Browsing by Author "Vega, Alberto L."
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- Application of maize and efficient rhizospheric microorganisms for the remediation of saline soilsPublication . Moreira, Helena; Pereira, Sofia A.; Vega, Alberto L.; Castro, Paula M. L.; Marques, Ana P. G. C.Soil salinity is a serious problem causing loss of fertility, as plants facing salt stress suffer alterations in physiology that adversely affects its growth. This work aimed to evaluate the effectiveness of combinations of microorganisms for the recovery of crop productivity in soils affected by different levels of salinity (0, 2.5 and 5 gNaCl.kg-1). The strategy relied on the culture in greenhouse conditions of a high value food and energetic crop (maize) inoculated with soil plant growth promoting microbiota – an arbuscular mychorrizal fungi (Rhizophagus irregularis), a rhizobacteria (Pseudomonas reactans) and a bacterial endophyte (Pantoea ananatis). Plant biomass was assessed at harvest and differences between treatments were analysed. As the work also aimed to relate the effects of bioinoculation to alterations in plant response to salt stress, further parameters were assessed. Elevated salt levels induce ionic stress, with consequent nutrient imbalance; therefore, levels of Na, K and Ca were determined in plant tissues. As salt is also a major stress to soil organisms, rhizosphere samples were analysed to follow up of microbiota survival by molecular biology techniques (DGGE), assessing the effect of soil salinity at the different tested levels on the inoculated soil microorganisms persistence and relationship with the existing community. The collected information allowed understanding the effects of the applied biologically based treatments in the quality of the tested saline soils, on the dynamics of the present microbiota and on maize growth, focusing on the further development of cropping strategies for saline soils, grounded on sustainable agriculture practices.
- Endophytic bacteria from aromatic plants and their potential for bioinoculation on green roofs vegetationPublication . Monteiro, Cristina M.; Pereira, Sofia I. A.; Vega, Alberto L.; Castro, Paula M. L.Background: Green roofs are a type of multilayer construction that uses vegetation on top of buildings. In the last decade, their use has become more frequent due to the environmental advantages they offer in impervious urban areas, regarding stormwater retention, removal of atmospheric pollutants, attenuation of the urban heat island effect, among others. Selection of vegetation able to growth on the harsh environment of a rooftop is of major importance for the successful establishment of a green roof. The use of plant growth promoting bacteria (PGPB) on green roofs is a sustainable alternative to aid plant establishment and growth. Method: Endophytic bacteria were isolated from Lavandula dentata L. plants collected at random from “Cantinho das Aromáticas”. These isolates were characterized for their in vitro growth promoting traits. Two green roofs pilot systems were further established, comprising inoculation with a selected mixture of four isolated endophytic bacteria. Four different aromatic plant species (Santolina chamaecyparissus, Santolina Lemon Queen, Armeria maritima, Festuca glauca) and a succulent species (Sempervivum tectorum) were used for experiments. Plant development is being followed. Results & Conclusions: A total of 56 culturable endophytic bacteria were isolated from the plant tissues of L. dentata plants corresponding to 38 different bacterial strains. All endophytic strains exhibit growth promoting traits and 21% were found to produce more than 40 mg/L of IAA. The strains Pseudomonas graminis (LR 1-9), P. congelans (LS 2-1) and Bacillus aryabhattai (LS 1-2) were amongst those that exhibited higher IAA levels and were selected for inoculation. Paenibacillus kribbensis (LR 2-11) was selected due to its antifungal activity. The vegetation used presented in general successful establishment and growth. The potential of bacterial endophytes as bioinoculants in green roofs vegetation is under analysis.
- Endophytic bacteria from aromatic plants and their potential for bioinoculation on Green Roofs vegetationPublication . Monteiro, C. M.; Pereira, Sofia I. A.; Vega, Alberto L.; Castro, Paula M. L.
- Performance of Quercus suber L. at nursery stage - application of two bio-inoculants under two distinct environmentsPublication . Araújo, Giovânia C.; Sousa, Nadine; Ramos, Miguel; Vega, Alberto L.; Castro, Paula M. L.Key message - Despite the fact that the technique of application of bioinoculants improved the quality of Quercus suber L. seedlings produced in nurseries, these benefits are dependent on the ecological conditions of the site and the composition of the applied inoculum, which interferes with the profile of the local fungal community. Context - Quercus suber L. plays a key ecological and socio-economical role in the Iberian Peninsula. Symbiotic ectomycorrhizal fungi-ECM are crucial partners of several tree species, and assessing the efficacy of bioinoculants at nursery stage helps devising tools to increase plant resilience. Aims - The aim of this study was to compare the effects of two inocula formulations of mixed ECM fungi and bacteria on the quality of seedlings produced in two forest nurseries, differing in environmental conditions and forest embedment. Methods - Quercus suber L. seedlings were inoculated with a commercial product containing Pisolithus tinctorius (Pers) Coker Couch - Scleroderma sp., and six bacterial species and with a non-commercial fungal and bacterial dual inoculum (Suillus granulatus (L.) Roussel + Mesorhizobium sp.). Biometric and nutritional parameters and morphological quality indexes were determined on seedlings. The ECMcommunity was assessed by denaturing gradient gel electrophoresis and cloning-sequencing. Results - In both nurseries, the seedling quality index in inoculated was up to 2-fold higher than in non-inoculated seedlings. Plant biomass differed significantly among nurseries. The inoculum influenced the profile of the fungal community. S. granulatus and P. tinctorius persisted for 6 months in the inoculated seedlings. Conclusion- The nursery ecosystem influenced plant growth. Inoculation treatments increased plant performance; however, the dual inoculum resulted in more consistent improvements of Q. suber at nursery stage, highlighting the importance of inocula selection.