Browsing by Author "Machado, Joana"
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- Avaliação dos efeitos da aplicação de micorrizas ericóides no crescimento de mirtilo (Vaccinium corymbosum L.)Publication . Gonçalves, Patrícia A. F.; Silva, M. A. Nunes da; Machado, Joana; Carvalho, Susana M.P.; Vasconcelos, Marta W.O mirtilo (Vaccinium corymbosum L.) apresenta um sistema radicular muito superficial e compacto, sem pêlos radiculares. Como tal, estas plantas tendem a estabelecer simbiose com fungos ericóides micorrízicos (FEM), o que lhes permite aumentar a absorção de nutrientes e água. Como a colonização natural é frequentemente reduzida e dependente da cultivar e das práticas agronómicas, a inoculação externa com fungos micorrízicos tem vindo a ser utilizada pelos viveiristas para aumentar a taxa de fungos simbiontes. Contudo, a relação planta/fungos ericóides está ainda pouco estudada e o modo como estes microsimbiontes melhoram o crescimento e a nutrição do mirtilo necessita de ser elucidado. Neste estudo, foram inoculadas duas cultivares de mirtilo (‘Aurora’ e ‘Duke’) com uma mistura comercial de FEM. Cerca de 14 meses após inoculação foi avaliada a taxa de colonização das raízes e foram registados vários parâmetros biométricos (peso seco, altura da planta, diâmetro do caule e comprimento da raíz), fisiológicos (teor de clorofila das folhas) e nutricionais (concentração de minerais inorgânicos) em plantas submetidas a tratamento com inóculo e plantas controlo. Os resultados obtidos demonstraram que a percentagem de peso fresco das raízes naturalmente colonizada por fungos ericóides foi aproximadamente 30 % para ambas as cultivares (plantas controlo), aumentando para 56 % na ‘Aurora’ e para 44 % na ‘Duke’ em plantas inoculadas com mistura de FEM. Nas plantas inoculadas da cv. ‘Aurora’, observou-se um aumento significativo do peso seco total das raízes (48 %) e dos caules (31 %) comparativamente às plantas controlo. Paralelamente, também se verificou um aumento significativo da altura das plantas e do comprimento das raízes. Já na cv. ‘Duke’ o efeito da inoculação não foi significativo em nenhum dos parâmetros biométricos estudados. A inoculação induziu a acumulação de Mo nas raízes e de K nos caules e folhas na cv. ‘Aurora’, e aumentou a concentração de Mn, Fe e Cu nas raízes e caules (em alguns casos por 280 %) na cv. ‘Duke’. A inoculação de plantas de mirtilo com fungos ericóides tem um potencial evidente no estímulo do crescimento das plantas e absorção de nutrientes; no entanto, a sua eficácia parece estar dependente da cultivar.
- Constructing and validating a scale to measure Social media brand community enjoyment (SMBCE)Publication . Roy, Subhadip; Machado, Joana
- Design, personality traits and consumer response to brand logosPublication . Machado, Joana; Torres, Anna; Carvalho, Leonor Vacas de; Costa, PatrícioDespite the relevance of logos as communication cues, empirical studies of logo design issues in marketing journals are still scarce (Peterson et al., 2015). This study seeks to address this research gap by examining consumers’ responses to logo design, and specifically to the different types of natural designs, at a behavioral and psychological level. Additionally, we explore whether socio-demographic variables and consumer personality traits are sources of differences in such reactions.
- Effect of drought stress on pea nutritional qualityPublication . Machado, Joana; Bikiewicz, Martyna; Santos, Carla; Vasconcelos, Marta W.
- Enzymatic and non-enzymatic antioxidant responses of young tomato plants (cv. micro-tom) to single and combined mild nitrogen and water deficit: not the sum of the partsPublication . Machado, Joana; Vasconcelos, Marta W.; Soares, Cristiano; Fidalgo, Fernanda; Heuvelink, Ep; Carvalho, Susana M. P.This study aims to perform a broad analysis of the antioxidant (AOX) responses of young tomato plants exposed to single and combined mild nitrogen (N) and water deficits through the evaluation of oxidative biomarkers, non-enzymatic and enzymatic AOX components. ‘Micro-Tom’ seedlings were subjected to four treatments: control (CTR; 100%N + 100%W), N deficit (N; 50%N), water deficit (W; 50%W), and combined deficits (N + W; 50%N + 50%W). An enhancement of several non-enzymatic and enzymatic components was found in plants subjected to N + W deficit, which presented higher anthocyanins accumulation (up to 103%) as well as higher levels of superoxide dismutase (SOD) transcripts at root level and of ascorbate peroxidase (APX) and catalase (CAT) transcripts at shoot level. This increase in the gene expression was also translated in augmented SOD (up to 202%), APX (up to 155%) and CAT (up to 108%) activity compared to CTR plants and the single deficits. Overall, tomato plants were able to employ defense strategies to cope with this combined deficit, as demonstrated by the higher total AOX capacity (up to 87%) compared to the single deficits, which contributed to the maintenance of their redox homeostasis, with unchanged values of lipid peroxidation and hydrogen peroxide compared with CTR plants.
- Exploring the relationship between phenolic content and seed colour in a Portuguese germplasm collection of common beans (phaseolus vulgaris L.)Publication . Machado, Joana; Vasconcelos, Marta W.; Vaz, Madalena; Barata, Ana Maria; Pereira, Maria Graça; Santos, Carla
- Exploring tomato phenotypic variability under combined nitrogen and water deficitPublication . Machado, Joana; Heuvelink, Ep; Vasconcelos, Marta W.; Cunha, Luís M.; Finkers, Richard; Carvalho, Susana M. P.Background: Despite drought and nitrogen (N) deficit being two of the most important crops’ growth limiting factors, only few studies have explored tomato phenotypic variability in response to both abiotic stresses. Aims: In this study, we aimed to perform a phenotypic evaluation and an analysis of the growth traits of 40 tomato genotypes (mostly focusing on old cultivars, but also including modern hybrids and wild tomato relatives’ accessions as anchors) grown in pots that were subjected to combined N and water deficit. Methods: Each genotype was divided into two groups: control (100% N, 100% field capacity) and combined deficit (20% N, 50% field capacity). A total of 14 morpho-physiological traits were evaluated and further analyzed using multivariate statistical methods. Results: The Principal Component Analyses revealed considerable phenotypical diversity among tomato genotypes, with four principal components explaining 82% of the variability. Data integration on a cluster analysis separated the studied genotypes into three distinct clusters based on their ability to handle the combined deficit. Tolerance was associated with traits such as lower specific leaf area, lower leaf area ratio and higher water use efficiency, comparing to the sensitive genotypes. Conclusions: This study shows that tomato tolerance to combined N and water deficit largely varies between genotypes and that old cultivars represent a valuable gene pool towards more sustainable food production systems.
- Highly proteolytic bacteria from semi-ripened Chiapas cheese elicit angiotensin-I converting enzyme inhibition and antioxidant activityPublication . Gonzalez-Gonzalez, Cid R.; Machado, Joana; Correia, Sandra; McCartney, Anne L.; Elmore, J. Stephane; Jauregi, PaulaChiapas cream cheese (CCH) manufacturing process involves a long acid-enzymatic coagulation period of full-fat cow raw milk to achieve an acid and crumbly cheese. These sensorial aspects are related to lactic acid bacteria activity during ripening. Our main objective was to test the hypothesis that CCH contained highly proteolytic strains able to release bioactive compounds upon milk-protein hydrolysis. First, the proteolysis of CCH was evaluated considering the peptide and amino acid profiles of cheese samples collected from Veracruz (AVCH) and Tabasco (HTCH). The angiotensin-converting-enzyme (ACE) inhibitory activity in cheese water-soluble fractions was evaluated. Thereafter, strains from both CCH samples were isolated and selected based on their proteolytic capability, genetic fingerprint differentiation and growth conditions. Finally, a range of activities in vitro were tested in milk fractions fermented with selected strains. CCH showed ACE inhibitory activity: IC50 = 1.75-2.75 mg/mL. Interestingly, AVCH contains 0.78 g/kg of the antihypertensive gamma-aminobutyric acid. Three highly proteolytic strains showed ACE and high antioxidant activities upon milk fermentation. In conclusion, CCH contain proteolytic strains able to release bioactive compounds from milk proteins and potentially useful to produce functional ingredients and foods.
- The impact of climate change-induced abiotic stresses on the nutritional quality of legume seedsPublication . Machado, Joana; Silva, Marta Nunes da; Vasconcelos, Marta W.; Santos, Carla S.Legumes are integral to agricultural sustainability, offering multifaceted benefits ranging from enhanced yields to companion crops and improved soil health. Despite their recognized advantages, challenges such as technological lock-ins, limited breeding resources, and adverse environmental conditions pose threats to their cultivation. In this review, the complex interaction between climate change stressors, specifically drought, high temperatures, and elevated CO 2 levels, and their individual and combined impacts on the nutritional quality of legumes will be discussed. This topic has not been thoroughly reviewed across multiple legume crops despite its importance under climate change. Here, we critically examine the impacts of environmental stresses on the nutritional quality of legume seeds and explore the underlying regulatory mechanisms, encompassing protein, amino acids, minerals, carbohydrates, lipids, and bioactive compounds. Key insights indicate a general need to shift legume cultivation practices, and the necessity of field studies beyond controlled environments for results that are more readily translated to the target population of environments for legume cultivation.
- Mitigation of climate change and environmental hazards in plants: potential role of the beneficial metalloid siliconPublication . Bokor, Boris; Santos, Carla S.; Kostoláni, Dominik; Machado, Joana; Silva, Marta Nunes da; Carvalho, Susana M. P.; Vaculík, Marek; Vasconcelos, Marta W.In the last decades, the concentration of atmospheric CO2 and the average temperature have been increasing, and this trend is expected to become more severe in the near future. Additionally, environmental stresses including drought, salinity, UV-radiation, heavy metals, and toxic elements exposure represent a threat for ecosystems and agriculture. Climate and environmental changes negatively affect plant growth, biomass and yield production, and also enhance plant susceptibility to pests and diseases. Silicon (Si), as a beneficial element for plants, is involved in plant tolerance and/or resistance to various abiotic and biotic stresses. The beneficial role of Si has been shown in various plant species and its accumulation relies on the root's uptake capacity. However, Si uptake in plants depends on many biogeochemical factors that may be substantially altered in the future, affecting its functional role in plant protection. At present, it is not clear whether Si accumulation in plants will be positively or negatively affected by changing climate and environmental conditions. In this review, we focused on Si interaction with the most important factors of global change and environmental hazards in plants, discussing the potential role of its application as an alleviation strategy for climate and environmental hazards based on current knowledge.