Imperatriz, Brazil
Imperatriz, Brazil

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De Freitas I.C.,UEMA | Carvalho C.S.,UEMA | Marques Monroe P.H.,UEMA | De Moura E.G.,UEMA
Renewable Agriculture and Food Systems | Year: 2011

In the humid tropics, the continuous use of the same area reduces nutrient availability and increases the incidence of weeds. To circumvent these obstacles, farmers practice itinerant agriculture associated with slashing and burning with negative effects on the local and global environment. In search for a suitable system for humid tropical agriculture, the objective of this study was to investigate the performance of no-till alley cropping in conjunction with the use of annual legume crops grown during the off-season. The experiment was implemented in a one-hectare alley cropping system in which the leguminous tree clitoria (Clitoria fairchildiana R.A. Howard) was used. The experimental design consisted of randomized blocks with four replications of the following treatments: Stylosanthis (Stylosanthis capitata), showey rattlebox (Crotalaria spectabilis), sunn hemp (Crotalaria juncea), jack bean (Canavalia ensiformis) and a control with clitoria alone, without an annual legume. In January 2007 and 2008, maize was planted in each alley. One hundred and twenty days after annual legumes were sown, the total biomass was recorded. Weed incidence was assessed 35 days after maize planting. Analyses of the C, N, P, K, Ca and Mg contents of the legumes were carried out. To assess soil organic matter (SOM), composite soil samples from the surface 0-5 cm were collected from experimental plots. Two adjacent areas were also sampled for comparison: a 10-year-old secondary forest and an area of conventional tillage. The SOM was fractionated using a densitometric and a granulometric method. Conventional systems reduce the silt and free light organic matter fractions more than no till. The use of annual legumes changes the composition of the weed community, replacing the more aggressive types with those less competitive. The use of showy rattlebox (C. spectabilis) may be an effective strategy for reducing weed density in the long-season crop. Furthermore, relative to the use of leguminous trees alone, higher yields of maize can be obtained with the use of showy rattlebox (C. spectabilis) and sunn hemp (C. juncea) without the application of additional N. © 2010 Cambridge University Press.

Marques L.J.P.,State University of Maranhão | Silva M.R.M.,Dep. de Fitotecnia e Fitossanidade | Araujo M.S.,UEMA | Lopes G.S.,UEMA | And 2 more authors.
Planta Daninha | Year: 2010

The no-tillage system in secondary vegetation is a replacement to the slash-and- burn method, using annual crops such as cowpea in family farming in the Amazon. Since weed management is an essential part of the production process, this study aimed to survey the flora in no-tillage areas of a chopped secondary forest cultivated with cowpea. This work was conducted in a rural farming area in the municipality of Zé Doca, MA in the agricultural years 2006/2007 and 2007/2008. The preparation of the area was carried out with a wheel tractor using the implement ahwi FM600. The area was originally planted with maize followed by BRS Guariba cowpea for two years.Weed evaluation was carried out 30 and 60 days after sowing with a rectangle (0.5 × 0.3 m), launched 30 times. Evaluation was performed every time, with the aerial parts of the weeds being harvested for counting, identification, and drying, to obtain the phytosociological indices (frequency, density, dominance index, and importance value). The families with the most weed species were Cyperaceae (7), Fabaceae (7), Poaceae (6), Malvaceae (5) and Rubiaceae (4). In the agricultural years 2006/2007, the species with the highest IVI were: Cyperus diffusus, Fimbristylis dichotoma, Spermacoce verticillata and Cyperus sp. In the agricultural years 2007/2008, the main species were: Digitaria horizontalis, followed by C. diffusus, Pavonia cancellata and F. dichotoma. The secondary forest plants originated from sprouting presented the highest IVIs in the agricultural year 2006/2007 and suffered a drastic reduction in 2007/2008. Thus, it can be concluded that progressive cultivation reduces secondary forest plant sprouting and increases the herbaceous extract.

Marques L.J.P.,State University of Maranhão | Silva M.R.M.,Dep. de Fitotecnia e Fitossanidade | Lopes G.S.,São Paulo State University | Correa M.J.P.,Dep. de Quimica e Biologia | And 3 more authors.
Planta Daninha | Year: 2011

This study investigated the floristic composition of weeds in a burnt area in Zé Doca, Maranhão, during three agricultural years. The preparation of the area at the first crop year (2006/ 2007) was by slash-and-burn for maize cultivation, followed by cowpea. In the second and third crop years, the preparation of the area consisted of plowing for maize cultivation, followed by cassava (2007/2008) and later, by cowpea in rotation with cassava (2008/2009). Weed collection in the cowpea and cassava crops was carried out 30 and 60 days after sowing (DAS) during the first and second agricultural year, respectively, and cowpea crop at 30 DAS in the third crop year with a rectangle (0.5 × 0.3 m) randomly placed in the area. Every launch was conducted to evaluate the aerial parts of the weeds harvested for counting, identification and drying to obtain the phytosociological indices. The slash-and-burn practice reduces the variety and number of weeds. Species with the highest IVI were Imperata brasiliensis, Sida glomerata and Corchorus argutus after slash-and-burn in the cowpea culture; and Juncus sp., Spermacoce verticillata, Aeschynomene americana and Cyperus sp. after plowing in the cassava and cowpea cultures. Secondary vegetation plants occurred after burn, but were reduced over time.

Lavra Vieira D.,UEMA | De Oliveira Barbosa V.,Federal University of Paraiba | Oliveira De Souza W.C.,Federal University of Paraiba | Goncalves Da Silva J.,Federal University of Paraiba | And 2 more authors.
Fruits | Year: 2016

Introduction. Citrus trees in Brazil are often attacked by the blackfly, Aleurocanthus woglumi Ashby. The induction of resistance to control this pest is required to maintain the sanitary and nutritional quality of the crop. The aim of this study was to evaluate the potential of silicon in the form of potassium silicate (K2SiO3) to modify the activity of enzymes involved in the defence of Citrus reticulata and to find any correlation between the activity of these enzymes and the development of A. woglumi. Materials and methods. The study was conducted in a greenhouse using seedlings of C. reticulate cv. 'Dancy' in the following one-application treatments: T1: Infestation with A. woglumi and no K2SiO3 (control, "C"); T2: No A. woglumi and no K2SiO3 (absolute control "AC"); T3: 17 g L-1K2SiO +A. woglumi, T4: 35 g L-1K2SiO +A. woglumi; T5: 52 g L-1 K2SiO +A. woglumi; and T6: 70 g L-1K2SiO +A. woglumi. To perform the enzymatic analyses, one leaf was removed separately from each mandarin seedling after 10, 30, 50, 70, and 90 days of continuous feeding of A. woglumi. The activity of peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase was assessed. Results and discussion. The correlation between peroxidase activity and A. woglumi development was positive. The peroxidase and polyphenol activities indicated strong induction of plant defences against A. woglumi. The increase in peroxidase and polyphenoloxidase activity revealed the induction of synthesis of compounds for plant defence against A. woglumi, but this effect depended on the time of A. woglumi feeding and on the concentration of silicon. Conclusion. Silicon was shown to be an elicitor that potentiates the defence mechanisms of C. reticulata to A. woglumi. © 2015 Cirad/EDP Sciences.

Reis V.L.,CMDI IFAM | Reis V.L.,Federal University of Campina Grande | Freire R.C.S.,Federal University of Campina Grande | Luciano B.A.,Federal University of Campina Grande | And 2 more authors.
Conference Record - IEEE Instrumentation and Measurement Technology Conference | Year: 2014

This paper presents and discusses the use of Hall effect sensors to measure the excitation current in single-phase transformers. The Hall effect sensors have galvanic isolation of the order of a few kVrms and may have total measurement errors less than 0.7% of the nominal value. It is common in transformer tests, to use a varivolt to avoid inrush current, which can reach more than 20 times the rated operating current, and can interfere with or even damage electronic circuits for measurement. However with the use of these sensors, their characteristics make it possible to have a measuring device relatively robust, accurate and fast, thus eliminating the use of a varivolt, for testing the load current transformer single phase or three phase. © 2014 IEEE.

Costa F.S.,UEMA | Grigoletto E.C.,University of Campinas | Vaz J.,University of Campinas | De Oliveira E.C.,University of Campinas
Communications in Applied and Industrial Mathematics | Year: 2014

The fractional version for the diffusion of neutrons in a material medium is studied. The concept of fractional derivative is presented, in the Caputo and Riesz senses. Using this concept, we discuss a fractional partial differential equation associated with the slowing-down of neutrons, whose analytical solution is presented in terms of Fox's H- function. As a convenient limiting case, the classical solution is recovered.

Silva R.M.L.,São Paulo State University | Rossi Junior O.D.,São Paulo State University | Costa F.N.,UEMA | Chaves N.P.,State University of Maranhão | And 2 more authors.
Boletim do Instituto de Pesca | Year: 2010

Among the widely distributed bacterial agents in the aquatic ecosystem, can be outstanding the family Aeromonadaceae detected such in fish as in the water of this system. This study intended to verify the occurrence of Aeromonas spp. in pond water of fishfarms located in Occidental Lowland Region of Maranhão. Twelve properties located in Pinheiro, Palmeirândia and Perimirim cities had been selected. The harvest of the samples occurred in the period from October, 2008 to March, 2009. A total of 48 pond water samples were harvested. Four water samples of each fishfarm. Aeromonas were confirmed in 100% of the samples. The 89 isolate identified had been classified in three species, A. hydrophila (88%), A. caviae (9%), A. veronii sobria (3%). The pond waters of the fishfarms analyzed presented contamination with potentially pathogenic species of aeromonas which represents risk for people's health, especially for the organisms cultivated in these properties.

De Araujo Melo S.,State University of Maranhão | Barros A.C.E.,UEMA | Costa F.B.,UEMA | De Carvalho Neta A.V.,UEMA | And 2 more authors.
Vector-Borne and Zoonotic Diseases | Year: 2011

In South American countries, bovine trypanosomiasis is caused mainly by Trypanosoma vivax. Among the infected animals, bovines are considered more susceptible, and this susceptibility varies among breeds. To determine the occurrence of T. vivax in Maranhão State, Brazil, a total of 559 cattle blood samples were collected for molecular and parasitological studies. On São Luís Island, no parasites were observed in the parasitological exam; however, with the polymerase chain reaction (PCR) method, three samples (1.06%) were positive. In four municipalities that compose the Pedreiras Basin, 3.39% of the animals were positive on the parasitological exam, and 6.21% of animals were positive by PCR. This finding demonstrates that PCR is more sensitive and confirms that the method is very useful in epidemiological surveys. A further interesting point is that molecular studies clearly define the differences in surface glycoproteins and antigenic variants. © 2011, Mary Ann Liebert, Inc.

Furtado L.M.,UEMA | Rodrigues A.A.C.,UEMA | de Araujo V.S.,UEMA | Silva L.L.S.,UEMA | Catarino A.M.,UEMA
Summa Phytopathologica | Year: 2010

The aim of this work was to evaluate the effects of ASM and Ecolife on the control of post-harvest antracnosis in banana. Banana fruits of Maçã, Prata, Pacovan and Figo varieties, at intermediate stage of maturation, were immersed in solutions of ASM and Ecolife and inoculated with Colletotrichum musae A completely randomized design was used, at a factorial scheme 4x2 (four varieties x two products) with four replicates. The presented results demonstrated the susceptibility of the fruits to the disease, mainly Maça variety with lesion of 17,99 mm. It was demosntrated the effectiveness of products at concentrations of 5ml. L-1 (Ecolife) and 0.50g. L-1 (ASM) on antracnosis control. The Figo variety presented the smallest injuries when treated with Ecolife (5.79 mm). Regarding ASM effects, Prata variety demonstrated the best performance, with 5.62 mm of injuries diameter. Throughout the maturation of the fruits the disease severity was declined in all varieties, except in the control treatment, where injuries continued growing until reaching the pulp.

The objective of this project is to focus on the environmental conflict involving the government and the residents of Jardim Icaraí in Curitiba, Brazil. This exercise examines environmental law as an instrument for producing and disseminating the "official version" of the environment and the city's intervention plan. Environmental Law not only provides legitimacy to this plan, but is also intimately associated to the urban policies in Curitiba.

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