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- Mycotrophic conditions of populus nigra and P. x euramericana. Evaluation of endo vs ectomycorrhizaPublication . Gonçalves, M. T.; Martins-Loução, M. A.This is the first work concerning the evaluation of mycorrhizal status of Populus nigra and P. x euramericana in Portugal. Concerning the stage of development, juvenile or mature, ectomycorrhizae and arbuscular mycorrhizae were found in both species, coexisting in different root branches of the same root system. Ectomycorrhizae are predominant in mature plants, while arbuscular mycorrhizae predominate in juvenile cuttings. Different morphotypes of ectomycorrhizas have been observed in P. nigra and only one in P. x euramericana.
- Final report COST action 729 : assessing and managing nitrogen fluxes in the atmosphere-biosphere system in EuropePublication . Martins-Loução, Maria Amélia; Branquinho, Cristina; Cruz, Cristina
- Mycorrhization of cork oak micropropagated plantlets : its vitality during acclimatization measured with fast fluorescence techniquesPublication . Romano, A.; Strasser, R. J.; Eggenberg, P.; Martins-Loução, M. A.In this work we propose some fluorescense tests, based on a fast data acquisition (10 us per data point with 12 bit resolution) over five orders of magnitude in time (10 us to 1s) with an optoelectronic shutterless instrument (Plant Efficiency Analyser - PEA), to evaluate the response of micropropagated cork oak plantlets with or without mycorrhiza, in vitro and ex vitro conditions. Indexes have been defined which indicate the activity, efficiency, stress resistance, adaptability and developmental complexity of a plant. The shape of the observed fluorescence transient (on a logarithmic time scale) showed the typical Fo-J-I-P levels. The results obtained showed that mycorrhization increases the quantum yield of photochemistry as well as the electron transport and the photosynthetic metabolism. The density of photosynthetic units per leaf area is highly increased in mycorrhized plantlets. Therefore the productivity per leaf area is increased in these plantlets as well. During acclimatization mycorrhized plantlets show a much higher general fitness than non-mycorrhized plantlets in relation to the defined indexes.
- A cultura da alfarrobeiraPublication . Loução, Maria A.; Carvalho, J. H. Brito de
- In vitro induction of nitrogenase activity in free-living rhizobia by a non-nodulating legumePublication . Martins-Loução, M. A.; Rodriguez-Barrueco, C.The effect of cultured carob cell extracts and exudates on acetylene reduction of three different species of Rhizobium, namely R. japonicum IS-33, “cowpea” Rhizobium Tal 169 and R. leguminosarum Tal 619, was studied. The exudates, excreted from plant callus cultures on an agar defined medium promote a synergistic activation of nitrogenase in pure cultures of rhizobia. “ Cowpea” Rhizobium nitrogenase in pure cultures of rhizobia. “ Cowpea” Rhizobium nitrogenase activity was stimulated by a high concentration of sucrose in the medium. Ability of exudates to influence Nase of R. leguminosarum and R. japonicum, respectively, increased in the presence of succinate. Stimulation could also take place when bactéria were grown on medium to which a crude cell extract was added. When the extract was incubated with rhizobia in a minimal nutrient medium a strong synergistic activation of R. leguminosarum and R. japonicum nitrogenase was observed. On this medium the cell extract showed an inhibitory effect on “cowpea” Rhizobium nitrogenase activity.
- Growth patterns of cork-oak (Quercus suber L.) under natural conditionsPublication . Oliveira, G.; Correia, O. A.; Martins-Loução, M. A.; Catarino, F. M.
- Assessment of critical levels of atmospheric ammonia for Lichen diversity in Cork-Oak Woodland, PortugalPublication . Pinho, Pedro; Branquinho, Cristina; Cruz, Cristina; Tang, Y. Sim; Dias, Teresa; Rosa, Ana Paula; Máguas, Cristina; Loução, Maria A. M.; Sutton, Mark A.