O PAPEL DOS FUNGOS ARBUSCULARES MICORRÍZICOS EM PROCESSOS DE FITORREMEDIAÇÃO DE SOLOS CONTAMINADOS COM METAIS PESADOS

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Assessment of mycorrhizal colonisation and soil nutrients in unmanaged fire-impacted soils from two target restoration sites

Publication . Dias, J. M.; Oliveira, R. S.; Franco, A. R.; Ritz, K.; Nunan, N.; Castro, P. M. L.

The mycorrhizal colonisation of plants grown in unmanaged soils from two restoration sites with a fire history in Northern Portugal was evaluated from the perspective of supporting restoration programmes. To promote restoration of original tree stands, Quercus ilex L. and Pinus pinaster Ait. were used as target species on two sites, denoted Site 1 and 2 respectively. The aim of the study was to assess whether mycorrhizal propagules that survived fire episodes could serve as in situ inoculum sources, and to analyse the spatial distribution of soil nutrients and mycorrhizal parameters. In a laboratory bioassay, P. pinaster and Q. ilex seedlings were grown on soils from the target sites and root colonisation by ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) fungi was determined. The ECM root colonisation levels found indicated that soil from Site 2 contained sufficient ECM propagules to serve as a primary source of inoculum for P. pinaster. The low levels of ECM and AM colonisation obtained on the roots of plants grown in soil from Site 1 indicated that the existing mycorrhizal propagules might be insufficient for effective root colonisation of Q. ilex. Different ECM morphotypes were found in plants grown in soil from the two sites. At Site 2 mycorrhizal parameters were found to be spatially structured, with signif icant differences in ECM colonisation and soil P concentrations between regions of either side of an existing watercourse. The spatial distribution of mycorrhizal propagules was related to edaphic parameters (total C and extractable P), and correlations between soil nutrients and mycorrhizal parameters were found.

2010Journal article

Open access

Ectomycorrhizal fungi as an alternative to the use of chemical fertilisers in nursery production of Pinus pinaster

Publication . Sousa, Nadine R.; Franco, Albina R.; Oliveira, Rui S.; Castro, Paula M.L.

Addition of fertilisers is a common practice in nursery production of conifer seedlings. The aim of this study was to evaluate whether ectomycorrhizal (ECM) fungi can be an alternative to the use of chemical fertilisers in the nursery production of Pinus pinaster. A greenhouse nursery experiment was conducted by inoculating seedlings obtained from seeds of P. pinaster plus trees with a range of compatible ECM fungi: (1) Thelephora terrestris, (2) Rhizopogon vulgaris, (3) a mixture of Pisolithus tinctorius and Scleroderma citrinum, and (4) a mixture of Suillus bovinus, Laccaria laccata and Lactarius deterrimus, using forest soil as substrate. Plant development was assessed at two levels of NePeK fertiliser (0 or 600 mg/seedling). Inoculation with a mixture of mycelium from S. bovinus, L. laccata and L. deterrimus and with a mixture of spores of P. tinctorius and S. citrinum improved plant growth and nutrition, without the need of fertiliser. Results indicate that selected ECM fungi can be a beneficial biotechnological tool in nursery production of P. pinaster.

2012Journal article

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Effect of diflubenzuron on the development of Pinus pinaster seedlings inoculated with the ectomycorrhizal fungus Pisolithus tinctorius

Publication . Ramos, Miguel A.; Sousa, Nadine R.; Franco, Albina R.; Costa, Vítor; Oliveira, Rui S.; Castro, Paula M. L.

Diflubenzuron (DFB) is an insecticide commonly used to control forest pests. The objectives of this study were to assess the effect of diflubenzuron on the development of Pinus pinaster seedlings and Pisolithus tinctorius under laboratory conditions and to study the possible protective role of this ectomycorrhizal fungus against the effects of diflubenzuron. In vitro experiments revealed that diflubenzuron inhibited fungal growth at all tested concentrations (0.01, 0.1, 1, 10 and 100 mg L−1). Root growth was inhibited at the two highest diflubenzuron concentrations. The activity of the antioxidant defence system of non-inoculated P. pinaster increased at 1 and 10 mg DFB kg−1 substrate, and inoculation increased the threshold to the highest concentration. The protective role of the ectomycorrhizal fungus was seen in the increase of CAT activity. This study revealed that despite causing no mortality, diflubenzuron has the ability to cause sub-lethal damage to P. pinaster. The disproportionate use of this insecticide may lead to higher amounts of its residues in soil and the biosphere, endangering trees, fungi and their symbiosis.

2013Journal article

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Management of nursery practices for efficient ectomycorrhizal fungi application in the production of Quercus ilex

Publication . Oliveira, Rui S.; Franco, Albina R.; Vosátka, Miroslav; Castro, Paula M. L.

The application of ectomycorrhizal (ECM) fungi on forest nursery production is regarded as part of good management practice. However, before employing large scale inoculations in a nursery the interaction between ECM symbionts, growth substrate and fertilisation input should be studied to select the most suitable nursery practices for promoting plant growth and ECM colonisation. In this study, seedlings of Quercus ilex were inoculated with Paxillus involutus, Hebeloma mesophaeum or Cenococcum geophilum and grown in three different substrates commonly used in forest nurseries: peat-based compost, forest soil or composted pine bark. The effect of various fertilisation regimes was also studied. The choice of substrate had a significant effect on plant growth and ECM colonisation. The most appropriate combination of substrate and ECM fungus for Q. ilex growth and nutrition was peat and H. mesophaeum. Plants grown on a peat-based compost and inoculated with H. mesophaeum had a significantly greater biomass and leaf phosphorus concentration without fertilisation. Composted pine bark was found not to be suitable for growth or for mycorrhization. If the appropriate growth substrate is selected, it is possible to replace the use of chemical fertilisers by inoculation with selected ECM fungi. This results in a significant increase in plant development, and thus ECM fungi can be recommended as a more environmental friendly biotechnological approach to plant management in the nursery.

2010Journal article

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Mycorrhizal symbiosis affected by different genotypes of Pinus pinaster

Publication . Sousa, Nadine R.; Ramos, Miguel A.; Franco, Albina R.; Oliveira, Rui S.; Castro, Paula M. L.

Background and aims Higher growth rate and morphological traits have been the major criteria for selecting trees in breeding programs. The symbiotic associations between P. pinaster and ectomycorrhizal fungi can be an effective approach to enhance plant development. The aimof thisworkwas to assess whether the establishment of mycorrhizal symbiosis at nursery stage was affected by tree breeding. Methods Seeds of P. pinaster from a clonal population, designed to select for various traits, and from neighboring wild plants were inoculated with compatible ectomycorrhizal fungi: Suillus bovinus, Pisolithus tinctorius or Rhizopogon roseolus, and grown in individual cells containing forest soil, in a commercial forest nursery. Growth and nutritional traits, colonisation parameters and the fungal community established were assessed. Results R. roseolus and P. tinctorius were the most efficient isolates in promoting plant development. Inoculated selected saplings had an overall superior development than their wild counterparts, with up to a 4.9-fold in root dry weight and a 13.6-fold increase in the total number of ectomycorrhizal root tips. Differences in fungal community were revealed through the denaturing gradient gel electrophoresis profile of each treatment. Conclusions The results from our study suggest that the selected genotype benefits more from the mycorrhizal association and therefore this could be a valuable biotechnological tool for the nursery production of P. pinaster.

2012Journal article

Restricted access