Papers by Maria Amélia Martins-Loução
Agronomy, Jul 7, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Soil Biology & Biochemistry, Oct 1, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Biogeosciences, Jan 11, 2012
Nitrogen (N) is one of the nutrients most limiting to ecosystem productivity. However, N availabi... more Nitrogen (N) is one of the nutrients most limiting to ecosystem productivity. However, N availability is increasing globally, which may affect ecosystem functions and stability. To understand the role of each ecosystem compartment in the cycling of increased N, we studied the initial response of a nutrient-poor ecosystem, a Mediterranean maquis, to increased N deposition. N availability (dose and form) was modified by three N additions over the year (middle autumn/winter, spring and summer). Soil inorganic N pools (nitrate in particular) strongly reflected the N additions in autumn, almost matching the total N added over the three additions. Cistus ladanifer, the dominant plant species, responded to the increased N (cover and N concentration in leaves and litter). Given that leaf shedding occurs in the summer, the importance of this N pool returning to the soil through litter decomposition on the total soil inorganic N in autumn was investigated. Data suggest that living plants and litter have a crucial role in preventing N losses from Mediterranean maquis. This is the first integrated field study on how European Mediterranean ecosystems retain increased N of different forms and doses, however longer-term studies are needed to explore the generality of this study's observations.
Biogeosciences discussions, Aug 9, 2011
Nitrogen (N) is one of the nutrients most limiting to ecosystem productivity. However, N availabi... more Nitrogen (N) is one of the nutrients most limiting to ecosystem productivity. However, N availability is increasing globally, which may affect ecosystem functions and stability. To understand the role of each ecosystem compartment in the cycling of increased N, we studied the initial response of a nutrient-poor ecosystem, a Mediterranean maquis, to increased N. N availability (dose and forms) was modified by three N additions along the year (spring, summer and middle autumn/winter). Soil inorganic N pools (nitrate in particular) strongly reflected the N additions in autumn, almost matching the total N added along the three additions. Cistus ladanifer, the dominant plant species, responded to the increased N (cover and N concentration in leaves and litter), and given that leaf shedding occurs in the summer, the importance of this N pool returning to the soil through litter decomposition on the total soil inorganic N in autumn was investigated. Data suggest that living plants and litter have a crucial role in preventing N losses from Mediterranean maquis. This is the first integrated field study on how European Mediterranean ecosystems retain increased N of different forms and doses, however longer-term studies are needed to explore the generality of this study's observations.
Taxon, Aug 1, 2017
Besides being one of the most popular ornamental bulbs in western horticulture, the Mediterranean... more Besides being one of the most popular ornamental bulbs in western horticulture, the Mediterranean genus Narcissus has been the subject of numerous studies focusing on a wide scope of topics, including cytogenetics, hybridization and the evolution of polymorphic sexual systems. Phylogenetic hypotheses based on chloroplast data have provided a backbone for the genus but a detailed phylogenetic framework is still lacking. To fill this gap, we present a phylogenetic study of the genus using five markers from three genomes: ndhF and matK (chloroplast DNA), cob and atpA (mitochondrial DNA), and ITS (nuclear ribosomal DNA). In addition, we use chromosome counts from 89 populations representing 69 taxa. All analyses confirm that Narcissus is monophyletic with two main lineages largely corresponding to subgenera Hermione and Narcissus, but with incongruences between organellar and nuclear ribosomal phylogenies. At the infrageneric level, our phylogenetic results challenge well-established taxonomic groups, such as sections Jonquillae, Bulbocodii and Pseudonarcissi, each of which contains at least two distinct lineages that do not constitute monophyletic groups, and highlight the influence of allopolyploid species in the monophyly of sections within subg. Hermione. The type species of the genus and its section is also nested within sect. Pseudonarcissi supporting new nomenclatural changes. Our results also confirm the intersubgeneric hybrid nature of several hybrids including allopolyploids (e.g., N. dubius, N. tortifolius, N. miniatus). Morphological and cytogenetic evidence independently support the hypothesis that some of the incongruence can be attributed to hybridization, such as the splits of sections Bulbocodii and Pseudonarcissi or the disparate phylogenetic placements of sections Ganymedes, Aurelia and the southern lineage of sect. Bulbocodii (sect. Nevadensis). Together, this 3 indicates a significant role for reticulate evolution in shaping the diversity of this genus. A Bayesian divergence time analysis suggests that the major diversification events took place during the Neogene and provides younger estimates for the main nodes than previous studies, which fit paleoclimatic and paleotectonic reconstructions of the western Mediterranean during this period.
Acta horticulturae, Nov 1, 2003
This study characterises some aspects of foliar anatomy of cork oak micropropagated plantlets, an... more This study characterises some aspects of foliar anatomy of cork oak micropropagated plantlets, and rates of water loss by different types of leaves during the acclimatization period. Water loss from leaves of in vitro cultured plantlets was much higher than that of acclimatized plants or seedlings. Leaves from in vitro plantlets lost 53% of their water within the first 30 min under water stress conditions, while leaves from acclimatized plants lost 14%. Leaves of in vitro grown plants presented open stomata and collapsed guard cells, while acclimatized leaves presented closed stomata. Shade-leaf structure was observed in transverse sections of in vitro leaves, with large intercellular air spaces and a low mesophyll cell density, but with a differentiated palisade cell layer. Leaves from acclimatized plants showed a sun-leaf structure with small intercellular air spaces, high cell density and two or three palisade cell layers. During acclimatization leaf thickness increased, as well as cell compactness and differentiation. Stomatal density, stomatal aperture and guard cell protuberance decreased during the acclimatization period, while trichome density increased.
Biologia Plantarum, Sep 1, 2004
Carob tree (Ceratonia siliqua L.) micropropagated shoots were rooted on half-strength Murashige a... more Carob tree (Ceratonia siliqua L.) micropropagated shoots were rooted on half-strength Murashige and Skoog medium, supplemented with different types and concentrations of sugars, in order to determine the effects of sugar composition and concentration on in vitro rooting and in vivo establishment of the plantlets. Among the various sugars tested, the best rooting response was obtained with 145 mM sucrose, both in terms of rooting frequency and index of rooting. The use of filter-sterilized rather that autoclaved fructose increased root number and root length. Sugar treatment during rooting slightly influenced plantlet survival and growth during acclimatization. A reduction in the glucose concentration during rooting was beneficial for plantlet acclimatization.
WIT Transactions on Ecology and the Environment, 1970
Tree shelters were used in an ecological restoration effort in 1999 and 2000 to test the decrease... more Tree shelters were used in an ecological restoration effort in 1999 and 2000 to test the decrease in transplant shock and increase in growth and survival of two selected Mediterranean species, carob tree (Ceratonia siliqua L.) and cork oak (Quercus suber L.), planted in a dry degraded region. At plantation, two treatments were established, one planted with 60 cm tall TUBEX MinitubesTM and the other planted without tree shelters. Results have shown that tree shelters dramatically increased survival of sheltered plants and also stimulated height growth, probably caused by reduced light regimes inside shelters, inducing shade adaptation. Different biomass partition occurred between sheltered and unsheltered plants, although no effect in increased biomass production was observed. This work shows that individual tree shelters successfully increase establishment of newly planted plants in dry, degraded areas of the Mediterranean.
Frontiers in Ecology and Evolution
Reviewing the ecological studies on the endangered endemic Plantago almogravensis Franco, an Al-h... more Reviewing the ecological studies on the endangered endemic Plantago almogravensis Franco, an Al-hyperaccumulator plant, and combining these with morphological, physiological, biochemical, and molecular data, significant knowledge on the limiting factors that cause its narrow geographical distribution and rarity status is achieved, which can contribute to suited conservation guidelines. Emphasis was given on (i) the major factors limiting P. almogravensis’ ecological niche (biotic and abiotic); (ii) phases of the life cycle and population dynamics; and (iii) and the phylogenetically close taxa (Plantago subulata aggregate) in order to fill the knowledge gaps in the uniqueness of P. almogravensis ecology, its phylogeny, and conservation status. The identification of relevant ecological data and using plant functional (morphological and physiological) traits, as well as genetic attributes, substantiate into a powerful tool to guide protection and conservation measures, usable toward th...
Sustainability, 2021
This article enhances some ideas and opinions related with the challenges that women across the w... more This article enhances some ideas and opinions related with the challenges that women across the world face nowadays to pursue a professional career. The route they take has frequent obstacles of a distinct nature, which are not always comparable with those faced by men. The starting point of this work is the conclusions of the workshop “Women empowerment and gender equality, responsible research and innovation”—Research Project “SOILdarity”. This workshop revealed a diversified view about the subject, evidencing its connection with the social sustainability, with a special focus on academia and research management. This document introduces the topic in the context of the workshop, revises key aspects of women’s empowerment in a society still dominated by men’s opinions and organization (gender balance, obstacles and strategies), highlights the situation of women in academia and in research management, and gives the authors’ opinions about some questions related to gender and equalit...
Ecologia mediterranea, 2002
Page 1. ecologia mediterranea, tome 28, fascicule 2, 2002, p. 5-13 5 Abstract Be l ow g round tra... more Page 1. ecologia mediterranea, tome 28, fascicule 2, 2002, p. 5-13 5 Abstract Be l ow g round traits va ry widely. Ap a rt from the influence of the environment both genetic and ontogenic factors are responsible for this variation. ...
The Journal of Horticultural Science and Biotechnology, 2003
ABSTRACT The hypothesis was tested that carob (Ceratonia siliqua L.) is able to develop morpholog... more ABSTRACT The hypothesis was tested that carob (Ceratonia siliqua L.) is able to develop morphological and physiological adaptations to tolerate or at least mitigate soil nutrient deficiencies. In this work we studied the effects of N, P, Mg, Ca and Fe deficiencies on plant morphology, biomass partitioning, concentrations of chlorophyll, fluorescence and root tip ferric chelate-reductase in carob rootstocks grown in hydroponics. Young rootstock trees were grown in hydroponics with half-strength Hoagland&#39;s solution (control) or without N, P, Mg, Ca and Fe (treatments N0, P0, Mg0, Ca0 and Fe0). Nitrogen, and P deficiency affected shoot and root growth but not biomass partitioning or photosynthetic efficiency. Plants without Mg had a few large non-ramificated roots and low photosynthetic efficiency, similar to the Fe-starved plants. Root ferric chelate-reductase activity (FC-R) expressed on a fresh weight basis was higher under P and Mg deficiencies compared with control plants, but Fe0 plants had lower FC-R activity if dry weights are used. The response of carob-tree to these particular nutrients depletion may support the ecological plasticity of this species. Under natural conditions, lack of Fe and Mg in the soil is not likely to occur, but if N and P are limiting, carob growth (shoot and root dry weights) may be negatively affected. Even so, photosynthetic efficiency is maintained, and under P stress FC-R activity may increase.
Acta Horticulturae, 2010
In the face of increasing demand for crop production and the detrimental environmental impact of ... more In the face of increasing demand for crop production and the detrimental environmental impact of the excessive use of fertilizers it is important to use all available tools to increase crop nutrient use, efficiency and quality. Nutrient acquisition by the plant roots is much influenced by the microbial composition and activity of the rhizosphere. Most crop plants (80%) form symbiotic associations with arbuscular mycorrhizal fungi. However, these fungi are obligatory biotrophs, and therefore cannot be cultivated without the plants. Piriformospora indica is a recently discovered endophyte that mimics many of the effects of arbuscular mycorrhizal fungi but can be cultivated in axenic cultures. The aim of our work was to evaluate the effects of the co-culture of Piriformospora indica with tomato (Solanum lycopersicum 'Roma') plants in respect to plant response to stress and production quality. Results show that P. indica is able to promote resistance to stress (salt and nutrient) through the activation of antioxidant metabolism, which leads to the accumulation of ascorbate (vitamin C). Fruits of plants inoculated with P. indica maintain their lycopene content independently of the growth conditions.
Comunicacao apresentada no Congreso Forestal Espanol nos dias 14 e 18 Junho de 1993, em Lourizan.
Gone are the days when the main mission of a botanic garden was to provide plants to medical facu... more Gone are the days when the main mission of a botanic garden was to provide plants to medical faculties or to cultivate new species coming from the colonised tropics (Rinker 2002). Now, botanic gardens have the great responsibility of ensuring the conservation of the genetic resources from plants all over the world, as well as for ex situ protection of threatened species. This is of great importance, as it is believed that two thirds of all plant species in the planet are in danger of extinction (Pitman and Jorgensen 2002; Trombulak et al. 2004). In 2010, the United Nations’ Convention on Biological Diversity (CBD) adopted the Updated Global Strategy for Plant Conservation (GSPC) 2011-2020, aiming to halt the continuing loss of plant diversity and to alert to the main threats that plants are exposed to (Plant
Este trabajo presenta resultados preliminares de um trabajo más amplio con el objetivo de clarifi... more Este trabajo presenta resultados preliminares de um trabajo más amplio con el objetivo de clarificar la importancia relativa del agua y del nitrógeno como factores capaces de controlar la producción primaria de Ceratonia siliqua L. Arboles adultos de algarrobo han sido sometidos a tres diferentes niveles de irrigación, basados en los valores diarios de evaporación a tres diferentes niveles de irrigación, basados en los valores diarios de evaporación de una clase A – respectivamente 100 % , 50 % y 0 %. Para cada uno de ellos fueron aplicados dos niveles de nitrógeno -21 y 63 Kg ha-1. Diferencias significativas fueron observadas en los aumentos en comprimido de los ramos y número de hojas al final del período de crescimiento, independientemente de las diferencias no significativas de los potenciales hídricos de la hoja al médio día, para todos los tratamientos. Estos resultados serán discutidos teniendo presente diferentes hipótesis. Los árboles más fertilizados presentaran um ligero aumento en el contenido en nitrógeno. Por otro lado, a pesar de los diferentes niveles de nitrógeno aplicados, es posible verificar un aumento del “N-pool” en los árboles, probablemente importante como mecanismo para aumentar la eficácia del uso del nitrógeno en condiciones de baja concentración de nutrientes en el suelo. Los resultados muestran que tanto el agua como el nitrógeno tienen un efecto positivo no crescimiento vegetativo del algarrobo. This paper presents preliminary results of a work which aim was to clarify the relative importance of water and nitrogen as factors controlling primary production of Ceratonia siliqua L. Carob mature trees were submitted to three different irrigation levels based on daily Epan values – 100 %, 50 % and 0%. For each water level two nitrogen amounts were applied – 21 and 63 Kg ha -1. Significant differences were observed in branch length increment at the end of the growth season. The short –term responses to the water and nitrogen application improve vegetative growth independently of the insignificant differences in leaf water potential at midday, for all treatments. These results are discussed according to differnt hypothesis. The high fertilized trees presented a slight increase in leaf nitrogen content. Moreover it is possible to observe a “N-pool” due to translocation from senescent leaves, presumably important as a mechanism to increase nitrogen use efficiency under low nutrient availability. The results obtained show that both water and nitrogen have a positive effect on the vegetative growth of carob trees
Inorganic Nitrogen Metabolism, 1987
Tree Physiology, 1997
Seasonal variations in leaf nitrogen, phosphorus and potassium concentrations were studied in a m... more Seasonal variations in leaf nitrogen, phosphorus and potassium concentrations were studied in a mature carob (Ceratonia siliqua L. cv ''Mulata'') orchard subjected to a 4-year irrigation and fertilization experiment. Three irrigation regimes (0, 50 and 100%), based on the evaporation values obtained from a class A pan, were tested in combination with two nitrogen (N) supply regimes in which 21 kg ha −1 year −1 (low-N) and 63 kg ha −1 year −1 (high-N) were supplied as ammonium nitrate. Leaf nitrogen concentration increased throughout the experiment, independently of treatments. There were no significant differences in leaf N concentration between trees in the high-N and low-N treatments. Irrigation regimes had no effect on leaf mineral concentration but influenced the amount of leaves shed and slightly modified the pattern of leaf shedding that occurred during the summer drought period. Nutritional balances between N and P and N and K were both closely and significantly correlated. Potassium was translocated from leaves to fruits during spring, independently of treatments. Severe water stress periods occurring during spring or autumn induced shedding of leaves leading to nutrient mobilization. Nutrient retranslocation during these drought periods may represent an adaptive mechanism. Nitrogen retranslocation was higher for trees in the high-N treatments than for trees in the low-N treatments, whereas phosphorus retranslocation was independent of the irrigation and fertilization treatments.
Physiologia Plantarum, 2008
Ammonium nutrition is of interest as an alternative to that of using nitrate. However, the former... more Ammonium nutrition is of interest as an alternative to that of using nitrate. However, the former has been reported as stressful to many plant species especially to some important crops, as most abiotic stresses may trigger oxidative imbalances in plants. In this work, we investigate the response of oxidative metabolism of two plant species, spinach (Spinacia oleracea L. cv. Gigante de invierno) and pea (Pisum sativum L. cv. Rondo), which have distinct tolerance to ammonium. Plants were grown in the presence of 1.5 and 3.0 mM N as ammonium and compared with equivalent nitrate nutrition. The antioxidant enzymes and metabolites as well as oxidative damage to proteins were determined. Protein and amino acid contents in both types of plants were also analysed. Ammonium nutrition in sensitive spinach or in the tolerant pea plants does not alter the redox status of ascorbate and glutathione or the phenolic contents, while no clear effect is seen in the antioxidant enzymes. The results sho...
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Papers by Maria Amélia Martins-Loução