Revista Brasileira de Engenharia Agrícola e Ambiental

(941 Artigos indexados)

Nutritional deficiency symptoms of young ‘cedro doce’ plants grown under macronutrient omission - (2025)

Simone T. M. de Aquino, Reila F. dos Santos, Karine D. Batista

Volume: 23 - Issue: 4

Resumo. ABSTRACT ‘Cedro doce’ [Pochota fendleri (Seem) Alverson & Duarte] is a native forest species in Amazon with great ecological and economic importance. Understanding nutritional requirements of the species allows cultivating Pochota fendleri with more efficient fertilization practices since its initial growth, as a seedling. Thus, this research aimed to evaluate the symptoms of nutritional deficiency of young ‘cedro doce’ plants. The experiment was carried out from September to December 2016, under greenhouse conditions, at Embrapa Roraima, in Boa Vista, RR, Brazil. The experiment was a randomized complete block design with seven treatments [complete solution and individual omission of the macronutrients (N, -P, -K, -Ca, -Mg, -S)] and three replications. Each experimental plot corresponded to a pot with one plant, corresponding to 21 plots. At 77 days after transplanting the seedlings to the pots, the plants were evaluated for symptoms of nutritional deficiency: total height, collar diameter, leaf number, chlorophyll a and b, chlorophyll a/b index ratio, shoot and root dry mass, and root/shoot ratio. The macronutrients omission caused nutritional deficiency symptoms in all ‘cedro doce’ plants. In general, P and N omission caused the least development of plants. This result is an indicative that ‘cedro doce’ is a high demanding species for both nutrients, especially phosphorus.

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Salt stress and exogenous application of hydrogen peroxide on photosynthetic parameters of soursop - (2025)

André A. R. da Silva, Geovani S. de Lima, Carlos A. V. de Azevedo, Luana L. de S. A. Veloso, Hans R. Gheyi, Lauriane A. dos A. Soares

Volume: 23 - Issue: 4

Resumo. ABSTRACT This study aimed to evaluate the gas exchanges and photosynthetic pigments of soursop seedlings cv. ‘Morada Nova’ irrigated with saline waters and subjected to exogenous application of hydrogen peroxide by seed soaking and foliar spraying. The study was carried out using plastic bags under greenhouse conditions at the Center of Technology and Natural Resources of the Federal University of Campina Grande, PB, Brazil, using a eutrophic Regolithic Neosol of sandy loam texture. Treatments were arranged in a randomized block design, in 5 x 5 factorial scheme, which consisted of five levels of electrical conductivity – ECw (0.7; 1.4; 2.1; 2.8 and 3.5 dS m-1) of irrigation water and five concentrations of hydrogen peroxide - H2O2 (0, 25, 50, 75 and 100 µM), with four replicates and three plants per plot. As the salt stress increased, there were reductions in internal CO2 concentration, instantaneous carboxylation efficiency and water use efficiency, and instantaneous carboxylation efficiency was the most sensitive variable. Hydrogen peroxide at concentrations of 25 and 50 µM attenuated the deleterious effects of water salinity on stomatal conductance, CO2 assimilation rate and chlorophyll a content, and the concentration of 25 µM was the most efficient. The content of chlorophyll b and carotenoids of soursop cv. ‘Morada Nova’ had the deleterious effects caused by the salinity of irrigation water mitigated by the exogenous application of hydrogen peroxide in the concentration of 25 μM.

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Sowing operation direction and population densities in corn growing - (2025)

Rafael D. G. Corrêa, Carlos E. A. Furlani, Cristiano Zerbato, Danilo T. de Oliveira, Rafael H. de F. Noronha, Newton K. Warikoda

Volume: 23 - Issue: 3

Resumo. ABSTRACT Among the factors that may influence corn yield are sowing operation direction and plant population, since they alter the shade index between crop rows, and consequently the efficiency of interception of the photosynthetically active radiation by the leaves of plants. The aim of this study was to evaluate the influence of sowing direction and plant populations on P2830VYH hybrid corn yield. The experiment was conducted at the facilities of FCAV-UNESP, latitude 21º 14’ S and longitude 48º 16’ W in Jaboticabal (SP). The treatments were composed of three sowing directions (North-South, Northeast-Southwest, and East-West) and three population densities (40,000, 60,000 and 80,000 plants ha-1). The treatment with 80,000 plants ha-1 had the lowest cost per sack of corn and profitability 21% higher than that of the treatment with 60,000 plants ha-1, and 45% higher than that of the treatment with 40,000 plants ha-1. Sowing direction had no influence on grain yield when environmental conditions were favorable to the development of the crop. Lower plant densities lead to higher individual results in relation to the number of cobs, length of cobs and number of grains per row.

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Thermal environment of masonry-walled poultry house in the initial life stage of broilers - (2025)

Diogo J. de R. Coelho, Ilda F. F. Tinôco, Cecília F. Souza, Fátima J. F. Baptista, Matteo Barbari, Kelle P. Oliveira

Volume: 23 - Issue: 3

Resumo. ABSTRACT The aim of this study was to monitor and evaluate the thermal environment and undertake a complete mapping of the variables air temperature, air relative humidity, and temperature-humidity index for broilers. The research was conducted during the winter, in Brazil, in a commercial poultry house fully walled with concrete-block masonry, equipped with a full-time negative-pressure mechanized ventilation system and indoor-environment air heating by a wood-burning furnace located outside the facility. The shed was fully automated and housed 30,000 birds at a density of 15 birds m-2. Thermal-environment data analysis revealed that the masonry-wall model did not ensure homogeneous thermal distribution within the poultry house, with the central region showing the highest air temperature and lowest air relative humidity values. The indoor environment did not provide thermal comfort to the housed birds, which were under thermal discomfort in certain situations in some internal regions of the shed.

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Agronomic performance of lettuce subjected to green manure with different leguminous species - (2025)

José J. A. Sarmento, José J. F. dos Santos, Caciana C. Costa, Marinês P. Bomfim

Volume: 23 - Issue: 2

Resumo. ABSTRACT Green manure is the practice of cultivation and incorporation of plants to the soil, mainly leguminous species, produced or not in situ, for the purpose of preserving and/or restoring soil organic matter and soil nutrients. To compare the effects of incorporating leguminous species in the pre-planting green manure on lettuce production, seven treatments were tested: mineral fertilization; crotalaria (Crotalaria juncea); cowpea (Vigna unguiculata); common bean (Phaseolus vulgaris); lablab bean (Dolichos lablab); pigeon pea (Cajanus cajan) and spontaneous plants. The treatments were arranged in the randomized blocks, with five repetitions. The experiment was conducted in the experimental area of the CCTA/UFCG, in the period from April to December 2016. At 30 days after transplanting, the following variables were analyzed: number of leaves, head diameter, shoot height, root volume, fresh weight of shoots and roots, dry weight of shoots and roots, total fresh weight of shoots and roots, total dry weight of shoots and roots and yield. The results were subjected to analysis of variance and, when significant, Tukey test at 0.05 probability level was applied to compare the means. The results showed that, among the leguminous species, the use of lablab bean led to greater development and yield of lettuce.

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Biophysical controls of evapotranspiration in cowpea cultivation under different water regimes - (2025)

Daniely F. S. de Souza, João V. de N. Pinto, Deborah L. P. Costa, Igor C. de O. Vieira, Thieres G. F. da Silva, Paulo J. de O. P. de Souza

Volume: 23 - Issue: 10

Resumo. ABSTRACT The objective of this study was to analyze the variations of the decoupling factor and the aerodynamic and stomatal conductances for cowpea subjected to different levels of water availability during the reproductive phenological stages of the crop. The study was conducted in the municipality of Castanhal located in the northeast of the state of Pará, Brazil, in an area planted with cowpea, in 2013, 2014 and 2015 with four irrigation treatments: T100 - replacement of 100% of the crop evapotranspiration (ETc); T50 - replacement of 50% ETc; T25 - replacement of 25% ETc; and T0 - without any replacement (without irrigation). The interaction between the crop and the atmosphere in water vapor exchange was estimated through the decoupling factor (Ω), which was between 0.5 and 1, except for the treatment without irrigation, indicating a moderate to high decoupling between the crop and the atmosphere, so that the water vapor exchange process was controlled by the energy supply, instead of stomatal control.

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Growth, production and water and nitrogen use efficiency of maize under water depths and nitrogen fertilization - (2025)

David H. Campelo, Adunias dos S. Teixeira, Luis C. J. Moreira, Claudivan F. de Lacerda

Volume: 23 - Issue: 10

Resumo. ABSTRACT The objective of this study was to evaluate the growth, the production components and the water (WUE) and nitrogen use efficiency (NUE) in maize (Zea mays L.), as function of water depths and nitrogen doses. The experimental design was randomized blocks in a split-plot scheme with four repetitions. The irrigation treatments applied in the plots were composed of four water depths: 80, 90, 100 and 110% of the water requirement, based on the soil field capacity, while the N doses, distributed in the subplots, were 0, 60, 120 and 180 kg ha-1. Increases in water depths and in N doses promote linear increases in plant height and leaf area index. For cycle I (2015) the maximum yield (16,778.3 kg ha-1) was reached with the irrigation depth of 538.1 mm and nitrogen dose of 180 kg ha-1; and for cycle II (2016), the maximum yield was reached with the irrigation depth corresponding to 505 mm and N dose of 180 kg ha-1, yielding 17,819.5 kg ha-1. The highest values of WUE (4.1 and 3.8 kg m-3) were estimated in cycle I (2015) for 432.7 mm and in cycle II (2016) for 359.6 mm, respectively; while the highest values of NUE (67.5 and 65.3 kg kg-1) were estimated in cycle I (2015), for the water depth of 555.7 mm and nitrogen dose of 113.3 kg ha-1, and in cycle II (2016), for the water depth of 506 mm and nitrogen dose of 107.7 kg ha-1.

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Operational and energy performance of the tractor-scarifier assembly: Tires, ballasting and soil cover - (2025)

José E. L. Lopes, Carlos A. Chioderoli, Leonardo de A. Monteiro, Mara A. M. dos Santos, Eric H. C. B. van Cleef, Elivânia M. S. Nascimento

Volume: 23 - Issue: 10

Resumo. ABSTRACT The heights of tire claws, tractor ballasting and soil cover can influence the operational and energy performance of the tractor-scarifier assembly. The objective of this study was to analyze the operational and energy performance of the tractor-scarifier assembly as a function of the heights of the tire claws, ballasting and rolling surface. The experiment was conducted at the experimental area of the Fazenda Experimental do Vale do Curu of the Universidade Federal do Ceará in Pentecoste municipality, CE, Brazil. The experiment was carried out in a randomized block in a 2 × 2 × 2 factorial arrangement with four repetitions. The treatments comprised two tire claw heights (T1-28% and T2-100%), two ballasts (B1-100% of solid and 75% liquid weights and B2 - 0% of solid and liquid weights), and two soil surfaces (S1 - soil with 4200 kg of straw ha-1 and S2 - mobilized soil). Worn tires provided a lower bar force (12.88 kN) and power requirement (20.06 kW) and a greater effective and operative field capacity of the tractor-scarifier assembly. The lowest slippage of the front wheels of the tractor was recorded for the worn tires (4.81%).For the rear wheels, slippages were found on the new tires (10.96%), and a higher speed of displacement was found for worn tires (5.54 km h-1). Lower specific fuel consumption was found for the mobilized soil (534.68 g kWh-1); furthermore, the hourly consumption of fuel and the consumption per area were not significantly affected by the treatments analyzed.

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Proposal of automated computational method to support Virginia tobacco classification - (2025)

Leonel P. C. Tedesco, Adriano da C. de Freitas, Rolf F. Molz, Jacques N. C. Schreiber

Volume: 23 - Issue: 10

Resumo. ABSTRACT This article proposes an automatic method for classification of cured tobacco leaves. Typically this process is performed manually, allowing the occurrence of human errors. In addition, the existence of an automated comparative procedure, helping to perform the classification, can make this process faster and more transparent. In order to implement the method, non-invasive to the agricultural product, 250 samples of Virginia tobacco digital images in the RGB and HSV color models were analyzed. The validation of the method was carried out using partial least squares (PLS) and artificial neural network (ANN), presenting a qualitative and quantitative analysis of both tools. It has been verified that the PLS can be applied to this method, as it has a shorter computational time, better suiting a real-time process. It can be verified that the ANN obtained better prediction results. Both methods employed had better results when adopting the RGB color model, reaching coefficient of determinations of 68 and 96% for the PLS and ANN methods, respectively.

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Application of artificial neural networks in the prediction of sugarcane juice Pol - (2025)

Anderson P. Coelho, João V. T. Bettiol, Alexandre B. Dalri, João A. Fischer Filho, Rogério T. de Faria, Luiz F. Palaretti

Volume: 23 - Issue: 1

Resumo. ABSTRACT Innovative techniques that seek to minimize the costs of production and the laboriousness of certain operations are one of the great challenges in the sugar-energy sector nowadays. Thus, the objective of the present study was to estimate the Pol values of sugarcane juice as a function of °Brix and wet cake weight (WCW) using artificial neural network (ANN) modeling. A database was organized consisting of 204 technological analyses from a field experiment with 15 treatments and 2 years of evaluation. 75% of the data were used for the calibration of the model and 25% for its validation. Multilayer Perceptron ANNs were used for calibration and validation of the data. Before calibration, the variables were normalized. The training algorithm used was backpropagation and the activation function was the sigmoid. The ANNs were established with two hidden layers and the number of neurons ranging from 4 to 20 in each. The 15 ANNs with the lowest root mean square errors were randomly presented by the software, among which 6 were chosen to verify the accuracy. The ANNs had a high accuracy in the estimation of sugarcane juice Pol, both in the calibration phase (R2 = 0.948, RMSE = 0.36%) and in the validation (R2 = 0.878, RMSE = 0.41%), and can replace the standard method of analysis. Simpler networks can be trained to have the same accuracy as more complex networks.

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Biomass of sugar-apple seedlings under saline water irrigation in substrate with polymer - (2025)

Aldeir R. Silva, Francisco T. C. Bezerra, Lourival F. Cavalcante, Walter E. Pereira, Leandro M. Araújo, Marlene A. F. Bezerra

Volume: 22 - Issue: 9

Resumo. ABSTRACT Application of saline water causes water and salt stress, changing the behavior of the plants. The aim of this work was to evaluate the accumulation and allocation of biomass in sugar-apple seedlings under frequencies of irrigation with saline water in a substrate with soil conditioner, as well as the effect of container volume. The treatments were obtained from the arrangement between polymer doses (0, 0.2, 0.6, 1.0 and 1.2 g dm-3) and electrical conductivity of irrigation water (0.3; 1.1; 2.7; 4.3 and 5.0 dS m-1), associated with irrigation frequencies (daily and alternated), plus two additional treatments to evaluate container volume (0.75 and 1.30 dm3), distributed in blocks. The evaluations were performed at 120 days after sowing. Irrigation frequency affected the variables, and the highest values were obtained with daily irrigation, except for root/shoot dry matter ratio. Increase in the electrical conductivity of the irrigation water inhibited biomass accumulation. The effect of the container was significant for daily irrigation; higher volume led to higher root, shoot and total biomass. Polymer doses did not affect the biomass of the seedlings. Daily irrigation with non-saline water favored biomass production in sugar-apple seedlings. In the production of sugar-apple seedlings, water with electrical conductivity below 1.0 dS m-1 should be used on a daily frequency of application in 1.30 dm3 containers.

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Gas exchanges and photochemical efficiency of West Indian cherry cultivated with saline water and potassium fertilization - (2025)

Adaan S. Dias, Geovani S. de Lima, Francisco V. da S. Sá, Hans R. Gheyi, Lauriane A. dos A. Soares, Pedro D. Fernandes

Volume: 22 - Issue: 9

Resumo. ABSTRACT The problem of the lack of adequate water resources for agriculture has intensified in recent years, making it necessary to use waters with relatively high concentration of salts for the irrigation of crops all over the world. The objective of this study was to evaluate the influence of potassium (K) fertilization as a salt stress attenuator on gas exchanges and photochemical efficiency of West Indian cherry. The crop was cultivated under greenhouse conditions in the municipality of Campina Grande, PB, in lysimeters filled with 250 kg of sandy loam soil. Treatments were distributed in randomized blocks, in a 2 x 4 factorial scheme, with two levels of electrical conductivity of irrigation water - ECw (0.8 and 3.8 dS m-1) and four K doses (50, 75, 100 and 125% of recommendation), in which the dose corresponding to 100% was equal to 19.8 g of K2O, with three replicates and one plant per repetition. Seedlings of the West Indian cherry cultivar BRS 366-Jaburu, grafted onto a locally developed rootstock from the clonal garden of the EMBRAPA Tropical Agroindustry, Pacajus, CE, were used. Irrigation with salinized water (electrical conductivity of 3.8 dS m-1) compromised the gas exchange and the photochemical efficiency of West Indian cherry plants. Potassium fertilization was not efficient at reducing the stress caused by water salinity on West Indian cherry plants.

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Weed interference in the initial growth of meristem-grown sugarcane plantlets - (2025)

Ricardo J. de Paula, Clara D. Esposti, Carlos R. de Toffoli, Phelippe S. H. Ferreira

Volume: 22 - Issue: 9

Resumo. ABSTRACT The use of new systems of sugarcane planting such as PleneTM, Plene EvolveTM, Plene PBTM and AgMusaTM requires specific studies on the initial interference of weed in the sugarcane crop. The objective of this study was to evaluate initial weed interference in meristem-grown sugarcane plantlets (Plene EvolveTM). The weed species used were Brachiaria decumbens and Panicum maximum, at four different densities (1, 2, 3 and 4 weed plants pot-1), plus a control treatment free from weed interference. The statistical design was completely randomized with four replicates per treatment, with an individual study for each weed species. The evaluations performed were: plant height at 45, 60 and 90 days after emergence (DAE), number of sugarcane tillers at 30, 60 and 90 DAE and dry matter of both sugarcane and weed plants at 90 DAE. B. decumbens and P. maximum caused reductions in the initial growth and development of sugarcane. P. maximum was more aggressive to meristem-grown sugarcane plants, during their early development, than B. decumbens.

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Effective diffusivity in yacon potato cylinders during drying - (2025)

Cícera G. C. de Lisboa, Josivanda P. Gomes, Rossana M. F. de Figueirêdo, Alexandre J. de M. Queiroz, Adelino de M. G. Diógenes, João C. S. de Melo

Volume: 22 - Issue: 8

Resumo. ABSTRACT The aim of this study was to obtain the effective diffusivity of yacon potato in fixed-bed dryer at different temperatures (50, 60 and 70 ºC) and drying air velocities (1.0, 1.5 and 2.0 m s-1). Non-linear regression analysis was performed by the Quasi-Newton method using the program Statistica 7.0, where the parameters of the models were estimated as a function of the drying air temperature. Approximation of Diffusion, Two Terms, Henderson & Pabis, and Page models fitted well the experimental data. Drying air temperature and speed influenced the drying time of the samples. The effective diffusivity increased with increasing temperature, ranging from 1.18 x 10-9 to 2.15 x 10-9 m2 s-1.

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Evidence of nitrogen and potassium losses in soil columns cultivated with maize under salt stress - (2025)

Claudivan F. de Lacerda, Jorge F. da S. Ferreira, Donald L. Suarez, Emanuel D. Freitas, Xuan Liu, Aureliano de A. Ribeiro

Volume: 22 - Issue: 8

Resumo. ABSTRACT The aim of this study was to evaluate the accumulation of salts in the soil from irrigation water and of N and K from fertilization. The experiment was conducted in PVC columns (20 cm in diameter and 100 cm in height), filled with non-saline soil, and cultivated with maize. A completely randomized block design in a 4 x 4 factorial was used, with four levels of salinity (0.5, 2.5, 5.0 and 7.5 dS m-1), four N rates, and five replicates. Nitrogen was applied as urea and potassium nitrate at the following rates: N1: N recommendation for maize (2.6 g column-1); N2: 0.3 times (0.78 g column-1) the recommended N1 dose; N3 and N4 with N based on N1 and N2 doses, respectively, reduced proportionally based on the evapotranspiration reduction caused by salinity. After 74 days from sowing, root and soil samples were collected at different soil depths. The electrical conductivity of the saturated extract (ECe) and the concentration of ions (Ca2+, Na+, and Cl-) increased as a function of salinity and soil depth. The opposite was observed for the root system. The increase in salinity also resulted in K+ and NO3- accumulation in the soil column, mainly in treatments with higher N rates (N1 and N3). At the end of the experiment, 88% of the NO3- applied at the highest salinity treatment (7.5 dS m-1) and the highest N rate (N1) was below 20 cm soil depth, evidencing a N loss process caused by leaching.

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Yield of lettuce grown in hydroponic and aquaponic systems using different substrates - (2025)

Rodrigo A. Jordan, Evaldo F. Ribeiro, Fabricio C. de Oliveira, Luciano O. Geisenhoff, Elton A. S. Martins

Volume: 22 - Issue: 8

Resumo. ABSTRACT This study had as objective to evaluate the effect of the substrate on the yield of lettuce grown in aquaponic and hydroponic systems. The study was conducted at the Federal University of Grande Dourados, located in Dourados, MS. A randomized complete block design was used, with three treatments and 16 replicates. The cultivation systems were analyzed independently. The substrates analyzed were: coconut shell fiber, phenolic foam and expanded vermiculite. The plants were grown in two systems (aquaponic and hydroponic), using the NFT (Nutrient Film Technique) system. The crop used was lettuce cv. ‘Alcione’. The parameters analyzed were: crop yield and percentage of roots per plant. In addition, macronutrient contents were analyzed in the leaves. The substrate composed of coconut shell fiber was more suitable for lettuce production, since it led to higher yields for both aquaponic (2.88 kg m-2) and hydroponic (2.58 kg m-2) systems. The use of phenolic foam as growing substrate led to lower mean crop yields in both production systems analyzed, 1.94 and 2.15 kg m-2 for aquaponic and hydroponic systems, respectively.

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Economically optimal water depth and grain yield of common bean subjected to different irrigation depths - (2025)

Chaiane G. da Conceição, Adroaldo D. Robaina, Marcia X. Peiter, Ana R. C. Parizi, João A. da Conceição, Jhosefe Bruning

Volume: 22 - Issue: 7

Resumo. ABSTRACT Common bean crop plays an important role in the world, not only in economic aspects but also in social development. The objective of this study was to evaluate the grain yield and the economically optimal water depth which reflects the maximum technical efficiency of the common bean crop. The experiment was conducted in greenhouse, in Alegrete - RS, from February to May 2016. A completely randomized design was used, consisting of five water replacement treatments (25, 50, 75, 100 and 125% crop evapotranspiration - ETc) and four replicates. Based on the obtained results, both water deficit and water excess directly affected the final grain yield of the crop. Maximum grain yield was 3,554.1 kg ha-1, obtained by applying 492.72 mm (100% ETc). On the other hand, the economically optimal water depth was estimated at 91.2% ETc, indicating that water depths above this value are not suitable for maximum technical efficiency in the common bean crop under these conditions. It was concluded that the water depth equivalent to 100% ETc maximizes grain yield for the region of Alegrete-RS, and irrigation is considered a solution in the water supply to the common bean crop during critical periods.

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Salt balance in substrate cultivated with ‘Sunki’ mandarin x ‘Swingle’ citrumelo hybrids - (2025)

Juliana F. Almeida, Giuliana N. B. Sales, Marcos E. B. Brito, Pedro D. Fernandes, Walter S. Soares Filho, Isidro P. Almeida Neto

Volume: 22 - Issue: 7

Resumo. ABSTRACT During initial plant development stage, an experiment was conducted to evaluate the balance of salts in the substrate used for the production of 10 hybrids from the cross between ‘Sunki’ mandarin (TSKC) and ‘Swingle’ citrumelo (CTSW), all with potential to be used as rootstock. ‘Rangpur Santa Cruz’ lime, ‘Sunki Tropical’ mandarin and the hybrid LVK (‘Volkamer’ lemon) x LCR (‘Rangpur’ lime) - 038 were included as controls, totaling 13 genotypes. Substrate samples were collected in the experiment conducted in a greenhouse at the Federal University of Campina Grande, Campus of Pombal, from December 2015 to June 2016. Two levels of irrigation water salinity were tested, using a 2 x 13 factorial scheme, with 4 replicates. The substrate was a mixture of vermiculite, pine bark and humus (1:1:1). For the salinity level of 3 dS m-1, the substrate is less salinized when cultivated with the hybrids TSKC x CTSW - 044, TSKC x CTSW - 045, TSKC x CTSW - 048, TSKC x CTSW - 049 and ‘Rangpur Santa Cruz’ lime. On the other hand, highest salt concentration was obtained in the substrate cultivated with TSKC x CTSW - 042, TSKC x CTSW - 047, TSKC x CTSW - 048, TSKC x CTSW - 053, TSKC x CTSW - 055 and TSKC x CTSW - 057.

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Structural static and modal frequency simulations in a coffee harvester’s chassis - (2025)

Evandro P. da Silva, Fábio M. da Silva, Ednilton T. de Andrade, Ricardo R. Magalhães

Volume: 22 - Issue: 7

Resumo. ABSTRACT Coffee harvesters are subject to stresses and vibrations in their structure, originating from engines and harvesting system. These structures must be designed to avoid rupturing of the components due to fragility of the materials, inadequate geometries, or the phenomenon of resonance, which increases the displacements/deformations of the components. In this scenario, the main objective of this study is to analyse the results of stresses and displacements from two static simulations and to present results of natural vibration frequencies from two modal simulations in a self-propelled coffee harvester. For this purpose, 20 modal shapes were generated, considering coffee harvester reservoir as empty and full. The simulations were carried out using the finite element method in which actual boundary conditions were applied to the motor chassis of the harvester. As results, stresses above the material’s yield strength were observed in some regions of the components. Greater displacements were observed at the rear of the chassis, suggesting a new positioning of the rear wheel to obtain a uniform load distribution. Some natural frequencies, which presented greater displacements/deformations, can be affected by the operation of the main motor, also associated with the vibrating system in the coffee harvest, which may cause rupture of components.

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Genetic fuzzy system for prediction of respiratory rate of chicks subject to thermal challenges - (2025)

Patrícia F. P. Ferraz, Tadayuki Yanagi Junior, Yamid F. Hernandez-Julio, Gabriel A. e S. Ferraz, Maria A. J. G. Silva, Flavio A. Damasceno

Volume: 22 - Issue: 6

Resumo. ABSTRACT The aim of this study was to estimate and compare the respiratory rate (breath min-1) of broiler chicks subjected to different heat intensities and exposure durations for the first week of life using a Fuzzy Inference System and a Genetic Fuzzy Rule Based System. The experiment was conducted in four environmentally controlled wind tunnels and using 210 chicks. The Fuzzy Inference System was structured based on two input variables: duration of thermal exposure (in days) and dry bulb temperature (°C), and the output variable was respiratory rate. The Genetic Fuzzy Rule Based System set the parameters of input and output variables of the Fuzzy Inference System model in order to increase the prediction accuracy of the respiratory rate values. The two systems (Fuzzy Inference System and Genetic Fuzzy Rule Based System) proved to be able to predict the respiratory rate of chicks. The Genetic Fuzzy Rule Based System interacted well with the Fuzzy Inference System model previously developed showing an improvement in the respiratory rate prediction accuracy. The Fuzzy Inference System had mean percentage error of 2.77, and for Fuzzy Inference System and Genetic Fuzzy Rule Based System it was 0.87, thus indicating an improvement in the accuracy of prediction of respiratory rate when using the tool of genetic algorithms.

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Germination and tolerance of cowpea (Vigna unguiculata) cultivars to water stress - (2025)

Emanoela P. de Paiva, Francisco V. da S. Sá, Salvador B. Torres, Marcos E. B. Brito, Romulo C. L. Moreira, Luderlândio de A. Silva

Volume: 22 - Issue: 6

Resumo. ABSTRACT The objective of this study was to evaluate the tolerance of cowpea cultivars to water stress, during seed germination and seedling establishment. For this, a completely randomized experimental design was used in a factorial scheme consisting of nine cultivars of cowpea (BRS Guariba, BRS Potengi, BRS Itaim, BRS 17 Gurguéia, BRS Aracê, Paulistinha, Maratanã, Costela-de-Vaca and Canapu-Branco) and two levels of osmotic potential induced by PEG 6000 (0.0 MPa (control) and -0.4 MPa) in four replicates of 50 seeds. The variables analysed were germination, germination first count, root and shoot lengths, and dry matter accumulation of shoots and roots. The dissimilarity between the genotypes was also determined by Euclidean distance. Germination and initial development of cowpea cultivars are impaired by the reduction in the potential to -0.4 MPa. The cultivars BRS Guariba, BRS Aracê, Paulistinha and Canapu-Branco are the most tolerant to water stress, while BRS Potengi, BRS Itaim, BRS 17 Gurguéia, BRS Maratanã and Costela-de-Vaca are the most sensitive in the early development stage.

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Contamination of soil and pineapple fruits under fertilization with sewage sludge - (2025)

Mauro F. C. Mota, Rodinei F. Pegoraro, Silvânio R. dos Santos, Victor M. Maia, Regynaldo A. Sampaio, Marcos K. Kondo

Volume: 22 - Issue: 5

Resumo. ABSTRACT Sewage sludge is rich in organic matter and nutrients for the plants, and can be used in pineapple production, but there are few studies with scientific evaluation of possible inorganic and biological contaminants in pineapple plantations. In view of the above, this study aimed to evaluate the contamination of the soil and in fruits of pineapple fertilized with sewage sludge. The study was conducted in the municipality of Janaúba-MG. Treatments were arranged in a randomized block design, with four replicates, in a 2 x 5 factorial scheme, consisting of two different fertilizers: sewage sludge (SS) and mineral fertilizers (MF), and five pineapple varieties (Pérola, Vitória, Smooth Cayenne, MD-2, Fantastic IAC). Nitrogen was adopted as the base element to calculate the sewage sludge dose in the pineapple crop. Fertilization with sewage sludge increased the Zn and Cu contents in the soil and the Zn content in the leaves of the pineapple plants. Sewage sludge did not change the contents of As, Pb, Ba, Cu and Zn in the fruit, and Cr, Ni and Cd contents were not detected by the method used. Pineapple fruits did not show microbiological contamination above the limits established by the Brazilian legislation.

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Prediction of ‘Gigante’ cactus pear yield by morphological characters and artificial neural networks - (2025)

Bruno V. C. Guimarães, Sérgio L. R. Donato, Alcinei M. Azevedo, Ignacio Aspiazú, Ancilon A. e Silva Junior

Volume: 22 - Issue: 5

Resumo. ABSTRACT Estimating cactus pear yield is important for the planning of small and medium rural producers, especially in environments with adverse climatic conditions, such as the Brazilian semi-arid region. The objective of this study was to evaluate the potential of artificial neural networks (ANN) for predicting yield of ‘Gigante’ cactus pear, and determine the most important morphological characters for this prediction. The experiment was conducted in the Instituto Federal Baiano, Guanambi campus, Bahia, Brazil, in 2009 to 2011. The area used is located at 14° 13’ 30” S and 42° 46’ 53” W, and its altitude is 525 m. Six vegetative agronomic characters were evaluated in 500 plants in the third production cycle. The data were subjected to ANN analysis using the R software. Ten network architectures were trained 100 times to select the one with the lowest mean square error for the validation data. The networks with five neurons in the middle layer presented the best results. Neural networks with coefficient of determination (R2) of 0.87 were adjusted for sample validation, assuring the generalization potential of the model. The morphological characters with the highest relative contribution to yield estimate were total cladode area, plant height, cladode thickness and cladode length, but all characters were important for predicting the cactus pear yield. Therefore, predicting the production of cactus pear with high precision using ANN and morphological characters is possible.

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Hydropriming as inducer of salinity tolerance in sunflower seeds - (2025)

Janete R. Matias, Salvador B. Torres, Caio C. P. Leal, Moadir de S. Leite, Sara M. C. Carvalho

Volume: 22 - Issue: 4

Resumo. ABSTRACT Sunflower is a species with multiple potentialities and its yield can be affected by the presence of soluble salts in the soil, which is common in arid, semi-arid and irrigated regions. The objective of this study was to evaluate the effect of hydropriming as inducer of salinity tolerance in seeds and seedlings of sunflower, hybrid MG305CP. The germination tests were set with four replicates of 50 seeds per treatment, maintained in germinator at 30 ºC for ten days. To simulate salinity, sodium chloride diluted in distilled water was used at electrical conductivities of 0 (control), 4, 8, 12 and 16 dS m-1. On the tenth day, the number of normal seedlings was counted and the length and dry matter of shoots and roots were determined. Seedling fresh matter was used to determine the contents of total chlorophyll, total soluble sugars and proline. The experimental design was completely randomized, in a 2 x 5 factorial scheme (with and without hydropriming and five levels of salinity). Hydroprimed sunflower seeds showed greater vigor expression, with higher number of normal seedlings and faster germination.

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Ozone saturation and decomposition kinetics in porous medium containing different hybrids of maize - (2025)

Jefferson V. da S. Souza, Ernandes R. de Alencar, Ana M. R. Junqueira, Gustavo P. de Oliveira

Volume: 22 - Issue: 4

Resumo. ABSTRACT The objective of this study was to evaluate ozone saturation and decomposition kinetics in porous medium containing grains of different hybrids of maize. The following hybrids were used: common maize hybrid AG 1051, super sweet maize hybrids Tropical Plus, GSS 42072, GSS 41499 and GSS 41243. 1 kg grain samples with water contents of 13.0% (w.b.) were placed in glass containers with 3.25 L capacity. The grains were ozonized at the concentration of 1.28 mg L-1, at 25 ºC, with gas flow rate of 5.0 L min-1. Saturation time and concentration, half-life time and physical properties such as apparent specific weight, actual specific weight, porosity, sphericity and circularity of each maize hybrid were determined. The experiments were conducted in a completely randomized design with three replicates, using regression analysis of the data. Ozone saturation times remained between 6.6 and 163.9 min, with saturation concentration varying from 0.34 to 1.12 mg L-1. As for the ozone half-life time, the highest value was 10.5 min for the common maize hybrid AG 1051 and the lowest value was 0.14 min for the super sweet maize hybrid GSS 41499. It was concluded that ozone saturation and decomposition kinetics in maize depends on the hybrid contained in the porous medium. Ozone decomposition is faster in porous medium containing super sweet maize hybrids compared with the common maize hybrid.

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