Londrina, Brazil
Londrina, Brazil

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Almeida H.O.,Federal University of Viçosa | Barbosa M.O.,Federal University of Viçosa | Marques A.E.,Federal University of Viçosa | Pereira T.H.A.,Federal University of Viçosa | And 9 more authors.
Pesquisa Agropecuaria Brasileira | Year: 2012

The objective of this work was to evaluate induced resistance to Asian soybean rust by means of enzyme activities in soybean genotypes contrasting as to their susceptibility to Phakopsora pachyrhizi. Total protein and the activities of five induced resistance marker enzymes (lipoxygenases, peroxidases, phenylalanine ammonia-lyase, chitinases and β-1,3-glucanases) were evaluated in leaf extracts of soybean plants of the genotypes Embrapa 48 (susceptible) and PI 561356 (resistant), inoculated or not with the pathogen. Discrepant defense responses were obtained between the two genotypes and among the leaf harvest times (12, 72, and 168 hours after inoculation). The induction response of these enzymes resembles the biphasic defense in Embrapa 48 and is consistent with that observed in other pathological systems. However, the genotype PI 561356 responded with a decrease in total protein concentration and in enzymatic activities, indicating a general reduction in the metabolism of the infected plants. There is an important mechanism of resistance for the genotype PI 561356, not yet reported, which is grounded on the metabolic ways involving these induced resistance marker enzymes and on the mechanisms that use lower concentrations of total protein, such as the ones with metabolic pathways in response cascade.

Tavares L.C.V.,Caixa Postal 231 | Bassoi M.C.,Caixa Postal 231 | Miranda L.C.,Embrapa Transferencia de Tecnologia | Prete C.E.C.,State University Londrina
Revista Brasileira de Sementes | Year: 2011

The objective of this study was to describe and analyze the technology transfer process of wheat cultivars developed by Embrapa Soybean and Embrapa Technology Transfer, in partnership with private seed producers of the Meridional Foundation. Systemic methodology, characterized by the stages of planning, establishment and management of demonstration units, establishment and monitoring of field days and evaluation and reporting of the results, was used. The work of the wheat breeding program of Embrapa Soybean with seed producers resulted in an increase in the participation of Embrapa cultivars in Paraná state's seed production. These results demonstrated the importance of associating technology transfer with wheat improvement in order to promote and speed up scientific and technological information to technical assistance, farmers and other Embrapa customers.

Adegas F.S.,Caixa Postal 231 | Oliveira M.F.,Caixa Postal 231 | Vieira O.V.,Rod. BR 285 | Prete C.E.C.,State University Londrina | And 2 more authors.
Planta Daninha | Year: 2010

A phytosociological survey of the weed communities present in sunflower crop was carried out during two distinct crop stages: Early development and pre-harvest. Weed species were identified and quantified according to the inventory square method (1.0 x 1.0 m), using 12 m2 of sampling per area surveyed. At each stage, the survey was carried out on 54 farms of six counties of the "cerrado" (savanna region, Central Brazil) and 38 farms of eight counties of the "Pampas" (region in the State of Rio Grande do Sul, the Southernmost state in Brazil), which are the two main Brazilian sunflower production regions. Frequency, relative frequency, density, relative density, abundance, relative abundance, relative importance index, and similarity index were computed. A total of 60 weed species were identified, 17 of which were present in both regions. Asteraceae and Poaceae were the two main families among the 16 found. The main species present in the "cerrado" were Euphorbia heterophylla, Chamaesyce hirta, Ageratum conyzoides, Commelina benghalensis, Zea mays and Bidens sp. The most abundant species present in the State of Rio Grande do Sul were Bidens sp., Raphanus raphanistrum, Lolium multiflorum, Gnaphalium spicatum, Sonchus oleraceus, Euphorbia heterophylla, Sida rhombifolia, Digitaria sp. and Ipomea sp. Weed density was higher at pre-harvest than at the early stage of the crop, in both regions: 30.84 plants m-2 and 23.58 plants m-2, respectively, for the "cerrado" region and 23.19 plants m-2 FORMATAR and 21.41 plants m-2, respectively, for the "Pampas" region. The similarity index within each region was 0.91 for the "cerrado" and 0.79 for the "Pampas". Nevertheless, the region indices remained below 0.5, showing median similarity between the weed flora affecting sunflower crop at the "cerrado" and that at the "Pampas" during the two growth stages studied.

Lima W.F.,State University Londrina | Prete C.E.C.,State University Londrina | Ribeiro A.S.,Caixa Postal 231 | de Toledo J.F.F.,Caixa Postal 231
Summa Phytopathologica | Year: 2012

The main objectives of this work were to study the soybean resistance and/or tolerance to Asian rust and to select the inbred lines more productive in relation to Asian rust. Data from six experiments involving the parental lines and their F 2, F 3 and F 4 generations were used in this experiment. It was carried out in Londrina, Parana state, during the 2005/06, 2006/07 and 2007/08 cropping seasons. A completely randomized experiment with individual plants sown in hill plot was used (01 hill plot = 01 plant). Soybean resistance and/or tolerance to Asian rust is controlled by major and minor genes expressing mainly additive effects dispersed in the parents. It is possible to select inbred lines superior to the best yielding parent from most crosses. The narrow sense heritability for the yield trait under rust pressure ranged from average to high (0.324 to 0.815) at the F 3 progeny level, which warrants gains from selection.

Lima W.F.,State University Londrina | Prete C.E.C.,State University Londrina | Ribeiro A.S.,Caixa Postal 231 | de Oliveira M.F.,Caixa Postal 231 | And 4 more authors.
Summa Phytopathologica | Year: 2012

The objectives of this work were to complement the studies on the genetic control of soybean resistance to rust and to suggest a breeding methodology that allows the recombination and selection of soybean genotypes carrying major and minor genes for rust resistance. Six experiments were carried out in Londrina, PR during three growing seasons from 2005/06 to 2007/08 involving five parents and their derived F 2, F 3 and F 4 segregating populations. A completely randomized design was used with single plant hill-plots. The proposed methodologies ware designed to overcome the difficulties breeders face while selecting for minor gene resistance in the presence of major genes. This is dealt with by breeding large F 2, F 3 and F 4 segregant populations to improve the changes of the favorable gene combinations to appear and increasing genotype homozygosis under pathogen pressure to enhance the frequency of the favorable genotypes in the populations F 5 populations. This will also increase the chances of superior F 6 to appear from plant selection in the populations.

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