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Endophytic culturable bacteria colonizing Lavandula dentata L. plants: Isolation, characterization and evaluation of their plant growth-promoting activities

Publication . Pereira, S.I.A.; Monteiro, Cristina M.; Vega, A. L.; Castro, Paula M. L.

Aromatic plants such as lavender are stirring the attention of many researchers due to their content in bioactive secondary metabolites that can be used in traditional medicine. However, information regarding naturally occurring lavender associated bacterial endophytes (BE) is limited. To the best of our knowledge, this is the first study which aims to assess the phylogenetic diversity of the culturable endophytic bacteria of Lavandula dentata cultivated under organic management and to evaluate their potential as plant growth promoting (PGP) agents. BE were grouped by random amplified polymorphic DNA and identified by 16S ribosomal RNA gene sequencing. Endophytes were further characterized for the ability to produce several PGP substances, like ammonia, siderophores, indol-3-acetic acid, and hydrogen cyanide and for the ability to solubilize phosphate. Plant cell-wall degrading enzymes were also determined. Densities of BE were higher in roots (log 6.39 CFU g−1 fresh weight) than in shoots (log 5.56 CFU g−1 fresh weight). Phylogenetic analysis showed that BE were affiliated to two major groups: -Proteobacteria (50%) and Firmicutes (31.6%) and a small part belonged to - (7.9%) and -Proteobacteria (10.5%), being Pseudomonas and Bacillus the most highly represented genera. Higher bacterial diversity was found in the lavender roots, with endophytes belonging to 6 different genera (Pseudomonas, Variovorax, Rhizobium, Caulobacter, Bacillus and Paenibacillus), than in shoots where only 3 genera (Bacillus, Pseudomonas and Xanthomonas) were found. Overall, BE showed ability to produce extracellular enzymes and multiple PGP traits, suggesting their potential use as efficient bioinoculants in sustainable cultivation of medicinal and aromatic plants.

2016Journal article

Restricted access

Growing substrates for aromatic plant species in green roofs and water runoff quality: pilot experiments in a Mediterranean climate

Publication . Monteiro, Cristina M.; Calheiros, Cristina S. C.; Palha, Paulo; Castro, Paula M. L.

Green roof technology has evolved in recent years as a potential solution to promote vegetation in urban areas. Green roof studies for Mediterranean climates, where extended drought periods in summer contrast with cold and rainy periods in winter, are still scarce. The present research study assesses the use of substrates with different compositions for the growth of six aromatic plant species - Lavandula dentata, Pelargonium odoratissimum, Helichrysum italicum, Satureja montana, Thymus caespititius and T. pseudolanuginosus, during a 2-year period, and the monitoring of water runoff quality. Growing substrates encompassed expanded clay and granulated cork, in combination with organic matter and crushed eggshell. These combinations were adequate for the establishment of all aromatic plants, allowing their propagation in the extensive system located on the 5th storey. The substrate composed of 70% expanded clay and 30% organic matter was the most suitable, and crushed eggshell incorporation improved the initial plant establishment. Water runoff quality parameters - turbidity, pH, conductivity, NH4(+), NO3(-), PO4(3-) and chemical oxygen demand - showed that it could be reused for non-potable uses in buildings. The present study shows that selected aromatic plant species could be successfully used in green roofs in a Mediterranean climate.

2017Journal article

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Substrate influence on aromatic plant growth in extensive green roofs in a Mediterranean climate

Publication . Monteiro, Cristina M.; Calheiros, Cristina S. C.; Martins, João P.; Costa, Francisco M.; Palha, Paulo; Freitas, Sara de; Ramos, Nuno M. M.; Castro, Paula M. L.

Green roofs have been described as technical solutions to overcome urban environmental problems, such as decrease of vegetation and stormwater management. In the present study, two pilot 20 m2 extensive green roofs were implemented in an urban Mediterranean region, at a 1st storey on a warehouse building structure, in order to test the adequacy of different substrates for supporting aromatic plants (Lavandula dentata, Helichrysum italicum, Satureja montana, Thymus caespititius and Thymus pseudolanuginosus). Experimental substrates included expanded clay and granulated cork as main components, supplemented with organic matter and crushed egg shell. A commercial substrate that obeys to FLL guidelines was also tested. Plant growth was assessed and compared within each platform. All experimental substrates proved to be adequate for vegetation growth, with the combination of 70% expanded clay, 15% organic matter and 15% crushed egg shell showing the best results regarding plant establishment and growth over time. Water runoff quality parameters - turbidity, pH, conductivity, NH4+, NO3−, PO43− - met standard values required for water reuse for non-potable purposes, such as toilet flushing or irrigation. Preliminary qualitative thermographic measurements comparing surface temperature of different plant species and the substrate showed that temperature of vegetation surface was lower than substrate, reinforcing green roofs benefits of lowering air temperature in their surroundings. The present research shows that aromatic vegetation combined with clay substrates are suitable for green roofs located in countries of the Mediterranean region.

2017Journal article

Restricted access

Aromatic plants for water treatment in Green roofs technology

Publication . Monteiro, Cristina M.; Calheiros, Cristina; Castro P. M. L, Paula M. L

2015Conference object

Open access

Contributos para a adoção dos telhados verdes como tecnologia de retenção e aproveitamento de águas pluviais

Publication . Monteiro, Cristina; Calheiros, Cristina; Pimentel-Rodrigues, Carla; Silva-Afonso, Armando; Castro, Paula M. L.

Os telhados verdes são uma solução arquitetónica que consiste na aplicação de substrato e vegetação sobre a cobertura impermeável de um edifício. A sua aplicação tem vindo a aumentar nos últimos anos, pelo facto de apresentar inúmeras vantagens, nomeadamente melhoria da qualidade do ar em áreas urbanas, promoção de ecossistemas nas cidades, redução do efeito “ilha de calor” e melhoria da eficiência tanto energética como acústica dos edifícios. Os telhados verdes reduzem também os caudais de ponta na drenagem pluvial, contribuindo para amortecer os picos de cheia em ambiente urbano, e são uma solução promissora para a melhoria da qualidade da água de escoamento, visando um posterior aproveitamento. Neste trabalho, desenvolveu-se um telhado verde experimental utilizando plantas aromáticas autóctones, com o objetivo de avaliar a qualidade da água da chuva após passagem por um substrato selecionado, bem como caracterizar o ciclo da água (escoamento, retenção, etc.) de forma a fornecer contributos para a expansão da aplicação deste tipo de tecnologias conjuntamente para o aproveitamento de águas pluviais em edifícios. Os principais resultados obtidos permitiram o desenvolvimento de um modelo referente à determinação do coeficiente de escoamento, bem como a caracterização da qualidade da água na perspetiva de posterior reutilização.

2014Conference object

Open access