Browsing by Author "Freitas, Helena"
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- Arbuscular mycorrhizal fungi are an alternative to the application of chemical fertilizer in the production of the medicinal and aromatic plantCoriandrum sativumLPublication . Oliveira, Rui S.; Ma, Ying; Rocha, Inês; Carvalho, Maria F.; Vosátka, Miroslav; Freitas, HelenaThe widespread use of agrochemicals is detrimental to the environment and may exert harmful effects on human health. The consumer demand for organic food plants has been increasing. There is thus a rising need for alternatives to agrochemicals that can foster sustainable plant production. The aim of this study was to evaluate the potential use of an arbuscular mycorrhizal (AM) fungus as an alternative to application of chemical fertilizer for improving growth performance of the medicinal and aromatic plant Coriandrum sativum. Plants were inoculated with the AM fungus Rhizophagus irregularis BEG163 and/or supplemented with a commercial chemical fertilizer (Plant Marvel, Nutriculture Bent Special) in agricultural soil. Plant growth, nutrition, and development of AM fungus were assessed. Plants inoculated with R. irregularis and those supplemented with chemical fertilizer displayed significantly improved growth performances when compared with controls. There were no significant differences in total fresh weight between plants inoculated with R. irregularis or those supplemented with chemical fertilizer. Leaf chlorophyll a + b (82%), shoot nitrogen (44%), phosphorus (254%), and potassium (27%) concentrations increased in plants inoculated with R. irregularis compared to controls. Application of chemical fertilizer inhibited root mycorrhizal colonization and the length of the extraradical mycelium of R. irregularis. Inoculation with R. irregularis was equally or more efficient than application of chemical fertilizer in promoting growth and nutrition of C. sativum. AM fungi may thus contribute to improve biologically based production of food plants and reduce the dependence on agrochemicals in agriculture.
- Arbuscular mycorrhizal fungi are more efficient than chemical fertilisers in the production of essential oils of common thyme (Thymus vulgaris )Publication . Oliveira, Rui S.; Moreira, Vanessa; Nunes, Mafalda; Rocha, Inês; Carvalho, M. Fátima; Vosátka, Miroslav; Cavaleiro, Carlos; Salgueiro, Lígia; Freitas, HelenaCommon thyme is an aromatic plant with medicinal, cosmetics and culinary uses. Due to its antimicrobial, antioxidant/antiradical and antitumor activity the essential oils of common thyme are in great demand (Nikolić et al., 2014). A significant part of the production of aromatic plants relies on the use of chemical fertilisers, which when applied in large scale can have significant environmental consequences (Malik et al., 2011). Arbuscular mycorrhizal fungi (AMF) are a group of soil microorganisms that forms mutualistic symbioses that can benefit plants by improving the uptake of mineral nutrients, mineralising organic nutrients and conferring drought resistance (Oliveira et al., 2005).AMF have the potential to be inoculatedin the production of common thyme as an ecotechnological tool to reduce the input of chemicals fertilisers.
- Bioaugmentation with Endophytic Bacterium E6S Homologous to Achromobacter piechaudii Enhances Metal Rhizoaccumulation in Host Sedum plumbizincicolaPublication . Ma, Ying; Zhang, Chang; Oliveira, Rui S.; Freitas, Helena; Luo, YongmingApplication of hyperaccumulator-endophyte symbiotic systems is a potential approach to improve phytoremediation efficiency, since some beneficial endophytic bacteria are able to detoxify heavy metals, alter metal solubility in soil, and facilitate plant growth. The objective of this study was to isolate multi-metal resistant and plant beneficial endophytic bacteria and to evaluate their role in enhancing plant growth and metal accumulation/translocation. The metal resistant endophytic bacterial strain E6S was isolated from stems of the Zn/Cd hyperaccumulator plant Sedum plumbizincicola growing in metalliferous mine soils using Dworkin and Foster salts minimal agar medium with 1-aminocyclopropane-1-carboxylate (ACC) as the sole nitrogen source, and identified as homologous to Achromobacter piechaudii based on morphological and biochemical characteristics, partial 16S rDNA sequence and phylogenetic analysis. Strain E6S showed high level of resistance to various metals (Cd, Zn, and Pb). Besides utilizing ACC, strain E6S exhibited plant beneficial traits, such as solubilization of phosphate and production of indole-3-acetic acid. Inoculation with E6S significantly increased the bioavailability of Cd, Zn, and Pb in soil. In addition, bacterial cells bound considerable amounts of metal ions in the following order: Zn > Cd >Pb. Inoculation of E6S significantly stimulated plant biomass, uptake and bioaccumulation of Cd, Zn, and Pb. However, E6S greatly reduced the root to shoot translocation of Cd and Zn, indicating that bacterial inoculation assisted the host plant to uptake and store heavy metals in its root system. Inoculation with the endophytic bacterium E6S homologous to A. piechaudii can improve phytostabilization of metalliferous soils due to its effective ability to enhance in situ metal rhizoaccumulation in plants.
- Biochemical and Molecular Mechanisms of Plant-Microbe-Metal Interactions: Relevance for PhytoremediationPublication . Ma, Ying; Oliveira, Rui S.; Freitas, Helena; Zhang, ChangPlants and microbes coexist or compete for survival and their cohesive interactions play a vital role in adapting to metalliferous environments, and can thus be explored to improve microbe-assisted phytoremediation. Plant root exudates are useful nutrient and energy sources for soil microorganisms, with whom they establish intricate communication systems. Some beneficial bacteria and fungi, acting as plant growth promoting microorganisms (PGPMs), may alleviate metal phytotoxicity and stimulate plant growth indirectly via the induction of defense mechanisms against phytopathogens, and/or directly through the solubilization of mineral nutrients (nitrogen, phosphate, potassium, iron, etc.), production of plant growth promoting substances (e.g., phytohormones), and secretion of specific enzymes (e.g., 1-aminocyclopropane-1-carboxylate deaminase). PGPM can also change metal bioavailability in soil through various mechanisms such as acidification, precipitation, chelation, complexation, and redox reactions. This review presents the recent advances and applications made hitherto in understanding the biochemical and molecular mechanisms of plant-microbe interactions and their role in the major processes involved in phytoremediation, such as heavy metal detoxification, mobilization, immobilization, transformation, transport, and distribution.
- Delivery of Inoculum of Rhizophagus irregularis via Seed Coating in Combination with Pseudomonas libanensis for Cowpea ProductionPublication . Ma, Ying; Látr, Aleš; Rocha, Inês; Freitas, Helena; Vosátka, Miroslav; Oliveira, Rui S.Cowpea (Vigna unguiculata L. Walp) is an important legume grown primarily in semi-arid area. Its production is generally inhibited by various abiotic and biotic stresses. The use of beneficial microorganisms (e.g., plant growth promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF)) can enhance agricultural production, as these microorganisms can improve soil fertility and plant tolerance to environmental stresses, thus enhancing crop yield in an eco-friendly manner. Application of PGPB and AMF in large scale agriculture needs to be improved. Thus, the use of seed coating could be an efficient mechanism for placement of inocula into soils. The aim of this study was to evaluate the effects of the AMF Rhizophagus irregularis BEG140 and the PGPB Pseudomonas libanensis TR1 alone or in combination on the biomass and physiological traits of cowpea. Four treatments were set: (i) non-inoculated control; (ii) PGPB; (iii) AMF applied via seed coating; and (iv) PGPB + AMF applied via seed coating. Cowpea plants inoculated via seed coating with R. irregularis and those inoculated with R. irregularis + P. libanensis showed root mycorrhizal colonization of 21.7% and 24.2%, respectively. PGPB P. libanensis was efficient in enhancing plant biomass and seed yield. There was no benefit of single (AMF) or dual (PGPB + AMF) inoculation on plant growth or seed yield. The application of beneficial soil microorganisms can be a viable approach for sustainable cowpea production in precision agriculture scenarios.
- Effectiveness of seed coating with microbial inoculants as na alternative to agrochemicals in sustainable agriculturePublication . Rocha, Inês; Látr, Aleš; Vosátka, Miroslav; Freitas, Helena; Oliveira, Rui S.Intensive agriculture is highly dependent on agrochemicals and in order to increase crop production, environment integrity is disturbed with biodiversity loss, emergence of pathogens, and soil and water resources negatively affected. The abuse of agrochemicals in agriculture constitutes a major worldwide problem as it does compromise environment and public health. Reducing the use of chemical fertilisers with increased application of organic onesis considered a required and natural route to ease the pressure on the environment derived from agricultural practices (Malusá et al., 2012).
- Growth and nutrition of cowpea (Vigna unguiculata) under water deficit as influenced by microbial inoculation via seed coatingPublication . Rocha, Inês; Ma, Ying; Vosátka, Miroslav; Freitas, Helena; Oliveira, Rui S.Drought can drastically reduce cowpea [Vigna unguiculata (L.) Walp.] biomass and grain yield. The application of plant growth‐promoting rhizobacteria and arbuscular mycorrhizal fungi can confer resistance to plants and reduce the effects of environmental stresses, including drought. Seed coating is a technique which allows the application of minor amounts of microbial inocula. Main effects of the factors inoculation and water regime showed that: severe or moderate water deficit had a general negative impact on cowpea plants; total biomass production, seed weight and seed yield were enhanced in plants inoculated with P. putida; inoculation of R. irregularis significantly increased nitrogen (N) and phosphorus (P) shoot concentrations; and R. irregularis enhanced both chlorophyll b and carotenoids contents, particularly under severe water deficit. Plants inoculated with P. putida + R. irregularis had an increase in shoot P concentration of 85% and 57%, under moderate and severe water deficit, respectively. Singly inoculated P. putida improved potassium shoot concentration by 25% under moderate water deficit. Overall, in terms of agricultural productivity the inoculation of P. putida under water deficit might be promising. Seed coating has the potential to be used as a large‐scale delivery system of beneficial microbial inoculants.
- “I Read”: reading and writing skills promotion softwarePublication . Sucena, Ana; Marques, Cátia; Silva, Ana Filipa; Ramalho, Ana; Machado, Ana Rita; Santos, Ana Raquel; Santos, Cláudia; Garrido, Cristina; Freitas, Helena; Santos, Inês; Rangel, Isabel; Mata, Maria José; Sucena, AnaPersistent difficulties in reading and writing learning are a risk factor for motivation in school and for children's schools learning. In this way, ludic instruments have been developed to face these difficulties. "I read" is a software that seeks through a systematic training and with different games, to develop and train reading and writing skills in a playful and complementary way. It should be used with children who are at the beginning of their school journey and who show difficulties in reading and / or writing or who have special educational needs. This article presents the goals and the structure of this software, as well as results of its use by 244 children between 5 and 7 years old. The results indicate that 58.2% completed the stage dedicated to the study of simple consonants (alphabetical decoding), 41.8% were able to reach the last stage of the game, dedicated to the study of the combined consonants (orthographic decoding), of these 15.2% finished the game. It is concluded that early qualified, continuous and systematic training seems to have an effect on reducing the difficulties of reading and writing.
- Improved grain yield of cowpea (Vigna unguiculata) under water deficit after inoculation with Bradyrhizobium elkanii and Rhizophagus irregularisPublication . Oliveira, Rui S.; Carvalho, Patricia; Marques, Guilhermina; Ferreira, Luís; Pereira, Sandra; Nunes, Mafalda; Rocha, Inês; Ma, Ying; Carvalho, Maria F.; Vosátka, Miroslav; Freitas, HelenaCowpea (Vigna unguiculata (L.) Walp.), a plant broadly cultivated for human consumption and animal feed, is among the most nutritious grain legumes. Most of the areas where cowpea is grown are drought-prone, and there is a need to address this issue, with water scarcity becoming a major concern in agriculture. Cowpea is known to form mutualistic associations with nitrogen-fixing (NF) bacteria and arbuscular mycorrhizal (AM) fungi. These beneficial soil microorganisms have the capacity to benefit plants by reducing the effects of environmental stresses, including drought. Our aim was to study the effect of inoculation with Bradyrhizobium elkanii and Rhizophagus irregularis on the growth and grain yield of cowpea under water-deficit conditions. Under moderate water deficit, grain yield was increased by 63%, 55% and 84% in plants inoculated with B. elkanii, R. irregularis and B. elkanii R. irregularis, respectively. Under severe water deficit, inoculation with B. elkanii and B. elkanii R. irregularis resulted in grain-yield enhancement of 45% and 42%, respectively. The use of cowpea inoculated with NF bacteria and AM fungi has great potential for sustainable agricultural production under drought conditions.
- Increased protein content of chickpea (Cicer arietinum L.) inoculated with arbuscular mycorrhizal fungi and nitrogen-fixing bacteria under water deficit conditionsPublication . Oliveira, Rui S.; Carvalho, Patrícia; Marques, Guilhermina; Ferreira, Luís; Nunes, Mafalda; Rocha, Inês; Ma, Ying; Carvalho, Maria F; Vosátka, Miroslav; Freitas, HelenaChickpea (Cicer arietinum L.) is a widely cropped pulse and an important source of proteins for humans. In Mediterranean regions it is predicted that drought will reduce soil moisture and become a major issue in agricultural practice. Nitrogen (N)-fixing bacteria and arbuscular mycorrhizal (AM) fungi have the potential to improve plant growth and drought tolerance. The aim of the study was to assess the effects of N-fixing bacteria and AM fungi on the growth, grain yield and protein content of chickpea under water deficit.