The knowledge of the climatic conditions of a region is crucial for its agricultural development. It is also extremely important for understanding the fact that certain cultures have to develop under prevailing temperature and humidity conditions and assist in the adoption of a suitable irrigation technique, as well as its management and operationalization. The Köppen system of climate classification is widely used for the identification of homogeneous climate zones as it considers only rainfall and temperature as the meteorological elements for classification. For this study, we used climatic databases of rainfall and temperature in a raster format, with a spatial resolution of 30″ of arc (an approximate area of 0.86 km 2 pixel −1 ), from 1961 to 1990. Through geoprocessing techniques, we obtained a map of climatic classification for the state of Minas Gerais. We found that the state has the following three major climatic groups: A, B and C, which correspond to tropical rainy, dry and warm temperate climates, respectively. The climate classes obtained were Aw, Am, BSh, Cwa and Cwb, with Aw, Cwa and Cwb classes occupying 99.89% of the territorial area of the state. The validation of the results showed a satisfactory agreement, with 93.75% reliability.
The recent and widespread expansion of the pioneer tree species Vochysia divergens Pohl into western Brazil has the potential to significantly alter the structure and function of the Pantanal-a UNESCO World Heritage Site and the World's largest tropical wetland. Here we assess the seasonal pattern of evapotranspiration (ET) and micrometeorological variables of V. divergens (locally known as cambarazal), located in the Northeast of the Brazilian Pantanal. ET was calculated from a number of micrometeorological measurements recorded between January 2007 and January 2008. The results indicate that ET was the dominant sink for net radiation (R n ) during the wet and dry seasons, primarily because the forest was either flooded (December-May) or retained a high level of soil moisture. ET decreased during the dry season due to a decline in R n and surface water availability, and an increase in atmospheric vapor pressure deficit. Based on this analysis we conclude that the spread of V. divergens into the Pantanal and the associated high rates of ET are due in part to high water availability, even during the dry season, and the consistently high leaf area index that increases the transpiration surface area when the water table is below the soil surface.
The advent of geostatistics and geographical information systems has made it possible to analyze complex spatial patterns of ecological phenomena over large areas in applied insect ecology and pest management. The objective of this study was to use geostatistics to characterize the spatial structure and map the spatial variation of damage caused by the berry borer (Hypothenemus hampei) and leaf miner (Leucoptera coffeella) in a coffee agroecosystem planted with the cultivar Catuai Vermelho IAC-99. Infestations of berry borer and leaf miner were evaluated in fruits and leaves, respectively. The pests were monitored at 67 georeferenced points in an area of 6.6 ha in 2005, 2006 and 2007. Variograms estimated by the method of moments (MoM) and residual maximum likelihood REML were compared. The latter were generally better in terms of the kriging error coefficients. Spherical variograms estimated by REML for berry borer infestation in fruits had ranges of spatial dependence of 34.62-118.4 m and for the leaf miner they were 53.93-133.7 m. For models fitted by weighted ordinary least squares (OLS) to the MoM experimental variogram, the ranges varied between 37.22 and 68.67 m for the berry borer and 100 and 155.4 m for leaf miner infestation. The variogram model parameters were used with the data for ordinary kriging to map the spatial variation of coffee pests for different monitoring periods. If there was no suitable variogram, inverse distance weighting was used to map the variation. The maps enabled visualization of the intensity of infestation of the insect pests for the different periods evaluated.
RESUMOObjetivou-se no presente trabalho caracterizar o progresso espaço-temporal da severidade da antracnose do feijoeiro comum e da ramulose do algodoeiro por meio da Geoestatística. Os experimentos foram conduzidos no campo, durante o período das águas, em diferentes épocas. Sementes inoculadas pelo método da restrição hídrica foram semeadas no centro de parcelas experimentais constituindo fonte de inóculo do tipo ponto. Foram realizadas semanalmente seis avaliações da severidade das doenças com base em escalas de notas. Pelos modelos de semivariograma isotrópicos esféricos e gaussianos das doenças nos primeiros estádios, com aumento gradual ao longo do tempo. A antracnose apresentou formação inicial de focos de inóculo secundário, além do foco com inóculo inicial, que coalesceram com o tempo. A severidade da ramulose diminuiu gradualmente de forma radial e contínua do centro da parcela para as extremidades, com maior capacidade de infecção de plantas vizinhas, quando comparada à antracnose, possivelmente pela maior agressividade do patógeno e hábito de crescimento arbustivo do algodoeiro.Palavras-chave adicionais: var. krigagem ordinária. ABSTRACTGeoestatistics as methodology to study the space-time dynamics of diseases transmitted by seed-borne Colletotrichum spp.The aim of this work was the characterization of the space-time severity progress of the common bean Anthracnose and cotton Ramulose through Geoestatistics. The experiments were conducted over different periods during the rainy standing as inoculum source of point type. Six evaluations of the epidemics' severity were done weekly following disease and gaussian semivariogram models adjusted to the data. With the ordinary block kriging method, it was possible to verify presented initially secondary inoculum focus formation besides the focus with initial inoculum with later coalescence. The severity of Ramulose decreased gradually, both radially and smoothly from the center of the plot to the borders, with a larger capacity to infect neighboring plants, when compared to the Anthracnose, possibly due to the fungi's aggressiveness and to the cotton plant's shrubby growth habit.
The determination of the amount of water needed for crops is one of the main parameters for correct irrigation planning. In this context the FAO Penman-Monteith method (FAO-PM) has been recommended as the best for the reference evapotranspiration (ETo) estimates. However it is not always possible to have all the necessary data for its application; in this case, alternative criteria must be used for this estimation. In this study, the objective was to estimate ETo by the FAO-PM method with only the maximum and minimum temperature values, here called Simplified FAO-PM, and compare it to the standard method (FAO-PM) with all input data, for Lavras, Minas Gerais State, Brazil. It was observed that the alternative method has the tendency to overestimate the standard method, however, this approach is feasible to estimate ETo for irrigation scheduling in localities where not all input data required for FAO-PM is available.Key words: evapotranspiration estimate, minimum temperature, maximum temperature, irrigation management. RESUMEN La cuantificación de las necesidades de agua del cultivo es un parámetro clave para la planificación del riego. En el presente, la ecuación de Penman-Monteith (FAO-PM) ha sido recomendada como la mejor para estimar la evapotranspiración de referencia (ETo
A Ferrugem Asiática (Phakopsora pachyrhizi H. Sydow & P. Sydow), relatada em diversas regiões do globo terrestre de climas tropicais e subtropicais, causa redução significativa na produtividade da soja [Glycine max (L.) Merr.]. Fatores bióticos como interação patógeno-hospedeiro e abióticos influenciam o progresso da doença. Objetivou-se neste trabalho estudar os efeitos da temperatura e de períodos de molhamento foliar no progresso da Ferrugem Asiática nas cultivares Conquista, Savana e Suprema. O experimento foi conduzido no Departamento de Fitopatologia da Universidade Federal de Lavras, em junho de 2004, em câmaras de crescimento vegetal nas temperaturas de 15, 20, 25 e 30 °C e períodos de molhamento foliar de 0, 6, 12, 18 e 24 horas. A inoculação foi realizada pulverizando-se as plantas com suspensão de 10(4) uredósporos de P. pachyrhizi.mL-1 de água. Dados da incidência e da severidade foram utilizados para avaliar o progresso da doença e integrados por meio da área abaixo da curva de progresso da incidência (AACPI) e da severidade (AACPS). Modelos de regressão não-linear foram ajustados para a AACPI e AACPS. Foi calculado o volume abaixo da superfície de resposta para incidência (VASRI) e severidade (VASRS) em relação à temperatura e molhamentos foliares com o objetivo de detectar diferenças entre cultivares. Molhamentos foliares acima de 15 horas e temperaturas próximas a 20 ºC, nas 3 cultivares avaliadas, determinaram maior intensidade da Ferrugem Asiática. Temperaturas próximas a 30 e 15 ºC ocasionaram menor intensidade da doença. Períodos de molhamento foliar abaixo de 6 horas reduziram a intensidade da doença. Todas as cultivares testadas foram suscetíveis à doença, entretanto, a cultivar Conquista apresentou maior VASRI e VASRS da Ferrugem Asiática comparada às cultivares Savana e Suprema, as quais não diferiram estatisticamente. Houve diferença entre as cultivares para AACPI em cada temperatura e molhamento foliar.
The aim of this study was to test the standard scanning electron microscopy (SEM) as a potential alternative to study seed-borne fungi in seeds, by two different conditions of blotter test and water restriction treatment. In the blotter test, seeds were subjected to conditions that enabled pathogen growth and expression, whereas the water restriction method consisted in preventing seed germination during the incubation period, resulting in the artificial inoculation of fungi. In the first condition, seeds of common bean (Phaseolus vulgaris L.), maize (Zea mays L.), and cotton (Gossypium hirsutum L.) were submitted to the standard blotter test and then prepared and observed with SEM. In the second condition, seeds of cotton (G. hirsutum), soybean (Glycine max L.), and common bean (P. vulgaris L.) were, respectively, inoculated with Colletotrichum gossypii var. cephalosporioides, Colletotrichum truncatum, and Colletotrichum lindemuthianum by the water restriction technique, followed by preparation and observation with SEM. The standard SEM methodology was adopted to prepare the specimens. Considering the seeds submitted to the blotter test, it was possible to identify Fusarium sp. on maize, C. gossypii var. cephalosporioides, and Fusarium oxysporum on cotton, Aspergillus flavus, Penicillium sp., Rhizopus sp., and Mucor sp. on common bean. Structures of C. gossypii var. cephalosporioides, C. truncatum, and C. lindemuthianum were observed in the surface of inoculated seeds. Microsc. Res. Tech. 72:482-488, 2009. V
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