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dissertação
Índice de curva ótima para implantação de lavouras cafeeiras
(Universidade Federal de Lavras, 2026-08-21) Souza, Fernando Henrique de; Faria, Rafael de Oliveira; Ferraz, Gabriel Araujo e Silva; https://orcid.org/0000-0001-6403-2210; Barros, Murilo Machado de; https://orcid.org/0000-0003-0378-4800; Silva, Flávio Castro da; https://orcid.org/0000-0003-1366-9806
Coffee cultivation is extremely important to the Brazilian agricultural economy, requiring the adoption of techniques that increase productivity and reduce operating costs. The use of highaccuracy elevation data is essential for the efficient planning of mechanized planting rows, particularly in mountainous regions such as southern Minas Gerais, Brazil. This study aimed to develop an Optimal Curve Index (OCI) for designing coffee planting rows by considering mechanization variables, topographic characteristics, and the optimization of the number of transplanted seedlings per hectare. The research involved analyzing mechanized areas, determining optimal curvature and slope parameters, and establishing practices to prevent plant damage caused by machinery traffic during agricultural operations. Technologies for acquiring topographic data were compared, including a LiDAR sensor mounted on a remotely piloted aircraft (DJI Matrice 350 RTK equipped with a Zenmuse L2) and GNSS receivers using RTK correction. LiDAR elevations were processed using the hgeoHNOR2020 geoid model and referenced to the SIRGAS 2000 / UTM Zone 23S coordinate system. The initial analysis indicated that the data were not normally distributed, as confirmed by the Shapiro–Wilk test (p = 2.79 × 10−21 for GNSS and p = 2.97×10−21 for LiDAR). The Wilcoxon test revealed a statistically significant difference between the measurements, with a mean bias of 1.56 m, indicating the need for vertical correction of the GNSS data. The OCI model, validated through Monte Carlo simulations, showed that tractor–implement combinations can negotiate tighter curves, whereas self-propelled harvesting imposes stricter constraints due to the geometry of the harvester. The harvesting-tunnel length adopted in the model was 3.66 m, resulting in an absolute critical radius of 6.61 m. Depending on the local slope, the harvester required minimum safe radii greater than 20 m to operate without mechanical collisions with coffee plant trunks, drastically reducing overall operational suitability in fields with sharp curves. It was concluded that the OCI, which can be supplied with data obtained affordably from sensors already installed on agricultural machinery, is a feasible tool for guiding planting-row design in the field and reducing the need for future physical interventions in coffee plantations
dissertação
Condições das pastagens nas regiões de Tangará da Serra e Mirassol d’Oeste (MT): análise temporal do vigor e da degradação entre os anos de 2010 a 2024
(Universidade Federal de Lavras, 2026-05-25) Correa, Adriel Fernandes; Ladeira, Márcio Machado; https://orcid.org/0000-0002-1585-8486; Casagrande, Daniel Rume; https://orcid.org/0000-0003-0732-6196; Faria, Dawson José Guimarães; https://orcid.org/0000-0003-2533-1765
Beef cattle production plays a strategic role in the Brazilian economy, particularly in the state of Mato Grosso, which holds one of the largest cattle herds in the country. However, pasture degradation remains one of the main challenges to the sustainability of livestock systems, reducing productivity, compromising natural resource conservation, and limiting land-use efficiency. In this context, remote sensing has become an important tool for monitoring pasture conditions and supporting management strategies and public policies aimed at restoring degraded areas. This study aimed to evaluate pasture conditions in the Immediate Geographic Regions of Tangará da Serra and Mirassol d'Oeste, Mato Grosso State, Brazil, by analyzing the temporal evolution of vegetation vigor and pasture degradation between 2010 and 2024. The study adopted a descriptive approach using secondary data obtained from the MapBiomas platform and the Atlas of Pastures (LAPIG/UFG). Total pasture area, areas classified as low, medium, and high vegetation vigor, and the Pasture Degradation Index (PDI) were analyzed using descriptive statistics, analysis of variance (ANOVA), Tukey's multiple comparison test, linear regression, and panel data models. Tangará da Serra presented a larger average pasture area (116,885.94 ha) and a higher mean PDI (0.45), whereas Mirassol d'Oeste showed an average pasture area of 108,186.41 ha and a mean PDI of 0.33. Significant differences among municipalities were observed in both regions (p < 0.0001), demonstrating high spatial heterogeneity in pasture conditions. Temporal analysis revealed annual fluctuations in pasture area and degradation levels; however, no statistically significant increasing or decreasing trend was detected between 2010 and 2024. It is concluded that Tangará da Serra exhibited greater pasture degradation than Mirassol d'Oeste and that both regions showed marked spatial variability among municipalities, highlighting the need for continuous monitoring and region-specific strategies to support pasture restoration and strengthen public policies for sustainable livestock production.
dissertação
Otimização de protocolos para transformação genética de arroz (Oryza sativa L.), mediada por Agrobacterium tumefaciens
(Universidade Federal de Lavras, 2026-07-27) Leveque, Suamith Hermínio Luís Leveque; https://orcid.org/0000-0002-1675-0944; Pádua, Marlúcia Souza; https://orcid.org/0000-0002-2657-3662; Berchembrock, Yasmin Vasques; https://orcid.org/0000-0003-3195-7537; https://orcid.org/0000-0003-3195-7537; https://orcid.org/0000-0002-3980-9013
Rice (Oryza sativa L.) is one of the world's most important food crops, playing a fundamental role in global food security and serving as a staple food for billions of people. The development of efficient tissue culture and genetic transformation protocols is essential to accelerate breeding programs and the development of cultivars with superior agronomic traits. This study aimed to optimize in vitro protocols for rice (Oryza sativa L.), encompassing seed asepsis procedures, morphogenic responses in tissue culture, and bacterial growth parameters of Agrobacterium tumefaciens. In the first experiment, the effects of physical pre-treatments (washing with running water and neutral detergent), sodium hypochlorite (NaClO) exposure time, and post-asepsis drying on contamination and callus induction were evaluated in different rice genotypes. The results showed that the physical washing and drying steps were decisive in reducing contamination, whereas increasing the exposure time to the chemical disinfectant had no consistent effect. Among the evaluated genotypes, CMG 1590 and Nipponbare showed the best performance, with lower contamination rates and greater stability in callogenesis. In the second experiment, the in vitro growth of the Agrobacterium tumefaciens strains EHA105 and LBA4404 was evaluated, and no significant differences in bacterial density were observed, indicating equivalent performance under controlled conditions. Additionally, the response of rice genotypes to callus induction and regeneration was evaluated on N6 medium supplemented with different concentrations (0.0, 1.0, 1.5, 2.0, 2.5, and 3.0 mg L⁻¹) of 2,4- dichlorophenoxyacetic acid (2,4-D). The results demonstrated a concentration-dependent response, with the highest efficiency observed between 2.0 and 2.5 mg L⁻¹, whereas the absence of the growth regulator prevented callus formation, and higher concentrations (above 2.5 mg L⁻¹) reduced the morphogenic response. Statistical analysis confirmed a significant interaction between genotypes and 2,4-D concentrations. It is concluded that the efficiency of in vitro rice protocols depends on the integration of physical asepsis procedures, appropriate hormonal adjustments, and genotype selection, all of which are essential for improving regeneration systems and supporting future applications in genetic improvement.
Artigo
Applying Potra-Pták iterative cycle for solving highly nonlinear structural problems
(2023-09-15) Rocha Segundo, Jackson da Silva; Silveira, Ricardo Azoubel da Mota; Silva, Andrea Regina Dias da; Barros, Rafael Cesário; Lemes, Igor José Mendes
When solving nonlinear algebraic equations that arise from discretization using the finite element method (FEM), it is often observed that the standard Newton-Raphson (N-R) iteration either fails to converge or necessitates a large number of iterations in the vicinity of critical points. This work proposes an additional numerical strategy, known as the Potra-Pták iterative cycle, to improve the efficiency of solving highly nonlinear structural problems. Therefore, the focus here is on making the nonlinear solver more robust and efficient, allowing the analysis of more complex nonlinear structures. In the Potra-Pták iterative cycle, two corrections of the objective function (energy function) are performed. The introduction of a second correction in the iterative cycle makes the Potra-Pták strategy more efficient than the standard or modified N-R iterations. This numerical strategy was implemented in the homemade Computational System for Advanced Structural Analysis (CS-ASA) program. The program is based on the FEM and is capable of performing static and dynamic nonlinear analysis of steel, concrete, and composite structures, and its efficiency is then verified through the analysis of slender frames and arches. The algorithm details for solving the nonlinear structural problem, characterized by the Potra-Pták scheme, are provided.
Artigo
Application of ethylene synthesis inhibitor in arabica coffee on field infestation, preference, and performance of Hypothenemus hampei
(2023-09-27) Martins, J. O. J.; Souza, B. H. S.; Costa, D. C. M.; Carneiro, F. S.; Dias, D. M.; Silva Júnior, M. B.
Coffee berry borer (CBB) Hypothenemus hampei is the major pest of coffee fruits worldwide. Bioregulators have been applied in crop plants with the aim of changing their physiology and metabolism for better yield and quality of produce, but little knowledge exists on the effects on insect pests. This study evaluated application of ethylene synthesis inhibitor in arabica coffee on CBB field infestation, preference, and performance in function of application time and dose. Field experiments were conducted in Lavras, Brazil, and the effects of ethylene synthesis inhibitor Mathury™ on CBB were evaluated using five treatments: control (water); Time1 + Dose1; Time1 + Dose2; Time2 + Dose1; and Time2 + Dose2. The first and second applications were performed at 80 and 110 days after flowering, respectively, using the doses of 2 and 15 L ha−1. CBB field infestation was recorded through time as the percent bored fruits, and the colonization in the beans and degree of fruit maturation were evaluated at harvest. CBB preference and colonization were assessed in dual-choice bioassay and the performance under no-choice condition in the lab. Plants treated with the bioregulator overall presented fruits less suitable for CBB preference and performance in terms of females choice and survival in the lab, but varying effects were found between field experiments for bored fruits (%), which increased with fruit maturation. In the second field experiment, reduced larvae and pupae infestations were found in bioregulator-treated fruits. Application of ethylene synthesis inhibitor is promising to complement CBB management in sustainable coffee crops. Future research should evaluate the underlying induced-resistance mechanisms.