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Brazilian Journal of Plant Physiology, Volume: 21, Número: 2, Publicado: 2009
  • Influence of chromium in Laguncularia racemosa (L). Gaertn f. physiology Research Articles

    Rocha, Andréa C.; Canal, Emerson C.; Campostrini, Eliemar; Reis, Fabrício O.; Cuzzuol, Geraldo Rogério F.

    Resumo em Inglês:

    Most studies of chromium have been realized in the sediments and in mangrove trees. However, little is known about its effect on growth and metabolism in this vegetation. L. racemosa plants were grown in solution with 20% of ionic strength of Hoagland and Arnon containing 100 mM NaCl and supplemented with 0.00, 0.05 and 0.50 mg L-1 of Cr+3. The growth, the pigments and gas exchange measurements showed no changes in response to doses of chromium. After 30 days the initiation of treatments, plants of L. racemosa had average 0.559 g of total dry weight, 1.34 mg L-1 of total chlorophyll and 7.9 µmol m-2 s-1 of A (CO2 photosynthetic assimilation). The photochemical potential efficiency was affected by the intermediate dose of 0.05 mg L-1 of Cr+3 (Fv/Fm=0.73) and it was associated with improved translocation of chromium from root to leaves. L. racemosa accumulated Cr+3 in the root, especially in the highest dose (560 mg g-1 DW) representing twenty-eight times the value obtained in control. The concentration of chromium in stem and leaves was not influenced by the tested doses. There was a reduction of fructose and sucrose in the largest dose of chromium, suggesting the drain of these carbohydrates to meet the energy demand of root absorption. The results suggest that L. racemosa owns characteristics of a chromium-tolerant species.
  • Modulações na fotossíntese e respiração celular relacionadas à deficiência hídrica em videira (Vitis vinifera L.) cv. Carbernet Sauvignon Research Articles

    Martim, Sílvia A.; Santos, Mirella P.; Peçanha, Anderson L.; Pommer, Celso; Campostrini, Eliemar; Viana, Alexandre P.; Façanha, Arnoldo R.; Bressan-Smith, Ricardo

    Resumo em Português:

    A qualidade e produtivade das uvas viníferas têm sido relacionadas a privação regulada de irrigação, o que sugere implicações importantes para a bioenergética da planta. Quando submetidas ao déficit hídrico as videiras apresentam alterações globais na fotossíntese e na respiração. O objetivo deste trabalho foi avaliar as modulações promovidas pelo estresse hídrico na fotossíntese e respiração em folhas da cv. Cabernet Sauvignon (cv. CS) visando o melhor entendimento das respostas fisiológicas relacionadas com sua tolerância à seca e melhoria da qualidade sob estresse hídrico. Para tanto, mensurou-se a eficiência fotossintética, o potencial hídrico foliar, as trocas gasosas e o consumo de oxigênio. O potencial hídrico foliar, fotossíntese, condutância estomática, transpiração e concentração interna de carbono foram significativamente reduzidas com o estresse, sugerindo que as plantas da cv. CS apresentam alta eficiência no uso da água (A N/E) e baixa eficiência carboxilativa (A N/Ci) sob essa condição. Por outro lado, a respiração celular estimada pelo consumo de O2 aumentou mais que 70 % aos doze dias após a suspensão da irrigação, sendo a maior parte desse efeito relacionada a um aumento de quatro vezes na atividade da oxidase alternativa mitocondrial (AOX). Estes dados indicam um papel chave para a AOX nas respostas fisiológicas das videiras ao estresse hídrico, e implica que análises dos padrões de ativação da AOX podem ser úteis para programas que objetivam melhorar a consistência da produção e qualidade dos frutos pela suspensão controlada da irrigação em uvas viniferas.

    Resumo em Inglês:

    Winegrape productivity and quality has been related to the regulated deficit irrigation, with important implications for the plant bioenergetics. When water deficit is imposed to grapevine plants, alterations in overall photosynthesis and cell respiration are observed. The aim of this study was to assess the modulations promoted by water stress on photosynthesis and respiration in leaves of the cv. Cabernet Sauvignon (cv. CS) for better understanding the physiological responses related to its drought tolerance and quality improvement under water deficit. For this purpose, measurements of photosynthetic efficiency, leaf water potential, gas exchange and O2 consumption were carried out. Leaf water potential, photosynthesis, stomatal conductance, transpiration and internal carbon concentration were significantly reduced upon stress, suggesting that plants of cv. CS present higher water use efficiency (A N/E) and lower carboxylative capacity (A N/Ci) under this condition. On the other hand, cell respiration increased more than 70 % as estimated by the increase of O2 consumption measured 12 days after suspension of irrigation. Most of this effect was related to a four-fold increase of the mitochondrial alternative oxidase (AOX) activity. These data indicate a key role for the AOX pathway in the physiological responses of grapevines to water deficit, and it implies that analyses of the AOX activation patterns should be useful for programs aiming to improve the consistency of fruit production and quality of winegrape cultivars by regulated deficit irrigation.
  • Heavy metals, Co, Ni, Cu, Zn and Cd, produce oxidative damage and evoke differential antioxidant responses in spinach Research Articles

    Pandey, Nalini; Pathak, Girish C.; Pandey, Dharmendra K.; Pandey, Ritu

    Resumo em Inglês:

    Exposure of 10-d-old spinach (Spinacea oleracea L.) plants to excess (500 µM) concentrations of Co, Ni, Cu, Zn and Cd in sand culture inhibited growth, induced toxicity symptoms, oxidative damage and changes in the antioxidant defense system. The severity of the metal-induced effects varied with the metals and the duration of exposure to excess supply of the metals. Each metal induced chlorosis. In addition, excess Co, Ni and Cd also produced metal specific toxic effects. Excess supply of each metal caused lipid peroxidation (TBARS). Their effectiveness in producing oxidative damage was in the order: Ni > Co > Cd > Cu >Zn. Of all the metals, Ni was also most effective in lowering the concentration of the chloroplast pigments (Chl, Car). While each metal increased the concentration of ascorbate and activated the key enzymes of the ascorbate-glutathione cycle, excess Cd and Zn were more effective in this regard. Each metal increased the activity of SOD and POD and decreased the activity of CAT. Enhancement in SOD activity and inhibition of CAT activity suggested high build-up of H2O2, possibly the main cause of oxidative stress, induced in response to excess supply of the heavy metals.
  • Avaliação de características fisiológicas do arroz de terras altas para adaptação em sistemas de plantio direto Research Articles

    Heinemann, Alexandre B.; Stone, Luís Fernando; Fageria, Nand K.; Castro, Lucas M. de

    Resumo em Português:

    Na região dos Cerrados brasileiros, o plantio direto é uma prática alternativa de manejo que visa a conservação do solo e redução dos custos de produção. Entretanto, muitos estudos sinalizam que há redução na produtividade quando o arroz de terras altas é cultivado nesse sistema. Portanto, há necessidade que as novas iniciativas do melhoramento contemplem a introgressão de características favoráveis à adaptação do arroz ao plantio direto. Essas características incluem mais rápida emergência, habilidade para germinar quando semeado profundo, mais rápido desenvolvimento radicular, e fechamento do dossel mais cedo durante os estádios vegetativos. Todas essas características podem ser resumidas como "vigor inicial". Um experimento em casa de vegetação com quatro cultivares de arroz de terras altas (BRS Primavera, BRS Curinga, BRS Soberana, and Douradão) foi semeado em três diferentes datas e cultivado em condições potenciais de crescimento. Os estádios de desenvolvimento, matéria seca acumulada, área foliar, comprimento das folhas do colmo principal, taxa de elongação e duração das folhas foram medidos e calculados. Baseado nas informações fisiológicas obtidas, os quatro cultivares mostraram diferenças no ciclo de desenvolvimento. Entretanto, para a biomassa acumulada, área foliar e características relacionadas a expansão das folhas eles não diferiram significativamente. Assim, a não presença de um "vigor inicial" genético pode ser uma característica das cultivares modernas. Os padrões de crescimento e desenvolvimento foram significativamente afetados pelas datas de semeadura e não pelo cultivar.

    Resumo em Inglês:

    In the cerrado region of Brazil, no-tillage is an alternative management practice to conserve soil and reduce cost of crop production. However, many studies have been showed that there is a decrease in the yield when upland rice is cropped in this system. Therefore, there is a need that new breeding initiatives introgress favorable traits into upland rice for no-tillage adaptation. Key traits include faster emergence, ability to germinate when deep seeded, faster root development, and early canopy closure during the vegetative stages. All those traits can be summarized as "early vigor". So, the objective of this study was to evaluate physiological traits of four contrasting parental upland rice cultivars to verify their adaptation to no-tillage system. A greenhouse experiment with four upland rice cultivars (BRS Primavera, BRS Curinga, BRS Soberana, and Douradão) were planted at three different dates and growth at potential conditions. Development stages, total dry matter, leaf area, leaf dry matter, leaf length, leaf elongation rate and leaf duration were measured and calculated. Based on physiological traits, the four cultivars showed differences in the growth cycle. However, for biomass and leaf area growth and leaf expansion traits they did not differ significantly, probably being the lack of genetic "early vigor" a characteristic of the modern cultivars. The growth and development pattern was significantly affected by planting dates and not by cultivars.
  • I. Heat stress in Triticum: kinetics of Ca and Mg accumulation Research Articles

    Dias, Ana S.; Lidon, Fernando C.; Ramalho, José C.

    Resumo em Inglês:

    In heat stressed genotypes of Triticum aestivum L. (Sever and Golia) and Triticum turgidum subsp. durum (Acalou and TE 9306), chosen according to its genetic background diversity, Ca and Mg accumulations were correlated with its photosynthetic performance. It was found that with high temperatures the concentrations of Ca increased in the shoots, whereas the accumulation of Mg augmented only in bread wheat genotypes. Under heat stress, the pattern of electrolytes release in Golia and Acalou remained similar, but the extrusion rates became higher in Sever. During grain filling, the levels of total chlorophylls decreased in the heat stressed genotypes (excepting in Sever). In all the Triticum genotypes, stomatal conductance and the net carboxilation rate displayed similar trends. After anthesis, the net carboxilation rates did not vary in Acalou and TE 9306 but changed significantly in the heat stressed bread wheat, being found antagonistic patterns in both genotypes. During grain filling, the mean internal CO2 concentration only increased significantly in the heat stressed Golia. In Golia and TE 9306, the transpiration rates didn't vary between the control and heat stress treatments, but in Sever and Acalou, significant increases were found. Our data identified synergistic patterns among Ca, Mg, chlorophylls accumulation, and stomatal conductance, whose implications on photosynthesis are discussed.
  • II. Heat stress in Triticum: kinetics of Cu and Zn accumulation Research Articles

    Dias, Ana S.; Lidon, Fernando C.

    Resumo em Inglês:

    The interactions between high temperatures and Cu/Zn accumulation were investigated in bread and durum wheat. Plants were grown in a greenhouse, at two different temperatures regimes (control - 25/14ºC and heat stress - 31/20ºC), and the contents and uptake/translocation of Cu and Zn were evaluated during three developmental stages of plant growth (booting, grain filling and maturity). During grain filling and at maturity it was found that root, shoot and spike concentrations of Cu increased in heat stressed plants of the genotypes Golia and Acalou. The same trend was observed for root and shoot concentrations of Zn in both durum wheat genotypes. It was concluded that plants submitted to high temperatures (during the grain filling period) become more efficient in the Cu translocation to the shoots.
  • III.Heat stress in Triticum: kinetics of Na, K and P accumulation Research Articles

    Dias, Ana S.; Fernando, Ana L.; Lidon, Fernando C.

    Resumo em Inglês:

    Genotypes of bread and durum wheat were submitted to heat stress after anthesis and the accumulation of Na, K and P, at booting, grain filling and maturity, were investigated. It was found that, after anthesis, the levels of Na in shoots were considerably higher in durum relatively to bread wheat, being this trend also observed in the total plant accumulation. In these genotypes, heat stress affected significantly Na concentration in shoots. In general, heat stressed plants had significant higher levels of K in the shoots and the proportion of this nutrient translocation from the roots also increased with heat stress. In general, the levels of P didn't show significant differences with heat stress. The effects of heat stress among the wheat genotypes life cycle are characterized and discussed.
  • IV.Heat stress in Triticum: kinetics of Fe and Mn accumulation Research Articles

    Dias, Ana S.; Lidon, Fernando C.; Ramalho, José C.

    Resumo em Inglês:

    The interactions between Fe/Mn accumulation and the photosynthetic light reactions were investigated in heat stressed bread and durum wheat genotypes (Triticum aestivum L. and Triticum turgidum subsp.durum). Four genotypes were chosen according to its genetic background diversity. Plants were grown in a greenhouse at two different day/night temperatures regimes (control - 25/14ºC and heat stress - 31/20ºC), during the grain filling phase. The contents and uptake/translocation of Fe and Mn were evaluated on booting, grain filling and maturity and correlated with chlorophyll a fluorescence parameters. It was found that, under heat stress, the concentrations of Fe in the culm and leaves diminished in bread wheat, but increased in durum wheat. An opposite trend was found on the contents of Fe in the spike, being this effect higher in Sever. During grain filling, the concentrations of Mn in the heat stressed plants raised significantly in the shoot for all genotypes (excepting Golia). After anthesis, the proportion of Mn translocated also augmented with high temperatures. At maturity, the same trend was found in the translocated proportion of Fe. During grain filling, all the studied fluorescence parameters did not vary significantly except qP and qE that decreased in the heat stressed Golia and F V and Fv/Fm that increases in Acalou. It was concluded that under heat stress, during the grain filling period, Fe and Mn translocation to the shoots accelerates, eventually to overcome the negative effects on several photosynthetic physiological traits.
Brazilian Journal of Plant Physiology Centro de Ciências e Tecnologias Agropecuárias, , Universidade Estadual do Norte Fluminense Darcy Ribeiro - UENF, 28013-602 - Campos dos Goytacazes, RJ - Brazil, Fax: (+55)-22-2739-7116 - Campos dos Goytacazes - RJ - Brazil
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