http://repositorio.ufc.br/handle/riufc/108 Thu, 11 Jun 2026 23:55:13 GMT 2026-06-11T23:55:13Z http://repositorio.ufc.br/handle/riufc/85939 Título: A desertificação da caatinga: impactos na estrutura da comunidade de fungos e na atividade enzimática do solo Autor(es): Santos, Ruggeri Mikahaknem Mariano Abstract: The loss of productive capacity in soils used for agricultural and livestock purposes has increased worldwide, mainly due to overexploitation and the adoption of inadequate management practices. Soil compaction, salinization, erosion, and reduced plant biomass growth are common consequences of soils undergoing desertification. However, the impacts of this process on soil fungal communities are still poorly understood. Several restoration techniques have been developed to mitigate or reverse soil degradation. Therefore, the hypothesis tested was that desertification alters soil fungal diversity, the composition of fungal groups, and soil enzymatic activity, and that environmental restoration techniques—such as grazing exclusion, cover crop planting, and reforestation—can restore and increase soil fungal diversity in degraded areas of the Brazilian semiarid region. Soil samples (0–10 cm) were collected from four desertification nuclei in northeastern Brazil and classified into three scenarios: (i) areas with native Caatinga vegetation, (ii) areas affected by desertification, and (iii) areas under environmental restoration. Soil samples were subjected to physical (aggregate stability), chemical (C and N content, pH, and salinity), and biological analyses (total organic carbon, microbial carbon, enzymatic activity and stoichiometry, glomalin content, and fungal diversity through DNA sequencing of the ITS region). Amplicon sequencing analyses were performed using QIIME 2, and uni- and multivariate analyses were conducted in RStudio to integrate the datasets. Extracellular enzymes were sensitive to degradation and restoration processes across all nuclei. Overall, the degradation process did not promote significant changes in alpha diversity but caused shifts in beta diversity in all nuclei. The fungal genera Aspergillus and Penicillium showed higher relative abundance in native vegetation and restoration areas, whereas Curvularia was more abundant in degraded areas. Both soil degradation and restoration appear to favor the emergence of specialist groups under different environmental scenarios. Enzymatic activity, microbial carbon, glomalin content, and soil C and N levels showed strong positive correlations with the fungal community structure. Co-occurrence network analysis demonstrated that both soil degradation and environmental restoration promote shifts in dominant fungal groups, which establish new and complex interaction networks. Overall, soil degradation alters the functional structure of fungal communities, characterized by an increase in phytopathogenic groups and a reduction in saprotrophic groups. Tipo: Dissertação Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/85939 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85758 Título: Comunidade microbiana sintética (SYNCOM) promove redução da adubação nitrogenada na bananeira Autor(es): Carrillo, Joseph Jordan Poveda Abstract: Banana cultivation is essential for food security; however, its high dependence on nitrogen fertilizers results in increased production costs and environmental impacts. In this context, the use of Synthetic Microbial Communities (SynCom) emerges as a biotechnological alternative to enhance nutrient use efficiency. This study aimed to evaluate the agronomic efficiency of a SynCom composed of Bacillus strains and diazotrophic bacteria in promoting the growth of banana seedlings cv. Prata Catarina, with reduced nitrogen fertilizer input. The strains were functionally characterized in vitro for biological nitrogen fixation (BNF), indole-3-acetic acid (IAA) production, phosphorus solubilization and mineralization, as well as the production of biosurfactants and siderophores. Bacillus subtilis BR10788 and Azospirillum lipoferum BR11501 stood out for their high IAA production (46.06 and 43.51 μg mL⁻¹, respectively) and positive BNF activity. Phosphorus solubilization and mineralization showed low levels for all strains but indicated complementary functional potential. Azospirillum lipoferum BR11501 and Acidovorax sp. BR11652 exhibited higher biosurfactant and siderophore production, evidenced by emulsification indices of up to 68% and siderophore halos reaching 2.07 mm, highlighting their role in nutrient mobilization and root colonization. Under greenhouse conditions, co-inoculation of the selected strains (Bacillus LPPC282 × Azospirillum lipoferum BR11501 and Bacillus subtilis BR10788 × Acidovorax sp. BR11652) showed a synergistic effect superior to individual inoculation, promoting increases of up to 127.90% in shoot dry mass and 100% in root dry mass, even under reduced nitrogen levels. It is concluded that the developed SynCom exhibits high biotechnological potential, as the functional complementarity among auxin production, biological nitrogen fixation, and biosynthesis of biosurfactants and siderophores contributed to enhanced growth and biomass accumulation of banana seedlings. Tipo: Dissertação Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/85758 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85696 Título: Avaliação de fósforo em solos utilizando espectroscópia de reflectância e algoritmos quimiométricos Autor(es): Silva, Francisco Mateus da Cunha Abstract: Maintaining adequate phosphorus levels in the soil is a determining factor for plant development, influencing vital metabolic processes. Its determination through laboratory methods based on chemical extraction reagents not only generates waste but also makes these techniques costly and time-consuming, rendering their continuous and regular application unfeasible in many agricultural scenarios. This hinders the precise characterization of agricultural areas. The present study aims to evaluate the predictive potential of reflectance spectroscopy for quantifying available phosphorus content in soils, through the application of different chemometric algorithms and transformations of spectral reflectance data acquired by an optical spectroradiometer within the 350–2500 nm range, along with variable selection. For this research, 75 samples of a Neossolo quartzarenico and 75 samples of an Argissolo acinzentado were collected in the Baixo Acaraú irrigation district, and subsequently treated with 15 different concentrations of the commercial fertilizer MAP in 5 replications. For spectral data acquisition, the FieldSpec Pro FR 3 optical sensor was used. In addition to raw reflectance, spectral normalization, Savitzky-Golay filtering, and continuum removal were applied for qualitative and chemometric analyses. Available phosphorus content in the samples was determined using a UV/VIS spectrophotometer based on the Mehlich 1 extraction solution. For the calibration of the phosphorus prediction models, multiple linear regression (MLR), principal component regression (PCR), and partial least squares regression (PLSR) were employed, considering all wavelengths as predictor variables, along with variable selection via Stepwise-Forward. The results showed that spectral normalization combined with PLSR regression on the full spectrum (450–2450 nm) was the most efficient approach for predicting available phosphorus. In the combined RQO + PAcd dataset, R² = 0.95, RMSE = 12.75 mg kg⁻¹, and RPD = 4.31 were obtained; for RQO alone, R² = 0.95, RMSE = 8.30 mg kg⁻¹, and RPD = 4.66; and for PAcd, R² = 0.92, RMSE = 17.76 mg kg⁻¹, and RPD = 3.30 consistently outperforming the PCR models in all cases. Variable selection through correlation filtering and stepwise–forward reinforced the relevance of bands associated with organic matter (650–850 nm), iron oxides (850–900 nm), and 2:1 clay minerals (1400, 1900, and 2200 nm). After variable selection, model performance was heterogeneous and generally inferior to models calibrated with all wavelengths, with PCR outperforming the other regression methods and only the normalized model of the combined dataset achieving an excellent category with R² = 0.84, RMSE = 23.65 mg kg⁻¹, and RPD = 2.49. Tipo: Dissertação Wed, 01 Jan 2025 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/85696 2025-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/85695 Título: Impactos do descarte de efluentes da carcinicultura nas frações da matéria orgânica de solos de manguezais do semiárido Autor(es): Gomes, Israel Oliveira Abstract: Mangroves are highly important ecosystems and play a fundamental role in mitigating climate change, mainly due to their capacity to sequester carbon (C). However, the expansion of shrimp farming in estuarine areas has promoted significant changes in soil physicochemical conditions, with potential impacts on the dynamics and stability of organic matter. Therefore, this study aimed to evaluate the effects of shrimp farming effluent discharge in three impacted areas, in comparison with non-impacted sections of the same sites. Soils were analyzed to quantify total organic carbon (TOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC), as well as to characterize the chemical composition of organic matter using diffuse reflectance infrared Fourier transform spectroscopy (FTIR-DRIFT). Recalcitrance indices and multivariate analyses were used to integrate the results and identify the main factors associated with the observed changes. The results indicate that impacted areas present lower TOC contents (21.66 g kg⁻¹) compared to non-impacted areas (23.16 g kg⁻¹), suggesting that the input of organic material and nutrients from shrimp farming enhances organic matter decomposition. However, a higher accumulation of particulate organic carbon was observed in impacted areas, especially in surface layers, confirming the input of recent and labile material. FTIR-DRIFT analyses revealed a reduction in aliphatic compounds and polysaccharides and a relative increase in aromatic and carbonyl groups, indicating faster degradation processes in impacted areas. Recalcitrance indices indicated lower carbon stability in impacted areas compared to non-impacted ones, with mean values for all combined fractions of 57.49% and 59.74%, respectively, confirming the intensification of mineralization processes associated with increased soil redox potential. It is concluded that shrimp farming alters the distribution and quality of soil organic matter in mangroves, promoting an increase in the labile carbon fraction without favoring its long-term stabilization in the soil. These results demonstrate that impacted mangroves are less efficient as carbon sinks, highlighting the need for management practices that consider not only carbon stocks but also soil conservation and ecosystem preservation. Tipo: Dissertação Thu, 01 Jan 2026 00:00:00 GMT http://repositorio.ufc.br/handle/riufc/85695 2026-01-01T00:00:00Z