980 resultados para seasons of seeding
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There is no agreement among authors that study fish condition by the allometric method (K=W/Lb) with regard to the best procedure for b coefficient calculation. Some authors use a constant coefficient for all sub-samples (seasons of the year, for instance), whilst others calculate b value for each sub-sample. To demonstrate which of these methods fits better, this study verified that the use of one b value for each sub-sample leads to distortion of Condition Factor values. Comparing the two tested methods, it may be concluded that the method which calculates b coefficient from groupings of all individuals and uses b as a constant value for all sub-samples is the most convenient method to study fish condition.
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The comet assay has been described as an efficient tool for the detection of changes in the DNA molecule of cells exposed to contaminating agents in vivo and in vitro. The possible environmental contamination due to the persistence of chromium residues from tannery effluents was determined in the waters of the Córrego dos Bagres stream, Municipal district of Franca/SP, by the comet assay on CHO-K1 cells. Water samples were collected during the four seasons of the year 2001 at three distinct stations along the river. The data suggest that the comet test showed good sensitivity for the environmental monitoring of these waters and indicated that this test can be efficient for the determination of the quality of waters contaminated with effluents containing heavy metal residues such as chromium.
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The aim of this study was to evaluate dry matter yield and nutritional value of palisade grass (Brachiaria brizantha cv. Marandu) using nitrogen doses and sprinkler irrigation in two periods of the year, aiming at reducing seasonality of forage production. It was used a randomized block design in a split-plot scheme, with five doses of nitrogen (0, 50, 100, 150, and 200 kg/ha/cut), and the sub-plots were defined by the seasons of the year (wet and dry season), with and without irrigation. During the wet season, in the plots with and without irrigation, doses of 175 and 161 kg/ha/cut promoted the highest dry matter yields. During the dry season, 171 kg ha -1N with irrigation resulted in the highest dry matter yield. During the same season, there was no response to N fertilization in the lack of irrigation. Average contents of CP were 10% with and without irrigation. Contents of neutral detergent fiber decreased with nitrogen doses, while acid detergent fiber was not affected by fertilization. Plots under irrigation reached the maximal acid detergent fiber content at N dose of 60 kg ha -1. Irrigation promotes increase of 15% increase in dry matter yield and it increases contents of neutral detergent fiber. © 2010 Sociedade Brasileira de Zootecnia.
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The relative growths of Persephona lichtensteinii, P. mediterranea, and P. punctata were investigated on the south-eastern Brazilian coast, focusing on differences in the growth rates between immature and mature phases, the onset of morphological sexual maturity, and the breeding seasons of these species. Crabs were collected every two months from January 1991 through to November 1992, from a shrimp fishing boat equipped with two otter-trawl nets. Significant differences in the patterns of body growth were observed between immature and mature phases of all three species. Changes in the growth rates of the chelipeds (males) and abdomen (females) observed for P. lichtensteinii, P. mediterranea, and P. punctata, seem to be related to the puberty moult for both sexes. Males of P. mediterranea and P. punctata reached larger mean sizes of carapace width than females, whereas no difference was recorded for P. lichtensteinii. The body size at which 50% of males attained sexual maturity was also larger in P. mediterranea and P. punctata, and smaller in P. lichtensteinii. The absence of a pronounced sexual dimorphism and the size at the onset of sexual maturity observed only for P. lichtensteinii might be explained by distinct reproductive strategies of males. The presence of ovigerous females during the entire sampling period suggests that all three species have a continuous reproduction pattern at the Ubatuba region. Future studies on the population structure, functional maturity, and mating system should improve the understanding of factors driving the biology and ecology of these species at a subtropical region. © Marine Biological Association of the United Kingdom 2013.
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Pós-graduação em Agronomia (Ciência do Solo) - FCAV
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Pós-graduação em Agronomia (Ciência do Solo) - FCAV
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Pós-graduação em Agronomia (Energia na Agricultura) - FCA
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O objetivo deste trabalho foi estimar parâmetros genéticos e avaliar a seleção simultânea quanto à produtividade de raízes e à adaptabilidade e estabilidade de genótipos de mandioca. Os efeitos dos genótipos foram considerados como fixos e aleatórios, e a metodologia de modelos mistos (REML/Blup) foi utilizada para estimar os parâmetros genéticos e a média harmônica do desempenho relativo dos valores genotípicos (MHPRVG), para seleção simultânea. Dez genótipos foram avaliados em delineamento de blocos ao acaso, com quatro repetições. O experimento foi realizado nos municípios de Altamira, Santarém e Santa Luzia do Pará, PA, nos anos agrícolas de 2009/2010, 2010/2011 e 2011/2012. As raízes foram colhidas 12 meses após o plantio, em todos os locais testados. A produtividade de raízes apresentou baixo coeficiente de variação genotípica (4,25%) e herdabilidade de parcelas individuais no sentido amplo (0,0424), o que resultou em baixo ganho genético. Em razão da baixa correlação genotípica (0,15), a classificação dos genótipos quanto à produtividade de raízes variou de acordo com o ambiente. Os genótipos CPATU 060, CPATU 229 e CPATU 404 destacaram-se quanto à produtividade, adaptabilidade e estabilidade.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The objective of this work was to study the intercropping of Brachiaria brizantha. Marandu with soybeans. The experiment has been planted in a 3 year prevailing area with no-tillage, in eutrophic Oxisol at Maripa - PR. The experimental design was a randomized block with five replications. For the forage study, four treatments were performed which consisted of seeding times brachiaria [early ( seven days before planting soybeans) joint (same day of soybean planting) and after (at stages V-3 and R-1 culture)] intercropping with soybean. To study the yield and crude protein and oil levels of the grain were adopted six treatments, which consisted of sowing dates of capim Marandu [early (seven days before planting soybeans), joint (same day of soybean planting) after (V-3, R-1 and R-5 soybean) and in single culture (single)]. The forager higher productivity of dry matter occurs with early sowing, however, the greatest reduction in soybean yield also occurs in this case. The sowing of Brachiaria until R-5 soy has no influence on the nutritional value of the forage. The intercropped of soybean with Brachiaria brizantha. Marandu has no impact on the leaf Nitrogen content, oil content and enzyme activity of soybean peroxidase. The highest yield of soybeans occurs when it is grown single or Brachiaria is sown in stage R-5. The crude protein content of soybean grain is reduced when brachiaria seeding is early or together with soybeans compared to single culture.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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We assessed the efficacy of free-ranging dogs, confined by buried fences and electronic collars, for reducing deer damage to apple trees in three commercial apple orchards in Oswego County, New York State. During 1995 and 1996, we monitored paired dog-protected and control plots in each orchard. Within dog-protected areas, the percentage of damaged buds was lower, and fruit yield was higher in both 1995 and 1996 than for control plots. Gross economic returns were higher from dog-protected than control plots in both 1995 (by 51%) and 1996 (by 184%). After two seasons of growth, trees planted in May 1995 had nearly three times the cross-sectional area, and were 60% taller if they were in dog-protected rather than control plots. Dogs provided increased economic returns for growers at much lower cost than conventional barrier fencing.
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Chlorophyll determination with a portable chlorophyll meter can indicate the period of highest N demand of plants and whether sidedressing is required or not. In this sense, defining the optimal timing of N application to common bean is fundamental to increase N use efficiency, increase yields and reduce the cost of fertilization. The objectives of this study were to evaluate the efficiency of N sufficiency index (NSI) calculated based on the relative chlorophyll index (RCI) in leaves, measured with a portable chlorophyll meter, as an indicator of time of N sidedressing fertilization and to verify which NSI (90 and 95 %) value is the most appropriate to indicate the moment of N fertilization of common bean cultivar Perola. The experiment was carried out in the rainy and dry growing seasons of the agricultural year 2009/10 on a dystroferric Red Nitosol, in Botucatu, São Paulo State, Brazil. The experiment was arranged in a randomized complete block design with five treatments, consisting of N managements (M1: 200 kg ha-1 N (40 kg at sowing + 80 kg 15 days after emergence (DAE) + 80 kg 30 DAE); M2: 100 kg ha-1 N (20 kg at sowing + 40 kg 15 DAE + 40 kg 30 DAE); M3: 20 kg ha-1 N at sowing + 30 kg ha-1 when chlorophyll meter readings indicated NSI < 95 %; M4: 20 kg ha-1 N at sowing + 30 kg ha-1 N when chlorophyll meter readings indicated NSI < 90 % and, M5: control (without N application)) and four replications. The variables RCI, aboveground dry matter, total leaf N concentration, production components, grain yield, relative yield, and N use efficiency were evaluated. The RCI correlated with leaf N concentrations. By monitoring the RCI with the chlorophyll meter, the period of N sidedressing of common bean could be defined, improving N use efficiency and avoiding unnecessary N supply to common bean. The NSI 90 % of the reference area was more efficient to define the moment of N sidedressing of common bean, to increase N use efficiency.
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The study of the impact of climate change on the environment has been based, until very recently, on an global approach, whose interest from a local point of view is very limited. This thesis, on the contrary, has treated the study of the impact of climate change in the Adriatic Sea basin following a twofold strategy of regionalization and integration of numerical models in order to reproduce the present and future scenarios of the system through a more and more realistic and solid approach. In particular the focus of the study was on the impact on the physical environment and on the sediment transport in the basin. This latter is a very new and original issue, to our knowledge still uninvestigated. The study case of the coastal area of Montenegro was particularly studied, since it is characterized by an important supply of sediment through the Buna/Bojana river, second most important in the Adriatic basin in terms of flow. To do this, a methodology to introduce the tidal processes in a baroclinic primitive equations Ocean General Circulation Model was applied and tidal processes were successfully reproduced in the Adriatic Sea, analyzing also the impacts they have on the mean general circulation, on salt and heat transport and on mixing and stratification of the water column in the different seasons of the year. The new hydrodynamical model has been further coupled with a wave model and with a river and sea sediment transport model, showing good results in the reproduction of sediment transport processes. Finally this complex coupled platform was integrated in the period 2001-2030 under the A1B scenario of IPCC, and the impact of climate change on the physical system and on sediment transport was preliminarily evaluated.