôlées. Dans chaque rhizotron ont été plantées deux individus d’une même ou de différentes espèces des trois espèces dominantes de notre site d’étude (Quercus coccifera, Cistus albidus, Brachypodium retusum). Les sécheresses sévères répétées ont eu un effet négatif sur la survie des deux espèces ligneuses mais pas sur celle de l’herbacée. La compétition interspécifique a généralement augmenté la survie de C. albidus et B. retusum comparé à la compétition intraspécifique. A l’inverse, la compétition interspécifique a diminué la survie de Q. coccifera. De la même manière, les traits morphologiques racinaires ont été plus affectés par l’identité des espèces voisines que par le traitement de sécheresse. Les profils métaboliques des communautés microbiennes (CLPP) de sol associé aux racines n’ont pas été affectés par les traitements de sécheresse ni par l’identité des espèces végétales. Cependant, avec l’augmentation de la profondeur du sol, les CLPP ont augmentés mais avec une utilisation de ressources moins diversifiées. Ces résultats suggèrent que la composition d’espèces végétales de la garrigue méditerranéenne étudiée a un effet plus important sur la croissance, la variabilité intraspécifique des traits racinaires et la survie que les sécheresses sévères répétées.Dans le contexte d’un projet collaboratif (CLIMED), j’ai utilisé un gradient naturel de diversité d’espèces d’arbustes d’un écosystème de garrigue méditerranéenne ayant reçu un traitement d’exclusion de pluie partielle (-12% de précipitation). Cette expérience m’a permis d’étudier les réponses des profils métaboliques des communautés microbiennes du sol CLPP à une diminution des précipitations ainsi qu’à un changement de diversité des litières végétales décomposant au sol comme ressource clé pour les microorganismes hétérotrophiques du sol, pendant deux ans. Alors que l’exclusion de pluie n’a eu qu’un impact mineur sur la diversité des substrats métabolisés par les communautés microbiennes, la richesse spécifique de la litière a favorisé l’activité microbienne du sol en augmentant la diversité catabolique de la communauté microbienne du sol. Ces résultats suggèrent que les effets indirects du changement climatique sur la composition et la richesse des espèces végétales pourraient avoir des conséquences plus importantes pour le fonctionnement microbien du sol que la réduction des précipitations prévue dans l’écosystème de garrigue méditerranéenne étudié.Mes deux études, de terrain et en rhizotron, ont clairement montrées que l’identité et la diversité des espèces végétales peuvent être plus importantes pour le fonctionnement de ces garrigues méditerranéennes qu’une augmentation des sécheresses. Je conclus que les changements de composition et de diversité d’espèces végétales induits par le changement climatique peuvent avoir des conséquences plus importantes pour le fonctionnement des garrigues méditerranéennes que les effets directs d’une modification des précipitations / Longer drought periods and/or overall less precipitation are thought to be major consequences of ongoing climate change in the Mediterranean region. These changes in the water regime will likely affect community composition, biodiversity and ecosystem processes, but very little is known about how biodiversity and changes in precipitation interactively affect ecosystem functioning. In my PhD thesis, I aimed to quantify the role of plant diversity in the response of Mediterranean shrubland ecosystem to a decrease in water availability, with a particular interest in belowground processes, such as soil microbial community functioning and functional responses in plant roots.I used a rhizotron approach under partially controlled conditions to study plant growth responses to repetitive severe droughts, with a particular focus on root growth. Two individuals of the same species or in all possible combinations of the three dominating species at our field site (Quercus coccifera, Cistus albidus, Brachypodium retusum) were grown together in a rhizotron. Repetitive severe droughts had a negative effect on survival of the two woody species (Q. coccifera, C. albidus), but not of the grass B. retusum. Interspecific competition generally increased survival of C. albidus and B. retusum compared to monospecific competition. Conversely, interspecific competition decreased the survival of Q. coccifera. Likewise, I found that root morphological traits were mostly affected by the neighbor species identity rather than by severe drought. The community level physiological profiles (CLPPs) of root associated soil microbial communities did not differ between drought treatments and were also not affected by plant species identity. However, CLPPs changed towards more total microbial activities but less diverse resource use at increasing soil depth. Collectively these results suggest that plant species composition of the studied Mediterranean shrubland has a stronger effect on growth, intraspecific variability in root traits and survival than repetitive severe droughts.In the context of a larger collaborative project (CLIMED), I used a natural gradient of shrub species diversity in a Mediterranean shrubland ecosystem (garrigue) to which a permanent partial rain exclusion treatment (12% less precipitation) was added. This field experiment allowed me to study the responses of soil microbial community level physiological profiles (CLPPs) to reduced precipitation and to a change plant-produced leaf litter material decomposing on the ground as a key resource for heterotrophic soil microorganisms over two years. While rain exclusion had only a minor impact on the diversity of substrates metabolized by the microbial communities, litter species richness promoted global soil microbial activity by increased catabolic diversity of the soil microbial community. These results suggest that indirect climate change effects on plant species composition and richness might have more important consequences for soil microbial functioning than reduced precipitation in the studied Mediterranean shrubland ecosystem.Both, the field study of soil microbial functioning and the rhizotron study of plant growth and survival clearly showed that plant species identity and diversity may be more important for the functioning of these Mediterranean shrublands than increased drought. I conclude that climate change induced shifts in plant species composition and diversity may have more important consequences for the functioning of Mediterranean shrublands than the direct effects of altered precipitation.