https://ri.ufs.br/jspui/handle/riufs/2452 2026-07-10T20:31:12Z https://ri.ufs.br/jspui/handle/riufs/25411 Título: Atividade antimicrobiana e antibiofilme de óleos essenciais de Lippia gracilis e seus compostos majoritários sobre fitopatógenos do gênero Xanthomonas spp. resistentes ao cobre Autor(es): Gois, Larissa de Souza Abstract: The genus Xanthomonas is formed by gram-negative phytobacteria that produce biofilms and that cause diseases in plants of economic importance. Prominent diseases include black rot of crucifers, water belly of melon, gummosis of sugar cane, bacterial leaf streak of corn, and bacterioses of cassava and plum. Due to the need for new alternatives for treatment of these diseases, essential oils (EOs) have been studied, which are plant secondary metabolites that have different biological activities, such as antibacterial activity. The objective of this study was to evaluate the antimicrobial and antibiofilm activity of EOs from seven accessions of Lippia gracilis Schauer (LGRA-106, 107, 108, 109, 110, 201, and 202) obtained through the hydrodistillation technique and their major compounds thymol and carvacrol, as well as evaluate copper resistance in five species of phytobacteria of the genus Xanthomonas: Xanthomonas campestris pv. melonis, Xanthomonas axonopodis pv. manihotis, Xanthomonas campestris pv. pruni, Xanthomonas axonopodis pv. vasculorum, and Xanthomonas campestris pv. campestris. Using spectrophotometric techniques, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), antibiofilm activity, cell viability, plasma membrane permeabilization, and resistance to sulfate and copper oxide were evaluated; and the biofilm was morphologically examined under microscopy in vitro. scanning electronics. The in vivo study was carried out in an agricultural greenhouse. The effect of the EO from the LGRA107 accession (previously selected for its greater bacteriostatic and bactericidal activity against X. campestris pv. campestris) and the effect of copper oxide were examined on two varieties of kale plants (Georgia and Ramoso Santana) inoculated with Xanthomonas campestris pv. campestris regarding the following variables: number of leaves, biomass, and incidence and severity of disease. The in vitro experiments were performed in duplicate with three replications. For the in vivo experiment, a completely randomized design was used in a 2 × 3 factorial arrangement, constituted by two inoculation methods (injected and sprayed) and three substances (two concentrations of EO from the LGRA-107 accession – 250 and 500 µg mL-1 , and a copper oxide concentration – 2000 µg mL-1 ). A control of 1% DMSO was also used. For analysis of disease severity and incidence, a scoring scale from 0 to 5 was used, and evaluations were carried out over a period of 15 days. The concentration of 1000 µg mL-1 of EOs from LGRA accessions and the major compounds thymol and carvacrol at concentrations between 250 and 500 µg.mL-1 , respectively, demonstrated bacteriostatic and bactericidal activity and led to an increase in cell plasma membrane permeability bacterial. The EOs of all accessions, as well as the major compounds and copper oxide, showed antibiofilm activity for the five phytobacteria. However, this activity was not observed for copper sulfate. As the result of the in vivo experiment, kale, when exposed to copper oxide, obtained higher values of fresh biomass, and broccoli kale had higher leaf numbers. The results of this study showed that the essential oils of the accessions LGRA-109, LGRA-201, and LGRA-107 had greater antimicrobial activity and are promising for control of phytobacteria of the genus Xanthomonas spp. 2022-07-29T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/25369 Título: Fenotipagem por Vant e aprendizado de máquina para predição da produtividade de milho em ambientes contrastantes de nitrogênio em região semiárida Autor(es): Santos, Barbara Nascimento Abstract: High-throughput phenotyping has contributed substantially to advances in agriculture and plant breeding programs. By using unmanned aerial vehicles (UAVs), its application has enabled the rapid acquisition of phenotypic data with high reliability and spatial resolution, promoting its adoption across diverse agricultural contexts. Despite these advances, several methodological limitations remain insufficiently explored, particularly when this approach is applied under conditions of environmental stress and high spectral homogeneity. This study aims to evaluate the accuracy of four predictive models, using regression and machine learning approaches to estimate the grain yield of maize half-sib progenies grown under contrasting nitrogen conditions, based on multispectral images obtained by UAV. The experiments were conducted during the 2024 growing season in two experimental areas located in the municipalities of Nossa Senhora da Glória and Graccho Cardoso, Sergipe, Brazil. A randomized block design with split plots and three replications was adopted, in which nitrogen levels (high and low) were assigned to the main plots and the half-sib progenies to the subplots. Multispectral drone images were acquired during three flights at heights of 60 and 80m throughout the crop cycle, corresponding to different phenological stages. Fourteen multispectral vegetation indices associated with canopy structure, chlorophyll content, and plant nutritional status were calculated. Four predictive approaches were evaluated: a classical linear model, a penalized regression model (LASSO), and two decision tree-based algorithms, Conditional Forest (Cforest) and Gradient Boosting Machine (GBM). Model performance was evaluated using the root mean square error (RMSE) and the mean absolute error (MAE), in addition to diagnostic analyses of the linear model assumptions and assessments of variable importance and SHAP values for the GBM and Cforest models. In both experimental areas and nitrogen conditions, the Cforest and GBM models consistently showed higher predictive accuracy than the linear approaches. Overall, images acquired at 60m resulted in superior model performance, highlighting the importance of higher spatial resolution for increased sensitivity to physiological variability within the canopy. Analyses of variable importance and SHAP values indicated that predictive contributions were concentrated in a limited subset of vegetation indices, particularly those sensitive to canopy structure and chlorophyll content. Furthermore, distinct predictive responses were observed among genotypes, depending on the modeling approach and environmental conditions. These results suggest that the acquisition and processing of spectral data can be optimized by prioritizing specific vegetation indices and strategically selected phenological stages. For predicting maize grain yield, the combined use of the Cforest and GBM models with vegetation indices such as TCARI, MCARI, and MSAVI2 is recommended. To increase the robustness and generalizability of these findings, future studies should evaluate the performance of such indices across a broader range of nitrogen levels, genotypes, and edaphoclimatic conditions. 2026-01-26T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/24113 Título: Diversidade fenotípica e metagenômica de Spondias tuberosa: subsídios para a bioeconomia da Caatinga Autor(es): Silva, Maria Suzana Oliveira da Abstract: Spondias tuberosa Arr. Câm., commonly known as umbuzeiro, is a species native to the Brazilian Caatinga biome and holds great potential for regional bioeconomic development. Its fruits are of notable nutritional, sociocultural, and commercial importance to communities in the semi-arid region. However, integrated studies on the phenotypic and microbiological diversity of this species remain scarce, particularly in natural populations from the state of Sergipe. This dissertation aims to investigate the phenotypic variability of fruits and natural populations of umbuzeiro, and to functionally characterize the microbiomes associated with their endocarps, with the goal of identifying relevant traits for conservation strategies, genetic improvement, and sustainable biotechnological applications. The study is structured into three scientific chapters. The first one chapter presents a systematic review of the role of endophytic microorganisms in fruits and seeds of fruit-bearing species, highlighting their functions in plant growth promotion, biological control, resistance induction, and postharvest conservation. The review includes 59 studies selected according to PRISMA criteria, revealing that bacterial genera such as Bacillus and Pseudomonas, as well as fungi like Trichoderma and Penicillium, are most frequently associated with beneficial functions. Despite significant advances in studies on fruit microbiota, substantial gaps remain in the understanding of seed-associated microbial communities, especially in tropical native species. The second chapter addresses the phenotypic characterization of fruits and natural populations of S. tuberosa in extractive areas of Sergipe. Morphological and biometric traits such as fruit weight, soluble solids content, firmness, diameter, and length were evaluated. The analyses revealed wide intra and inter-population variability, highlighting genotypes with agronomic promise and commercial potential. Chromatic attributes, particularly luminosity, proved to be the most consistent descriptors for differentiating the origin of umbuzeiro fruits and endocarps. The Gararu population exhibited a more uniform and distinct phenotype, Poço Verde showed greater internal cohesion, whereas Canindé displayed greater variability among matrices, with matrix nine standing out due to its relevant phenotypic characteristics, such as size and sweetness, which make it distinct from the others. The third chapter employs functional metagenomic approaches to explore the composition and biotechnological potential of the microbiota found in fruit endocarps. DNA extraction, sequencing, and bioinformatic analyses were conducted to identify key microbial groups. Results revealed a diverse microbial community, with bacteria harboring genes related to nitrogen fixation, phosphate solubilization, auxin production, and ACC deaminase activity. These microbial functions support the potential use of S. tuberosa as a source of natural bioinputs in low-impact agricultural systems. The findings of this dissertation contribute significantly to the recognition of umbuzeiro as a strategic resource for fostering the bioeconomy of the Caatinga biome. The integration of morphological and molecular data provides scientific and technical foundations for public policies aimed at biodiversity conservation, the development of cultivars adapted to semi-arid conditions, and the sustainable use of native microbial resources. Ultimately, the dissertation emphasizes the value of combining traditional knowledge with modern science to strengthen sustainable and inclusive agricultural practices. 2025-07-03T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/24112 Título: Biochar e sua influência no solo, nas plantas e na dinâmica do carbono Autor(es): Silva, Andreza Nunes Conceição da Abstract: The application of biochar to degraded or highly weathered soils has been recommended in several countries with climate regions vulnerable to environmental problems but requiring high agricultural productivity to meet population demands. This technology stimulates the circular economy through the use of various organic residues and supports both traditional and regenerative agriculture. This study evaluated the effect of different types of biochar on soil properties, microbiota, plant growth, and the distribution of carbon and nitrogen among soil particle-size physical fractions. The first experiment, conducted in a randomized block design in an agricultural greenhouse, assessed the effect of four types of biochar (pear orange bagasse – BL, sugarcane bagasse – BC, corn cob – BM, and green coconut residue – BCV) on some chemical and biological properties of a Red-Yellow Ultisol and on the growth of curly mustard (Brassica juncea L.). All biochars increased soil carbon (by 108–175%) and total phosphorus (by 22–38%) concentrations. However, the biochar type affected total nitrogen and exchangeable calcium concentrations, as well as microbiota behavior and plant biomass, confirming findings reported in the literature on the importance of evaluating the effects of different biochars. The second study, conducted in a completely randomized design in the laboratory, evaluated the effect of three types of biochar (dry coconut residue – BCS, pear orange bagasse – BL, and biosolid – BB) on the distribution of carbon and nitrogen in the particulate organic matter (POM) and mineral-associated organic matter (MAOM) fractions of a RedYellow Ultisol after a three-year incubation. The biosolid biochar had the smallest contribution to increasing soil carbon (40%) but stood out as the best nitrogen source, increasing soil N content by 145%. This effect is clearly associated with its chemical composition. In general, the biochars did not affect the proportional mass of the POM and MAOM fractions but caused significant changes in the distribution of C and N between them, with a proportional increase of C in the POM and a reduction in the MAOM. In soil without biochar, 17% and 85% of carbon were distributed in the POM and MAOM fractions, respectively. However, biochar increased C in the POM by 4.5 (BB) to 8 times (BCS and OB), causing a shift in the carbon proportion between the two fractions. These results complicate the use of particle-size physical fractionation of organic matter as a tool for assessing changes in soil quality due to management practices, as the POM fraction is no longer a reliable indicator of carbon lability in biochar-amended soils. 2025-07-30T00:00:00Z