http://hdl.handle.net/10174/42 2026-07-08T13:05:27Z 2026-07-08T13:05:27Z Serrano, João M. P. R. Noéme, J. http://hdl.handle.net/10174/42318 2026-07-07T15:25:38Z 2026-01-01T00:00:00Z

Title: Tecnologias integradas numa estratégia de apoio à rega de precisão no Milho Authors: Serrano, João M. P. R.; Noéme, J. Editors: Carmo, Vitor Abstract: Este trabalho resume a metodologia seguida no projeto “GO: Regadio de Precisão” (PDR2020-101-FEADER-032167) para implementação e demonstração de sistemas de rega de taxa variável (“Variable Rate Irrigation”, VRI) utilizando a rega por pivot na cultura do milho, num campo experimental de 28 ha (“Eucaliptos”, em Samora Correia; Figura 1-a). Este projeto baseia-se em tecnologias de monitorização: (i) da condutividade elétrica aparente do solo (CEa) e da altimetria; (ii) da produtividade da cultura; (iii) do teor de humidade e da fertilidade do solo; (iv) do índice de vegetação de diferença normalizada (“Normalized Difference Vegetation Index”, NDVI), obtido a partir de imagens de satélite; e em tecnologias de controlo automático da velocidade de deslocamento da rampa rotativa de rega (pivot; Figura 1-b, c e d). Os mapas de CEa e altimétrico serviram para a definição inicial de zonas de gestão de rega (ZG) e elaboração inicial de prescrição de rega (VRI-1). As séries temporais de NDVI obtidas ao longo do ciclo vegetativo da cultura, a partir do “Sentinel-2”, foram utilizadas para ajustar estas ZG e os respetivos mapas dinâmicos de prescrição da rega (VRI-2 e VRI-3). Esta estratégia de gestão espacialmente variável da rega, com o ajustamento da velocidade de deslocamento do pivot e, consequentemente, da dotação de rega em função das necessidades em cada local, tem um impacto imediato na economia de água. No estudo em causa levou ainda à redução da variabilidade espacial do rendimento de produção, em comparação com a gestão convencional da rega, o que representa uma contribuição importante para os desafios da produtividade e da sustentabilidade da produção agrícola.

2026-01-01T00:00:00Z Horta Marques, J. Carreira, E. Lloberas, D. Martins, M. Ribeiro, H. Serrano, João http://hdl.handle.net/10174/42294 2026-07-03T15:23:28Z 2026-05-31T23:00:00Z

Title: Within-field soil variability in agro-silvo-pastoral systems: a baseline for Precision Agriculture adoption Authors: Horta Marques, J.; Carreira, E.; Lloberas, D.; Martins, M.; Ribeiro, H.; Serrano, João Abstract: The Montado represents a dominant agro-silvo-pastoral system across the Mediterranean basin. It integrates pastures, trees (cork oak and/or holm oak), and livestock (ruminants or swine), While Precision Agriculture is more commonly applied to purely agricultural systems, it offers significant potential to optimize Montado management, thereby increasing economic, environmental, social, and cultural sustainability. This study aims to quantify spatial soil variability within Montado plots to identify which essential nutrients for plant production exhibit the greatest distribution range. This study was conducted on two permanent applied research plots, grazed by cattle under a rotational grazing system (total area = 20 ha; location: Mitra/University of Évora, Portugal, Figure 1). Sampling’s carried out at 24 points: 12 under the tree canopy influence and 12 outside the canopy influence. The methodology’s described in Serrano et al (2023) and Horta Marques (2026). Results indicate high within-field variability (Coefficient of Variation around 40% or higher) in the levels of K2O, Mg, P2O5, Ca and all studied micronutrients except for Fe. The findings demonstrate that the observed within-field variability, alongside agronomic expertise and economic and environmental sustainability goals, justifies the implementation of Precision Agriculture in Mediterranean agro-silvo-pastoral systems.

2026-05-31T23:00:00Z Fonseca, Daniela Martins, Nuno Garcia, Raquel Cabrita, Maria João http://hdl.handle.net/10174/42293 2026-07-06T13:28:39Z 2026-01-01T00:00:00Z

Title: GCxGC-TOFMS with flow modulation for fingerprinting volatile compounds in Portuguese grape varieties Authors: Fonseca, Daniela; Martins, Nuno; Garcia, Raquel; Cabrita, Maria João Abstract: Comprehensive two-dimensional gas chromatography offers a powerful analytical tool for profiling volatile compounds in complex matrices. The characterization of grapevine varieties that are resilient to water stress, such as autochthonous varieties, while safeguarding quality characteristics, is fundamental to viticulture. For this reason, the objective of this study was to characterize the volatile composition of four white varieties from the Alentejo region (Portugal), subjected to three different irrigation regimes: water comfort, moderate water deficit, and rainfed. The first step was to optimize the modulation conditions, and it was found that the most effective modulation period was 5 s, with a flush time of 0.20 s. After optimizing these conditions, the grapes of the Diagalves, Manteúdo, Perrum and Rabo de Ovelha varieties were analyzed by HS-SPME-GCxGC-TOFMS. A total of seventy-six volatile compounds, of which fifty-one were varietal volatiles, were identified and semi-quantified in these varieties. The results reveal that the irrigation regime influences the volatile profile with varying responses across the varieties. While Diagalves exhibited no significant differences between irrigation regimes, Manteúdo and Perrum demonstrated higher levels of varietal volatile compounds, particularly terpenes and C13 norisoprenoids, under rainfed conditions. According to PCA, irrigation regimes affect each variety differently. In conclusion, Manteúdo and Perrum emerge as the most statistically promising varieties in terms of adaptability to water scarcity. These findings highlight the significance of selecting resilient autochthonous grape varieties as an effective strategy to mitigate the impacts of climate change while maintaining the wine's distinctive aromatic character.

2026-01-01T00:00:00Z Serrano, João Carreira, Emanuel Shahidian, S. Paniagua, L. Moral, F. Pereira, A. http://hdl.handle.net/10174/42289 2026-07-03T15:20:16Z 2026-05-31T23:00:00Z

Title: Impact of Sheep Stocking Rates in Soil Compaction: Case Study in Montado Mediterranean Ecosystem Authors: Serrano, João; Carreira, Emanuel; Shahidian, S.; Paniagua, L.; Moral, F.; Pereira, A. Abstract: The economic return on extensive sheep farming (pasture-based systems) of the Southern of Portugal is low, as it occupies degraded soils. Therefore, the environmental perspective prevails, with the recovery of soil functionality and the preservation of the Montado as an ecosystem of high nature value. This study assesses the impact of two grazing management systems and stocking rates (SR), continuous grazing (CG) with low SR versus deferred grazing (DG) with high SR, on soil compaction. The study was carried out between December 2023 and June 2025 on a 4-ha pasture. This area of natu-ral grassland was divided into four grazing parks of 1 ha each, two under DG management and two under CG management. During the study, the cone index (CI, in kPa) was measured in the topsoil layer (0–30 cm) on eight dates, with an electronic cone penetrometer at 48 georeferenced areas. The results of CI measurement showed no significant differences between treat-ments in all depths measured (0–10, 10–20, and 20–30 cm). These findings are encouraging from the point of view of soil conservation and sustainabil-ity, revealing good prospects for the possible intensification of extensive livestock production.

2026-05-31T23:00:00Z