19 documents found, page 1 of 2
Matemática escolar, matemática acadêmica e matemática do cotidiano : uma teia d...
David, Maria Manuela; Moreira, Plínio Cavalcanti; Tomaz, Vanessa SenaNeste artigo, apresentam-se as ideias gerais em torno das quais vem se constituindo e se desenvolvendo um programa de pesquisas sobre as práticas escolares e a formação de professores de matemática, idealizado por um grupo de pesquisadores da área de Educação Matemática da UFMG e da UFOP. O foco central dos estudos desenvolvidos dentro do programa são as relações entre a matemática escolar, a matemática acadêmi...
Carob trees (Ceratonia siliqua L.) regenerated in vitro can acclimatize success...
Osório, Maria Leonor; Osório, Júlio; Gonçalves, Sandra; David, Maria Manuela; Romano, Anabela; Correia, Maria JoãoThe use of in vitro regenerated plants in forestry and orchard depends ultimately on the development of efficient transplantation protocols, ensuring high survival rates and successful establishment under field conditions. We tested the performance of micropropagated carob trees (Ceratonia siliqua L.) throughout the acclimatization process in terms of survival, growth and physiological traits, including field c...
Response of five citrus rootstocks to iron deficiency
Pestana, M.; Correia, P. J.; David, Maria Manuela; Abadía, Anunciación; Abadía, Javier; de Varennes, A.Citrus established in calcareous soils can be affected by iron (Fe) deficiency chlorosis which limits yield and the income of the farmer. The degree of the deficiency depends on the rootstock, but their tolerance to Fe chlorosis still requires further investigation. To study physiological parameters of citrus rootstocks that could be used to evaluate tolerance to Fe deficiency, plants of Troyer citrange (Citrus...
Seasonal changes in CO2 assimilation in leaves of seedlings and micropropagated...
Osório, Maria Leonor; Osório, Júlio; David, Maria Manuela; Correia, Maria João; Romano, AnabelaIn this communication we evaluate the field performance of two micropropagated Portuguese carob cultivars (Galhosa and Mulata) throughout the season, particularly at extreme conditions of light and temperature. Two irrigated plots were established in the field: 1) micropropagated plants, vs 2) seedlings. During the first year following transplantation to the field, we followed net photosynthetic rate, stomatal ...
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...
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...
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...
Carbon metabolism of Carob young trees under low temperature: different respons...
Cavaco, A. M.; Ferreira, V. L.; Santos, A. M.; David, Maria ManuelaYoung trees of two carobs (Ceratonia siliqua L.) cultivars, Mulata and Galhosa, ,propagated in vitro and grown for 3-4 years in a greenhouse were moved into a growth chamber under environmental controlled conditions where they were exposed to 25/15º C (control), 10/5º C (chilling) and again to 25/15º C (recovery).
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...
The effects of drought on net CO2 uptake, chlorophyll fluorescence and photosyn...
Osório, Maria Leonor; Barrote, Isabel; Osório, Júlio; David, Maria Manuela; Correia, Maria JoãoPhotosynthesis, photosystem II activity and photosynthetic pigments were analysed in mature and Young leaves of sunflower (Helianthus annuus L.) during dehydration and rehydration, in order to determine the influence of leaf age on the sensitivity to drought. Dehydration caused a more pronounced inhibition in photosynthetic rates in mature leaves compared to younger leaves, but 24 h after rewatering the recover...