RFJ Spatial variability in fertigated coffee yields and plant nutrients in soil saturation extracts

The spatial distribution and levels of available plant nutrients (elements) in the soil can limit coffee yield and must be evaluated for effective crop management. Therefore, we analyzed spatial variability in yield and plant nutrients in the saturation extract of a clayey Oxisol cropped with fertigated coffee. The experiment was carried out on 14 hectares of coffee in Monte Carmelo, Minas Gerais, Brazil.  Soil samples were collected (0 - 0.2m layer) at 61 regular grid points (spaced 50x50m) and used to determine plant nutrients in the saturation extract. Coffee yield was also determined at these points. Descriptive statistics were calculated for each variable and geostatistics were used to build a spatial variability model representing the physical attributes of the soil. Variographic analysis was performed using semivariograms. These showed that yield and soil chemistry varied throughout the study site. Thus, the maps generated from geostatistics can be useful tools for soil management in fertigated coffee crops

Spatial variability in the physical properties of an Oxisol under coffee cultivation in the Brazilian Cerrado

The physical properties of the soil are limiting factors for coffee cultivation and yields.  Therefore, we analyzed spatial variability in the physical properties of a clayey Oxisol under coffee cultivation. The experiment was carried out on 14-hectares of a coffee (Coffea arabica) plantation in the city of Monte Carmelo, in the Brazilian state of Minas Gerais. Soil samples were collected from two layers (0 - 0.1 m and 0.1 - 0.2 m) at 61 grid-points spaced at 50 x 50 meters.  These samples were saturated to determine total porosity and soil bulk density. Soil resistance readings were also taken from the same grid points and layers using an impact penetrometer. Descriptive statistics were used to evaluate all variables. Additionally, geostatistics were used to model spatial variability within the soil physical properties. Variographic analysis was performed using semivariograms. We found that density, total porosity and soil resistance to penetration varied throughout the study area, which demonstrates that management type can alter soil physical properties and that maps generated by geostatistics can help coffee growers make decisions related to soil management

CARACTERIZAÇÃO ESPECTRAL DA CANA-DE-AÇÚCAR INFECTADA POR NEMATOIDES E MIGDOLUS FRYANUS POR ESPECTRORRADIOMETRIA DE CAMPO

O cultivo da cana-de-açúcar no Brasil, embora assistido por técnicas modernas de plantio, é alvo constante de parasitas do sistema radicular. Por registrar seletivamente o fluxo espectral da radiação eletromagnética refletida pela vegetação, o sensoriamento remoto tornou-se uma poderosa ferramenta na detecção das plantas infectadas por patógenos do solo. Com o objetivo de caracterizar espectralmente a cana-de-açúcar sadia e infectada por nematoides e pela larva do besouro Migdolus fryanus, foram tomadas medidas radiométricas in situ e geradas curvas hiperespectrais de plantas sadias e infectadas. Técnicas específicas de análise espectral, como a determinação da posição da borda do vermelho limítrofe (Red Edge Position Determination – REPD) e diferentes índices espectrais foram avaliados para discriminar as três ocorrências. As curvas de reflectância mostraram diferenças em magnitude principalmente nos comprimentos de onda do vermelho e infravermelho próximo e, assim como a determinação do REP e os índices de clorofila b, NDVI, MCARI e TCARI, permitiram distinguir apenas entre plantas sadias e infectadas. As razões espectrais sensíveis aos pigmentos clorofila a e carotenoides, porém, discriminaram as três ocorrências, inclusive plantas infectadas por nematoides e Migdolus fryanus. A melhor discriminação foi obtida com o índice de carotenoides, um pigmento fortemente relacionado com estresse da planta

Avaliação de registro arquitetônico por meio de modelo tridimensional fotogramétrico gerado a partir de câmaras convencionais

The technologies such as the Laser Scanner stand out within the area of architectural registry. Laser Scanner represents a precise technology, which enables the creation of three-dimensional models through the acquisition of milions of points. On the other hand, photogrammetric techniques are also used for similar purposes, making use of images in order to generate three-dimensional representation. Both methodologies aim to obtain reliable representations of reality. However, there are potential discrepancies regarding the accuracy and costs of generating these models. The objective of this letter is to compare the models generated by terrestrial Photogrammetry and Laser Scanner, in order to evaluate the feasibility and efficiency of conventional cameras applied to three-dimensional models for facade restoration purposes. For that, the surveys by terrestrial Photogrammetry and Laser Scanner were used on the facades of a century-old church in Monte Carmelo, MG. From the products, it was observed that the distance between the surfaces generated by the clouds of points from the photogrammetric process and Laser was less than 5 cm424338348As tecnologias como o Laser Scanner se destacam no âmbito de registros arquitetônicos. Laser Scanner representa um equipamento extremamente preciso, que possibilita a criação de modelos tridimensionais por meio da coleta de milhares de pontos. Por outro lado, as técnicas fotogramétricas também são utilizadas para tais fins, onde imagens são utilizadas na geração de estereomodelos fotogramétricos tridimensionais. Ambas as metodologias buscam obter representações fieis da realidade, porém, podem haver grandes discrepâncias quanto à precisão e os custos para geração destes. O objetivo deste trabalho foi realizar uma comparação entre os modelos gerados a partir de Fotogrametria terrestre e de Laser Scanner, visando avaliar a viabilidade e eficiência de câmaras convencionais aplicadas a modelos tridimensionais voltados a fins de restituição de fachadas. Para tanto, os levantamentos por Fotogrametria terrestre e Laser Scanner foram empregados sobre as fachadas de uma igreja centenária em Monte Carmelo, MG. A partir dos produtos, observou-se que a distância entre as superfícies geradas pelas nuvens de pontos provenientes do processo fotogramétrico e Laser foi inferior a 5 c

Sensitive electrochemical determination of yohimbine in primary bark of natural aphrodisiacs using boron-doped diamond electrode

For the first time, a simple and sensitive analytical method for the direct determination of yohimbine is presented using differential pulse voltammetry with a boron-doped diamond electrode. Two irreversible oxidation peaks, a distinct one at +0.80 and a second poorly-defined one at +1.65 V, were observed when cyclic voltammetry was carried out in Britton-Robinson buffer solution at pH 7 (vs. Ag/AgCl). With optimized differential pulse voltammetric parameters (pulse amplitude 100 mV, pulse time 25 ms, step potential 5 mV and scan rate 10 mV s(-1)), the current response of yohimbine at +0.80 V was linearly proportional to the concentration in the range from 0.25 to 90.9 mu mol L-1 with a low detection limit of 0.13 mu mol L-1 (0.046 mg L-1) and a good repeatability (relative standard deviation of 2.5% at 18.4 mu mol L-1 for n = 6). The practical applicability of the developed method was demonstrated by the assessment of the total content of yohimbine in extracts of the primary bark of natural aphrodisiacs such as Pausinystalia yohimbe and Rauvolfia serpentina with recoveries in the range of 92-97%. The proposed electrochemical procedure represents an inexpensive and effective analytical alternative for the quality control analysis of products containing yohimbine and other biologically and structurally related alkaloids used as natural dietary supplements

Enhancing clenbuterol immunosensor based on poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotube performance by response surface methodology

Clenbuterol (CLB) is an illegal antibiotic for livestock, which is misused as a growth promoter drug. In this study, an immunosensor modified with poly(3,4-ethylenedioxythiophene) (PEDOT), multi-walled carbon nanotubes (MWCNT) and anti-clenbuterol antibody (Ab) was developed for the detection of CLB. A screen-printed carbon electrode (SPCE) was modified with PEDOT/MWCNT as a sensor platform before immobilizing Ab for specific CLB binding through a competitive-type immunoassay. Free CLB in the sample solution competed with clenbuterol-horseradish peroxide (CLB–HRP) to bind with Ab. A high current signal was obtained after optimization of the electrochemical immunoassay conditions (pH, incubation temperature, antigen (Ag) incubation time and % blocking) using the response surface methodology/central composite design (RSM/CCD). The developed immunosensor is highly reproducible and sensitive with good storage stability, which are necessary for practical application. In real sample application, this immunosensor produces comparable results with liquid chromatography-mass spectrometry; thus, it is useful for CLB screening and monitoring in real meat samples

Using Geospatial Information to Map Yield Gain from the Use of Azospirillum brasilense in Furrows

The application of biological products in agricultural crops has become increasingly prominent. The growth-promoting bacterium Azospirillum brasilense has been used as an alternative to promote greater yield in maize crops. In the context of precision agriculture, interpreting geospatial data has allowed for monitoring the effect of the application of products that increase the yield of corn crops. The objective of this work was to evaluate the potential of Kriging techniques and spectral models through images in estimating the gain in yield of maize crop after applying A. brasilense. Analyses were carried out in two commercial areas treated with A. brasilense. The results revealed that models of yield prediction by Kriging with a high volume of training data estimated the yield gain with a root-mean-square error deviation (RMSE%), mean absolute percentage error (MAPE%), and R2 to be 6.67, 5.42, and 0.88, respectively. For spectral models with a low volume of training data, yield gain was estimated with RMSE%, MAPE%, and R2 to be 9.3, 7.71, and 0.80, respectively. The results demonstrate the potential to map the spatial distribution of productivity gains in corn crops following the application of A. brasilense

Caracterização espectral e espacial de áreas infestadas por nematóides e Migdolus fryanusem em cultura canavieira

O cultivo da cana-de-açúcar possui grande importância econômica para o Brasil por fornecer a matéria prima para a produção de açúcar, etanol e de energia elétrica, além de exercer um papel relevante tanto no mercado interno quanto externo. Nas últimas décadas, essa atividade agrícola tornou-se uma realidade na maioria das lavouras brasileiras, sendo assistida por sofisticadas técnicas de plantio e manejo utilizando uma diversidade de insumos agrícolas. Porém, mesmo sob a era da tecnologia, as lavouras de cana-de-açúcar são constantes alvos de pragas e parasitas, tais como a larva do besouro Migdolus fryanus e os nematoides do solo. Sabendo que esses problemas constituem um dos principais fatores responsáveis pela queda da produção canavieira e que a detecção e o controle destas infestações são, por muitas vezes, ineficazes cresceu, nos últimos anos, a necessidade de se desenvolver técnicas para detectar a ocorrência destes agentes nas culturas agrícolas, para um posterior controle e manejo das áreas de infestação. Neste contexto, a presente pesquisa embasa-se no uso de técnicas de Sensoriamento Remoto para detectar a ação dos nematoides e da larva do besouro Migdolus fryanus, mais especificamente em situações em que a ocorrência da infestação não é perceptível com uma simples verificação visual em campo. A metodologia proposta considera a integração de dados hiperespectrais e imagens multiespectrais para avaliar as diferenças espectrais e na configuração espacial de áreas sadias e afetadas por parasitos do sistema radicular da cana-de-açúcar. Portanto, o estudo teve como...The cultivation of sugar cane has great economic importance to Brazil for providing the raw material for the production of sugar and alcohol, as well as plays a relevant role both domestically and externally. In recent decades, this farming became a reality in most Brazilian crops, assisted by sophisticated planting techniques and management using a variety of inputs. But even in the age of technology, the fields of sugar cane are constant targets of pests and parasites, such as beetle larvae Migdolus fryanus and soil nematodes. Knowing that these problems constitute one of the main factors responsible for the decline in sugarcane production and the detection and control of these infestations are, often ineffective grown in recent years, the need to develop techniques to detect the occurrence of these agents on crops agricultural, for further control and management of areas of infestation. In this context, the present research underlies on the use of remote sensing techniques to detect the action of these parasites, specifically in situations where the occurrence of infestation is not noticeable with a simple visual check on the field. The proposed methodology considers the integration of hyperspectral data and multispectral images to assess the differences in spectral and spatial configuration of areas affected by parasites and healthy root system of cane sugar. Therefore, in this context, the study aimed to characterize the spatial... (Complete abstract click electronic access below