Encontrados 10 documentos, a visualizar página 1 de 1
Influence of transient shade periods on the effects of drought on photosynthesi...
Correia, Maria João; Osório, Maria Leonor; Osório, Júlio; Barrote, Isabel; Martins, Mónica; David, Maria ManuelaThe effects of a slow-imposing two-weeks soil drying period, and subsequent re-watering, on leaf water potential (Ψ), gas exchange rates, chlorophyll fluorescence and on the concentrations of malondialdehyde (MDA) and non-structural carbohydrates (starch, hexose and sucrose) were determined in mature leaves of sunflower plants growing under controlled environmental conditions. To assess how transient shade peri...
Influence of nutrient availability on drought-induced changes in the activity o...
David, Maria Manuela; Barrote, Isabel; Correia, Maria JoãoWe aimed to evaluate if plants with different nutrient availability evidenced a different capacity to overcome drought-induced oxidative stress. Membrane peroxidative damages as MDA concentration and the activity of several antioxidant enzymes were determined in leaves of well watered (WW) and water stressed (WS) H. annuus plants grown either with adequate (Adeq Nutr) or limited (Limit Nutr) nutrient regimes. C...
O conhecimento matemático do professor: formação e prática docente na escola bá...
Moreira,Plínio Cavalcanti; David,Maria Manuela Martins SoaresDesenvolve uma análise do processo de formação matemática na licenciatura, confrontando o conhecimento matemático veiculado nesse processo com algumas das questões que se colocam para o professor na sua prática docente na escola básica. O estudo focaliza os números naturais e toma como referência o curso diurno de licenciatura em matemática da Universidade Federal de Minas Gerais (UFMG). As fontes utilizadas sã...
Effects of water deficit on the activity of nitrate reductase and content of su...
Correia, Maria João; Fonseca, Filomena; Azedo-Silva, João; Dias, Celeste; David, Maria Manuela; Barrote, Isabel; Osório, Maria Leonor; Osório, JúlioThe effects of a two weeks soil drying period on the activity of nitrate reductase (NR; EC 1.6.6.6) were studied on Helianthus annuus L. and non-nodulated Lupinus albus L. plants, growing under two nutrient supply regimes. NR activity was assessed in leaf and root extracts, by measuring the activity of the unphosphorylated active form (NRact), the maximal extractable activity (NRmax) and the activation state. T...
Field performance of seedlings and microproppagated plants of carob tree
Osório, Maria Leonor; Osório, Júlio; David, Maria Manuela; Romano, AnabelaMicropropagated plantlets of cv. Mulata and cv. Galhosa growing in pots, after acclimatization in the glasshouse and growth for several months under natural conditions, were transferred to a field trial. Carob seedlings of ‘Mulata’ were also transferred under the same conditions. The field trial has been established with 100% of success in micropropagated plants and 97% in seedlings. Three months after transfer...
Photosynthetic responses of Lupinus albus to soil water fluctuations
Barrote, Isabel; Osório, Maria Leonor; Osório, Júlio; David, Maria Manuela; Correia, Maria JoãoLupinus albus plants were grown in 3 dm3 pots in a semi-controled greenhouse. Two water regimes were imposed: water deficit (S, 47% of soil capacity), and control (T, 86% of soil capacity). Plants water status was monitored through foliar relative water content (TRA) and pre-dawn (ypd) and midday water potential (ymd). Gas exchanges, chlorophyll a fluorescence and photosynthetic capacity (Amax) were measured. P...
Responses of “Newhall" orange trees to iron deficiency in hydroponics: effects ...
Pestana, M.; David, Maria Manuela; De Varennes, Amarilis; Abadía, Javier; Faria, E. A.Orange (Citrus sinensis L. Osb. cv. ‘Newhall’) plants grafted on Citrange troyer rootstock were grown in nutrient solution with 0, 5, 10 or 20 M Fe, with and without calcium carbonate. Calcium carbonate was added in order to mimic the natural conditions in calcareous soils. Leaf chlorophyll concentration was estimated every 3–4 days using the portable instrument SPAD-502 meter. Chlorophyll fluorescence paramet...
Response to seasonal drought in three cultivars of Ceratonia siliqua: leaf grow...
Correia, Maria João; Coelho, Dulce; David, Maria ManuelaThe responses of leaf growth and leaf water relations to seasonal drought were monitored, during two successive years, in three cultivars of Ceratonia siliqua L. growing in the field, in the South of Portugal. In leaves from the current year growth bulk leaf water relations parameters were characterised using pressure-volume analysis, and morphometric measurements of xylem in petioles were undertaken. The three...
Alterações sazonais da fotossíntese e do ciclo das xantófilas em alfarrobeira (...
Barrote, Isabel; Correia, Maria João; David, Maria ManuelaThis study aimed to follow the seasonal changes in the photosynthetic performance of two Ceratonia siliqua cultivars – Mulata and Mulata do Espargal – growing in a non-irrigated orchard in Algarve (South Portugal). Measurements and sampling (leaf water potential, leaf gas exchange, pigments and dark-adapted chlorophyll fluorescence) were taken in days with similar photon flux density, during the dry season in J...
Fotossíntese e acumulação de ácido abcísico em Lupinus albus sujeito a stress h...
Correia, Maria João; David, Maria Manuela; Barrote, IsabelThe objective of the present work was to assess whether the depression of photosynthetic activity in droughted Lupinus albus L. plants was more closely associated with carbohydrate build-up or ABA accumulation. With that purpose we have measured the concomitant drought-induced changes in photosynthetic capacity and the concentrations of Rubisco, chlorophylls, non-structural carbohydrates and ABA in young and ol...
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