Basic physical parameters of a selected sample of evolved stars

We present the detailed spectroscopic analysis of 72 evolved stars, including the [Fe/H] determination for the whole sample. These metallicities, together with the Teff values and the absolute V magnitude derived from Hipparcos parallaxes, are used to estimate basic stellar parameters (ages, masses, radii, (B-V)o and log g using theoretical isochrones and a Bayesian estimation method. The (B-V)o values so estimated turn out to be in excellent agreement with the observed (B-V), confirming the reliability of the (Teff,(B-V)o) relation used in the isochrones. The estimated diameters have been compared with limb darkening-corrected ones measured with independent methods, finding an agreement better than 0.3 mas within the 1-10 mas interval. We derive the age-metallicity relation for the solar neighborhood; for the first time such a relation has been derived from observations of field giants rather than from open clusters and field dwarfs and subdwarfs. The age-metallicity relation is characterized by close-to-solar metallicities for stars younger than ~4 Gyr, and by a large [Fe/H] spread with a trend towards lower metallicities for higher ages. We find that the [Fe/H] dispersion of young stars (less than 1 Gyr) is comparable to the observational errors, indicating that stars in the solar neighbourhood are formed from interstellar matter of quite homogeneous chemical composition. The three giants of our sample which have been proposed to host planets are not metal rich, what is at odds with those for main sequence stars. However, two of these stars have masses much larger than a solar mass so we may be sampling a different stellar population from most radial velocity searches for extrasolar planets. We also confirm that the radial velocity variability tends to increase along the RGB.Comment: 17 pgs, 19 fig

Fixadores e porta-enxertos para enxertia hipocotiledonar de maracujazeiro amarelo.

O maracujazeiro-amarelo (Passiflora edulis Sims. f. flavicarpa Deg.) é a principal Passifloraceae cultivada no Brasil. Mas apesar da posição de destaque, a vida útil do maracujazeiro vem sendo reduzida, principalmente em decorrência dos danos causados por doenças do sistema radicular, com destaque para a fusariose, cujo agente causal é o fungo Fusarium oxysporum f. sp. passiflorae (FOP)

Analysis of colour-magnitude diagrams of rich LMC clusters: NGC 1831

We present the analysis of a deep colour-magnitude diagram (CMD) of NGC 1831, a rich star cluster in the LMC. The data were obtained with HST/WFPC2 in the F555W (~V) and F814W (~I) filters, reaching m_555 ~ 25. We discuss and apply a method of correcting the CMD for sampling incompleteness and field star contamination. Efficient use of the CMD data was made by means of direct comparisons of the observed to model CMDs. The model CMDs are built by an algorithm that generates artificial stars from a single stellar population, characterized by an age, a metallicity, a distance, a reddening value, a present day mass function and a fraction of unresolved binaries. Photometric uncertainties are empirically determined from the data and incorporated into the models as well. Statistical techniques are presented and applied as an objective method to assess the compatibility between the model and data CMDs. By modelling the CMD of the central region in NGC 1831 we infer a metallicity Z = 0.012, 8.75 < log(tau) < 8.80, 18.54 < (m-M)_0 < 18.68 and 0.00 < E(B-V) < 0.03. For the position dependent PDMF slope (alpha = -dlog(Phi(M))/dlog(M)), we clearly observe the effect of mass segregation in the system: for projected distances R < 30 arcsec, alpha ~ 1.7, whereas 2.2 < alpha < 2.5 in the outer regions of NGC 1831.Comment: 12 pages, 14 figure

A low-absorption disk zone at low Galactic latitude in Centaurus

We investigate the properties of two stellar concentrations in a low-absorption disk zone in Centaurus, located respectively at $\ell=306.47^{\circ}$, $b=-0.61 ^{\circ}$, and $\ell=307.01^{\circ}$, $b=-0.74 ^{\circ}$. The present analysis is based mostly on 2MASS photometry, as well as optical photometry. Based on colour-magnitude diagrams and stellar radial density profiles, we show that these concentrations are not open star clusters. Instead, they appear to be field stars seen through a differentially-reddened window. We estimate that the bulk of the stars in both stellar concentrations is located at $\sim1.5$ kpc from the Sun, a distance consistent with that of the Sgr-Car arm in that direction. This low-absorption window allows one to probe into distant parts of the disk besides the Sgr-Car arm, probably the tangent part of the Sct-Cru arm, and/or the far side of the Sgr-Car arm in that direction. The main sequence associated to the Sgr-Car arm is reddened by \ebv\sim0.5, so that this window through the disk is comparable in reddening to Baade's window to the bulge. We also investigate the nature of the open cluster candidate Ru 166. The presently available data do not allow us to conclude whether Ru 166 is an actual open cluster or field stars seen through a small-scale low-absorption window

Qualidade de frutos de limeira ácida Tahiti em porta-enxertos.

O cultivo de limeira ácida 'Tahiti' [Citrus latifolia (Yu. Tanaka) Tanaka] é crescente no Brasil, especialmente na Região Nordeste, para produção de frutos para mercado interno e exportação. A enxertia sobre limoeiro 'Cravo' (C. limonia Osbeck) predomina, apesar da susceptibilidade dessa combinação à gomose de Phytophthora spp. e da boa produção desta cultivar copa em porta-enxertos híbridos de trifoliata e afins

Atributos físico-químicos e curva de maturação de frutos de seleções tardias de laranjeira doce.

Esse trabalho avaliou atributos físico-químicos e curva de maturação de frutos de seleções tardias de laranjeira doce (Citrus sinensis (L.) Osbeck). Os trabalhos foram conduzidos no Banco Ativo de Germoplasma de Citros e no laboratório de Fisiologia Pós-Colheita da Embrapa Mandioca e Fruticultura, em Cruz das Almas, BA, entre agosto e dezembro de 2011

Crescimento e sobrevivência de Passiflora edulis enxertado em P. gibertii em área com histórico de fusariose.

Entre os principais patógenos que limitam o cultivo do maracujá-azedo no Brasil, destacam-se os fungos de solo Fusarium oxysporum f. sp. passiflorae e F. solani, que vêm impossibilitando a produção em áreas com histórico da doença, fazendo com que a cultura apresente ciclo anual e caráter itinerante

Grafting height does not affect Fusarium wilt control or horticultural performance of Passiflora gibertii N.E.Br. rootstock.

The influence of the grafting height (5, 10, 20 and 30 cm above the root collar) of P. edulis on P. gibertii was evaluated on the incidence of Fusarium wilt and horticultural performance. Plants of P. gibertii grafted on P. edulis and non-grafted plants of both species were also studied. In addition, histopathological studies were also performed on the roots of non-grafted P. edulis collected at three severity stages of Fusarium wilt. In greenhouse, the graft take was inversely related to the grafting height in general. In the field conditions, the plant growth of P. gibertii grafted on P. edulis was superior to its reciprocal grafting, even though the former combination was susceptible to Fop. Plants of P. edulis grafted on P. gibertii at all grafting heights did not present symptoms of Fop, and the number of fruit yield and quality were equivalent, but plant growth was decreased in relation to the non-grafted plants. Starch depletion in the root system of P. edulis was directly related to the severity of the Fusarium wilt. P. gibertii was confirmed as a Fusarium wilt resistant rootstock of P. edulis, with minimal influence of the grafting height for the control of the disease

Comportamento produtivo de cinco variedades comerciais de laranjas enxertadas em diferentes porta-enxertos de citros cultivados na Região Sul do Estado do Sergipe.

Embora a citricultura brasileira tenha papel de destaque no cenário mundial, existe uma crescente preocupação com a sustentabilidade do cultivo de citros no Brasil. Caracterizada pela ampla diversidade agroclimática, a atual citricultura brasileira exige genótipos varietais adaptados a sistemas de produção que permitem conduzir pomares mais produtivos e obter frutas de melhor qualidade (CERQUEIRA et al., 2004)