bluuebunny/crossref_metadata_2025 huggingface dataset:
Fear Conditioning Enhances Gamma Oscillations and Their Entrainment of Neurons Representing the Conditioned Stimulus
Authors: Headley Drew B. , Weinberger Norman M.
Published: March 2013

Learning alters the responses of neurons in the neocortex, typically strengthening their encoding of behaviorally relevant stimuli. These enhancements are studied extensively in the auditory cortex by characterizing changes in firing rates and evoked potentials. However, synchronous activity is also important for the processing of stimuli, especially the relationship between gamma oscillations in the local field potential and spiking. We investigated whether tone/shock fear conditioning in rats, a task known to alter responses in auditory cortex, also modified the relationship between gamma and unit activity. A boost in gamma oscillations developed, especially at sites tuned near the tone, and strengthened across multiple conditioning sessions. Unit activity became increasingly phase-locked to gamma, with sites tuned near the tone developing enhanced phase-locking during the tone, whereas those tuned away maintained a tendency to decrease their phase-locking. Enhancements in the coordination of spiking between sites tuned near the tone developed within the first conditioning session and remained throughout the rest of training. Enhanced cross-covariances in unit activity were strongest for subjects that exhibited robust conditioned fear. These results illustrate that changes in sensory cortex during associative learning extend to the coordination of neurons encoding the relevant stimulus, with implications for how it is processed downstream.
The Rat Prefrontostriatal System Analyzed in 3D: Evidence for Multiple Interacting Functional Units
Authors: Mailly Philippe , Aliane Verena , Groenewegen Henk J. , Haber Suzanne N. , Deniau Jean-Michel
Published: March 2013

Previous studies in monkeys disclosed a specific arrangement of corticostriatal projections. Prefrontal and premotor areas form dense projection fields surrounded by diffuse terminal areas extending outside the densely innervated region and overlapping with projections from other areas. In this study, the mode of prefrontostriatal innervation was analyzed in rats using a 3D approach. Following injections of tracers in defined cortical areas, 3D maps from individual cases were elaborated and combined into a global 3D map allowing us to define putative overlaps between projection territories. In addition to providing a detailed 3D mapping of the topographic representation of prefrontal cortical areas in the rat striatum, the results stress important similarities between the rodent and primate prefrontostriatal projections. They share the dual pattern of focal and diffuse corticostriatal projections. Moreover, besides segregated projections consistent with parallel processing, the interweaving of projection territories establishes specific patterns of overlaps spatially organized along the dorsoventral, mediolateral, and anteroposterior striatal axis. In particular, the extensive striatal projection fields from the prelimbic and anterior cingulate areas, which partly overlap the terminal fields from medial, orbital, and lateral prefrontal cortical areas, provide putative domains of convergence for integration between reward, cognitive, and motor processes.
Hierarchical Learning Induces Two Simultaneous, But Separable, Prediction Errors in Human Basal Ganglia
Authors: Diuk Carlos , Tsai Karin , Wallis Jonathan , Botvinick Matthew , Niv Yael
Published: March 2013

Studies suggest that dopaminergic neurons report a unitary, global reward prediction error signal. However, learning in complex real-life tasks, in particular tasks that show hierarchical structure, requires multiple prediction errors that may coincide in time. We used functional neuroimaging to measure prediction error signals in humans performing such a hierarchical task involving simultaneous, uncorrelated prediction errors. Analysis of signals in a priori anatomical regions of interest in the ventral striatum and the ventral tegmental area indeed evidenced two simultaneous, but separable, prediction error signals corresponding to the two levels of hierarchy in the task. This result suggests that suitably designed tasks may reveal a more intricate pattern of firing in dopaminergic neurons. Moreover, the need for downstream separation of these signals implies possible limitations on the number of different task levels that we can learn about simultaneously.
Mathematical modelling in developmental biology
Authors: Vasieva Olga , Rasolonjanahary Manan'Iarivo , Vasiev Bakhtier
Published: March 2013

In recent decades, molecular and cellular biology has benefited from numerous fascinating developments in experimental technique, generating an overwhelming amount of data on various biological objects and processes. This, in turn, has led biologists to look for appropriate tools to facilitate systematic analysis of data. Thus, the need for mathematical techniques, which can be used to aid the classification and understanding of this ever-growing body of experimental data, is more profound now than ever before. Mathematical modelling is becoming increasingly integrated into biological studies in general and into developmental biology particularly. This review outlines some achievements of mathematics as applied to developmental biology and demonstrates the mathematical formulation of basic principles driving morphogenesis. We begin by describing a mathematical formalism used to analyse the formation and scaling of morphogen gradients. Then we address a problem of interplay between the dynamics of morphogen gradients and movement of cells, referring to mathematical models of gastrulation in the chick embryo. In the last section, we give an overview of various mathematical models used in the study of the developmental cycle ofDictyostelium discoideum, which is probably the best example of successful mathematical modelling in developmental biology.
First principles calculations and experiments for Cu-Mg/Li hydrides negative electrodes
Authors: Braga M.H. , Stockhausen V. , Wolverton M. , Ferreira J.A. , Oliveira J.C.E.
Published: March 2013

We have studied CuLi0.08Mg1.92 and determined that the compound reacts with hydrogen to form CuLi0.08Mg1.92H5 [1]. Additionally, we have proposed the compound as a negative electrode material which is the main purpose of the present study. Moreover, we have observed that the latter compound acts as a catalyst in the formation of MgH2, LiH, TiH2 [2] and hydrogen desorption. In this work, first principles and phonon calculations were performed in order to establish the reactions occurring at the negative electrode of a Li conversion battery in presence of CuLi0.08Mg1.92H5 and (Li) – solid solution of Mg in Li – approximately Li2Mg3. We have calculated the minimum theoretical specific capacity to be 1156 mAh/g (for an anode with 100% of CuLi0.08Mg1.92H5) and the △Eeq = 0.81 V (vs. Li+/Li) at 298 K. Furthermore, we have determined all the reactions occurring in the referred system and its sequence using Inelastic Incoherent Neutron Scattering (IINS) and X-Ray Diffraction (XRD).
Pré-melhoramento de milho quanto à resistência a enfezamentos
Authors: Teixeira Flavia França , Costa Flaviane Malaquias , Sábato Elizabeth de Oliveira , Leite Carlos Eduardo Prado , Meirelles Walter Fernandes , Guimarães Claudia Teixeira , Belicuas Silvia Neto Jardim
Published: March 2013

O objetivo deste trabalho foi selecionar famílias de milho derivadas do retrocruzamento entre o composto "NAP Corn Stunt" (genitor doador) e linhagens-elite (genitores recorrentes), quanto à produtividade de grãos e à resistência a enfezamentos, e avaliar a eficiência do emprego de marcadores moleculares para avaliação fenotípica na seleção de genótipos com alta produtividade de grãos. Foram avaliados 100 genótipos, em cinco condições ambientais, na safra agrícola 2009/2010. Foram selecionadas famílias RC1F2, que aliam a alta produtividade dos genitores recorrentes à resistência aos enfezamentos, presente no genitor doador. As famílias selecionadas quanto ao desempenho agronômico e à resistência aos enfezamentos foram: L228-3-324-S, L228-3-237-R, L228-3-109-R, que foram indicadas para cruzamentos com linhagens do grupo heterótico duro; e L3-422-R e L3-586-R, que foram indicadas para cruzamentos com linhagens do grupo heterótico dentado. Na seleção de genótipos de alta produtividade de grãos, a seleção assistida por marcadores moleculares não é eficiente para a recuperação do genótipo do pai recorrente, em comparação à avaliação fenotípica.
Qualidade de vida de doentes esofagectomizados: adenocarcinoma versus carcinoma epidermoide
Authors: Pereira Maricilda Regina , Lopes Luiz Roberto , Andreollo Nelson Adami
Published: March 2013

OBJETIVO: Avaliar e comparar a qualidade de vida de pacientes esofagectomizados para tratamento de adenocarcinoma da junção esofagogástrica e de carcinoma epidermoide. MÉTODOS: estudo transversal no pós-operatório de doentes esofagectomizados por adenocarcinoma da junção esofagogástrica (Adenoca) e carcinoma epidermóide (CEC), empregando o questionário SF-36 aplicado em 24 pacientes (10 por Adenoca e 14 por CEC), a partir do 5º mês de pós-operatório, incluindo os sintomas clínicos e a variação de peso. RESULTADOS: A avaliação da QV mostrou melhor resultado de capacidade funcional (p=0,018) para o grupo Adenoca. Houve correlação entre os domínios "saúde mental" e "limitação por aspectos emocionais" (p=0,003) e entre "dor" e "limitação por aspectos físicos" (p=0,003) nos dois tipos histológicos. A perda de peso foi maior nos esofagectomizados por Adenoca (45,9Kg), sem diferença significativa entre o IMC atual (p>0,66). A disfagia foi relatada por 83,3% dos pacientes, a anorexia por 58,3%, a dificuldade de mastigação por 42%, a náuseas e os vômitos por 41,7% e a diarréia por 29,2%, sem correlação com a QV relatada (p>0,05). CONCLUSÃO: O escore mais alto para capacidade funcional indica que o paciente com Adenoca foi capaz de realizar todo tipo de atividade física, incluindo as mais vigorosas em um nível maior que o paciente com CEC. Alguns sintomas persistiram no pós-operatório, porém não interferiram na qualidade de vida dos pacientes.
Impacto do volume de gordura aspirado na resistência insulínica após lipoaspiração
Authors: Oliveira Sérgio de Souza , Cibantos Jubert Sanches , Ripari Wagner Targa , Aguilar-Nascimento José Eduardo de
Published: March 2013

OBJETIVO: investigar a resistência insulínica imposta pela lipoaspiração, correlacionando sua intensidade com a extensão da operação. MÉTODOS: A amostra foi formada de 20 pacientes do sexo feminino sem comorbidades, com idade entre 21 e 43 anos, índice de massa corporal entre 19 e 27 Kg/m², submetidas à lipoaspiração isolada ou associada à prótese de mamas. Foram coletados os indicadores de resistência insulínica no início e término da cirurgia para o cálculo do Homeostasis Model Assessment (HOMA-IR). As variáveis operatórias foram tempo de lipoaspiração, tempo de prótese de mamas, áreas corporais lipoaspiradas e gordura total aspirada. RESULTADOS: O tempo de lipoaspiração foi 94 a 278 min (média=174 min), tempo de prótese de mamas de 20 a 140 min (média=65 min), gordura total aspirada de 680 a 4280 g (média=1778 g). A análise estatística foi realizada por uma linha de corte de 1500 g de gordura aspirada e revelou uma resistência insulínica pelo índice de HOMA significativamente mais intensa no grupo >1500 g (aumento de 123%) em relação ao grupo d"1500 g (aumento de 53%,) a partir dos dados basais (p=0,02). As demais variáveis operatórias não apresentaram correlação significativa. CONCLUSÃO: A resistência insulínica apresenta aumento significativo na lipoaspiração, correlacionada ao volume de gordura aspirado.
Análises macro e microscópicas de enxertos cutâneos por semeadura após laserterapia de baixa intensidade
Authors: Silva Elisângela Barboza da , Maniscalco Cintia Lúcia , Ésper Greyson Victor Zanatta , Guerra Ricardo Romão , Kerppers Ivo I.
Published: March 2013

OBJETIVO: observar se a laserterapia de baixa intensidade acelera o processo inflamatório, a cicatrização e epitelização de enxertos cutâneos por semeadura. MÉTODOS: vinte ratos foram submetidos a esta técnica de enxertia e divididos em dois grupos iguais, um tratado com laser e outro controle. RESULTADOS: houve menor tempo de reação inflamatória, maior velocidade de cicatrização, epitelização e queratinização nos animais tratados com laser em relação aos não tratados. CONCLUSÃO: a laserterapia de baixa intensidade é efetiva no auxílio ao tratamento de enxertos por semeadura.
Verificação da viabilidade do transplante autógeno de testículo no omento e na parede abdominal em ratos
Authors: Nunes Sergio Ibañez , Fernandes Carolaine Bitencourt Ferreira , Rezende Dilermando Fazito de , Bernardes Jonatas Barros de Guimarães , Silva Marcus Vinicius de Paula da
Published: March 2013

OBJETIVO: verificar a viabilidade do transplante autógeno de testículos na parede abdominal e omento, em ratos, sem anastomose vascular, analisando a estrutura histológica das células testiculares após o implante. MÉTODOS: foram utilizados 60 ratos Wistar, machos, de 10-12 semanas de idade, distribuídos em três grupos: grupo controle: 20 ratos sem orquiectomia, com operação simulada; grupo 2: 20 ratos com orquiectomia bilateral sendo um testículo implantado no omento maior; grupo 3: 20 ratos com orquiectomia bilateral, sendo um testículo implantado na parede abdominal. Após dois meses eles foram mortos e os testículos avaliados pelo exame anatomopatológico. RESULTADO: o peso dos implantes teve perda de 0,62g no grupo 2, de 0,73g no grupo 3 e no grupo controle houve aumento de 0,1g. Ao estudo anatomopatológico, no grupo controle a estrutura testicular foi preservada; no grupo 2 encontrou-se 80% de inflamação e necrose, não foram visualizadas células de Sertoli ou de Leydig, em dois animais encontraram-se túbulos seminíferos; no grupo 3 encontrou-se 75% de inflamação e 60% de necrose, somente em um conseguiu-se visualizar células de Sertoli e em três células de Leydig. CONCLUSÃO: não é viável o transplante autógeno de testículo sem anastomose vascular em ratos no omento maior e na parede abdominal.
Meteorological and hydrological variables on occurrence of riverbank erosion along lower São Francisco river
Authors: Rocha Igor P. da , Holanda Francisco S. R. , Araújo Filho Renisson N. , Casado Ana P. B. , Bandeira Arilmara A.
Published: March 2013

The objectives of this paper were to analyze the seasonal distributions of climatic and hydrological variables along the Lower São Francisco River, Northeastern Brazil, between the States of Sergipe and Alagoas, and further, to verify their relationships with the erosion of the right margin in Sergipe State. The investigated area comprises the sedimentary portions of the Lower São Francisco River, located at the Cotinguiba-Pindoba Irrigated Perimeter. Historical records of variables such as rainfall, river streamflow velocity, river discharge, wind velocity and the predominant direction were collected from a climatological station as well as rain and streamflow gauges located in the municipality of Propriá. The rainfall that occurs in the region is considered non-erosive, 96.2% of the rain had intensity less than 25.0 mm h-1. The evolution of erosion is explained by the increase in the outflow in February that peaked at 9,894.50 m³ s-1 and led to increases in the flow velocity. The rainfall regime interacts with the wind that blows predominantly from the eastern direction during the dry season and from the southeastern direction during the rainy season with maximum velocities of 5.5 and 8.0 m s-1, respectively.
Comportamento morfofisiológico da mamoneira BRS Energia submetida à irrigação com água salina
Authors: Santos João B. dos , Santos Delfran B. dos , Azevedo Carlos A. V. de , Rebequi Alex M. , Cavalcante Lourival F. , Cavalcante Ítalo H. L.
Published: March 2013

Um experimento foi conduzido na estação experimental de Irrigação e Drenagem do Instituto Federal Baiano, para avaliar o crescimento da mamoneira BRS Energia, em função da salinidade da água de irrigação, em sistema de lisimetria. Os tratamentos foram constituídos dos níveis de salinidade da água de 0,12; 0,8; 1,6; 2,4; 3,2; 4,0 e 4,8 dS m-1, dispostos em delineamento inteiramente casualizado, com três repetições e quatro plantas por tratamento. Quinzenalmente foram avaliados, dos 20 até os 80 dias após a emergência, o crescimento e as taxas de crescimento absoluto e relativo da altura de plantas, diâmetro do caule e a área foliar das plantas. O crescimento avaliado pela altura, diâmetro do caule, área foliar e as taxas de crescimento absoluto e relativo de cada variável, diminuíram com o aumento da salinidade da água de irrigação, em todos os períodos estudados. As inibições foram respostas da elevação do nível salino do solo de não salino, para ligeiramente, moderadamente e fortemente salino.
Estimativa da produtividade do milho em função da disponibilidade hídrica em Guarapuava, PR, Brasil
Authors: Wagner Marcus V. , Jadoski Sidnei O. , Maggi Marcio F. , Saito Larissa R. , Lima Adenilson dos S.
Published: March 2013

Com este trabalho objetivou-se estimar o potencial médio de produção da cultura do milho em função das variações da disponibilidade hídrica considerando-se a realização da semeadura em diferentes momentos dentro do período recomendado para o município de Guarapuava, Estado do Paraná. Os estudos foram realizados com base na série ininterrupta de dados climáticos do período de 1984 a 2007. A duração do ciclo da cultura foi calculada pelo acúmulo de soma térmica e a disponibilidade de água avaliada pelo balanço hídrico da cultura, ponderando-se a distribuição da precipitação pluvial e a evapotranspiração da cultura. A probabilidade de redução de produtividade de grãos por deficiência hídrica foi estimada considerando-se a porcentagem de redução de produção de grãos a partir da ocorrência de deficiência hídrica nos diferentes estádios do ciclo de desenvolvimento no campo. Verificou-se que a cultura do milho é afetada pela distribuição da disponibilidade hídrica ao longo do ciclo, sendo que a maior probabilidade de perdas de produção por deficiência hídrica ocorre no estádio da antese-fecundação. As semeaduras mais tardias no período recomendado tendem a ocasionar menores riscos de obtenção de produtividade de grãos abaixo da média regional.
Leaf development of cultivated rice and weedy red rice under elevated temperature scenarios
Authors: Streck Nereu A. , Uhlmann Lilian O. , Gabriel Luana F.
Published: March 2013

The objective of this study was to simulate leaf development of cultivated rice genotypes and weedy red rice biotypes in climate change scenarios at Santa Maria, RS, Brazil. A leaf appearance (LAR) model adapted for rice was used to simulate the accumulated leaf number, represented by the Haun Stage, from crop emergence to flag leaf appearance (EM-FL). Three cultivated rice genotypes and two weedy red rice biotypes in six emergence dates were used. The LAR model was run for each emergence date using 100 years of synthetic daily weather data and six climate scenarios, including current, +1, +2, +3, +4 and +5 ºC increase in mean air temperature, with symmetric and asymmetric increase in daily minimum and maximum temperature. The increase in air temperature scenarios decreased the duration of the EM-FL phase in the earlier emergence dates (08/20, 09/20, 10/20) whereas in mid (11/20) and late emergence dates (12/20 and 01/20) the longest EM-FL phase was in the symmetric +5 ºC scenario and the shortest duration was in the asymmetric +3 and +4 ºC scenarios. The timing of the onset of flooding irrigation and nitrogen dressing may be altered if global warming takes place and weedy red rice has a potential to enhance its competitiveness with cultivated rice in future climates.
Criopreservação de eixos embrionários zigóticos de algodoeiro
Authors: Lopes Kilson P. , Almeida Francisco de A. C. , Carvalho Julita M. F. C. , Bruno Riselane de L. A.
Published: March 2013

A busca por cultivares cada vez mais adaptadas que atendam à demanda vigente, exige que os recursos genéticos das espécies vegetais sejam facilmente obtidos. Objetivando avaliar um protocolo para criopreservação de eixos embrionários de algodoeiro, realizou-se um experimento com o emprego de sementes das cultivares BRS 200 e BRS 201, cujos eixos embrionários foram extraídos e submetidos à dessecação por 0, 30, 60 e 90 min e à criopreservação em nitrogênio líquido (-196 °C) durante 0, 5, 30 e 60 dias. A reativação dos eixos embrionários foi realizada a cada período de armazenamento após sua retirada e descongelamento em condições de ambiente, durante 60 min, sendo cultivados em meio MS em condições de câmara regulada a uma temperatura de 25 °C, fotoperíodo de 16/8 h (claro/escuro) e intensidade luminosa de 30 /vmol m-2 s"'. Aos 30 dias de cultivo foram realizados avaliações da regeneração, comprimento de plântulas e número de raízes emitidas. Eixos embrionários de algodoeiro, com umidade em torno de 9,7%, podem ser conservados em bancos de germoplasma em condições criogênicas e regenerar mais de 80% de plântulas in vitro após 60 dias de armazenamento em nitrogênio líquido (-196 °C).
Incidencia de un ambiente de aprendizaje blended, en la transformación de competencias matemáticas en estudiantes universitarios
Authors: Chiappe Andres , Manjarrés Guillermo Antonio
Published: March 2013

El presente artículo describe una investigación que da cuenta de la incidencia de un Ambiente Virtual de Aprendizaje (AVA) en el fortalecimiento de algunas competencias matemáticas en estudiantes universitarios. La investigación permitió contrastar el estado de desarrollo de varias competencias matemáticas en estudiantes universitarios de primer semestre, antes y durante una experiencia de interacción en un Ambiente Virtual de Aprendizaje, como complemento de un curso presencial de Geometría. Los resultados obtenidos en la investigación permitieron identificar algunas transformaciones en los estudiantes, sobre todo en su capacidad de identificar, plantear y resolver problemas, en sus habilidades para comunicarse de manera oral y escrita y en su capacidad de aplicación de los conocimientos matemáticos al campo de la Ingeniería Civil.
Contribuições axiológicas à educação científica: valores cognitivos e a seleção natural de Darwin
Authors: Batista Irinéa de Lourdes , Lucas Lucken Bueno
Published: March 2013

Nos últimos anos, muitos autores têm discorrido sobre o papel dos valores nas atividades científicas. Ao se buscar por novas maneiras de se compreenderem os motivos, processos e resultados dessas atividades, considerável relevância é atribuída ao fato de que as práticas científicas devem ser compreendidas segundo seu contexto histórico-social. Pautando-se na pertinência de pesquisas comprometidas com o estudo das influências axiológicas na dinâmica da Ciência, apresenta-se, neste artigo, uma discussão acerca do papel que os valores cognitivos podem desempenhar na compreensão de uma teoria biológica - seleção natural - mediante uma síntese histórico-epistemológica e demais aportes histórico-filosóficos, com o objetivo de investigar o desenvolvimento de uma nova estratégia de abordagem para o ensino dos conteúdos evolutivos no ensino de Biologia.
Comparison of antioxidant activity of Moringa oleifera and selected vegetables in South Africa
Authors: Pakade Vusumzi , Cukrowska Ewa , Chimuka Luke
Published: March 2013

The antioxidant activity of the leaves and flowers of the Moringa oleifera plant were investigated and the results were compared to those of selected vegetables (cabbage, spinach, broccoli, cauliflower and peas). Antioxidant activity was determined by analysing the total phenolics content, total flavonoids content, reducing power and radical scavenging activity using the 2,2-diphenyl-1-picrylhydrazyl free radical method. The total phenolics content of moringa was almost twice that of the vegetables and the total flavonoids content was three times that of the selected vegetables. The reducing power of moringa was higher than that of the vegetables and the percentage of free radicals remaining was lower compared with the vegetables. These results combined show that moringa is a good source of antioxidants. This finding also explains why moringa forms part of the diet of people in many developing countries, especially in the southern hemisphere.
Evaluating Alternative Weed Management Strategies for Three Montana Landscapes
Authors: Frid Leonardo , Hanna David , Korb Nathan , Bauer Brad , Bryan Katherine , Martin Brian , Holzer Brett
Published: March 2013

Determining the best strategy for allocating weed management resources across and between landscapes is challenging because of the uncertainties and large temporal and spatial scales involved. Ecological models of invasive plant spread and control provide a practical tool with which to evaluate alternative management strategies at landscape scales. We developed a spatially explicit model for the spread and control of spotted knapweed and leafy spurge across three Montana landscapes. The objective of the model was to determine the ecological and economic costs and benefits of alternative strategies across landscapes of varying size and stages of infestation. Our results indicate that (1) in the absence of management the area infested will continue to increase exponentially leading to a substantial cost in foregone grazing revenues; (2) even though the costs of management actions are substantial, there is a net economic benefit associated with a broad range of management strategies; (3) strategies a that prioritize targeting small new infestations consistently outperform strategies that target large established patches; and (4) inconsistent treatment and short-term delays can greatly reduce the economic and ecological benefits of management.
Susceptibility of Old World Climbing Fern (Lygodium microphyllum) Gametophytes to Metsulfuron Methyl
Authors: Hutchinson Jeffrey T. , Langeland Kenneth A.
Published: March 2013

Old World climbing fern (OWCF) is a highly invasive plant that is spreading rapidly and disrupting natural areas in Florida, with the potential to spread by wind-blown spores into Central and South America. Experiments were performed using gametophytes to determine the dose response of OWCF to metsulfuron methyl (metsulfuron). OWCF gametophytes were highly susceptible to metsulfuron with ≤ 1.4% survival at concentrations ≥ 27 mg ai L−1. Metsulfuron OWCF gametophyte 50 and 95% inhibition (I50 and I95) values were 6.1 and 26.4 mg ai L−1, respectively. Survival of treated gametophytes that developed into sporophytes was ≤ 0.014% at concentrations ≥ 27 mg ai L−1, but no sporophytes developed at concentrations ≥ 432 mg ai L−1. Metsulfuron OWCF sporophyte inhibition I50 and I95 values were 5.6 and 24.1 mg ai L−1, respectively. At 216 mg ai L−1 metsulfuron, half of the standard operational use rate, 1.1 × 10−8% of the treated gametophytes developed into sporophytes. The results indicate that the potential for tolerant, and potentially resistant, OWCF populations is higher using lower concentrations of metsulfuron as no gametophytes developed into sporophytes at the standard field treatment concentration of 432 mg ai L−1.
Understanding Factors that Correlate or Contribute to Exotic Russian-olive (Elaeagnus angustifolia) Invasion at a Wildland–Urban Interface Ecosystem
Authors: Madurapperuma Buddhika D. , Oduor Peter G. , Anar Mohammad J. , Kotchman Larry A.
Published: March 2013

Understanding the ecological distribution range of exotic trees in an arboreal ecosystem is essential to managing natural forest resources sustainably. Forest resource mapping can be applied as a powerful tool in the identification of forest resource threat patterns, and in monitoring ongoing changes associated with a landscape. This study offers an insight on Russian-olive and its impact on a spatially bound ecosystem, namely, Bismarck–Mandan Wildland–Urban Interface (BMWUI). Data from the National Agricultural Imagery Program collected in 2005 and 2010 and in situ reference data were used to estimate the potential habitat of Russian-olive using ArcGIS ArcInfo® 9.3 (ESRI, Redlands, CA). Russian-olive plants are discernible on aerial photographs with a fine spatial resolution because of silvery gray-green leaves in the upper strata of their canopies. Results showed that Russian-olive occupied 110 ha (272 acres) in BMWUI in 2005 and of that, 13 ha (12%) was in inundated habitats. In addition, Russian-olive in 2010 covered 125 ha within the BMWUI and of that, 25 ha (20%) was in inundated habitats. Russian-olive showed a close association with the silt loam and silty clay soil type, which occurs along the Missouri River floodplain. Our findings revealed that the species is well established in riparian habitats and other open habitats such as roadside and agricultural lands. There is a greater likelihood of lateral spread of Russian-olive throughout the BMWUI that may require active management to avert undesirable conservation impacts.
The Seasonality of Survival and Subsequent Growth of Common Reed (Phragmites australis) Rhizome Fragments
Authors: Juneau Kevyn J. , Tarasoff Catherine S.
Published: March 2013

Common reed [Phragmites australis (Cav.) Trin. ex Steud.] is an invasive plant that reproduces poorly by seed but regenerates vigorously by rhizomes. Because Phragmites australis propagates well through rhizome growth, invasion often occurs from transported rhizome tissue. We investigated both rhizome-fragment biomass and seasonal effects on survival and growth of ramets. Rhizomes were collected along roadside ditches during the fall of 2009 and 2010 and during the summer of 2010 and 2011. Fall and summer were chosen because the plants were either dormant or actively growing, respectively. Rhizomes were cut into fragments then grown in a greenhouse for 60 d in vermiculite with no added nutrients. Rhizomes collected in the fall had a survival rate of 71.1%, whereas only 15.6% of those collected in the summer survived. Within season, rhizomes with low initial biomass had lower survival rates and growth than did large rhizomes. There was no seasonal difference in the total biomass produced by the surviving plants; however, allocation of biomass did differ. Summer-collected rhizomes showed a higher belowground to aboveground biomass ratio than did those collected in the fall. Understanding the viability of Phragmites australis rhizome fragments provides land managers a greater awareness of the high-establishment risks of Phragmites australis. This information should be included in an integrated weed management program, and actions should be taken to reduce the spread of this weed during roadside maintenance. Although the risk of survival is lower during the summer, soil contaminated with Phragmites australis should not be transported or must be sifted with a screen to ensure all rhizome fragments are removed.
Temporal and Spatial Pattern of a Privet (Ligustrum vulgare) Invasion
Authors: Zhao Wanying , Goebel Charles , Cardina John
Published: March 2013

Privet has escaped from cultivation and is invading natural areas throughout eastern North America. Understanding the pattern of invasion over time could help us develop more efficient management strategies. We studied the invasion history and spatial distribution pattern of privet by mapping age and spatial data for established patches in a 132-ha (326 ac) forested natural area in northeast Ohio. We determined the age of 331 geo-referenced patches by counting annual rings, and mapped them with corresponding land habitat. Age distribution and cumulative number of privet patches over about 40 yr showed three phases of invasion. The initial 19-yr lag phase was characterized as a dispersed spatial pattern (based on nearest neighbor analysis), with patches located mostly at edges of different habitats and open places. In a second phase of about 15 yr, an average of 19 patches were initiated yearly, in a pattern that trended towards clustered. The final phase began around 2007, as the rate of new patch establishment declined, possibly because of saturation of the suitable habitat. Establishment of new patches was not associated with specific habitats. Aggregation of patches with similar ages increased after 1998 and became significantly clustered. Mapping of clusters of old and young patches identified invasion hot spots and barriers. Results affirmed that the best time for invasive control is during the lag phase. By monitoring edge habitats associated with early establishment, managers might detect and control early invaders and delay the onset of the expansion phase.
Passive Reestablishment of Riparian Vegetation Following Removal of Invasive Knotweed (Polygonum)
Authors: Claeson Shannon M. , Bisson Peter A.
Published: March 2013

Japanese knotweed and congeners are invasive to North America and Europe and spread aggressively along rivers establishing dense monotypic stands, thereby reducing native riparian plant diversity, structure, and function. Noxious weed control programs attempt to eradicate the knotweed with repeated herbicide applications under the assumption that the system will recover to a native assemblage which will inhibit future invasions. However, eradication efficacy studies typically only measure the amount of knotweed reduced, not the reestablished species diversity or plant origins. For a community scale efficacy study, we measured vascular plant species diversity and cover in riparian areas along five rivers in Washington State, 3 to 6 years after Bohemian knotweed was initially treated with herbicide. Plant species composition was compared between riparian sites treated to remove knotweed and reference sites where knotweed was absent. Sites where knotweed had been removed had significantly more exotic species and vegetative cover than reference sites; however, native species richness and cover were greater in reference sites and areas with more overstory vegetation. The native plants observed were primarily shade tolerant and perennial, as opposed to many of the exotics, which were shade-intolerant annuals. In general, reestablishment of native and exotic vegetation was not related to pretreatment knotweed stem count, size of the invaded area, or timing of herbicide application. However, residual native tree cover was negatively correlated with initial knotweed stem count. Monitoring the success of restoration objectives (e.g., native plant reestablishment or increased species diversity) and characterizing associated habitat features following knotweed eradication will help in the development of site-specific protocols for successful plant community scale restoration.
Effect of Salinity on Growth of Barnyardgrass (Echinochloa crus-galli), Horse Purslane (Trianthema portulacastrum), Junglerice (Echinochloa colona), and Rice
Authors: Chauhan Bhagirath S. , Abugho Seth B. , Amas Junrey C. , Gregorio Glenn B.
Published: March 2013

In Asia, a significant area under rice is affected by salinity. Salt stress can affect growth of crops as well as weeds. A study was conducted in a greenhouse to determine the effect of salinity (electrical conductivity [EC] of 1, 6, 12, 18, and 24 dS m−1) on growth of barnyardgrass, horse purslane, junglerice, and rice. Growth variables were analyzed using regression analysis. The tested levels of EC influenced leaf production of barnyardgrass and junglerice but not that of horse purslane. As compared with the control treatment (EC of 1 dS m−1), shoot biomass of barnyardgrass decreased by only 24% at 12 dS m−1, whereas rice biomass declined by 59% at this level of EC. At EC of 24 dS m−1, barnyardgrass still produced 4% of the biomass of the control treatment, whereas rice did not survive at this level of EC. Junglerice shoot biomass decreased by 73% at 18 dS m−1EC compared with the control treatment, whereas rice shoot biomass declined by more than 86% at 18 dS m−1EC. An EC of 10 dS m−1was required to inhibit 50% shoot biomass of rice, whereas the EC to inhibit 50% shoot biomass of barnyardgrass and junglerice was 15 and 13 dS m−1, respectively. Shoot biomass of horse purslane was not influenced by the tested levels of EC. At the highest EC (24 dS m−1), at which rice did not survive, horse purslane shoot biomass was similar to that of the control treatment. In all weed species, data for root biomass showed trends similar to those of shoot biomass. The results of this study suggest that weeds were more tolerant to salt than rice, and horse purslane was the most tolerant species among the weeds.
Nitrogen Release from Weed Residue
Authors: Lindsey Laura E. , Steinke Kurt , Warncke Darryl D. , Everman Wesley J.
Published: March 2013

Weed residues can impact nitrogen (N) cycling in agro-ecosystems that primarily utilize POST weed control. Quantifying this potential N source or sink may influence weed control and fertilization practices. A laboratory experiment measured the rate and quantity of N release from common lambsquarters, common ragweed, and giant foxtail. Weeds were grown in the field at four N rates (0, 67, 134, or 202 kg N ha−1) and collected at two weed heights (10 or 20 cm) to give a range of residue chemical composition. Residue chemical composition parameters of carbon : N (C : N) ratio and total N, nitrate-N, acid detergent fiber, and neutral detergent fiber concentration were measured and correlated with N release. Nitrogen release from weed residue mixed with soil was determined over a 12-wk period. Nitrogen was released from all weed residues at 12 wk. Prior to 12 wk, N was immobilized by giant foxtail grown with no N application. Prior to 4 wk, N was immobilized by 20-cm weeds grown with no N application. Nitrogen release from weed residue was negatively correlated with C : N ratio. Weed residue with a C : N ratio of < 19 (weeds grown with N application and 10-cm weeds) released 25 to 45% total N concentration within 2 wk and may contribute N within the growing season. Weed residue with a C : N ratio > 19 (giant foxtail and 20-cm weeds grown with no N) initially immobilized N and may not contribute N within the growing season.
The Potential Global Distribution of Tall Buttercup (Ranunculus acris ssp. acris): Opposing Effects of Irrigation and Climate Change
Authors: Bourdôt Graeme W. , Lamoureaux Shona L. , Watt Michael S. , Kriticos Darren J.
Published: March 2013

Tall buttercup, a native of central and northern Europe, has become naturalized in the United States and Canada, and in South Africa, Tasmania and New Zealand. In Canada and New Zealand it has become an economically significant weed in cattle-grazed pastures. In this study we develop a CLIMEX model for tall buttercup and use it to project the weed's potential distribution under current and future climates and in the presence and absence of irrigation. There was close concordance between the model's projection of suitable climate and recorded observations of the species. The projection was highly sensitive to irrigation; the area of potentially suitable land globally increasing by 30% (from 34 to 45 million km2) under current climate when a “top-up” irrigation regime (rainfall topped up 4 mm d−1 on irrigable land), was included in the model. Most of the area that becomes suitable under irrigation is located in central Asia and central North America. By contrast, climate change is projected to have the opposite effect; the potential global distribution diminishing by 18% (from 34 to 28 million km2). This range contraction was the net result of a northward expansion in the northern limit for the species in Canada and the Russian Federation, and a relatively larger increase in the land area becoming unsuitable mainly in central Asia and south eastern United States.
Tolerance of Hooker's Evening Primrose (Oenothera elata) Transplants to Postemergence Herbicides
Authors: Bates Amber N. , Henry Gerald M. , McKenney Cynthia B.
Published: March 2013

Greenhouse trials were conducted to determine Hooker's evening primrose transplant tolerance to POST-applied herbicides. Herbicide treatments consisted of glyphosate at 1.68 kg ae ha−1, glufosinate at 0.84 kg ai ha−1, fenoxaprop at 0.10 kg ai ha−1, fluazifop at 0.45 kg ai ha−1+ a nonionic surfactant (NIS) at 0.25% v/v, sulfosulfuron at 0.06 kg ai ha−1+ NIS at 0.25% v/v, quinclorac at 0.42 kg ae ha−1+ methylated seed oil (MSO) at 0.5% v/v, mesotrione at 0.21 kg ai ha−1, and the combination of quinclorac + mecoprop + dicamba at 0.42 + 0.21 + 0.06 kg ae ha−1+ MSO at 0.5% v/v. Fluazifop (14%) and fenoxaprop (19%) treatments did not result in any significant phytotoxicity 7 d after treatment (DAT) compared with the nontreated check. Hooker's evening primrose exhibited 26 to 37% phytotoxicity in response to quinclorac, glyphosate, or sulfosulfuron 7 DAT. Phytotoxicity ≥ 50% was observed for mesotrione, glufosinate, and the combination of quinclorac + mecoprop + dicamba 7 DAT. Phytotoxicity increased for all treatments 28 DAT. Fluazifop (21%) was the only treatment that did not exhibit phytotoxicity symptoms different from the nontreated check 28 DAT. Hooker's evening primrose exhibited 31 to 40% phytotoxicity with applications of fenoxaprop, glyphosate, or glufosinate 28 DAT. Phytotoxicity was ≥ 58% with all other treatments 28 DAT. Fluazifop exhibited similar above-ground (12.4 g) and below-ground (16.4 g) biomass as the nontreated check (10.8 and 14.7 g, respectively) 28 DAT. All other treatments resulted in 1.6 to 5 g of above-ground biomass and 0.8 to 4.3 g of below-ground biomass 28 DAT. Fluazifop (24.3) and fenoxaprop (18.8) applications resulted in a plant growth index (PGI) that was not significantly different from the nontreated check (24.7) 28 DAT. A PGI ≤ 16.2 was observed for all other treatments 28 DAT.
Weed Interference Impacts and Yield Recovery after Four Years of Variable Crop Inputs in No-Till Barley and Canola
Authors: Harker K. Neil , O'Donovan John T. , Turkington T. Kelly , Blackshaw Robert E. , Johnson Eric N. , Brandt Stu , Kutcher H. Randy , Clayton George W.
Published: March 2013

A 2-yr (2009 to 2010), no-till (direct-seeded) “follow-up” study was conducted at five western Canada sites to determine weed interference impacts and barley and canola yield recovery after 4 yr of variable crop inputs (seed, fertilizer, herbicide). During the initial period of the study (2005 to 2008), applying fertilizer in the absence of herbicides was often worse than applying no optimal inputs; in the former case, weed biomass levels were at the highest levels (2,788 to 4,294 kg ha−1), possibly due to better utilization of nutrients by the weeds than by the crops. After optimal inputs were restored (standard treatment), most barley and canola plots recovered to optimal yield levels after 1 yr. However, 4 yr with all optimal inputs but herbicides led to only 77% yield recovery for both crops. At most sites, when all inputs were restored for 2 yr, all plots yielded similarly to the standard treatment combination. Yield “recovery” occurred despite high weed biomass levels (> 4,000 kg ha−1) prior to the first recovery year and despite high wild oat seedbank levels (> 7,000 seeds m−2) at the end of the second recovery year. In relatively competitive narrow-row crops such as barley and canola, the negative effects of high soil weed seedbanks can be mitigated if growers facilitate healthy crop canopies with appropriate seed and fertilizer rates in combination with judicious herbicide applications to adequately manage recruited weeds.
Response of Sweet Corn to Pyroxasulfone in High-Organic-Matter Soils
Authors: Odero Dennis C. , Wright Alan L.
Published: March 2013

Field experiments were conducted in 2011 and 2012 in Belle Glade, FL to evaluate the response of sweet corn and weed control to pyroxasulfone on high-organic-matter soils in the Everglades Agricultural Area (EAA) of southern Florida with the use of dose-response curves. Pyroxasulfone was applied PRE at 31.25, 62.5, 125, 250, 500, and 1,000 g ai ha−1 on soil with 80% organic matter. Dose-response curves based on a three-parameter log-logistic model were used to determine pyroxasulfone rate required to provide 90% control (ED90) of spiny amaranth, common lambsquarters, and common purslane in sweet corn. The ED90 values for spiny amaranth, common lambsquarters, and common purslane control were 209, 215, and 194 g ha−1 of pyroxasulfone, respectively, at 21 d after treatment (DAT). At 42 DAT, the ED90 values for spiny amaranth, common lambsquarters, and common purslane control were 217, 271, and 234 g ha−1 of pyroxasulfone, respectively. Sweet corn yield increased with increasing rates of pyroxasulfone. An estimated 214 g ha−1 of pyroxasulfone was required to maintain sweet corn yield at 90% level of the weed-free yield. In addition, pyroxasulfone did not result in sweet corn injury. These results indicate that pyroxasulfone can provide effective weed control in sweet corn on high-organic-matter soils of the EAA.
Tank Mixing Saflufenacil, Glufosinate, and Indaziflam Improved Burndown and Residual Weed Control
Authors: Jhala Amit J. , Ramirez Analiza H. M. , Singh Megh
Published: March 2013

Saflufenacil and indaziflam, POST and PRE herbicides, respectively, have been registered recently for weed control in Florida citrus. Glufosinate is under evaluation and may be registered in the future for POST weed control in citrus. Citrus growers often want to have a tank mixture of herbicides that provide broad-spectrum weed control. Saflufenacil is a broadleaf herbicide and needs to be tank mixed with other herbicide(s) to increase weed control spectrum. Information is not available on interaction of saflufenacil, glufosinate, and indaziflam applied in tank mixtures on weed control efficacy. Greenhouse and field experiments were conducted at two locations (Polk and Orange County, FL) to evaluate the efficacy and potential antagonism or synergy of saflufenacil and glufosinate applied in tank mixes, and various three-way mixes with indaziflam. The results suggested that tank mixing saflufenacil with glufosinate had no effect on grass weed control, but had additive effect on broadleaf weed control. Indaziflam tank mixed at the recommended label rate (0.073 kg ha−1) provided better residual weed control compared with the lower rate (0.05 kg ha−1). Tank mixing indaziflam with saflufenacil and glufosinate improved broadleaf and grass weed control, reduced weed density, and biomass compared with tank mixing saflufenacil and glufosinate. Tank mixing indaziflam at 0.073 kg ha−1with saflufenacil and glufosinate provided ≥ 88% control of broadleaf and grass weeds at 30 d after treatment (DAT), and it was comparable with tank mixing saflufenacil, glyphosate and pendimethalin. This treatment combination recorded the lowest weed density (≤ 7 plants m−2) and biomass (< 80 g m−2) at 60 DAT. Glyphosate applied alone was less effective than tank mixing with saflufenacil and glufosinate for broadleaf and grass weed control. This indicates additive effect of tank mixture on glyphosate efficacy. It is concluded that saflufenacil can be tank mixed with glufosinate for control of broadleaf and grass weeds; however, addition of indaziflam in tank mixture provided long-term, broad-spectrum weed control in Florida citrus compared with other treatments.