http://hdl.handle.net/10174/153 2026-08-02T07:54:32Z 2026-08-02T07:54:32Z Bryla, David Machado, Rui Leon-Chang, D.P. Orr, S:T. http://hdl.handle.net/10174/39608 2025-11-17T15:20:50Z 2024-07-23T23:00:00Z

Title: Fertigation with nitrogen and other nutrients in northern highbush blueberry Authors: Bryla, David; Machado, Rui; Leon-Chang, D.P.; Orr, S:T. Abstract: Abstract Most highbush blueberry (Vaccinium sp.) fields are irrigated by drip. A major advantage of drip is the ability to fertigate and apply fertilizers directly through the irrigation water. A series of studies were conducted in western Oregon, USA to identify the best practices for applying N and other nutrients by fertigation. Fertigation with various fluid NH4-N sources, including ammonium sulphate, urea, and urea sulfuric acid, produced more growth and greater yield than conventional granular fertilizers in ‘Buecrop’ blueberry. Furthermore, applying humic substances in combination with N fertigation nearly doubled root production during the first 2 years after planting. To apply other nutrients, soluble potassium sulphate and potassium thiosulfate are good sources for fertigation in blueberry. Both fertilizers had an immediate effect on availability of K and other nutrients in the soil solution and after 2 years increased the nutrient status of ‘Duke’ blueberry. However, whether applied by fertigation or as a granular product, there was no benefit to fruit production at sites with sufficient soil K. Phosphorus fertilizers also had no effect on mineral nutrition or fruit production, even under P-limited conditions, in ‘Duke’ or ‘Bluecrop’. In this case, the soil was high in clay and likely bound much of the P. The use of B fertilizers, on the other hand, increased the concentration of B in the leaves and fruit of ‘Earliblue’ and ‘Elliott’ blueberry, particularly when it was applied by fertigation or as a foliar fertilizer. Fertigation with Ca products, including micronized gypsum and calcium thiosulfate, had little effect on Ca in the leaves or fruit of ‘Duke’, ‘Earliblue’, ‘Bluecrop’, or ‘Aurora’ but increased fruit firmness of ‘Elliott’ blueberry, particularly in cold storage. Given its potential benefits on fruit quality, we will continue to test fertigation with Ca fertilizers in conventional and organic blueberry fields.

2024-07-23T23:00:00Z Machado, R.M.A Alves-Pereira, Isabel Grilo, Ana Ferreira, Rui http://hdl.handle.net/10174/39527 2026-07-29T09:57:02Z 2025-08-31T23:00:00Z

Title: Effects of adding walnut shell to coir-based substrates on yield and quality of lettuce Authors: Machado, R.M.A; Alves-Pereira, Isabel; Grilo, Ana; Ferreira, Rui Abstract: Enhancing the sustainability of growing media is an important objective in soilless vegetable cultivation. Here, we evaluated the potential of pine bark to replace perlite in coir-based substrates for lettuce (Lactuca sativa L. cv. ‘Godzilla’) cultivation. The experiment followed a factorial design with two coir-based substrate blends—one amended with perlite and the other with pine bark—and two nutrient solution EC levels (1.5 ± 0.2 and 2.5 ± 0.2 dS m→1). The plants were cultivated in Styrofoam containers containing a substrate mix of 80% coir, 12% compost, and 8% perlite or pine bark (v/v). Replacing perlite with pine bark did not affect leaf macronutrient concentrations but increased leaf Fe and B levels. Increasing the EC of the nutrient solution increased leaf N, P, and K, with a significant rise in nitrogen. The substitution of perlite with pine bark in coir-based substrates did not affect leaf dry weight, head fresh weight, or chlorophyll content, total phenols, ascorbic acid, or proline, even under different salinity levels. The findings indicate the pine bark is an alternative to perlite, supporting comparable agronomic and quality outcomes in lettuce. Further research is recommended to confirm these results in crops with longer growing cycles

2025-08-31T23:00:00Z Camilo-Alves, Constança http://hdl.handle.net/10174/38250 2025-03-20T18:34:22Z 2024-09-30T23:00:00Z

Title: Cork oak afforestation using innovative techniques to mitigate climate change Authors: Camilo-Alves, Constança Abstract: Cork oak (Quercus suber) woodlands are distributed across the western Mediterranean. Renowned for their cork, their most iconic product is the stopper, essential for the wine industry. Cork is also extensively used in civil construction, aerospace, and sports industries. The renewable nature of cork allows harvesting every 9 to 10 years, with trees living for approximately two centuries and being debarked up to 17 times. However, cork oak woodlands face severe threats. Widespread cork oak mortality events have been occurring since the 1990s. Initially attributed to root disease caused by the oomycete Phytophthora cinnamomi, subsequent research suggests that multiple factors acting synergistically contribute to the decline (Camilo-Alves et al. 2013). These factors include drought events, soil constraints on root development, and improper management practices. Though the cork oak distribution area has remained relatively stable, tree loss has resulted in a steady reduction of canopy cover. Furthermore, an alarming decline in tree regeneration has been occurring, compromising the sustainability of these ecosystems. Faced with this situation, particularly the predicted cork shortage in the near future, the cork sector is collaborating with the scientific community to find solutions to promote tree regeneration, survival, vitality, and productivity.

2024-09-30T23:00:00Z Machado, Rui Hong, Hai http://hdl.handle.net/10174/30189 2021-10-07T15:10:36Z 2021-08-30T23:00:00Z

Title: Physicochemical characteristics of substrates of the mixture of coir with municipal solid waste compost and with biochar Authors: Machado, Rui; Hong, Hai Abstract: Abstract The aim of this study was to evaluate the effect of mixing municipal solid waste compost and of biochar with coconut coir, in different ratios, on some chemical and physical properties of mixtures and its potential to grow plants. Coir was mixed with MWS and with biochar in the following ratios: 1:0, 3:1, 2:1, 1:1, 2:1 and 0:1 (v:v). The physicochemical characteristics measured were pH, electrical conductivity, organic carbon, organic matter, mass wetness, moisture content and bulk density. The characteristics that raises more issues in the MSW compost were the high electrical conductivity (4.81 dS m-1) and pH (8.21) and in the biochar was the high pH (9.11). The increase of coir in mix improved the chemical and physical characteristics and in either case, the most suitable mixture is the one with the ratio 3:1 (75% coir by volume in the mixture). However, the electrical conductivity (2.69 dS m-1) of the mix 3:1 coir/MSW compost was still higher than the salinity threshold of the majority of the crops. The pH in coir/MSW compost and coir/biochar at the 3:1 ratio was 6.73 and 6.74, respectively, slightly above the maximal value of adequate range (6.4). These findings indicate that the mix of coir with MSW compost and biochar increases the potential of those materials to be used as substrates to grow plants, but it is still necessary to do some adjustments

2021-08-30T23:00:00Z