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Growth and nutrition of cowpea (Vigna unguiculata) under water deficit as influenced by microbial inoculation via seed coating

Publication . 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.

2019Journal article

Open access

Arbuscular mycorrhizal fungi are an alternative to the application of chemical fertilizer in the production of the medicinal and aromatic plantCoriandrum sativumL

Publication . Oliveira, Rui S.; Ma, Ying; Rocha, Inês; Carvalho, Maria F.; Vosátka, Miroslav; Freitas, Helena

The 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.

2016Journal article

Open access

Biodegradation of mono-, di- and trifluoroacetate by microbial cultures with different origins

Publication . Alexandrino, Diogo A.M.; Ribeiro, Inês; Pinto, Luís M.; Cambra, Rafael; Oliveira, Rui S.; Pereira, Filipe; Carvalho, Maria F.

This work focused on the biodegradation of three structurally related fluoroacetates (FAs), mono- (MFA), di- (DFA) and trifluoroacetate (TFA), using as microbial inocula samples collected from a site with a long history of industrial contamination and activated sludge obtained from a municipal wastewater treatment plant. Biodegradation experiments were carried out under different modes of substrate supplementation, which included (i) FAs fed as sole carbon sources; (ii) FAs (only for DFA and TFA) fed in co-metabolism with sodium acetate; and (iii) mixtures of MFA with DFA or TFA. Biodegradation of the target compounds was assessed through fluoride ion release. Defluorination was obtained in the cultures fed with MFA, while DFA and TFA were recalcitrant in all tested conditions. When present in mixture, DFA was shown to inhibit biodegradation of MFA, while TFA had no effect. A total of 13 bacterial isolates obtained from MFA degrading cultures were found to degrade 20mgL-1 of this compound, as single strains, when supplemented as a sole carbon source. Sequencing of the 16S rRNA gene indicated that among these degrading bacteria only Delftia acidovorans had been previously reported to be able to degrade MFA. This work shows that, despite their similar chemical structures, biodegradation of the three tested FAs is very distinct and draws attention to the unknown impacts that the accumulation of DFA and TFA may have in the environment as a result of their high recalcitrance.

2018Journal article

Open access

Increased protein content of chickpea (Cicer arietinum L.) inoculated with arbuscular mycorrhizal fungi and nitrogen-fixing bacteria under water deficit conditions

Publication . Oliveira, Rui S.; Carvalho, Patrícia; Marques, Guilhermina; Ferreira, Luís; Nunes, Mafalda; Rocha, Inês; Ma, Ying; Carvalho, Maria F; Vosátka, Miroslav; Freitas, Helena

Chickpea (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.

2017Journal article

Open access