Browsing by Author "Pereira, Sofia A."
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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.
- Effects of the inoculation with soil microbiota onmaize grown in saline soilsPublication . Moreira, Helena; Pereira, Sofia A.; Castro, Paula M. L.; Marques, Ana P. G. C.
- Growth promotional traits of three pgpr: possible uses for phytoremediation of degraded soilsPublication . Moreira, Helena; Pereira, Sofia A.; Vegas, Alberto L.; Rangel, António O. S. S.; Castro, Paula M. L.; Marques, Ana P. G. C.Maize is a fast-growing and high yield crop with both energy value and remediation potential. Plant growth promoting rhizobacteria (PGPR) are a biological tool available to enhance plant establishment in degraded or depleted environments such as the case of saline soils or heavy-metal contaminated land. Although PGPR are able to produce metabolites such as siderophores, HCN and ammonia, or solubilize nutrients such as phosphate, these beneficial traits for the plant may be influenced by exposure to excessive levels of such contaminants. In this study, three PGPR (Pseudomonas fluorescens, Ralstonia eutropha and Cryseobacterium humi) were screened for those traits in the presence of different levels of Cd and Zn, and also to different salinization conditions. Their ability to influence maize germination and root and shoot elongation was also analyzed. Results showed that the level of exposure generally affected the ability of the tested strains to produce plant growth promoting substances. However, dissimilar sensibilities in the behavior of the different strains were observed when exposed to similar stress conditions. These differences were also noticeable in the plant development, with the tested PGPR generally positively influencing the analyzed parameters. Results suggest that PGPR can be exploited to promote stress relief of maize when grown in degraded land. Such knowledge may provide a new insight concerning the advantages of such biotechnologically based tools for phytoremediation.