Não ocorrência de sigatoka-negra em bananeiras oriundas de São Paulo, Brasil.

Objetivando confirmar a presença ou não de M. fijiensis procedemos à análise ao microscópio estereoscópio e ótico, ao isolamento fúngico em BDA e teste de PCR com primers específicos para M. fijiensis e M. musicola (tendo como controle M. fijiensis em BDA e, amostra de bananeira de Seropédica ? RJ, infectada com M. musicola)

Phosphate solubilizing bacteria from the rhizosphere of Theobroma grandiflorum (Willd. ex Spreng.) Schum. and Bactris gasipaes H.B.K.: potential for plant growth promotion.

We have isolated bacteria from the rhizosphere of two perennial crop plants (Bactris gasipaes and Theobroma grandiflorum) growing on the SHIFT experimental site near Manaus

Epidemiologia das doenças das plantas úteis nos diferentes sistemas de plantio.

São discutidos a ocorrência de Microcyclus ulei e Thanatephorus cucumeris em seringueira; Phytophthora sp., Septobasidium pseudopediculatum e S. sacardinum em laranja; Crinipellis perniciosa em cupuaçu; Meloidogyne sp. em mamão; e de Xanthomonas campestris pv. manihotis em mandioca.bitstream/item/180863/1/Recuperacao-88-95.pd

Incidence of foliar diseases in mixed cultivation systems.

Incidência de doenças foliares em sistemas de policultivo: Mixed cropping systems can be an alternative to traditional cultivation methods in humid tropical areas such as Amazonia. The dispersion of species in the cultivated area will probably reduce the incidence of disease, because the non-host plants serve as a barrier to the spread of pathogens. Recultivation of abandoned area with the aid of mixed cropping systems has been studied. Since July 1993, the severity of infection of rubber trees has been assessed weekly and the incidence of disease in the other crops monitored monthly. Only rubber, orange, cassava and papaya have been affected. As the plants have not yet reached asufficient height to form pathogen barriers, the differences between the monocultures and the mixed cultivation systems are not significant.The occurrence of Microcyclus ulei and Thanatephorus cucumeris in rubber, Phytophthora citrophthora, Septobasidium pseudopediculatum and S. sacardium in orange. Meloidogyne sp. in papaya and Xanthomonas campestris p.v. manihotis in cassava are discussed

Balances of bioelements in useful tropical plants.

The productivity of different useful tropical plants is compared with respect to their biomass production. Furthermore, analyses of nutrient contents serve to explain the interrelationship between nutrient supply and primary production. The biomass and nutrient contents from three to six month old plants from Bertholletia excelsia H.B.K. (castanha-do-Brasil), Cedrela odorata L. (cedro vermelho), Dipteryx alata (cumaru), Theobroma grandiflorum (Spreng.) K. Schum. (cupuacu), Elaeis guineensis Jacq. (dende), Swietenia macrophylla King (mahogany), Sclerobium paniculatum Vogel (taxi branco) and Bixa orellana L. (urucum) within the different plant fraction were determined. The elements Ca, Mg, K, Na, Fe, Al, Zn, Cu, and P were analysed with the inductively coupled argon plasma with optical-emission-spectrometry (ICP-OES) method. Compared to plants of temperate regions, the mineral content is distinctly higher than that for tropical plants, but most values still lie within the range of existing data. Extremely high values were found for aluminium and iron

An accurate and transferable machine learning potential for carbon

We present an accurate machine learning (ML) model for atomistic simulations of carbon, constructed using the Gaussian approximation potential (GAP) methodology. The potential, named GAP-20, describes the properties of the bulk crystalline and amorphous phases, crystal surfaces, and defect structures with an accuracy approaching that of direct ab initio simulation, but at a significantly reduced cost. We combine structural databases for amorphous carbon and graphene, which we extend substantially by adding suitable configurations, for example, for defects in graphene and other nanostructures. The final potential is fitted to reference data computed using the optB88-vdW density functional theory (DFT) functional. Dispersion interactions, which are crucial to describe multilayer carbonaceous materials, are therefore implicitly included. We additionally account for long-range dispersion interactions using a semianalytical two-body term and show that an improved model can be obtained through an optimization of the many-body smooth overlap of atomic positions descriptor. We rigorously test the potential on lattice parameters, bond lengths, formation energies, and phonon dispersions of numerous carbon allotropes. We compare the formation energies of an extensive set of defect structures, surfaces, and surface reconstructions to DFT reference calculations. The present work demonstrates the ability to combine, in the same ML model, the previously attained flexibility required for amorphous carbon [V. L. Deringer and G. Csányi, Phys. Rev. B 95, 094203 (2017)] with the high numerical accuracy necessary for crystalline graphene [Rowe et al., Phys. Rev. B 97, 054303 (2018)], thereby providing an interatomic potential that will be applicable to a wide range of applications concerning diverse forms of bulk and nanostructured carbon

Variação genética entre procedências de seringueira.

Plantas de seringueira (Hevea spp.) com um ano de idade originadas de sementes de seringais nativos dos estados do Acre, Mato Grosso e Rondonia, envolvendo 36 amostras de 14 locais distintos, foram avaliadas para diametro de caule, altura de planta e numero de lancamentos. A incidencia de doencas foi avaliada quando as plantas tinham 17 meses de idade. O delineamento utilizado foi o latice triplo 6 x 6, com 50 plantas por parcela, no espacamento de 4,0 m x 4.0 m. As procedencias RO/CM/10, MT/C/04 e MT/C/06 apresentaram-se como as mais vigorosas, enquanto que AC/S/08 e AC/S/11 demonstraram pobre vigor nessa fase de desenvolvimento. As procedencias de seringais nativos localizadas em areas de varzeas estao apresentando melhor vigor. Em geral, as originadas de Rodonia apresentam-se mais vigorosas que as do Acre e Mato Grosso. As procedencias originadas de Rondonia, Mato Grosso e Acre apresentaram proporcionalmente maior contribuicao sobre a variacao estimada dentro de procedendia em cada Estado para as caracteristicas que determinam vigor de planta. Os parametros utilizados para avaliacao da variabilidade genetica na populacao detectaram alta variabilidade aproveitavel na selecao. Todas as procedencias foram altamente infectadas pelo Microccyclus ulei, ao passo que a incidencia de Thanatephorus cucumeris e Colletotrichum gloeosporioides foi menos intensa e mais variavel

Biomass production and mineral element supply of selected useful tropical plants.

This current investigation is part of a cooperative project of CPAA-Manaus and Hamburg University entitled "Recultivation of degraded and abandoned monocultures instable mixed cultures with special reference to soil biological factors". In this study the biomass product and the mineral element supply of selected useful tropical plants will be determined. Parallel to it the availability of nutrient element in the soil will be analyzed. These experiments may allow an evaluation, in which way a sustainable growth of the suggested plant system under the prevailing site conditions is possible.Poster 11

Ocorrência de Badnavirus em frutos de bananeira no Estado do Amazonas, Brasil.

A produção brasileira de bananas atende principalmente ao mercado interno, no entanto, em função de problemas fitossanitários, a produtividade dos bananais, principalmente no Estado do Amazonas é extremamente baixa. Recentemente, foi constatada no Estado do Amazonas a ocorrência de lesões necróticas de formato irregular, nos frutos de plantas híbridas tetraploides ?FHIA 01?, ?FHIA 18?, ?BRS Caprichosa?, ?BRS Garantida?, ?Preciosa? e ?Pacovan Ken? depreciando-os completamente para a comercialização. Através de PCR, utilizando-se dos primers BADNA 1A e BADNA 4 foi detectada a presença de Badnavirus correlacionada com a estirpe BSV-BR1, e com o Banana streak Uganda B vírus. Esta é a primeira vez em que se relatam tais sintomas em frutos associados à Badnavirus, no País

Metrological assessment of DC current comparator resistance bridges

Direct-current comparator bridges (DCC) are the working horses of primary resistance metrology in the intermediate resistance range. Having a ratio accuracy reaching 10^-7 or better, they allow the realization of resistance scales and the calibration of artifact standard resistors for customers. In this paper we compare the performances of three commercial DCC bridges, by performing measurements on resistors in decadal ratios (1 Ω to 10 kΩ) of very high stability in a thermostated environment. The results show that the three bridges give mutually compatible results within the manufacturer’s specifications, therefore mutually validating the bridges; nevertheless, the readings time series show quite different statistical behavior, with internal correlations, making an evaluation of the Type A measurement uncertainty not trivial