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1.
PLoS One ; 19(3): e0298186, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38536896

RESUMO

The transport of methane from sediments to the atmosphere by rising gas bubbles (ebullition) can be the dominant, yet highly variable emission pathway from shallow aquatic ecosystems. Ebullition fluxes have been reported to vary in space and time, as methane production, accumulation, and bubble release from the sediment matrix is affected by several physical and bio-geochemical processes acting at different timescales. Time-series analysis and empirical models have been used for investigating the temporal dynamics of ebullition and its controls. In this study, we analyzed the factors governing the temporal dynamics of ebullition and evaluated the application of empirical models to reproduce these dynamics across different timescales and across different aquatic systems. The analysis is based on continuous high frequency measurements of ebullition fluxes and environmental variables in a mesotrophic subtropical and polymictic freshwater reservoir. The synchronization of ebullition events across different monitoring sites, and the extent to which ebullition was correlated to environmental variables varied throughout the three years of observations and were affected by thermal stratification in the reservoir. Empirical models developed for other aquatic systems could reproduce a limited fraction of the variability in observed ebullition fluxes (R2 < 0.3), however the predictions could be improved by considering additional environmental variables. The model performance depended on the timescale. For daily and weekly time intervals, a generalized additive model could reproduce 70 and 96% of ebullition variability but could not resolve hourly flux variations (R2 = 0.19). Lastly, we discuss the potential application of empirical models for filling gaps in ebullition measurements and for reproducing the main temporal dynamics of the fluxes. The results provide crucial information for emission estimates, and for the development and implementation of strategies targeting at a reduction of methane emissions from inland waters.


Assuntos
Ecossistema , Metano , Metano/análise , Água Doce , Atmosfera
2.
Arq. Inst. Biol ; 81(4): 351-359, Oct.-Dec. 2014. tab
Artigo em Português | LILACS, VETINDEX | ID: biblio-1015895

RESUMO

O objetivo deste trabalho foi testar a eficiência do uso do kitQuickStix™ para a identificação de esporos de Phakopsora pachyrhizi, agente causal da ferrugem asiática da soja, coletados por meio de um coletor SIGA. O kit QuickStix é capaz de detectar a presença de Phakopsora pachyrhizi nos estágios iniciais da infecção foliar, determinando a presença ou ausência do patógeno na amostra. Ele captura propágulos de fungos presentes no ar, que são identificados ou quantificados por varredura de lâminas em microscópio óptico comum. Foram testados diferentes números de esporos com 4, 8 e 12 gotas da solução extratora. Para os resultados positivos, foram avaliados a intensidade da linha de teste e o tempo para sua ocorrência. O kit foi capaz de detectar pequenas quantidades de esporos, sendo que a proporção de resultados positivos foi diretamente proporcional ao número de esporos e inversamente proporcional ao total de gotas. A porção adequada de gotas da solução extratora foi de quatro, pois apresentou mais resultados positivos para todas as classes dos números de esporos. Não foi possível observar uma diferença entre o tempo para a ocorrência dos resultados positivos aos diferentes tratamentos. A intensidade da linha de teste foi superior para as classes com mais esporos.(AU)


The aim of this study was to test the efficiency of QuickStix™ kit use for identification of Phakopsora pachyrhizi spores, which are the causal agents of Asian soybean rust, collected by "SIGA" spores collector. This kit is capable of detecting the presence of Phakopsora pachyrhizi in the early stages of leaf infection by determining the presence or absence of pathogen in the sample. It captures propagules of fungi present in the air that are identified or quantified by scanning blades in ordinary optical microscope. Different numbers of spores were tested with 4, 8 and 12 drops of extraction solution. For positive results, intensity of the test line and time for its occurrence were evaluated. The kit was able to detect small amounts of spores and the proportion of positive results was directly proportional to the number of spores and inversely proportional to the amount of drops. The proper portion of drops of extraction solution was four, as it showed more positive results for all classes of numbers of spores. No difference was found between the time to occurrence of positive results for the different treatments. The intensity of the test line was higher for classes with larger numbers of spores.(AU)


Assuntos
Glycine max , Phakopsora pachyrhizi , Esporos Bacterianos , Micoses
3.
Ciênc. rural ; 42(8): 1341-1346, ago. 2012. ilus, tab
Artigo em Português | LILACS | ID: lil-647776

RESUMO

O objetivo do trabalho foi avaliar o efeito dos fungicidas difenoconazole e carboxin + thiram aplicados em sementes de trigo cultivares 'CD 104' e 'OR Mirante', inoculadas com Cochliobolus sativus. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 2x3 (2 cultivares e 2 fungicidas + testemunha sem controle) em sete repetições. O fungo foi isolado e reproduzido em meio de cultura BDA (batata-dextrose-ágar) e, posteriormente, multiplicado em sementes de trigo pré-cozidas, constituindo a fonte de inóculo. As avaliações foram do número de lesões na folha basal de cinco plantas por vaso aos 22, 25, 29, 31, 35 e 38 dias após a semeadura (DAS) e aos 41 dias foram avaliados o comprimento (cm), massa fresca (g) e seca (g) da parte aérea e das raízes. A partir das avaliações do número de lesões, também foi calculada a área abaixo da curva de progresso da doença (AACPD), cujos dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey, a 5% de probabilidade. A cultivar 'CD 104' foi mais suscetível ao patógeno do que 'OR Mirante'; difenoconazole foi eficiente no controle da doença na parte aérea, enquanto carboxin + thiram se igualou à testemunha; os dois fungicidas interferiram negativamente no desenvolvimento das plantas, uma vez que as médias de comprimento, massa fresca e seca da parte aérea e das raízes obtidas das sementes tratadas é inferior à média das sementes não tratadas.


The objective of this research was to evaluate the effect of fungicides difenoconazole and carboxin + thiram applied in seed wheat cultivars 'CD 104' and 'OR Mirante', inoculated with Cochliobolus sativus. The experimental design was completely randomized in a 2x3 factorial design (2 cultivars and 2 fungicides + untreated control) in seven replications. The fungi was isolated and reproduced in PDA culture medium (potato-dextrose-agar) and subsequently multiplied in seeds of wheat pre-cooked and is the source of inoculum. The evaluations were the number of lesions in the basal leaf of five plants per pot at 22, 25, 29, 31, 35 and 38 days after sowing (DAS), and at 41DAS were evaluated the length (cm), fresh weight (g) and dry weight (g) of shoot and root. From the evaluations of the number of lesions was also calculated the area under the disease progress curve (AUDPC). The datas were subjected to analysis of variance and means were compared by Tukey test at 5% probability. The 'CD 104' cultivar was more susceptible to the pathogen than 'OR Mirante'; difenoconazole was efficient to control the disease as carboxin + thiram equaled the witness; both fungicides interfered negatively on plant development, since the average length, fresh weight and dry shoot and root obtained from treated seed is lower than the untreated seeds.

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