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Desenvolvimento de equipamento óptico para avaliação nutricional em plantas: aplicação na cultura do milho

Mon, 01 Jan 2024 00:00:00 GMT

Título: Desenvolvimento de equipamento óptico para avaliação nutricional em plantas: aplicação na cultura do milho Autor(es): Nogueira, Felipe Hermínio Meireles Abstract: The search for technologies that promote more sustainable and efficient practices is an increasingly important priority on the global agricultural scene. With this in mind, the use of spectroradiometry techniques to assess nitrogen concentration in maize crops has proved to be a promising alternative for conducting precision agriculture practices. In addition, the development of new instruments with optical sensors for agricultural applications has become increasingly important given the challenges of maintaining the sustainability of production systems. With this in mind, this work sought to improve elements of the use of MSPAT (Multispectral Soil Plant Analysis Tools) to determine reflectance. The improvements involved the development of a reference plate with sintered barium sulphate, new approaches using programming techniques, electronics and 3D printing. In addition, the performance of the optical instruments used to estimate leaf nitrogen in the maize crop was also assessed. With this in mind, an experiment was carried out in the experimental area of the Agricultural Electronics and Mechanisation Laboratory (LEMA), located at the Federal University of Ceará (UFC), with AG-1051 maize planted under treatments N0, N60, N90, N120, N150 and N180 (0, 60, 90, 120, 150 and 180 kg.ha-1 of N, respectively) with four replications, in two crop cycles and a Completely Randomized Design (CRD). The assessments took place during the V5, V10 and R2 phenological stages and were carried out using the MSPAT, SPAD and FieldSpec PRO FR 3 equipment. The spectroradiometer was used under the conditions provided by the dark-room of the UFC Geoprocessing Laboratory. The samples were then prepared for nitrogen (N) determination according to the methodology proposed by Kjeldah. In addition to leaf nitrogen, morphological parameters were also assessed throughout plant development, production, biomass and dry matter. The spectral indices (NRI, Normalise Ratio Index) were then correlated with the leaf N data and the individual bands were evaluated using Pearson's coefficient (r). Linear regression was then carried out (p-value < 0.01) with the NRI's to select the models, by optical instrument, that showed the best coefficient of determination (R²) with the leaf N data sets: i) at each stage of development, for the two crop cycles and ii) with the entire data set. Cross-validation (k-fold) was then carried out to assess the error parameters RMSE, MAE and adjusted coefficient of determination (R²adj.). The results for the best predictive models reveal different patterns for the selected bands between the data sets, as well as low generalisation capacity. However, it was possible to validate relevant models with MSPAT, SPAD and FieldSpec, which showed an R²adj. of 0.7871; 0.6959; 0.7199 and RMSE of 0.0425; 4.47; 0.0214 g.kg-1; respectively. From the model that showed the best performance with MSPAT, when using the NRI with the 900 and 560nm bands, the application in an agricultural area provided an RMSE of 2.73 g.kg-1 and MAE of 2.47 g.kg-1. However, it is clear that the use of new technologies has great potential for assessing leaf N in maize crops. Tipo: Dissertação

Reserva explotável e modelo de otimização para alocação de água em aquífero aluvial no semiárido brasileiro

Thu, 01 Jan 2026 00:00:00 GMT

Título: Reserva explotável e modelo de otimização para alocação de água em aquífero aluvial no semiárido brasileiro Autor(es): Costa, Antonia Thayna Sousa Abstract: The Northeast region of Brazil has faced long periods of drought, resulting in the depletion of surface water reserves. Given this scenario, groundwater sources, especially in alluvial aquifers, have become vital to support agricultural activities, particularly in areas with public irrigation projects, such as the Morada Nova Irrigation Project (PIMN) in the state of Ceará. In view of this problem and considering the potential risks of overexploitation of this resource, the overall objective of this study was to obtain an optimal agricultural exploitation plan for the PIMN, with the main constraint being the annual exploitable water reserve of the alluvial aquifer. Specifically, the research had the following objectives: to calculate the annual exploitable water reserve of the alluvial aquifer in the PIMN section; to perform an economic analysis of shrimp farming based on the profitability indicators of the investment analysis; to generate a linear programming model with the objective function of maximizing the net revenue of the PIMN. The model was solved using the LINDO (Linear Interactive and Discrete Optimizer) computer program, which solves systems of linear equations using the iterative “revised simplex method” algorithm. The exploitable reserve was calculated based on the variation in the potentiometric surface between the end of the dry season and the end of the rainy season, a period in which the maximum recharge of the aquifer is observed, either through rainfall and/or river-aquifer interaction. The results of the research led to the following conclusions: The groundwater reserves of the alluvial aquifer in the PIMN are quite significant, but the aquifer is overexploited due to the high-water demand of shrimp farming, an activity that has grown exponentially. Shrimp farming proved to be economically viable at a real annual interest rate of 12% and a return on invested capital in the third year, standing out as the most profitable activity and accounting for 96% of total annual net revenue. The area occupied by shrimp farming in the PIMN in 2024 already exceeded the area limit suggested by the optimal occupation plan by 13.3%. Water insecurity signals risks in the economic dimension, as a 40% reduction in water availability leads to a reduction in net revenue of nearly 50% Tipo: Dissertação

Diversidade genética de progênies de feijão-caupi utilizando marcadores ISSR e SSR

Thu, 01 Jan 2026 00:00:00 GMT

Título: Diversidade genética de progênies de feijão-caupi utilizando marcadores ISSR e SSR Autor(es): Freitas, Leslyene Maria de Abstract: Cowpea (Vigna unguiculata (L.) Walp.) is a crop of great socioeconomic and nutritional importance in Brazil, particularly in the Northeast region, due to its excellent adaptability to diverse environmental conditions and its high nutritional value. However, crop productivity remains limited in some regions, highlighting the need for advances in cowpea breeding programs. In this context, the assessment of genetic variability is an essential step for identifying and selecting superior and genetically divergent parents, contributing to the development of populations with greater genetic variability and, consequently, improving the efficiency of breeding programs. Therefore, the present study aimed to confirm the hybridization of F1 progenies, evaluate the genetic diversity of F1 and F2 cowpea populations using ISSR molecular markers, and assess the potential of multiplex PCR associated with capillary electrophoresis using SSR markers. Seven parental genotypes, eight F1 progenies, and 97 individuals from the F2 population were evaluated. Genomic DNA was extracted from young leaves and subsequently subjected to PCR amplification using ISSR and SSR markers. The hybrid status of five previously selected F1 progenies was confirmed using seven ISSR markers, which enabled the identification of polymorphic bands inherited from the male parent and the discrimination of true hybrids from potential self-pollinated individuals. The formation of distinct clusters in the F2 population revealed the existence of genetic variability among the individuals. Four individuals exhibited the greatest genetic divergence compared with the remaining materials evaluated, indicating their potential for advancement in subsequent selection generations. In addition, multiplex PCR associated with capillary electrophoresis showed potential for allele identification in cowpea, although methodological adjustments and optimization of the experimental conditions are still required to improve the efficiency and standardization of the analyses. Overall, ISSR markers proved to be effective for molecular characterization, genetic diversity assessment, and hybrid confirmation in cowpea, highlighting the potential of the F2 population as a valuable source of genetic variability for cowpea breeding programs. Tipo: Dissertação

Utilização de espectrorradiometria na quantificação de metais pesados no solo da jazida de Itataia, Santa Quitéria-CE

Mon, 01 Jan 2018 00:00:00 GMT

Título: Utilização de espectrorradiometria na quantificação de metais pesados no solo da jazida de Itataia, Santa Quitéria-CE Autor(es): Castro Filho, Acrisio Feitosa de Oliveira Abstract: Contamination of soils by heavy metals causes great harm to the environment. Thus, techniques that can measure the content of metals in the soil quickly and efficiently produce great benefits to society. The Itataia deposit fits within this context of soil pollution by heavy metals. Being the largest uranium reserve in Brazil, it has great potential for pollution, making it necessary to continuously monitor the soil of the deposit. However, these analyzes are costly and have negative environmental impacts. In view of this problem, remote sensing appears as a viable alternative for the characterization of the soil and for the quantification of the elements present in it. Therefore, the hypothesis tested will be: From the electromagnetic energy reflected by the soil, it is possible to estimate the heavy metals, since each metal presents differentiating attributes, when they interact with the incident energy. The objective of this research is to elaborate and evaluate predictive models of heavy metal quantification (Cr, Mn, Mo, Pb, Ti, Zn) in the soil using hyperspectral remote sensing. In order to test the hypothesis, 100 soil samples of 50 points were collected, being collected at depths of 0-10 and 10-20 cm. After the soil was collected, air dry thin earth was used for the chemical analyzes in order to quantify the heavy metals present in the samples. The electromagnetic spectrum of each sample was obtained by the FieldSpec Spectroradiometer 350-2500 nm, with a spectral resolution of 1 nm. After this step, three different types of preprocessing (Savitzky-Golay filtering with first and second derivatives and OSC filtering) were performed on the data and the linear regression model of the Partial Least Squares (PLSR) was tested. The models were evaluated using statistical parameters such as the coefficient of determination (r²), root mean square error (RMSE) and percentage deviation ratio (RPD). The best results were obtained with the OSC filter and Savitzky-Golay with the first derivative, where RPD values were higher than 3, indicating an excellent prediction model. The study showed that the use of remote sensing has a good application potential for the prediction of heavy metals in the soil. Tipo: Dissertação