http://repositorio.ufc.br/handle/riufc/41 2026-05-30T22:40:22Z http://repositorio.ufc.br/handle/riufc/86124 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 2024-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86535 Título: Criação e manejo de Xylocopa frontalis e sua utilização comparativa na polinização do urucuzeiro (Bixa orellana) Autor(es): Silva, Felipe Jackson de Farias Abstract: We aimed to propose improvements to a rational nest model for bees of the genus Xylocopa, especially X. frontalis, as well as techniques for the rearing, multiplication, and management of this species, and its efficiency as a pollinator of the annatto tree (Bixa orellana), compared to three other native bee species (Augochloropsis sp., Melipona fasciculata, and Melipona flavolineata). The first colonized nests appeared few months after their installation in the study area. The number of galleries built per nest ranged from one to six (3.82 ± 1.4). The galleries had a total average length of 104.19 (±43.41) cm and an excavated volume of 327.15 (±136.29) cm³. Active nests were observed throughout the study period and were transported and relocated without abandonment. Regarding pollination, peak flower visits occured between 7:00 and 8:00 AM, with X. frontalis foraging earlier than other bees and making shorter flower visits. No statistically significant differences were detected in any fruit parameters between treatments. The treatment with free pollination showed the highest fruit set rate (37.5%), followed by a visit from M. flavolineata (25%), although no statistically significant difference was observed. We conclude that our rational nesting device is a suitable alternative for the rearing and management of Xylocopa frontalis and, presumably, other species of the genus for crop pollination or research purposes, without evidence of negative interference in the nesting biology of these bees. Xylocopa frontalis proved to be an efficient pollinator of Bixa orellana. Tipo: Tese 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86528 Título: Avaliação do Auxílio Moradia da UFC no campus de Fortaleza no âmbito da Política Nacional de Assistência Estudantil (PNAES) Autor(es): Leão, Isabelle Silva Abstract: This dissertation evaluates the Housing Assistance Program of the Federal University of Ceará (UFC), at the Fortaleza campus, within the scope of the National Student Assistance Policy (PNAES), aiming to understand its contribution to the retention of students in situations of socioeconomic vulnerability in higher education. The study is based on the understanding that the expansion of access to higher education, especially through the quota policy, has changed the student profile of federal institutions and intensified the relevance of student assistance policies for undergraduate student retention. The research adopts an evaluative perspective inspired by Fourth Generation Evaluation and combines qualitative and quantitative approaches. To this end, documentary and institutional data regarding the beneficiaries of the program were mobilized, in addition to interviews with managers, staff members responsible for implementing the policy, and assisted students, with data processed through content analysis. The results show that the Housing Assistance Program plays a significant role in student retention by impacting material conditions of subsistence, mobility, academic continuity, and expectations of remaining at the university. At the same time, the study identifies tensions related to poverty, budget constraints, targeted assistance, management and operational challenges, partial lack of knowledge about PRAE services, and the increasing complexity of student demands. It is concluded that the program constitutes an important instrument for inclusion and student retention; however, its effectiveness depends on the institutional and budgetary strengthening of PNAES, as well as on information, monitoring, and evaluation strategies capable of reducing exclusions within the inclusion policy itself. Tipo: Dissertação 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/86508 Título: Uso da lignina de coproduto do pedúnculo do caju como ativo de filmes à base de amido de milho com propriedade de bloqueio da radiação UV Autor(es): Barros, Gleyde Anny Cruz Abstract: Ultraviolet (UV) radiation can accelerate oxidative processes in foods, compromising their sensory and nutritional characteristics. As a strategy to minimize these effects, packaging materials with UV-blocking capacity, as well as active packaging capable of scavenging free radicals, have been increasingly developed. In this context, biodegradable and low-cost biopolymers, such as lignin, have attracted growing attention. This study aimed to develop and characterize corn starch-based biofilms incorporated with lignin extracted from residues of cashew peduncle processing, aiming at their potential application in active food packaging. Films containing 1, 3, and 5% (w/w) lignin were prepared using the casting method and evaluated for rheology, mechanical properties, color, hydrophobicity, UV-blockin/g properties, antioxidant activity, biodegradability, and recyclability. The film-forming solutions exhibited non-Newtonian pseudoplastic rheological behavior (n < 1), with viscosity decreasing as shear rate increased, and the data were adequately described by the Power Law model. The presence of lignin promoted changes in the structural properties of the films, with a reduction in tensile strength (from 13.89 to 6.32 MPa) and an increase in elongation at break (from 29.04 to up to 57%), indicating greater flexibility and deformability of the polymer matrix as lignin concentration increased. Progressive darkening of the films was also observed, with a reduction in lightness (L*) and an increase in reddish and yellowish tones. Furthermore, lignin addition significantly increased the hydrophobicity of the films, reducing water absorption from 86.32% (control) to 68.64% (3% lignin) and increasing the contact angle from 68.62° to 77°. Sorption isotherms showed type III behavior and were satisfactorily fitted by the GAB and Peleg models at 25 and 35 °C. Films containing 3% and 5% lignin completely blocked UV radiation, while antioxidant activity increased proportionally with lignin content. Biodegradation ranged from 33% to 46% after 35 days, and films containing 1% and 3% lignin showed effective recyclability, maintaining their antioxidant and UV-blocking properties after reprocessing. These results demonstrate that lignin derived from cashew peduncle residues is a promising sustainable component for the development of multifunctional active packaging materials, with strong potential to protect foods against photo-oxidative degradation and contribute to extending shelf life. Tipo: Dissertação 2026-01-01T00:00:00Z