Browsing by Author "Goufo, P."
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- O cultivo do arroz em Portugal e a resposta do agrossistema às alterações ambientais de temperatura e concentração de dióxido de carbonoPublication . Figueiredo, N.; Menino, R.; Prazeres, A.; Fareleira, P.; Vargues, A.; Carranca, C.; Marques, P.; Pereira, J.; Goufo, P.; Trindade, H.; Carneiro, J.; Couto, N.; Mateus, E.; Ribeiro, A.; Coutinho, J.
- A dinâmica do azoto mineral no solo e na lâmina de água, em resposta a diferentes condições ambientaisPublication . Figueiredo, N.; Trindade, H.; Pereira, J.; Coutinho, J.; Goufo, P.; Prazeres, A.; Marques, P.; de Varennes, A.; Carranca, C.
- Effect of elevated carbon dioxide (CO2) on phenolic acids, flavonoids, tocopherols, tocotrienols, γ-oryzanol and antioxidant capacities of rice (Oryza sativa L.)Publication . Goufo, P.; Pereira, J.; Figueiredo, N.; Oliveira, M.; Carranca, C.; Rosa, E.; Trindade, H.There have been no studies conducted with the objective of investigating the effect of elevated CO2 concentrations ([CO2]) on antioxidants in grains. Therefore, a two-year field experiment was conducted using open-top chambers with two levels of atmospheric CO2 (375 and 550 mmol/mol) to evaluate their effects on rice grain antioxidants. Following exposure to high [CO2], the total phenolic content of all rice milling fractions decreased (3%e18%), with the highest reduction in the brown rice for sinapic acid (167%), and in the white rice for p-hydroxybenzoic acid (100%). The total flavonoid content also decreased under elevated [CO2] in all rice milling fractions (8%e14%), with apigenin (25%) being highly affected in the white rice, and tricin (12%) in the bran. The same trend was found for g-oryzanol, with decreases of 35%, 32%, 25%, and 2% in the white rice, brown rice, husk, and bran, respectively. In the white and brown rices, tocopherols and tocotrienols were all lower under elevated [CO2], with reductions larger for a-tocotrienol (69%), g-tocotrienol (46%), and a-tocopherol (38%). Good correlations between antioxidant contents and DPPH radical scavenging capacities indicated that these decreases may be meaningful in the preventive ability of rice against free radical-mediated degenerative diseases
- Effects of elevated temperature and atmospheric carbon dioxide concentration on the emissions of methane and nitrous oxide from Portuguese flooded rice fieldsPublication . Pereira, J.; Figueiredo, N.; Goufo, P.; Carneiro, J.; Morais, R.; Carranca, C.; Coutinho, J.; Trindade, H.Methane (CH4) and nitrous oxide (N2O) emissions from flooded rice fields have been rarely measured in Europe. A field study was carried out in an intermittent flooded rice field at central Portugal to investigate if global warming under Mediterranean conditions, elevated soil temperature (þ2 $C) and atmospheric [CO2] (550 ppm), could lead to significant effects in CH4 and N2O emissions. The experimental design consisted of three treatments arranged in a randomized complete block design with three replicates. To assess the effects of ambient temperature and actual atmospheric [CO2] (375 ppm), plots were laid under open-field rice conditions. Using open-top chambers, two other treatments were established: one to assess the effect of elevated temperature and actual atmospheric [CO2] and a third treatment to evaluate the combined effect of elevated temperature and atmospheric [CO2]. Measurements of CH4 and N2O fluxes were made throughout two consecutive growing seasons in the field using the closed chamber technique. Elevation of temperature with or without elevated atmospheric [CO2] increased CH4 emissions by 50%, but this increase was not significant compared to the open-field condition. As for N2O, elevated temperature alone or combined with elevated atmospheric [CO2] had no significant effect on emissions relative to the open-field treatment. The estimated seasonal CH4 EF for the Portuguese flooded rice fields was 10.0 g CH4 m"2 , while the EF for N2O emissions was 1.4% of N input. These results suggested that default seasonal CH4 and N2O EFs currently used by the Portuguese inventory were not appropriated.
- Elevated carbon dioxide and temperature effects on rice yield, leaf greenness, and phenological stages durationPublication . Figueiredo, N.; Carranca, C.; Trindade, H.; Pereira, J.; Goufo, P.; Coutinho, J.; Marques, P.; Maricato, R.; de Varennes, A.Abstract The present field experiment was conducted during two consecutive cropping seasons in central Portugal to study the effects of simultaneous elevation of carbon dioxide concentration ([CO2]) (550 lmol mol-1 ) and air temperature (?2–3 C) on japonica rice (Oryza sativa L. ‘‘Ariete’’) yield, crop duration, and SPAD-values across the seasons compared with the open-field condition. Open-top chambers were used in the field to assess the effect of elevated air temperature alone or the combined effect of elevated air temperature and atmospheric [CO2]. Open-field condition was assessed with randomized plots under ambient air temperature and actual atmospheric [CO2] (average 382 lmol mol-1 ). Results obtained showed that the rice ‘‘Ariete’’ had a moderate high yielding under open- field condition, but was susceptible to air temperature rise of ?2–3 C under controlled conditions resulting in reduction of grain yield. The combined increase of atmospheric [CO2] with elevated air temperature compensated for the negative effect of temperature rise alone and crop yield was higher than in the open-field. SPAD-readings at reproductive stage explained by more than 60 % variation the straw dry matter, but this finding requires further studies for consolidation. It can be concluded that potential increase in air temperature may limit rice yield in the near future under Mediterranean areas where climate change scenario poses a serious threat, but long term field experiments are required.
- Impact of agricultural practices, elevated temperature and atmospheric carbon dioxide concentration on nitrogen and pH dynamics in soil and floodwater during the seasonal rice growth in PortugalPublication . Figueiredo, N.; Carranca, C.; Goufo, P.; Pereira, J.; Trindade, H.; Coutinho, J.Data on the movements of available N and non-exchangeable NH4 + in the soil are of crucial importance in designing an efficient plant N nutrition management scheme in paddy rice fields. To investigate the processes affecting the dynamics of N and pH under Mediterranean conditions, rice (Oryza sativa L. cv. Ariete) was cultivated in 2011 and 2012 in Salvaterra de Magos (central Portugal) under the following climate scenarios: (i) ambienttemperature and ambient [CO2] in the open-field, (ii) elevated temperature (+3 C) and ambient [CO2] in open-top chambers, and (iii) elevated temperature (+3 C) and elevated [CO2] (+175mmol mol1 ) in open-top chambers. Plants were grown under an intermittent flooding regime. Soil and water samples were taken at eight different stages of plant growth, including before and after N basal and topdressing. Our study indicated that the processes underlying N changes in response to the timing of N fertilization were different depending on the N form. After basal dressing under aerobic conditions, both available and non-exchangeable NH4 + contents were increased. Following the topdressing under flooded conditions, the available content of soil N increased, whereas the non-exchangeable NH4 + content decreased. A negative relationship was found between soil pH and NH4 + “fixation” when roots were active, and vice-versa. Elevated temperature alone or in combination with elevated [CO2] had no effect on the total available N content in the soil and floodwater. Under elevated temperature, however, the non-exchangeable NH4 + content was significantly reduced (11%), with the same magnitude of change (10%) observed under co-elevation of temperature and [CO2]. These results suggested that non-exchangeable NH4 + in paddy fields might be insensitive to [CO2] elevation under Mediterranean conditions, while reductions observed under co-elevation of [CO2] and temperature might be associated with temperature alone. This information could be used to alter rice management practices and to adjust N application under climate change.
- Produção e valores de SPAD na cultura do arrozPublication . Figueiredo, N.; Carranca, C.; Trindade, H.; Pereira, J.; Goufo, P.; Coutinho, J.; Marques, P.; Maricato, R.; de Varennes, A.
- Proposta de novos factores de emissão de gases com efeito de estufa para a cultura de arroz em PortugalPublication . Pereira, J.; Figueiredo, N.; Goufo, P.; Carneiro, J.; Morais, R.; Carranca, C.; Coutinho, J.; Trindade, H.
- Relatório Final do Projeto PTDC/AGR-AAM/102529/2008 “Emissões gasosas medidas em campos regados de arroz produzido em dois solos diferentes, em Portugal, por efeito das práticas culturais, do clima e do aumento da concentração de CO2 na atmosfera”Publication . Carranca, C.; Figueiredo, N.; Fareleira, P.; Vargues, A.; Prazeres, A.; Marques, P.; Trindade, H.; Coutinho, J.; Pereira, J.; Moreira, N.; Goufo, P.; Carneiro, J.; Ribeiro, A.; Mateus, E.; Gomes da Silva, M.; da Nazaré Alves, M.; Oliveira, C.; Justino, J.Os objetivos do estudo foram os seguintes: i) avaliação da dinâmica do azoto (N) em cada talhão, e na lâmina de água à superfície dos solos, durante os ciclos culturais do arroz, ii) avaliação da mineralização potencial do N nos solos, em condições aeróbias e anaeróbias, simulando o período cultural (25 ºC) e pós-colheita (10 ºC), iii) avaliação das actividades enzimáticas, biomassa microbiana e presença de cianobactérias em cada talhão, iv) avaliação da resposta do arroz (Oryza sativa L. cv. Ariete) às práticas culturais, tipo de solo e condições climáticas, v) avaliação da eficiência da utilização do N pela cultivar de arroz Ariete, num ensaio em vasos, vi) avaliação da cor das folhas (SPAD), capacidade fotossintética da cultura e qualidade do grão, em resposta aos tratamentos, vii) avaliação das emissões de gases com efeito de estufa (CH4, N2O, COV) e NH3 em cada talhão, viii) estabelecimento das relações entre as emissões de COVs e as práticas de cultivo, o tipo de solo e as características climáticas.
- Rice (Oryza sativa L.) phenolic compounds under elevated carbon dioxide (CO2) concentrationPublication . Goufo, P.; Pereira, J.; Moutinho-Pereira, J.; Correia, C.; Figueiredo, N.; Carranca, C.; Rosa, E.; Trindade, HPrevious studies have shown that elevated levels of carbon dioxide [CO2] may increase, decrease, or have no effect on the concentrations of phenolic compounds in plants. The underlying causes of these variations in responses remain poorly understood. In the present study, it was hypothesized that different plant responses come mainly from the duration of exposure to the gas, growing conditions, and sampling procedures. A two-year field study was conducted in open-top chambers (375 vs. 550 mmol CO2mol−1 air) using a japonica rice variety (Oryza sativa L. cv. Ariete) as the test crop, with plants grown under elevated [CO2] during their entire life cycle. Leaf, stem and root samples were collected at five different growth stages, and submitted to a series of physiological and biochemical measurements. The carbon:nitrogen ratio and total non-structural carbohydrates were increased by elevated [CO2] in all plant tissues. Data showed that under elevated [CO2], there was a reduction in the total phenolic and total flavonoid contents measured during the seedling, tillering, elongation, and flowering stages in all plant organs, probably resulting from a relaxation of the antioxidative system during seed germination. By contrast, the total phenolic and flavonoid contents increased under elevated [CO2] at maturity, a change in response which coincided with acclimation of photosynthesis. The same trends were observed for sixteen individual phenolic compounds, including the allelopathic tricin, the phytoalexin sakuranetin and several O-glycosylated flavonoids of ecological importance. Overall, the results indicated that during the early stages of plant development, photosynthates were mainly used to synthesize proteins and meet the growth demand of the plant. Growth reduction at maturity made more resources available for the synthesis of phenolic compounds.