Estimulação do enraizamento de estacas de Vitis rotundifolia Michx

A videira muscadínia, nativa da Flórida, têm-se distinguido pela produtividade, resistência a pragas e doenças e pela característica de desbastar-se facilmente na colheita, possibilitando sua comercialização em cestas, de forma semelhante ao morango. As dificuldades na propagação desse grupo de videira têm impedido sua disseminação na região tropical úmida, em áreas onde a exploração de outras videiras tem sido dificultada pela alta incidência de doenças. O objetivo desse trabalho foi estabelecer o sistema mais adequado de propagação vegetativa de Vitis rotundifolia Michx., utilizando estacas a picáis, medianas e basais, tratamentos com auxina e com baixa temperatura. Verificou-se que o enraizamento de estacas basais e medianas da videira muscadínia foi mais eficiente do que o de estacas apicais. Tratamento das estacas com temperatura de 4°C por 24 horas, ou imersão das estacas em solução de Exuberone 10 e 20 ml.l-1, promoveram o enraizamento de estacas medianas e basais, respectivamente. O desenvolvimento da parte aérea das estacas basais e medianas da videira mostrou-se superior no tratamento com baixa temperatura.The muscadine grape (Vitis rotundifolia Michx.) is native to Florida and has been cultivated for many years in U.S.A. It is harvested as single berries instead of in bunches and has small leaves. The fruit skin is thicker than those of bunch-type grapes. One reason for its popularity is that the muscadine is seldom seriously affected by diseases or insects. The muscadine grape is not readily propagated by hardwood cuttings, therefore the present work was carried out to develop a method for commercial propagation of its cuttings, using treatments with growth regulators (auxins) and low temperature. The results showed that the rooting of both basal and middle shoots of muscadine grape is better than the rooting of terminal sections of the shoots. Cuttings treated with low temperature (4°C) during 24 hours, or immersion of the cutting's bases in solutions of Exuberone 10 and 20 ml.l-1, promoted rooting of middle and basal cuttings, respectively. The growth of leaves in both basal and middle cuttings was superior in the treatment with low temperature

Physical property characterization of single step synthesized NdFeAsO0.80F0.20 bulk 50K superconductor

We report an easy single step synthesis route of title compound NdFeAsO0.80F0.20 superconductor having bulk superconductivity below 50 K. The title compound is synthesized via solid-state reaction route by encapsulation in an evacuated (10-3 Torr) quartz tube. Rietveld analysis of powder X-ray diffraction data shows that compound crystallized in tetragonal structure with space group P4/nmm. R(T)H measurements showed superconductivity with Tc (R=0) at 48 K and a very high upper critical field (Hc2) of up to 345 Tesla. Magnetic measurements exhibited bulk superconductivity in terms of diamagnetic onset below 50 K. The lower critical field (Hc1) is around 1000 Oe at 5 K. In normal state i.e., above 60 K, the compound exhibited purely paramagnetic behavior and thus ruling out the presence of any ordered FeOx impurity in the matrix. In specific heat measurements a jump is observed in the vicinity of superconducting transition (Tc) along with an upturn at below T=4 K due to the AFM ordering of Nd+3 ions in the system. The Thermo-electric power (TEP) is negative down to Tc, thus indicating dominant carriers to be of n-type in NdFeAsO0.80F0.20 superconductor. The granularity of the bulk superconducting NdFeAsO0.8F0.2 sample is investigated and the intra and inter grain contributions have been individuated by looking at various amplitude and frequencies of the applied AC drive magnetic field.Comment: 26pages text + Figures: comments/suggestions welcome ([email protected] & http://www.freewebs.com/vpsawana