Influência da colonização micorrízica arbuscular sobre a nutrição do quiabeiro

An experiment was carried out in greenhouse to determine the influence of inoculation of two groups of arbuscular mycorrhizae on the nutrition and radicular morphology of the okra plant (Abelmoschus esculentus (L.) Moench cv. Piranema. One group had only Acaulospora longula spores and the other a spore mixture of eight species: Glomus occultum, Glomus aggregatum, Glomus microcarpum, Acaulospora longula, Acaulospora morrowae, Sclerocystis coremioides, Sclerocystis sinuosa, Scutellospora pellucida. The experiment was held in greenhouse conditions with three levels of P (0, 10 and 60 kg ha-1 of P2O5), three samplings dates (22, 32 and 47 days) and four replications. The accumulation of N, P, K, Ca and Mg in roots and shoots, root area and their influx ratio were determined. The results made evident that the mixture of species was more efficient although there were higher ratios of influx with Acaulospora longula between 0 and 47th. day.Foram estudados em casa de vegetação alguns parâmetros de crescimento em plantas de quiabo (Abelmoschus esculentus (L.) Moench cv. Piranema) colonizadas por dois grupos de fungos micorrízicos arbusculares, com o objetivo de determinar a influência dos inóculos na nutrição e morfologia radicular do quiabeiro. Um grupo continha apenas esporos de Acaulospora longula (A) enquanto o outro, esporos de oito espécies: Glomus occultum, Glomus aggregatum, Glomus microcarpum, Acaulospora longula, Acaulospora morrowae, Sclerocystis coremioides, Sclerocystis sinuosa, Scutellospora pellucida. As plantas foram submetidas a três níveis de P (0, 10 e 60 kg ha-1 de P2O5) e coletadas em três diferentes idades (22, 32 e 47 dias), com quatro repetições para cada tratamento. Foi determinado o acúmulo de N, P, K, e Mg na raiz e parte aérea, bem como o influxo médio desses elementos e a área radicular. Os resultados indicaram, além da resposta positiva do quiabeiro ao P, uma maior eficiência da inoculação com mistura de espécies apesar de o influxo médio, determinado aos 47 dias, apresentar maiores valores para o tratamento com A. longula

Alumínio e nitrogênio, nas variações do pH e capacidade de troca catiônica em Brachiaria decumbens

Brachiaria decumbens was grown in nutrient solution with nitrogen applied either as NO3; or as NH4. Al was added (to four - week old plants) at 0, 0.75, 3, and 6 ppm, pH was read daily, and adjusted to 4.2 each 48 hours. Plants under NO3 were able to raise the solution pH up to 5 at Al levels up to 1.5 ppm. Above this level, plants under NO3 showed higher accumulation of Al and a marked reduction in root cation - exchange capacity (CEC). Changes in pH NO3 - fed plants were related to the size of root system but not to imbalances in (N+ P) - (Ca + K) uptake. Plants under NH4 showed an uniform trend in pH change, and no effects of Al levels on root and shoot Al contents were detected. Effects of Al levels on root CEC were much less accentuated in plants under NH4 than under NO3. The mechanisms through which N-carriers can affect the responses of Brachiaria plants to Al stress is discussed.Plantas de Brachiaria decumbens foram cultivadas em solução nutritiva, contendo Al (0; 0,75; 1,5; 3 e 6 ppm) e N(N-NO3 e N-NH4 ). A mudança do pH foi acompanhada durante quatro semanas, e o próprio pH foi ajustado para 4,2 a cada 48 horas. Plantas sob NO3; aumentaram o pH da solução acima de 5 até o nível de 1,5 ppm de Al; a partir desse nível, uma acumulação significativa de Al foi verificada nas raízes, o que resultou em drástica redução da capacidade de troca catiônica (CTC). Sob NO3, a variação do pH da solução guardou relação com o tamanho do sistema radicular, mas não com a magnitude da diferença entre o total de (N + P) - (Ca + K) absorvidos. Sob NH4 a acidificação da solução foi relativamente uniforme, embora o consumo de ácido tenha sido muito mais elevado que o de base para ajustar a solução ao pH de referência. Nas plantas sob NH4, não houve acumulação significativa de Al em raízes e parte aérea, e os efeitos de Al sobre a CTC foram menos pronunciados do que sob NO3. Aparentemente, a fonte de N condiciona as respostas ao Al tóxico, nesta forrageira, por mecanismos que são discutidos no texto

Eficiência do uso de nitrogênio para produção de grão e proteína por cultivares de arroz

A greenhouse experiment was conducted to evaluate the nitrogen use efficiency (EUN) in relation to grain production (PG) and crude protein content (PB) of nineteen cultivars of rice. Fifteen of them are adapted to soils of low levels of nutrients from the state of Maranhão, Brazil. They were chosen according to their contrasting capacity to accumulate proteins. The other four cultivars were bred to give high yields under optimal agricultural conditions. They were grown in pots with and without addition of foliar N (0.035 g N/plant) applied 10 and 20 days after flowering as N-URAN. All plants received 0.07 g of N/plant after planting. Nitrogen increased the level of protein production but did not influence PG. These results induced a lower EUN for grain and protein production for all cultivars. There were genotypic significative differences for EUN and its components: uptake and utilisation efficiency. Cultivars bred for higher yield had higher EUN due to its greater N uptake efficiency. To the non-bred ones, EUN was more dependent on higher capacity for N remobilization. The non-bred cultivars Arroz de Revenda, Cana Roxa, Ligeiro Vermelho and the bred IAC-899 and IAC-1278 had the greatest EUN values.Foi feito um experimento em casa de vegetação, para avaliar a eficiência do uso de nitrogênio (EUN) para produção de grão (PG) e de proteína bruta (PB), em dezenove cultivares de arroz. Quinze cultivares tradicionais do Estado do Maranhão, separadas por alto e baixo teor de PB, e quatro cultivares IAC melhoradas, foram cultivadas em vasos com solo, com dois níveis de N: sem suplementação (0,07 g N/planta, no plantio) e com suplementação foliar (0,035 g N/planta) aplicada 10 e 20 dias após a floração, na forma de URAN. A aplicação foliar aumentou o teor de PB mas não a PG, resultando em redução em EUNG e EUNP das cultivares. Houve diferenças genotípicas significativas quanto a EUN e seus componentes: eficiência de absorção, e eficiência de utilização. As cultivares melhoradas apresentaram maiores EUN, graças a sua maior eficiência de absorção. Quanto às tradicionais, as EUN resultaram mais associadas à eficiência de utilização. As cultivares Arroz de Revenda, Cana Roxa, e Ligeiro Vermelho entre as tradicionais e IAC-899 e IAC-1278 entre as melhoradas, apresentaram os maiores valores de EUN

Response of nitrate transporters and PM H + -ATPase expression to nitrogen flush on two upland rice varieties contrasting in nitrate uptake kinetics

These authors contributed equally to this work. Abstract The aim of this study was to evaluate the behavior of high-affinity nitrate (NO 3 -) transporters and plasma membrane H + -ATPase isoforms in rice varieties, contrasting in NO 3 -uptake kinetics parameters. Two varieties of rice were studied: cv. IAC-47 (improved for high N input) and cv. Piauí (a local landrace variety cultivated for low input farmers). We evaluated the expression of two PM H + -ATPase isoforms (OsA2 and OsA7), two NO 3 -transporters (OsNRT2.1 and OsNRT2.2), and OsNAR2.1, the rice regulatory genes for nitrate transport. The results showed that the Piauí variety has higher expression of OsNRT2.1-2.2, OsNAR2.1 and OsA2 and 7, compared to IAC-47 variety, mainly after 24h under low N condition. After 24h of 0.2 mM NO 3 --N resupply, the Piauí variety showed a net nitrate uptake and PM-H + -ATPase activity, 71% and 47% higher than IAC-47, respectively. This behavior of Piauí variety may be a strategy for better harnessing of available N that occurs in the tropical environment in a short period of time, after the onset of the rainy season. Changes in the expression levels of OsNRT2.1-2.2/OsNAR2.1 and OsA2 and 7 occur synchronously over time. Our results suggest the synchronized behavior of high affinity nitrate transporters and PM-H + -ATPases under N flush conditions

Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions

We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV

Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV

Peer reviewe

Elliptic flow of muons from heavy-flavour hadron decays at forward rapidity in Pb-Pb collisions at root s(NN)=2.76TeV

The elliptic flow, v(2), of muons from heavy-flavour hadron decays at forward rapidity (2.5 <y <4) is measured in Pb-Pb collisions at root s(NN)= 2.76TeVwith the ALICE detector at the LHC. The scalar product, two- and four-particle Q cumulants and Lee-Yang zeros methods are used. The dependence of the v(2) of muons from heavy-flavour hadron decays on the collision centrality, in the range 0-40%, and on transverse momentum, p(T), is studied in the interval 3 <p(T)<10 GeV/c. A positive v(2) is observed with the scalar product and two-particle Q cumulants in semi-central collisions (10-20% and 20-40% centrality classes) for the p(T) interval from 3 to about 5GeV/c with a significance larger than 3 sigma, based on the combination of statistical and systematic uncertainties. The v(2) magnitude tends to decrease towards more central collisions and with increasing pT. It becomes compatible with zero in the interval 6 <p(T)<10 GeV/c. The results are compared to models describing the interaction of heavy quarks and open heavy-flavour hadrons with the high-density medium formed in high-energy heavy-ion collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V.Peer reviewe

Pseudorapidity and transverse-momentum distributions of charged particles in proton-proton collisions at root s=13 TeV

The pseudorapidity (eta) and transverse-momentum (p(T)) distributions of charged particles produced in proton-proton collisions are measured at the centre-of-mass energy root s = 13 TeV. The pseudorapidity distribution in vertical bar eta vertical bar <1.8 is reported for inelastic events and for events with at least one charged particle in vertical bar eta vertical bar <1. The pseudorapidity density of charged particles produced in the pseudorapidity region vertical bar eta vertical bar <0.5 is 5.31 +/- 0.18 and 6.46 +/- 0.19 for the two event classes, respectively. The transverse-momentum distribution of charged particles is measured in the range 0.15 <p(T) <20 GeV/c and vertical bar eta vertical bar <0.8 for events with at least one charged particle in vertical bar eta vertical bar <1. The evolution of the transverse momentum spectra of charged particles is also investigated as a function of event multiplicity. The results are compared with calculations from PYTHIA and EPOS Monte Carlo generators. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe