Sapientia
Repositório Científico da UAlg
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UAV-Based soil erosion assessment in mediterranean agricultural orchards
Publication . Pagter, Tijs de; Canedo, João Nuno Gomes Vicente; Pijl, Anton; Guerreiro David Coelho, Luísa Isabel; Nunes, João Pedro; Prats, Sergio
Unmanned Aerial Vehicle (UAV) imagery has become an important tool for erosion monitoring, but little is known about its application in Mediterranean agricultural systems such as vineyards and olive groves. In this study, drone flights were conducted in vineyards and olive groves where mulch and biochar treatments had been applied. Digital terrain models (DTMs) and orthomosaics were constructed using a photogrammetry workflow, and model error was determined via global positioning system (GPS) transects. Erosion was assessed using Digital elevation models of Difference (DoD) and compared with field-based erosion plot measurements. Explanatory variables for erosion (soil roughness, slope length, steepness, vegetation cover) were derived from DTMs and orthomosaics and were evaluated in a multiple linear regression model. Although direct measurement of erosion from the DoDs was difficult, this was primarily influenced by the unexpectedly low erosion rates during the study period, and the high root mean square error (RMSE) of the DTMs. Significant differences in DTM-derived variables were found between study areas, and especially between areas with organic and integrated management, even though treatments showed similar patterns. The multiple linear regression model demonstrated strong explanatory power, accounting for a large part of the variation in measured erosion using the UAV-derived variables (R2 = 0.81). Slope and slope length were the most important predictors of erosion together with the interaction between these two variables. The results suggest that soil erosion in the study areas was mostly determined by topographic and management factors, rather than the applied treatments. This study highlights the value of UAV imagery in advancing the understanding of erosion processes in Mediterranean agricultural systems, while also identifying the challenge of accurately measuring erosion from DoDs under conditions of low erosion rates.
Exploring molecular markers associated with Crumbly in Rubus idaeus L.
Publication . de Souza Oliveira, Melissa Yves; Valdiviesso, Teresa; Luz, Francisco Rosado; Duarte, Amilcar; Oliveira, Pedro Brás de; Varela, Ana Rita
The raspberry (Rubus idaeus L.), an economically important crop, is affected by the crumbly fruit disorder, a malformation that leads to fruit disintegration at harvest due to poor drupelet cohesion. Despite previous efforts to identify genetic determinants of this phenotype, its complex inheritance and strong environmental component have limited the development of robust predictive markers. This study assessed the behavior and transferability of previously reported SSR and SNP markers associated with crumbly fruit across plants from a diverse panel of 34 R. idaeus cultivars, including in adjacent genomic regions not screened previously. Phenotyping was based on multi-season fruit performance and drupelet cohesion, and genetic variation was analysed using PCR-based genotyping within a multilocus approach. Consistent clustering patterns were observed across multiple SSR and SNP loci, suggesting a reproducible association between these genomic regions and the crumbly phenotype. Overall, the results support a multilocus genetic architecture underlying crumbly fruit, but also demonstrate that previously reported markers are not universally transferable across genetic backgrounds. These findings highlight the importance of integrated, population-aware marker validation to enable more reliable implementation of marker-assisted strategies in raspberry breeding programs.
Feature papers in BioChem, 2nd Edition
Publication . Aureliano, Manuel; Ma, Buyong
As mentioned in the Editorial of the first edition of the Special Issue on “Feature Papers in BioChem”, biochemistry acts as a key cog in the “clock of the knowledge, permitting that wheels from several science areas move each other” [1]. Moreover, the understanding of life on earth is a perpetual topic in biochemistry, with boundaries dependent on the specificities of each time period and scientific environment [1]. Thus, following the first edition, this Special Issue on “Feature Papers in BioChem, 2nd Edition” still emphases interdisciplinary research in diverse and interconnected scientific areas, with a majority from molecular medicine, cell biology and of course biochemistry (Table 1). Among these scientific fields, a wide range of topics were addressed, as expressed by the diversity of the titles and keywords that can be found in each contribution.
A Noite e o Momento
Publication . Carvalho, Ana Alexandra Mendonça Seabra da Silva Andrade de; Grácio Editor
"A Noite e o Momento" ou "As Matinas de Citera", segundo Claude Crébillon. Tradução e posfácio de Ana Alexandra Seabra de Carvalho.
Analysis of the main physical properties of seawater along the coast of Angola
Publication . Guilherme, Fernão; Neves, Maria C.; Relvas, Paulo
This study investigates the seasonal and latitudinal variability of the key physical properties of seawater along the Angolan coast, focusing on temperature, salinity, density, and dissolved oxygen. Vertical profile data from the World Ocean Database (2005–2020) were analyzed using Ocean Data View to examine stratification patterns and their relationship with regional circulation features, including the Angola–Benguela Front and coastal upwelling. The results reveal a pronounced south–north gradient, with colder, saltier, and denser surface waters in the southern sector during the cold season, indicative of intensified upwelling influence. The vertical structure is characterized by a surface mixed layer extending to approximately 20–30 m underlain by a sharp thermocline, halocline, and pycnocline between 25 m and 50 m. Dissolved oxygen profiles show the presence of an oxygen minimum layer below the thermocline, particularly pronounced in the central and southern regions, reflecting limited ventilation of subsurface waters. These findings highlight the combined role of stratification, regional circulation, and upwelling dynamics in shaping the physical structure of the Angolan coastal ocean and provide a baseline for future studies in a region that remains poorly documented.