SUMMARYAraucaria angustifolia (Bert.) O. Kuntze is the main component of the Mixed Ombrophilous forest and, in the State of São Paulo, it is associated with a high diversity of soil organisms, essential for the maintenance of soil quality, making the conservation of this ecosystem a major and pressing challenge. The objective of this study was to identify the physical and chemical properties that are most closely correlated with dehydrogenase enzyme activity, basal respiration and microbial biomass under native (NF) and replanted (RF) Araucaria angustifolia forests in three regions of the state of São Paulo, in winter and summer. The main differentiating factors between the areas were also determined. Each forest was represented by three true replications; at each site, from around the araucaria trees, 15 soil samples (0-20 cm) were collected to evaluate the soil physical, chemical and microbiological properties. At the same points, forest litter was sampled to assess mass and chemical properties. The following microbiological properties were evaluated: microbial biomass carbon (MBC), basal respiration (CO 2 -C), metabolic quotient (qCO 2 ), dehydrogenase enzyme activity (DHA) as well as the physical properties (moisture, bulk density, macroporosity and total porosity), soil chemical properties [pH, organic carbon (org-C), P, Ca, K, Mg, Al, H+Al], litter dry mass, and C, N and S contents. The data were subjected to analysis of variance (Two-way ANOVA). A Canonical Discriminant Analysis (CDA) and a Canonical Correlation Analysis (CCA) were also performed. In the soil under NF, the values of K, P, soil macroporosity, and litter dry mass were higher and qCO 2 and DHA lower, regardless of the sampling period, and DHA was lower in winter. In the RF areas, the levels of moisture, porosity and qCO 2 were higher in both sampling periods, and DHA was higher in winter. The MBC was only higher under NF in the summer, while the litter contents of C, N and S were greater in winter. In winter, CCA showed a high correlation of DHA with CO 2 -C, pH and H+Al, while in the summer org-C, moisture, Mg, pH and litter C were more associated with DHA and CO 2 -C. The CDA indicated H+Al, available P, total porosity, litter S content, and soil moisture as the most discriminating variables between NF and RF, but moisture was the most relevant, in both seasons and CO 2 -C only in winter. The combined analysis of CCA and CDA showed that the contribution of the microbiological variables to a differentiation of the areas was small at both samplings, which may indicate that the period after reforestation was long enough to allow an almost complete recovery of the microbial activity.Index terms: multivariate analysis, soil quality, soil chemical properties, microbiological properties. RESUMO: RELAÇÃO ENTRE ATIVIDADE MICROBIANA E ATRIBUTOS FÍSICOS E QUÍMICOS DO SOLO EM FLORESTA DE Araucaria angustifolia NATIVA E REFLORESTADA NO ESTADO DE SÃO PAULO A Araucaria angustifolia (Bert.) O. Kuntze é a principal componente da Floresta Ombrófila Mista n...

Com o objetivo de quantificar o efeito da cercosporiose do milho (Cercospora zeae-maydis) no rendimento de 12 híbridos comerciais de milho e correlacionar a redução na produtividade de grãos com a severidade da doença, foram conduzidos em duas épocas de semeadura, dois experimentos em área experimental da Universidade Federal de Lavras, em Lavras MG, no ano agrícola de 2005/2006. O primeiro experimento foi instalado em 11/11/2005 e o segundo em 23/12/2005. O controle da doença nas parcelas sadias de todos os híbridos foi obtido através de duas aplicações de epoxiconazol + piraclostrobina (37,5 + 99,75 g i.a.ha-1) em intervalo de 15 dias. Nas parcelas sem controle químico da doença, a epidemia iniciou o seu desenvolvimento com o inóculo natural presente na área. Foram realizadas oito avaliações da severidade da doença em intervalos de sete dias, a partir dos 60 dias após a emergência, por meio de escala de notas variando de 1 (resistente) a 9 (suscetível). Estimou-se a área abaixo da curva de progresso da doença (AACPD) e obteve-se a produtividade de grãos. Com os dados estimou-se a porcentagem de danos e as correlações entre a produtividade de grãos e a porcentagem de danos com as estimativas da AACPD. Constatou-se que: o nível de dano varia entre as épocas de semeadura e híbridos avaliados, sendo em média de 13,3%; a cercosporiose é uma doença que reduz a produtividade de grãos de milho, principalmente para a semeadura tardia e o uso de híbridos resistentes dispensa o controle químico da doença.

Although the inequalities known as the “glass ceiling” are not a recent phenomenon in society, research addressing their effects still is. Studies show that scientists' interest in this type of inequality has been in evidence since the 1990s. Although research on mature women within organizations and the barriers posed by the “glass ceiling” effects are on the rise, there is still a theoretical gap about the obstacles young women, between 21 and 30 years old face. Based on qualitative research, carried out through semi-structured interviews with this group, we show that the “glass ceiling” and “crystal wall” effects can be felt even at the beginning of the career. Professional barriers, such as lack of experience, intensify gender inequalities and age discrimination in the selection process for internship or hiring. We conclude that young women adopt credibility strategies to deal with these difficulties.

-The objective of this experiment was to characterize the dry matter production of vegetative components (stalk, leaf, husk, and cob) and reproductive components (grain) of the corn plant according to planting time and the grain maturity stage. Eight corn hybrids with different agronomic characteristics were used to carry out the experiments. Two experiments were performed with planting undertaken on 11/11/2007 and 12/12/2007 under a conventional tillage system. The eight corn cultivars were harvested at three grain maturity stages, half milk line, three quarters milk line and black layer. An 8 × 3 factorial (eight hybrids and the three cutting times) randomized blocks design was used, with three replications. Individual analysis of variance was performed for each experiment. Then joint analysis of variance was performed involving the two planting times. The means were grouped and the hybrids used as replications to characterize the components. Delay in planting significantly reduced the dry matter productivity of the whole plant; however, it did not reduce its degradability. The greatest dry matter productivity obtained was that of grain, followed by stalk, leaf, husk and cob. The vegetative components, leaves and husk, lose quality with delay in planting. The leaf is the vegetative component of highest quality, while the cob is the worst. Delay in planting increases the neutral detergent fiber content of the stalk, husk and cob.

Plants density in soybean cultivation is an important management practice to achieve high grain yield. In this way, the objective was to evaluate the agronomic traits and grain yield in soybean in different plant densities, in two locations in the south of Minas Gerais. The experimental design was in randomized blocks, arranged in a split plot design, with three replications. Plots were composed of four population densities (300, 400, 500 and 600 thousand plants per hectare) and the subplots were composed of six cultivars (‘BMX Força RR’, ‘CD 250 RR’, ‘FMT 08 - 60.346/1’, ‘NA 5909 RR’, ‘TMG 7161 RR’ and ‘V - TOP RR’) grown in Lavras and Inconfidentes, both in Minas Gerais. At the time of harvest was determined the plant height, lodging, insertion of the first pod, harvest index, number of pods per plant, number of grains, number of grains per pod and yield. Regardless of the soybean cultivar, the plant density of up to 600,000 per ha does not affect grain yield, plant height, lodging, harvest index, and number of grains per pod. The cultivars ‘V-TOP RR’ and ‘BMX FORÇA RR’ showed high grain yield and good agronomic traits in Lavras and Incofidentes.

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ABSTRACT:Studies on soil quality in Araucaria forests contribute to understanding changes in this ecosystem and serve as a tool in conserving its biodiversity. The aim of this study was to evaluate the potential of soil macrofauna in discriminating native and replanted Araucaria forests for selection of soil quality indicators. Native (NF) and replanted (RF) Araucaria angustifolia forests were evaluated in three regions of the state of São Paulo, representing three true replications. Fifteen soil samples were collected in each area for evaluation of the physical, chemical, and microbiological properties and the macrofauna through use of monolith excavation and the manual screening method [Tropical Soil Biology and Fertility (TSBF) method]. In addition, we evaluated the weight of the surface litter dry matter and the C, N, and S contents. The abundance of macrofauna was subjected to Principal Components Analysis (PCA) and the physical, chemical, and microbiological properties were used as explanatory environmental variables for changes in the soil community. These variables and the macrofaunal properties were applied in analyses of variance and in canonical discriminant analysis (CDA) to indicate the best properties for discrimination of the forests studied. The abundance of macrofaunal groups was influenced by the state of conservation of the forest and by the sampling period; the native forest and the summer season provided greater diversity of taxonomic groups. The richness of taxonomic groups was the property that most contributes to discriminating reforested areas from native forests. The Oligochaeta group was a prominent indicator of soil quality and/or environmental disruption in Araucaria forests. Soil moisture, total porosity, and S content in the surface litter were likewise variables that contributed to distinguishing the areas. The ecological indexes (diversity, dominance, and equitability) were not sensitive to the changes in macrofaunal properties in the forests studied.

The study of micronutrients accumulation as a function of plant development stage is of fundamental importance to subsidize strategies for fertilizer application and minimum amount to maintain soil fertility. This study evaluated micronutrient accumulation in two maize cultivars at different development stages. The experimental design was randomized blocks with four replications in split-plots, with two maize hybrids as the plots and sampling time according to development stages as sub-plots. Maize accumulated minimum amounts of B, Cu, Mn, and Zn in the initial stages of development, and the maximum accumulated values were observed after 100 days seedling emergency. The evaluated hybrids accumulated maximum of Zn and Cu close to physiological maturity. Maize plants accumulate nutrients in the above ground parts as follows: Zn > Mn > Cu > B. The total amount of nutrients required to produce one ton of corn is: 0.0009 kg B; 0.019 to 0.02 kg Cu; 0.042 to 0.046 kg Mn; 0.100 to 0.194 kg Zn. Index terms:Zea mays, accumulation, nutrients, cultivars. RESUMOEstudar o acúmulo de micronutrientes em função dos estádios fenológicos da cultura é de fundamental importância para subsidiar estratégias de definição das quantidades e das épocas de realização de adubações na cultura, e das quantidades mínimas que devem ser restituídas ao solo para fins de manutenção da fertilidade. Neste trabalho, objetivou-se avaliar o acúmulo de micronutrientes em função dos estádios fenológicos da cultura, considerando dois híbridos de milho. O delineamento utilizado foi o DBC com quatro repetições, em esquema de parcelas subdivididas, sendo os dois híbridos de milho dispostos nas parcelas e, nas sub-parcelas, as épocas de coleta das plantas, considerando os estádios fenológicos da cultura do milho. Híbridos de milho acumulam quantidades mínimas de B, Cu, Mn e Zn nos estádios iniciais de desenvolvimento da cultura, sendo os valores máximos acumulados obtidos a partir de 100 dias após a emergência. Os híbridos de milho avaliados acumulam zinco e cobre até próximo à maturidade fisiológica, quando são obtidos os acúmulos máximos. Híbridos de milho acumulam micronutrientes em sua parte aérea na seguinte ordem decrescente: Zn>Mn>Cu>B. As quantidades de micronutrientes necessárias para produzir uma tonelada de grãos de milho são: 0,0009 kg de B; 0,019 a 0,020 kg de Cu; 0,042 a 0,046 kg de Mn; 0,100 a 0,194 kg de Zn. Termos para indexação:Zea mays, acúmulo, nutrientes, híbridos.