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, plants were divided into two groups and submitted to the following water regimes: daily watering and withholding watering for 7, 10, 14 and 37 days, followed by daily rehydration for 7 days. From day 10 on, significant changes in leaf water potential were observed in plants under water suppression in both treatments, with total recovery after rehydration. The A was higher in plants submitted to ↑[CO 2 ] atm , even under water suppression, compared to the daily watering regime. No change in the leaf carbohydrate content was observed in plants cultivated under ↑[CO 2 ] atm and water restriction when compared to those under ↑[CO 2 ] atm and daily watered treatment. However, plants submitted to 400 ppm CO 2 and water restriction showed a significant decrease in the sugar content, mainly in the leaves. Starch contents did not change in response to CO 2 and water treatments. An increase in the rates of leaf proline was observed at the beginning of water restriction, but decreased throughout the experiment. Our results indicate a mitigating effect of the ↑CO 2 on water deficit through the maintenance of carbohydrate accumulation of coffee plants.

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-(Changes in leaf water potential and photosynthesis of Bauhinia forficata Link under water deficit and after rehydration). To evaluate the influence of different intensities of water deficit and rehydration on water relations and gas exchanges of Bauhinia forficata Link, plants were grown in a greenhouse for three months under the following water regimes: daily watered (control) and watered every 7 (7D) and 15 days (15D) returning to daily watering on 7D and 15D treatments at 75 days of the experiment. Aiming to evaluate short-term responses to re-hydration, plants of 7D and 15D treatments were re-watered 2 days before measurements and sampling was carried out at the 45 th day of experiment. At fortnightly intervals (15, 30, 45, 60, 75, and 90 days) soil moisture (Usoil), leaf water potential (Ψwf), photosynthesis in response to photosynthetically active radiation (A × PPFD) to obtain the maximum net photosynthesis (Amax), and light saturation point (PARsat) were evaluated. The water deficit has affected water relations and photosynthesis with the lowest values observed in the treatments Usoil 7D, and 15D respectively, coinciding with the lowest Ψwf and Amax. Changes in PARsat in response to water deficit were observed showing mean values of 665, 275 and 254 µmol photons m -2 s -1 in control, 7D and 15D respectively. The return of daily watering after 75 days of experiment, promoted the recovery of Amax (7.8 and 9.6 µmol CO 2 m -2 s -1 ) and PARsat (588 and 643 µmol photons m -2 s -1 ) in 7D and 15D respectively with values higher than control plants (4.7 µmol CO 2 m -2 s -1 and 631 µmol photons m -2 s -1 ), suggesting a strong dependence of photosynthesis of Bauhinia forficata to the soil water availability. Key words: Brazilian Orchid-tree, drought tolerance, plasticity RESUMO -(Alterações no potencial hídrico foliar e fotossíntese de Bauhinia forficata Link sob déficit hídrico e após reidratação). Para avaliar a influência de déficits hídricos de diferentes intensidades e da reidratação nas relações hídricas e trocas gasosas, plantas de Bauhinia forficata Link foram cultivadas em casa de vegetação durante três meses e submetidas aos regimes de regas diárias (controle) e regas a cada 7 (7D) e 15 dias (15D) retornando as regas diárias nos regimes 7D e 15D aos 75 dias de experimento. Com o objetivo de avaliar respostas de curto prazo à re-hidratação, plantas dos tratamentos 7D e 15D foram re-irrigadas 2 dias antes das medidas realizadas no 45º de experimento. Em intervalos quinzenais (15, 30, 45, 60, 75 e 90 dias) foram avaliadas a umidade do solo (Usolo), potencial hídrico foliar (Ψwf), a fotossíntese em resposta a radiação fotossinteticamente ativa (A × PPFD) para obtenção da fotossíntese máxima (Amax) e da radiação fotossinteticamente ativa na saturação (PARsat). O déficit hídrico afetou as relações hídricas e fotossíntese, sendo que os menores valores de Usolo observados nos tratamentos 7D e 15D respectivamente, coincidiram com os menores Ψwf e Amax. Alterações nos PARsat em resposta ao déficit hí...

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Water stress is an environmental factor that can regulate growth, limit production and lead to physiological and biochemical changes. Plants present a series of adaptive responses to drought, such as osmotic adjustment, in which carbohydrates play an important role. To evaluate the influence of water deficit on carbohydrates accumulation in V. discolor, the plants were divided into two groups: daily watering and water suppression for 14 days being re-watering after this period. Leaves and roots were collected at 0, 3, 6, 9, 12, 15 and 18 days, for ecophysiological and biochemical analyzes. Variations in carbohydrate contents in V. discolor showed a close relationship with changes in the plant water status, with higher concentrations of soluble sugars, total fructans, oligosaccharides, reducing sugars coinciding with the lower values of soil moisture and leaf water potentials and relative water content. In the tuberous roots, there is an increase in carbohydrate concentrations after re-watering. The increase of these low molecular weight carbohydrates is involved in osmotic adjustment and therefore acts to protect against dehydration.

É inegável a importância de diferentes matrizes energéticas no processo de desenvolvimento da sociedade, contudo, o consumo de combustíveis fósseis tem aumentado a poluição atmosférica e se tornado uma grave ameaça à saúde da população. O diesel, mesmo que seu uso seja inferior ao da gasolina, possui um perfil de emissões muito mais nocivo. Os biocombustíveis são uma alternativa presente e eficiente na mitigação dos gases do efeito estufa e material particulado na substituição ou na mistura com os combustíveis fósseis. Pesquisas apontam que os sistemas mais afetados pela dessa poluição são os respiratórios, circulatórios e reprodutivos. Dados recentes da Organização Mundial da Saúde (OMS) mostram que somente o material particulado é responsável por 7 milhões de mortes no mundo em função principalmente de problemas respiratórios. O presente estudo pesquisou na literatura científica os benefícios na produção de biodiesel e sua contribuição na mitigação dos efeitos negativos causados pela poluição atmosférica. O biodiesel, é capaz de reduzir substancialmente as emissões de gases provenientes da combustão incompleta do diesel fóssil e com o diferencial da captura de carbono (CO2) na fase do cultivo da soja, principal matéria prima brasileira.

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