Efeito do espaçamento sobre o desenvolvimento inicial de híbridos de Eucalyptus na Chapada do Araripe, Pernambuco.

Seção: Silvicultura e Produção de Biomassa

Optical limiting behavior of bismuth oxide-based glass in the visible range

The authors report experimental results on the optical limiting behavior of a bismuth oxide-based glass by exciting the samples with nanosecond laser pulses at 532 and 598 nm. The results show that two-photon and free-carrier absorption processes contribute for the nonlinear absorption. Values for β, the two-photon absorption coefficient, and σe, the absorption cross section due to free carriers, were determined. The values for β and σe are dependent on the amount of bismuth oxide in the glass composition

Levantamento populacional de cigarrinhas (Hemiptera: Cicadelidae), associadas à transmissão de Xilella fastidiosa em porar de citros no Recôncavo da Bahia.

A Clorose Variegada dos Citros - CVC ou Amarelinho, é uma das principais doenças da citricultura no Brasil, e tem como agente causal a bactéria Xilella fastidiosa (Lee et al, 1993). A CVC foi constatada inicialmente no estado de São Paulo, em 1987 (De Negri, 1990). No estado da Bahia, seu registro se deu em 1990 nos municípios de Rio Real e Itapicurú (Santos Filho et al 1999), e mais recentemente no Recôncavo Sul (Santos Filho et al, 2010)

Body-bending behaviour in snakes: new records of a poorly documented defensive behaviour.

Se describe el comportamiento poco conocido de "Body-bending behaviour" en varias especies de culebras y se discute el mismo.Fil: França, D. P. F.. Museu de Zoologia - Usp; BrasilFil: Oliveira, I. F.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Gennari, D.. Universidade Federal do Rio Grande do Norte. Centro de Biociencias. Departamento de Boanica, Ecologia e Zoologia; BrasilFil: Rocha, B. Universidade de Sao Paulo; BrasilFil: Smith, P.. Centro Ideal; ParaguayFil: Scrocchi Manfrini, Gustavo Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Machado Filho, P. R.. Universidade de Sao Paulo; Brasi

Different composition of plant residues as a driver of microbial community structure and soil organic matter composition: a microcosm study.

Soil organic matter (SOM) is the main pathway of carbon (C) input to the soil with the decomposition of shoot residues, roots and their exudates. The objective was to evaluate the contribution of different vegetal composition and plant parts of Caatinga species and the effects of introducing a grass in the soil microbial community structure and biochemical composition of SOM. A trial was conducted under controlled conditions (120 days) using, separately, the shoot and roots residues of native species from the herbaceous (HERB) and shrub-arboreal (ARB) strata and a grass (GRASS). Megathyrsus maximum, which is native from Africa, but well adapted to the semi-arid conditions of Brazil, was used. Combinations of these species in different proportions were also evaluated: (i) 55 % shrub and trees + 45 % grass (MIX1) and (ii) 75 % shrub and trees + 25 % grass (MIX2). At the end of incubation, soil samples were collected to evaluate the microbial community structure through the phospholipid fatty acids (PLFA). Physical fractioning of SOM into particulate organic matter (POM) and mineralassociated organic matter (MAOM) was also performed, followed by biochemical characterization of these fractions by thermochemolysis analysis. The ARB shoot residue resulted in a 181.5 % increase (p < 0.05) in total PLFA biomass in the soil. A significant increase (p < 0.05) in the abundance of fungi and bacteria was observed with the incorporation of shoot residues. MAOM was characterized by a higher abundance of aliphatic (31.6 ± 5.0 %) and nitrogen-bearing compounds (21.0 ± 2.0 %), while higher lignin derivatives were observed in POM (18.0 ± 0.6 %). The ground cover provided a diversity of compounds in the SOM, thus regulating the structure of the microbial community. These results highlight the importance of conserving biodiversity, both in natural ecosystems and in agroecosystems in the semi-arid environment

Adubação Fosfatada para Cultivares de Mamoneira na região Sul do Rio Grande do Sul.

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Sowing season of corn with cowpea and corn intercropping in the weed control. I. Green ears yield.

Green ears yield losses caused by weeds may reach up to 52%. Reducing the use of herbicides is one of agriculture's major goals and several alternatives are currently being investigated, including intercropping. The goal of this work was to evaluate the effects of cowpea sowing season, intercropped with corn, on green ear yield of two corn cultivars. The experiment was carried out as random blocks with four replicates. Corn cultivars AG 1051 and AG 2060 were submitted to the following treatments: no hoeing, two hoeings (20 and 40 days after planting), and cowpea planting (cultivar BR 4, with indeterminate growth) at corn planting and at 5, 10, and 15 days later. Twenty-eight weed species were found in the experiment area. The highest marketable green ear yields were obtained with hoeing, while the lowest were obtained without hoeing. Intercropping with cowpea, especially when done early, provided intermediate results, indicating that the legume controlled weeds to a certain extent, which was, however, insufficient to avoid corn yield loss. The cultivars do not differ with regard to green ear yield. Cowpea yields were nearly null (data not shown)