Revista Engenharia na Agricultura - REVENG

Growth of urochloa irrigated in clayey and sandy soil submitted to nutritional management in the cerrado

2022-01-18T07:48:31-03:00

The reduction in water supply in specific areas and the high costs of agricultural inputs resulted in the need for agronomic management capable of reducing the pressure on water resources and promoting economic development. The objective of this work was to evaluate the response of Urochloa brizantha cv. Marandu grown in clayey and sandy soils submitted to nutritional and water management in the municipality of Rio Verde, state of Goiás. The treatments consist in combining two levels of fertilization (A1: 30, 7 and 36 and A2: 45, 10.5 and 54 of NPK per Mg of DM produced,) and seven water depths (0%; 25%; 50%; 75%; 100%; 125% and 150% of crop evapotranspiration (ETc)), in four replications. Crop performance was evaluated employing SPAD index, plant height, leaf length, leaf width, neutral detergent crude fiber, and dry matter. The rise in the irrigation depths significantly affected the performance of the forage and despite not having a significant difference, the production of dry matter may be higher when in soil with A2 fertilization. A significant influence was observed in the number of seedlings emergence from 7 to 21 days in Sandy soil as a function of clayey soil, on chlorophyll, and plant height as a function of A2 fertilization concerning A1 and irrigation depths in all analyzed variables.

Sugarcane wax extraction using hexane and limonene mixtures

2021-11-21T14:43:33-03:00

Hexane is the most widely solvent used in the lipids extraction process, as the case of the sugarcane wax. However, the use of this solvent is highly harmful to the environment and to human health. Limonene is a monoterpene found in the citrus peel, with great potential for use as a green solvent. In this study, the partial and total substitution of hexane by limonene was performed in the process of the sugarcane peel wax extraction to evaluate the effect of this substitution on the physicochemical characteristics of the wax. The extracted samples were compared with a commercial wax sample (carnauba) using the Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Infrared by Fourier Transform (FTIR) analyses. Through this study, we can conclude that the waxes obtained from the use of the hexane and limonene mixture solvents presented similar physicochemical characteristics to those found in commercial waxes. Thus, the total and/or partial substitution of the hexane by solvents less harmful to health and the environment, such as limonene, can be an alternative in the wax extraction process.

Post-harvest of coffee: factors that influence the final quality of the beverage

2021-12-15T15:28:58-03:00

Brazil is the world’s largest producer and exporter of coffee and the second largest consumer market. Brazil offer differentiated and high quality products to maintain its leading position in coffee production and export. However, Brazilian coffee has suffered some limitations in its commercialization in the international market, due to qualitative aspects. The development of taste and aroma is highly complex, since hundreds of chemical reactions take place at the same time, such as the breakdown of proteins, polysaccharides, trigonelline and chlorogenic acid, mainly in the roasting process. Then, it is necessary that, in addition to pre-harvest management, there are post-harvest practices that meet consumer demands regarding the final quality of the beverage. Studies on physical and chemical changes in the composition of coffee beans must continue to be performed in a comprehensive manner, since factors such as damage to coffee beans, drying methods, processing, storage time, type of packaging and chemical components are directly related to sensorial properties and thus define the quality of the beverage at this point of view. Thus, the objective of this review was to relate the physicochemical, biochemical and physiological characteristics of coffee beans after harvest with the quality of the product after roasting.

Intraspecific competition of hybrids using mixtures of pollinator lines for hybrid rice production

2021-12-08T14:45:18-03:00

The aim of this study was to evaluate the use of pollinator seed mixture to obtain hybrid rice seeds. The study was performed at Embrapa Clima Temperado, in the harvests of 2015/2016 and 2016/2017. Seeds of hybrids H7 and BRS AH 703 CL and the pollinator, Puitá INTA-CL cultivar were used in the proportions of 0.00%, 0.75%, 1.50%, 3.00%, 6.00%, 12.00% and 24.00% in the first year and 0.00%, 0.75%, 1.50%, 3.00%, 6.00%, 12.00% and 24.00%, 50.00% and 100.00% for the second year. The experimental design was a randomized complete block design with four repetitions and the data was submitted to analysis of variance. Seeding was performed in November and October. The plots were 5 meters long with 4 meters of plot area, being evaluated: Number of plants.m^-2, Number of culms.m^-2, Number of panicles.m^-2, Panicle length, Productivity of grain, plot uniformity, plant height, percentage of whole grains, broken grains. Plants from hybrid rice seeds in the mix had no effect on yield components. Plants from hybrid seeds showed plot uniformity like plants from self-fertilization. The industrial quality of the grains was like grains of self-fertilized plants but differing in the intermediate mixtures used.

Evaluation of the quality and mechanical resistance of eggs with the application of biodegradable coatings

2021-12-08T21:15:23-03:00

The chicken egg is one of the most complete and balanced foods for human nutrition, representing an important source of animal protein of the highest quality. The application of coatings can extend the shelf life of these foods, minimizing the migration of moisture, gases (CO₂ and O₂), solutes and volatile aromatic compounds, and can even function as a vehicle for food additives. The objective of the present work was to test the effect of whey protein concentrate (WPC) based coatings with and without the addition of a lipid source (palm oil) on the quality and mechanical resistance of chicken eggs. The result of this study showed that the coating that offered the least loss of egg quality during storage was the WPC+oil coating. The presence of a lipid combined with a protein constituted a barrier to moisture and CO₂; consequently, this coating presented lower values for weight loss and pH, as well as higher values for Haugh unit and shell strength, characterizing better quality eggs.

Model applicability to predict growth rates of insects throughout the storage of corn (Zea mays L.) grain

2021-12-08T21:16:26-03:00

Insect pest infestation in stored grains can cause several losses during storage, in addition to promoting the spread of fungi, changing the temperature of the grain mass, and reducing the value of the final product. Knowing the behavior of these insect pests and how they reproduce in the grain mass is essential to design more efficient control strategies and ensure a quality final product. Thus, this work aimed to accomplish modeling and simulation of the population growth of insects Rhyzopertha dominica, Sitophilus oryzae, Oryzaephilus surinamensis and Tribolium castaneum throughout the storage of corn grain, using data retrieved from digital sensors of temperature installed in three Brazilian storage facilities in different regions. Data were collected through managing system CERES (company Procer Automação e Sistemas) and retrieved from 1^st of July to 29^th September 2019. In each one of the facilities, a silo equipped with the aforementioned sensors was used. Mean weekly values of temperature of the grain mass and the intergranular relative humidity were used, calculated using the Modified Henderson equation. The silos evaluated in facilities 1, 2, and 3 have a static capacity of 2,100; 6,304, and 93 tones, respectively, considering soybean with a bulk density of 750 kg m-3. Higher growth rates of all assessed species were observed for the storage facility number 2; and lowest values for storage facility number 1. Storage facilities that presented a higher potential for the growth rate of insects are subjected to elevated levels of insect populations throughout time.

Use of geotechnologies for morphometric analysis of experimental basin in the semiarid region to support hydrological simulation

2021-11-10T10:04:47-03:00

The morphometric characteristics help to regulate the hydrological processes of a basin. The understanding of these characteristics is essential for an adequate planning of water resources. The aim of this study was to analyze the sensitivity of the hydrological simulation to different pixel thresholds for the generation of the drainage network and to perform a detailed morphometric characterization of the sub-basin upstream of a fluviometric section (SBSF) installed in the experimental basin of the Jatobá stream, semiarid region of Pernambuco. The following thresholds were considered: 264, 132, 66, 55 and 44 pixels, corresponding to scenarios 1 to 5, respectively. The morphometric analyses were performed through hydrological modeling and the use of mathematical equations, where 25 morphometric indices were evaluated. The results indicated that scenarios 3, 4 and 5 adequately represented the hydrological processes. The physical parameters indicate that the basin has an elongated shape, with a low tendency for flood peaks under normal conditions of climatic events. Although the SBSF presents a low average slope, it was verified the existence of regions with high slopes, favoring the surface runoff, which requires the adoption of conservationist practices and the maintenance of native vegetation.

Soil physical attributes and agronomic characteristics relationships of soybean in no-tillage

2021-12-17T10:17:40-03:00

The objective of this work was to evaluate the soil physical attributes and their relationship to soybean productivity under no-tillage system. The study was conducted in a Oxisol, based on randomized blocks design, with the treatments: no-tillage for 10 years (0 tractor traffic) and five tractor-traffic intensities (2, 4, 6, 8, and 12 passes), with five repetitions. An increase of macroporosity up to 10% under soil bulk density ranging from 1.51 to 1.56 mg.m^-3 and soil penetration resistance between 1.5 to 2.0 MPa, on the 0.00-0.10 m layer benefited the soybean productivity. The number of pods per plant, grain number per plant, stem diameter, and soybean productivity is higher in Oxisol, under intermediate compression. Soil bulk density and soil penetration resistance showed to be sensitive an indicators of soil physical quality, with more relation to soybean grain productivity.

Fertigation of humic substance: effects on soil properties of a xanthic ferralsol (DENSIC)

2022-02-09T07:46:14-03:00

The complexity of humic substances (HS) and their properties in agricultural applications have attracted the attention of many researchers. However, controversial results have been obtained, because of the difficulty in identifying a precise relationship between the structure and activity of these substances. This study aimed to evaluate the influence of different frequencies and concentrations of humic substances on the behavior of physical, chemical and microbiological soil attributes. The experiment was carried out at Embrapa Cassava and Fruticulture in Latossolo Amarelo Distrocoeso [(Xanthic Ferralsol (Densic); Oxisol], with a completely randomized block design with four repetitions in a split-plot scheme, with three application frequencies (F1 = 15 days, F2 = 30 days and F3 = 45 days) and four concentrations of humic substances (C1 = 0 ml.L^-1, C2 = 3 ml.L^-1, C3 = 6 ml.L^-1 and C4 = 9 ml.L^-1). The humic substance applied at a frequency of 45 days positively favored the physical and chemical attributes of the soil, mainly at concentrations of 6 and 9 ml.L^-1, due to the increase in microporosity. This information can be used to improve the performance of agricultural practices, especially those related to soil preparation, use of agricultural inputs, water management, soil water content and, especially, soil management practices.

Characterization and frequency analysis of long-term maximum rainfall from São Martinho, Santa Catarina, Brazil

2021-12-28T08:20:01-03:00

The study of the frequency of intense rainfall is important for agricultural and environmental planning and the dimensioning of drainage works. This study aimed to characterize and determine the relationships of intensity, duration, and frequency of long-term rainfall in São Martinho, Santa Catarina. The series of annual maximums lasting from one to ten days, observed in the period from 1977 to 2020, were determined. The probability distributions Gumbel, GEV, Log-Normal with two parameters, Log-Normal with three parameters, Pearson type III, and Log-Pearson Type III were evaluated. The parameters were estimated by the method of moments, maximum likelihood method, method of L-Moments, and for the Gumbel distribution, the Chow method was used. The Kolmogorov-Smirnov, Anderson-Darling, and Filliben fitting tests were used, and for the selection of the distribution, the standard error of the estimate was also used. The Log-Normal distribution with three parameters was selected for series lasting one, five and six days. The Pearson III distribution was selected for a duration of three and four days and the GEV distribution for the other five series. The adjusted IDF equation allows the estimation of rainfall intensity with duration from24 hours to 240 hours and a return period ranging from 2 to 100 years.

Risk of agrochemical contamination in a hydrographic basin in the matopiba region in Brazil

2022-04-05T17:09:10-03:00

The intensive use of agrochemicals has been associated with global human health problems and environmental contamination. Brazil is the world’s largest agrochemical consumer, and this position highlights the growth of agribusiness in the MATOPIBA region (Maranhão, Tocantins, Piauí, and Bahia states). The use of agrochemicals is recurrent in local agricultural practices. However, there is little information on the environmental impacts and risks of contamination regarding river basins in this region. Thus, this study aimed to evaluate the risk of contamination by agrochemicals in the basin area of the Açailândia River in Maranhão. From the multicriteria evaluation, environmental information plans were used to determine the trend of water behavior, infiltration, and runoff, along with agrochemical transportation. The joint evaluation of this information was used to generate the final map of the areas of contamination risk posed by agrochemicals in the region. The hydrographic basin presented high anthropization, with an increase of approximately 27% in land use and occupation by crops in the period from 1984 to 2018. The area of 1087.62 km², corresponding to 35.9% of the basin area, presented a high and extremely high risk of contamination.

Spraying quality using unmanned aerial vehicle in citrus

2022-03-15T09:58:11-03:00

This study aimed to evaluate the effect of the operating flight height of an unmanned aerial vehicle with different spray tip rotations on the parameters of droplet coverage, density and volumetric median diameter of the sprayed droplets, in acid lime culture ´Tahiti’. The experiment was performed in randomized blocks design, with repetition within the block, in a factorial system (3x2), with four repetitions. Three planting lines were selected for each treatment. The two outer lines were used as borders and the central one for evaluation. In each treatment, one plant was selected from the planting line and four water-sensitive papers were fixed in the middle third of the outermost portion of the canopy.A solution containing water and a drift reducing adjuvant was prepared to analyze the quality of the spray. A significant difference was found for the variables of spray tip rotation and flight height with no interaction between them. This result indicates that these variables act independently on the volumetric median diameter values. Furthermore, the spray heights of 3.0 m and 4.0 m have a notable effect on the amount of deposition. However, their influence on droplet size is negligible.

Effective operational capacity of brushcutter with different cutting tools

2022-02-09T16:27:47-03:00

Brushcutters use different cutting tools with variations in operating capacity. Thus, the present study evaluate the effective operational capacity of a brushcutter equipped with different cutting tools in different areas of plant cover. It was subdivided into three experiments with 44 replicates of 4m² each. The first was carried out in an area with plants cover with wheat and ryegrass, with blades of triple and double discs, and double wire. The second was carried out in another area with a cover composed of wheat, ryegrass, and fallow (composed of different species plants), with double- and triple-discs blades. The last experiment was carried out in a fallow area, with all cutting tools, except for the double wire. The results indicate that the brushcutter equipped with the triple-disc blade had greater operational capacity compared to the other cutting tools. For a working day of 8 h.day^-1, the highest amount of mowed biomass was obtained with the triple-disc blade in areas with ryegrass and wheat cover, while for the fallow area, there is no significant difference between the double- and triple-disc blades. The adequate selection of the cutting tool contributes to the increase of the cut biomass in a shorter time, reducing the exposition of the operator to the vibrations and noise produced by the machine.

Statistical process control and geostatistics on the characterization of the noise produced by a backhoe loader

2022-02-09T16:17:57-03:00

Workers in their labor activities may be subject to operational risks, such as noise. The objective of this work was to use geostatistics and Statistical Process Control (SPC) through individual charts to map and characterize the magnitude of the spatial variability of noise produced by a backhoe, to identify areas of health for workers. The experiment was developed at the technical college of the Federal Rural University of Rio de Janeiro. A 63-kW backhoe loader and a digital decibel meter were used to collect noise levels at points distributed in a regular 2.0 x 2.0 m sampling grid around the machine. The spatial dependence of the noise was analyzed by adjusting the Wave-type semi-variogram, interpolation by ordinary kriging, and SPC. It was possible to characterize the spatial dependence of noise levels produced by the backhoe as well as to carry out, through individual letters in dialogue with geostatistics, the mapping of their spatial distribution to identify healthy areas for workers. It could have been found in the evaluation of the backhoe loader control chart, that there was no reduction in the variability of noise data, which was approximately 73.29 dB(A) for the sampled points. This shows an average very close to the analysis found in the execution of the descriptive statistics of the noise generated by the backhoe loader.

An alternative method for identification of industrial tomato hybrids using NIRS

2021-12-08T07:39:14-03:00

The use of high productive-potential hybrids was one of the reasons for the increase in productivity in the agricultural segment of tomatoes for industrial processing. Thus, among the cultivars available on the market, in general, those that combine greater productivity with quality and that satisfy the needs of industries are chosen. In this context, the objective of this work was to evaluate the best time to implement near-infrared spectroscopy (NIRS) as an alternative method for identifying industrial tomato hybrids. Seeds from the hybrids: CRV8126, H9553, HMX4890, TPX28699 were used and 10 spectra were collected from a set of 20 seeds, from cotyledonary leaves of ten seedlings at 15 days after sowing (DAS) and from the true leaf of ten seedlings at 30 DAS. The results showed that the technique of spectroscopy in the near-infrared range, associated with multivariate analysis, allowed the discrimination of the studied hybrids. The phase in which the best results were obtained in the identification of each hybrid was in the seed, obtaining accuracy values above 90.00% and sensitivity of 100.00%, which proves the use of this instrumental technique on a portable scale for tomato hybrids with a high assertiveness rate.

Hand-arm vibration while operating a side brush cutter with three cutting implements in two crops

2022-05-10T10:09:29-03:00

The use of side brushcutters exposes users to vibration and noise, which can cause damage to the operator, as they act as a stressor agent. Excessive vibration is responsible for countless disorders, including Raynaud’s syndrome. This study aimed to assess the effect of the vibrations of a side brush cutter on the human body. A side brush cutter was used with three cutting implements (double blade, triple blade and double nylon thread) applied to two crops (wheat and ryegrass). The vibration was measured through a three-dimensional accelerometer placed on the handgrips of the brush cutter, in compliance with the provisions of the ISO 5349-1 Standard. The analyzed variables were submitted to the Shapiro-Wilk and Bartlett tests. Due to the abnormality, the data were transformed by the Neperian logarithm and submitted to analysis of variance, and the means were compared by the Tukey test at 5% probability. As a result, the orthogonal y-axis presented a higher vibration level; the three-point blade showed the lowest vibration level compared to the other cutting implements for both crops; these vibration levels did not exceed the NHO10 recommendation. Hence, using the appropriate attachment for each operation may reduce the harm caused by vibration to the operator’s body.

Development of a low-cost iot platform for data collection

2021-10-26T09:04:09-03:00

Precision agriculture in the Internet of Things (IoT) integrates different technologies able to raise crop productivity, optimize resource efficiency, and accelerate decision making. However, the adoption of this technology is usually costly, affecting the acquisition by the farmers. Thus, the objective of this work was to develop and evaluate low-cost hardware to obtain data in a hydroponic system via IoT. The experiment was conducted at the Pici Campus of the Federal University of Ceará and split into three distinct stages. Firstly, the DS18B20 temperature sensors were calibrated in water, using the KR380 infrared thermometer as a comparison method. For the second step, when the hydroponic system was installed, the water temperature was monitored in the channel and not in the solution reservoir. In this same phase, the quality of data sending and receiving was investigated. In the third step, the sensory data were analyzed with those obtained by the local Meteorological Station. The calibration results revealed that the DS18B20 sensor has reasonable accuracy and excellent agreement and reliability between data. As for receiving and storing, only 6% of the total data was lost.

Sampling density to detect spatial dependence of potassium, calcium and magnesium in sandy soils

2022-04-07T15:02:32-03:00

The sampling grid density for georeferenced soil collection must be large enough to allow the identification of the spatial dependence of attributes with representative accuracy of the cultivated area, but not large enough to make fertility mapping unfeasible. The objective of this study was to define, from the evaluation of geostatistical parameters obtained from a super dense soil sampling, an efficient grid for detecting the spatial dependence of potassium (K⁺), calcium (Ca²⁺), and magnesium (Mg²⁺) in a sandy soil. The experiment was conducted in a 3.2 hectare annatto crop (Bixa orellana L.), in 2017. The geostatistical grid consisted of 31 points per hectare, totaling 101 georeferenced points in an 18x18 m spacing. Soil was sampled at the depths of 0-0.20 m and 0.20-0.40 m. A strong spatial dependence was found for all soil attributes in both depths, while the semivariograms fitted to the spherical model with good coefficients of determination (R²) indicating a spatial correlation between the attributes. The range of spatial dependence was close to 100 m for all attributes in both layers. In sandy soils, an efficient sampling grid to detect the spatial dependence of K⁺, Ca²⁺ and Mg²⁺ must consider a semivariogram range of approximately 100 meters.

Determination of quality attributes and ripening stage using vis-nir spectroscopy in intact seriguela and umbu fruits

2022-01-06T11:05:59-03:00

To produce seriguela and umbu on a large scale, it is important to detect the ripening stages and quality attributes of the fruits, to define the ideal harvest point. Thus, this study aimed to determine, in a non-destructive way, the quality attributes and ripening stages of intact seriguela and umbu fruits using Vis-NIR spectroscopy. A total of 150 seriguela fruits and 150 umbu fruits were used, at different ripening stages, and subjected to spectral analysis and reference laboratory testing to determine total soluble solids (TSS) and firmness. Spectral data were subjected to different pre-processing techniques. Regression and classification models were created through the statistical learning and machine learning methods. The models with the best performance for TSS were RF (R2P = 0.94) and PLSR (R2P = 0.68), and for firmness were PLSR (R2P = 0.92) and RF (R2P = 0.58), for seriguela and umbu, respectively. The model with the best performance in the classification was LDA, with a precision greater than 95% to discriminate the ripening stages of both fruits. Therefore, the Vis-NIR spectroscopy is a potential tool to determine the quality attributes and ripening stages, in a non-destructive way, of intact seriguela and umbu fruits.

Evaluation of low-cost capacitive moisture sensors in three types of soils in the Cerrado, Brazil

2022-04-26T10:08:29-03:00

Soil moisture sensors enabled new automation and computerization solutions in agriculture. However, its use still requires prior calibrations to attest its accuracy to estimate soil moisture. Thus, in this study a prototype for soil moisture monitoring was developed using the capacitive sensor SKU:SEN0193 integrated with the Arduino microcontroller. The prototype was calibrated based on the relationship between volumetric moisture and sensor output voltage in deformed samples of Red-yellow Latosol (RYL), Regolitic Neosol (RN), and Red Latosol (RL) of the Cerrado region, Federal District, Brazil. The calibration of sensors resulted in a second-degree polynomial model with R² between 0.93 and 0.96 for RYL, 0.89 and 0.92 for RN, and 0.86 and 0.88 for RL. Root mean square errors (RMSE) of volumetric moisture were 0.08, 0.12, and 0.15 cm³.cm^-3 for RYL, RN, and RL, respectively. Sensors at operating voltage of 5.00 V showed less variability of readings, with coefficient of variation (CV) between 0.21 and 1.54%, while sensors at 3.30 V showed CVs between 3.27 and 17.84%. It is recommended to calibrate the SKU:SEN0193 for each soil type in order to obtain reliable estimates of water content for RYL, RN, and RL.

Aerial images to monitor grapevine vegetative growth

2022-01-10T17:23:41-03:00

Images obtained by Remotely Piloted Aircraft (RPA) used to monitor the crop can help evaluate leaf mass, plant formation, and plant population. In this context, the objectives of this study were to analyze plant growth in a grapevine crop trained in the trellis system, detect failures and determine the plant covered area using images obtained by RPA. The flight was parameterized with frontal overlap of 75%, lateral overlap of 70%, Ground Sample Distance (GSD) of 60 m, and flight speed of 5 m.s^-1, using a sensor in the visible range. Processed images showed a stand 3% smaller than projected, an area covered by vine branches occupying 60.8%, undergrowth and invasives represented 5.3%, and exposed soil 33.9%. Vines were identified in the vegetation indices as green points, invasive plants as yellow points, and exposed soil as red points. Image processing obtained with RPA allowed identification of plants in various stages of development, with predominance of vines in the formation process. It was possible to identify the plants and quantify the leaf mass using the MPRI vegetation index, as well as to differentiate exposed soil from plant material. It was also observed that the plot had an incomplete stand at the time the flight was performed.

CO2 monitoring system for storage of grains and seeds

2022-04-11T15:45:37-03:00

The monitoring of grain and seeds characteristics is fundamental to maintain postharvest quality. Grain mass changes through CO₂ levels monitoring can reduce the product deterioration by anticipating actions to maintain the grain mass quality. This study aimed to develop a CO₂ monitoring system in stored grains/seeds and to analyze its efficiency. The analysis was performed in four crop species (brachiaria, sunflower, corn, and soybean) with different water content and sanity condition. The system hardware was composed of a controller micro board, CO₂ sensor and data stored module. The system routine was developed in C++ language. The monitoring of CO₂ and flammable gases was performed for system analysis and verification. The system monitoring developed showed efficiency in CO₂ levels determination in stored grains/seeds and low-cost, being a viable and applicable tool aiming to the maintenance of postharvest quality.

Analysis of pest incidence on apple trees validated by unsupervised machine learning algorithms

2021-09-15T15:14:19-03:00

Integrated pest control is a practice commonly used in apple orchards in southern Brazil. This type of management is an important tool to help improve quality and increase yields. This study aimed to identify areas with higher and lower incidence of aerial pests in a commercial apple orchard, regarding data collected from three different crops using georeferenced traps. Geostatistical analyses were performed, based on the modeling of semivariograms and spatial interpolation using the kriging method; and clustering, based on specific unsupervised machine learning algorithms for count data. The algorithms were selected from measures of stability, connectivity and homogeneity, seeking to identify areas with different incidence of pests that could help farmer decision making regarding insect population control using pesticides. The geostatistical analysis verified the presence of individual pest infestations in specific sites of the study area. Additionally, the analysis using machine learning allowed the identification of areas with incidence above the average for all analyzed pests, especially in the central area of the map. The process of evaluation described in this study can serve as an aid for risk analysis, promoting management benefits and reducing cost in the farms.

Photovoltaic generators: use by rural customers in Mato Grosso state

2021-10-27T15:29:48-03:00

In the current Brazilian energy scenario, the use of photovoltaic systems for generating energy is an excellent choice, as it combines electricity savings and energy production with less harmful impact on the environment. Mato Grosso is a state of great importance for agricultural production, in a country where agribusiness has a large share in the Gross Domestic Product (GDP). The aims of this study are to investigate the growing use of distributed photovoltaic system by rural customers in the state of Mato Grosso and compare it with the number of installations implemented in other consumer classes to eventually evaluate the participation in the state energy matrix and its applications. The analysis was carried out with data up to 2020 available from the registration system of the distributed generation of the National Electric Energy Agency (ANEEL) and the local electricity company Energisa Mato Grosso (EMT). The number of consumer units having photovoltaic generation systems in the state has grown on average 342% since 2015, when the first units were installed. When analyzing only rural facilities, this percentage rises to 347%. Although the participation of rural customers in the total number of installations is 7.04%, which are less significant than the other consumer classes, these systems are 6.44 times larger than residential systems, with a participation in the total state installed power of 21.74%.

Lettuce growth promoted by artificial lighting using light-emitting diodes (LED)

2022-02-04T15:47:13-03:00

Understanding how the use of light-emitting diodes (LED) in artificial lighting affects plant growth is of considerable interest to Science because the application of specific light wavelengths to crops can enhance agricultural production. Therefore, the influence of LED lamps in the photosynthetically active spectrum (blue and red light) on the growth of lettuce (Lactuca Sativa) was evaluated. A factorial design was used to test 4 combinations of LED lighting (5:1; 3:1; 1:1 and 6:3) and 2 lettuce varieties (butterhead and crisphead). The plants were grown in pots in a controlled environment with a 12h-photoperiod, for 21 days. Leaf number (LN), leaf area (LA) and leaf fresh mass (LFM) were determined along with gas exchange variables (A: net photosynthesis; Ci: CO₂internal concentration; and WUEi: instantaneous water use efficiency. Growth of lettuce plants was greatest in the source of variation of LED lighting with the combination 5:1, as well as the greatest photosynthetic efficiency. The crisphead lettuce was superior to the butterhead lettuce in all analyzed variables, which suggests a better adaptation to the treatments applied.