http://hdl.handle.net/10174/42 2026-04-06T05:17:02Z 2026-04-06T05:17:02Z Machado, Rui Alves-Pereira, Isabel Grilo, Ana Esteves, Pedro Rui, Ferreira http://hdl.handle.net/10174/41736 2026-03-23T16:41:25Z 2026-01-07T00:00:00Z

Title: Walnut Shells to Enhance Substrate Sustainability: Effects on Lettuce Yield, Nitrate Accumulation, and Phytochemical Content. Authors: Machado, Rui; Alves-Pereira, Isabel; Grilo, Ana; Esteves, Pedro; Rui, Ferreira Abstract: Coir is widely used as a soilless substrate yet partially replacing it with walnut shells in coir-based mixes may improve the sustainability of lettuce production and quality. This study evaluated the effect of incorporating walnut shells, with or without biochar, into coir-based substrates on lettuce yield and quality. Lettuce was grown in five substrates: coir (C), three coir–walnut mixes (1:1, 1:0.5, and 1:0.25 v/v), and one coir–walnut–biochar mix (C:W:B, 10:1.5:1 v/v). Increasing the walnut-shell proportion increased the cumulative leaching fraction, likely because of the coarse walnut particles, and reduced head fresh weight. However, shoot dry weight in the 1:0.5 and 1:0.25 mixes was similar to that in coir alone and reduced leaf nitrate content. In contrast, the C:W:B mix maintained head fresh weight (7.1 kg m→2) and shoot dry weight comparable to coir, while markedly lowering leaf nitrate concentration from 4130 to below 200 mg NO3→ kg→1 fresh weight. Leaf nitrate content increased linearly with shoot Zn uptake, suggesting a Zn-mediated control of nitrate accumulation. The coir–walnut–biochar mix emerges as a suitable alternative to pure coir, as it maintains lettuce productivity, reduces leaf nitrate accumulation, enhances anthocyanin content, and reflects more favorable physiological conditions by not requiring a strong activation of antioxidant defenses.

2026-01-07T00:00:00Z Wang, Hsiao-Hsuan Alagador, Diogo http://hdl.handle.net/10174/41698 2026-03-17T12:20:27Z 2025-05-31T23:00:00Z

Title: The critical challenge of nonstationarity in ecological modelling Authors: Wang, Hsiao-Hsuan; Alagador, Diogo Abstract: Ecological systems are dynamic and shaped by complex interactions that vary across space, time, and levels of biological organization (Fischer et al., 2025). Therefore, most ecological systems display confounding spatial and temporal trends, such as nonstationarity, at some scale. Nonstationarity (abrupt change in the mean or variance of a system property in space or time) can result from variation in environmental conditions (e.g., topography) or occurrence of a disturbance (e. g., a flood). Models of systems exhibiting nonstationarity that are based on non-spatial and equilibrium representations of system properties can produce misleading inferences and predictions. The potential consequences include misidentification of habitat priorities, underestimation of extinction risks, and the development of conservation strategies that ignore critical local contexts (Alagador and Cerdeira, 2020). Therefore, we must aim to incorproate nonstationarity in ecological models and address its impact on processes occurring on the multiple scales of time, space and organisation relevant to management (Wang et al., 2023).

2025-05-31T23:00:00Z Pereira, Pedro Godinho, Carlos Roque, Inês Rabaça, João Lourenço, Rui http://hdl.handle.net/10174/41696 2026-03-17T12:19:17Z 2024-03-31T23:00:00Z

Title: IBISurvey: Introduced Bird Interaction Survey – Report 2021-2023 Authors: Pereira, Pedro; Godinho, Carlos; Roque, Inês; Rabaça, João; Lourenço, Rui Abstract: This report summarizes the outcomes of the IBISurvey citizen science project, focusing on reported interactions involving exotic bird species introduced in Europe during the period 2021–2023.

2024-03-31T23:00:00Z Póvoa, G. Silva, L. Dias, S. D'Antonio, P. Lidon, F. Serrano, J. Conceição, L.A. http://hdl.handle.net/10174/41677 2026-03-13T17:27:20Z 2026-03-01T00:00:00Z

Title: Diagnosing Early Establishment of Hybrid Sorghum in Response to Seeding Rates Using UAV-Based Remote Sensing and Soil ECa Analysis Authors: Póvoa, G.; Silva, L.; Dias, S.; D'Antonio, P.; Lidon, F.; Serrano, J.; Conceição, L.A. Editors: Escobar Gutiérrez, Abraham J. Abstract: Sorghum is a resilient crop important for sustainable intensification in semi-arid regions, yet the impact of variable seeding rates on its early development remains under-researched. This research investigated the early establishment of hybrid sorghum under three seeding strategies, "Uniformise" (medium density across all zones), "Optimise" (increased density in low-soil apparent Electrical Conductivity (ECa)), and "Maximise" (increased density in high-soil ECa), at the Herdade da Comenda (Innovation Center - Elvas, Portugal). Crop performance was monitored over 33 days, the established window for safe direct grazing, using Unmanned Aerial Vehicle (UAV) multispectral imagery to derive the Normalised Difference Vegetation Index (NDVI) and Canopy Cover (Cveg), alongside physical sampling of plant height and biomass. Statistical analysis revealed that both the seeding strategy and soil variability significantly affected early growth. The "Uniformise" strategy recorded the highest plant height, NDVI, and Cveg values, whereas the "Optimise" strategy performed the poorest. Additionally, an accumulation of 407.5 Growing Degree-Days (GDDs; ºC) accelerated the phenological cycle by five days relative to the climatological normal. Despite differences in vegetative vigour, no statistically significant variations were observed in final biomass across the strategies. These results indicate that while the "Uniformise" approach provided a more balanced environment for early establishment under these specific Mediterranean conditions, the lack of biomass differentiation highlights the potential for resource optimisation. The study demonstrates that UAV-based remote sensing is a useful diagnostic tool to identify these spatial limitations, providing the data to refine variable-rate seeding (VRS) algorithms and improve the economic efficiency of precision sowing.

2026-03-01T00:00:00Z