Logo Locus

Communities in DSpace

Select a community to browse its collections.

Now showing 1 - 6 of 6

Recent Submissions

  • Thumbnail Image
    Item type:Item,
    Carbon flux variability and the economic valuation of sequestration in abandoned citrus orchards under mediterranean conditions
    (Universidade Federal de Viçosa, 2026-03-19) João, Gila Abílio; Imbuzeiro, Hewlley Maria Acioli; http://lattes.cnpq.br/1890073857403128
    Although terrestrial ecosystems are widely recognized as atmospheric carbon sinks, increasing scientific evidence indicates that the intensification of droughts may shift them into carbon sources. Given the limited understanding of how reduced precipitation influences carbon fluxes in Mediterranean citrus agroecosystems, this study evaluates the response of a citrus orchard under semi-arid Mediterranean conditions to an extreme drought event by examining the temporal variability of net ecosystem carbon exchange. No previous study has examined the response of citrus agroecosystems to the widespread and extreme drought of 2022. Precipitation and NEE data were used in this analysis. Monthly and annual precipitation anomalies were calculated relative to the mean values for the period 2002–2023, allowing the identification of the anomalous year within 2016–2023. The temporal variability of NEE was then assessed for that year. Despite a precipitation deficit of approximately 50% in 2022, the agroecosystem maintained its net carbon sink function, indicating a nonlinear and partially decoupled response between extreme hydroclimatic stress and carbon exchange. However, across the Mediterranean Basin, citrus orchards are increasingly being abandoned, and this trend is expected to intensify in the coming decades. Using the InVEST model (2018–2030), this study also quantified the economic impacts of carbon sequestration losses resulting from citrus orchard abandonment in Lentini, Sicily. Economic valuation indicates that orchard abandonment reduces carbon sequestration, generating average losses ranging from 89.3 to 393.0 EUR ha¹ as the social cost of carbon increases, thereby weakening the contribution of these agroecosystems to climate change mitigation. Keywords: carbon sequestration; citrus agroecosystems; precipitation; economic valuation; citrus orchard abandonment.
  • Thumbnail Image
    Item type:Item,
    Integrating autoencoder deep neural networks with principal component-based methods for subpopulation identification
    (Crop Breeding and Applied Biotechnology, 2026) Azevedo, Camila Ferreira; Costa, Jaquicele Aparecida da; Nascimento, Ana Carolina Campana; Nascimento, Moyses; Cruz, Cosme Damião
    This study evaluated statistical dimensionality reduction techniques—Principal Component Analysis (PCA), Sparse PCA (SPCA), Independent PCA (IPCA), deep learning based on autoencoders (AE), and their hybrid combinations—for subpopulation identification in genomic data. High-dimensional single nucleotide polymorphism (SNP) datasets pose computational challenges and may hinder clustering performance. We compared methods based on clustering agreement with known subpopulation labels using Oryza sativa data (413 genotypes; 44,100 SNPs). PCA and SPCA exhibited strong performance (Adjusted Rand Index [ARI] = 0.715), with PCA achieving the lowest computational time (4.89 s). The standalone autoencoder performed poorly, likely due to the high?dimensional (p >> n) setting. Among the hybrid approaches, IPCA-AE achieved the highest agreement (ARI = 0.758), demonstrating that combining dimensionality reduction with nonlinear representation learning improves population structure identification.
  • Thumbnail Image
    Item type:Item,
    Diversity between Jatropha curcas L. accessions based on oil traits and X-ray digital images analysis from it seeds
    (Crop Breeding and Applied Biotechnology, 2018) Pinto, Milena Silva; Damasceno Junior, Pedro Corrêa; Oliveira, Lucas Couto de; Machado, Adelia Ferreira de Faria; Souza, Marco Andre Alves de; Muniz, Dandara Rêgo; Dias, Luiz Antônio dos Santos
    Jatropha curcas L. is a species with high potential for the biodiesel production. Therefore, the oil yield and quality from it seeds should be known. This study aimed to estimate the correlation between morphological traits, yield and oil quality evaluated in the seeds, to know the genetic diversity between J. curcas accessions and it behavior regarding to three harvest seasons. For this purpose, X-ray digital images from seeds of 18 accessions were obtained, and the seeds analyzed for external and internal morphological aspects. The same seeds were analyzed for oil yield and quality. In general, the results concerning diversity indicated a narrow genetic base. More rounded and very long seeds had lower oil yield. Larger seeds presented higher oil yield only when their internal cavity was filled by their endosperm. Most of the accessions showed variation regarding the size of the endosperm, yield and oil quality between harvest seasons.
  • Thumbnail Image
    Item type:Item,
    Combined BLUP selection indexes with parents and F2 populations in soybean (Glycine max) breeding
    (Crop Breeding and Applied Biotechnology, 2023) Bezerra, André Ricardo Gomes; Resende, Marcos Deon Vilela de; Silva, Felipe Lopes da; Sediyama, Tuneo; Cruz, Cosme Damião; Silva, Francisco Charles dos Santos; Silva, Amilton Ferreira da
    This study aimed to apply selection indexes in situations in which F2 populations and their parents are evaluated simultaneously in field trials to predict population genotypic values and selecting the best populations. Fifteen F2 soybean populations were evaluated for number of days to flowering and to maturity and grain yield. The data was analyzed using restricted maximum likelihood/best linear unbiased prediction (REML/BLUP) to obtain genotypic effects, variance components and accuracies. Four selection methods were compared: genotypic values of the F2 populations (gF2), combined index with the mean genotypic value of parents and F2 population (Ia) and two indexes that add (to gF2 and to Ia) and consider genetic variability within populations (Ib and Ic). The index Ia presented a result similar to that obtained with the gF2 selection method. Selection indexes (Ib and Ic) based on several sources of information were more efficient than selection based on gF2 values only.
  • Thumbnail Image
    Item type:Item,
    Realidade aumentada no ensino de matemática: uma abordagem inovadora interdisciplinar com geogebra
    (Universidade Federal de Viçosa, 2026-06-09) Caçador, Lucas Henrique; Faria, Rejane Waiandt Schuwartz de Carvalho
    Este trabalho de conclusão de curso objetiva analisar as contribuições da Realidade Aumentada do GeoGebra no ensino de geometria espacial na Educação Básica em uma perspectiva interdisciplinar. A pesquisa, de natureza qualitativa, foi fundamentada na valorização dos significados e contextos das práticas humanas e desenvolvida com alunos do 2 o ano do Ensino Médio da Escola Estadual Raul de Leoni, em Viçosa-MG. A intervenção pedagógica adotou uma perspectiva interdisciplinar, integrando conceitos de Matemática (esferas, circunferências e proporcionalidade) com temas de Física e Geografia (movimentos e escalas planetárias). A produção de dados ocorreu ao longo de três encontros, totalizando cinco horas-aula, e foram registrados por meio de fotografias, folhas das atividades respondidas pelos alunos e registros do pesquisador em um caderno de campo. A análise dos dados envolveu processos de categorização, interpretação e discussão dos elementos observados durante os encontros. Os resultados evidenciaram que o uso do GeoGebra 3D com Realidade Aumentada favoreceu a compreensão pelos participantes de conceitos de Geometria Espacial, contribuindo para a percepção espacial e para a relação entre representações algébricas e geométricas. A abordagem interdisciplinar entre Matemática, Física e Geografia tornou os conteúdos mais contextualizados e significativos. Além disso, o uso do celular promoveu maior engajamento, participação e colaboração entre os estudantes. Apesar de registrarmos limitações tecnológicas, como incompatibilidade de dispositivos com a função Realidade Aumentada e instabilidades do aplicativo, estratégias colaborativas possibilitaram a participação de todos os alunos nas atividades. Palavras-chave: Ensino Médio. GeoGebra. Realidade Aumentada. Interdisciplinaridade. Educação Matemática.