Indução de perfilhamento em mudas de pupunheira (bactris gasipaes Kunth var. gasipaes Henderson)

Orientadora : Profª. Drª. Katia Christina Zuffellato-RibasCo-orientador : Prof. Dr.Henrique Soares KoehlerCo-orientador : Prof. Dr. Ivan WendlingDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Agrárias, Programa de Pós-Graduação em Agronomia. Defesa: Curitiba, 23/05/2013Bibliografia: f. 48-53Área de concentração: Produção vegetalResumo: Bactris gasipaes, popularmente conhecida como pupunheira, é uma espécie de palmeira pertencente à família Arecaceae. É cultivada em diversas regiões brasileiras, sendo o palmito o principal produto extraído dessa espécie. A principal característica da pupunheira é o perfilhamento, o que torna a cultura perene. Tendo em vista a escassez de estudos sobre técnicas de propagação vegetativa dessa espécie e que o aumento do número de perfilhos pode ajudar nessa metodologia, o presente estudo teve como objetivo a indução do perfilhamento em mudas de pupunheira submetidas a diferentes métodos de indução de perfilhamento, em 4 épocas distintas. Os experimentos foram conduzidos em estufa situada na Embrapa Florestas, município de Colombo - PR, utilizando mudas de Bactris gasipaes var. gasipaes provenientes de sementes. Os tratamentos constituiram-se de: 1) arqueamento do caule; 2) arqueamento do caule e aplicação de 150 mg kg-1 de citocininca (BAP); 3) arqueamento do caule e aplicação de 150 mg kg-1 de ácido giberélico (GA3); 4) anelamento do caule; 5) testemunha. Foram realizadas quatro instalações, nas épocas de agosto e dezembro/2011 e abril e agosto/2012, por um período de 90 dias cada. O delineamento estatístico foi inteiramente casualizado com 4 repetições por tratamento e 20 plantas por repetição. Também foram realizadas análises anatômicas na região do colo das plantas. Os tratamentos de arqueamento do caule foram ineficientes quanto à emissão de perfilhos, causando uma alta mortalidade das plantas. A maior mortalidade foi registrada para os tratamentos de arqueamento do caule com aplicação de reguladores vegetais, com 83,75% na época de instalação de dezembro/2011. O tratamento de anelamento apresentou baixa taxa de mortalidade (6,25%), igualando-se estatisticamente à testemunha. Em relação ao perfilhamento, o tratamento de anelamento diferiu estatisticamente da testemunha somente em agosto/2011, apresentando um total de 61,25% de mudas perfilhadas. Os resultados de sobrevivência para os tratamentos de arqueamento do caule foram baixos para as épocas de agosto e dezembro/2011, sendo o menor valor de 16,25% de mudas sobreviventes. Os resultados de sobrevivência para os tratamentos anelamento e testemunha foram altos, com a maior porcentagem para a testemunha na época de dezembro/2011 (88,75%). A indução do perfilhamento mostrou-se ineficiente quando aplicados os tratamentos de arqueamento do caule, sendo estes considerados muito invasivos. O tratamento de anelamento revelou um potencial em induzir o perfilhamento. As análises anatômicas realizadas possibilitaram caracterizar os tecidos na região do caule da espécie e a localização de seu meristema apical.Abstract: Bactris gasipaes, commonly known as peach palm, is a palm tree species which belongs to the Arecaceae family. It is cultivated in various regions of Brazil, being the heart of palm the main product obtained from this palm tree. The peach palm has the potential of emission of off-shoots, characterizing its cultivation as perennial. There are few studies about vegetative propagation technics for this species, and an improve of the numbers of off-shoots per palm plant could help enhance these methodologies. The present dissertation aimed to verify the induction of basal shoots in peach palm plants treated in 5 different off-shoots induction methodologies in 4 distinct months. The experiments were conducted in a greenhouse located at Embrapa Florestas, city of Colombo - PR, using young Bactris gasipaes var. gasipaes plants originated from seeds. The treatments were: 1) stem camber; 2) stem camber and application of 150 mg kg-1 of cytokinin (BAP); 3) stem camber and application of 150 mg kg-1 of gibberellic acid (GA3); 4) stem girdling; 5) witness. There were 4 experiments placed through 4 distinct months: August and December/2011 and April and August/2012, through a period of 90 days each. The experimental design was random with 4 repetitions per treatment and 20 plant per repetition. An anatomical analysis was conducted at the base of the stem of the plants. The stem camber treatments were inefficient in terms of basal shoots emission and causing great plant mortality. The highest mortality percentage was registered for the stem camber treatments with growth regulators (83.75%) in the month of december/2011. The girdling treatment presented a low mortality percentage (6.25%), being statistically equal to the witness treatment. For the variable emission of basal shoots, the stem girdling treatment was statistically different from the witness only for the month of August/2011, showing a percentage of 61.25 plants with off-shoots. The three stem camber treatments presented a low percentage of survival for the months of August and December/2011, being the minor value 16.25%. The results of the survival variable for the stem girdling and witness treatments were high, with the highest percentage for the witness being in the month of December/2011 (88.75%). The emission of off-shoots was inefficient when cambering treatments were applied, being considered too invasive. The girdling treatment showed a potencial to induce off-shoot emission. The anatomical analysis made provided a characterization of the plant stem tissues and the site of its meristematic apex

Optical response of metallic and insulating VO2 calculated with the LDA approach

We calculated the optical response of metallic and insulating VO2 using the LDA approach. The band structure calculation was based in the full-potential linear-muffin-tin method. The imaginary part of the dielectric function e2(w) is related to the different optical transitions. The Drude tail in the calculation of the metallic phase corresponds to intra-band d-d transitions. The calculation in the insulating phase is characterized by the transitions to the d||* band. The low frequency features, 0.0-5.0 eV, correspond to V 3d-V 3d transitions, whereas the high frequency structures, 5.0-12 eV, are related to O 2p-V 3d transitions. The calculation helps to explain the imaginary part of the dielectric function e2(w), as well as the electron-energy-loss and reflectance spectra. The results reproduce not only the energy position and relative intensity of the features in the spectra, but also the main changes across the metal-insulator transition and the polarization dependence. The main difference is a shift of about 0.6 eV in the calculation of the insulating phase. This discrepancy arises because the LDA calculation underestimates the value of the band gap

Importance of the V 3d-O 2p hybridization in the Mott-Hubbard material V2O3

We studied the changes in the electronic structure of V2O3 using a cluster model. The calculations included fluctuations from the coherent band in the metallic phase, and non-local Mott-Hubbard fluctuations in the insulating phase. The incoherent structure is mostly related to the usual ligand screening channel (3d2L). The coherent peak in the metallic phase corresponds to coherent band fluctuations (3d2C). The non-local screened state in the insulating phase (3d2D) appears at higher energies, opening the band gap. The photon energy dependence of the spectra is mostly due to the relative V 3d and O 2p cross sections. The present model reproduces also the observed changes in the V 1s core-level spectra. The above results suggest that the Mott-Hubbard transition in V2O3 requires a multi-band model.Comment: 4 pages, 4 figure

Estrutura eletronica e transição de fase metal-isolante composto VO2

Orientador: Miguel AbbateDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Curso de Pós-Graduaçao em Física. Defesa: Curitiba, 2007Inclui bibliografi

Indução de perfilhos em mudas de pupunheira.

A pupunheira é uma palmeira produtora de palmito com capacidade de perfilhamento, o que torna a cultura perene, sendo uma alternativa ao extrativismo ilegal de palmito nativo. Tendo em vista a importância e escassez de estudos sobre a propagação vegetativa dessa espécie e que o aumento do número de perfilhos é pré-requisito chave nessa metodologia, o presente trabalho teve por objetivo estudar diferentes métodos para indução de perfilhos em mudas de pupunheira em quatro épocas diferentes. Os tratamentos constituíram-se de: 1) arqueamento do caule; 2) arqueamento do caule com aplicação de 150 mg kg -1 de benzilaminopurina; 3) arqueamento do caule com aplicação de 150 mg kg-1 de ácido giberélico e; 4) anelamento do caule. O delineamento estatístico foi inteiramente casualizado, com 4 repetições de 20 plantas por tratamento. Estudos anatômicos dos caules foram realizados e a formação de perfilhos e mortalidade das plantas submetidas aos diferentes tratamentos avaliados. As análises anatômicas possibilitaram caracterizar os tecidos do caule e localizar o meristema apical. O arqueamento do caule não foi eficiente, enquanto o anelamento apresenta potencial para a indução de perfilhos

Materials Design using Correlated Oxides: Optical Properties of Vanadium Dioxide

Materials with strong electronic Coulomb interactions play an increasing role in modern materials applications. "Thermochromic" systems, which exhibit thermally induced changes in their optical response, provide a particularly interesting case. The optical switching associated with the metal-insulator transition of vanadium dioxide (VO2), for example, has been proposed for use in "intelligent" windows, which selectively filter radiative heat in hot weather conditions. In this work, we develop the theoretical tools for describing such a behavior. Using a novel scheme for the calculation of the optical conductivity of correlated materials, we obtain quantitative agreement with experiments for both phases of VO2. On the example of an optimized energy-saving window setup, we further demonstrate that theoretical materials design has now come into reach, even for the particularly challenging class of correlated electron systems.Comment: 4+x pages, 2 figure

Systematic tight-binding analysis of ARPES spectra of transition-metal oxides

We have performed systematic tight-binding (TB) analyses of the angle-resolved photoemission spectroscopy (ARPES) spectra of transition-metal (TM) oxides A$M$O$_3$ ($M=$ Ti, V, Mn, and Fe) with the perovskite-type structure and compared the obtained parameters with those obtained from configuration-interaction (CI) cluster-model analyses of photoemission spectra. The values of $\epsilon_d-\epsilon_p$ from ARPES are found to be similar to the charge-transfer energy $\Delta$ from O $2p$ orbitals to empty TM 3d orbitals and much larger than $\Delta-U/2$ ($U$: on-site Coulomb energy) expected for Mott-Hubbard-type compounds including SrVO$_3$. $\epsilon_d-\epsilon_p$ values from {\it ab initio} band-structure calculations show similar behaviors to those from ARPES. The values of the $p-d$ transfer integrals to describe the global electronic structure are found to be similar in all the estimates, whereas additional narrowing beyond the TB description occurs in the ARPES spectra of the $d$ band.Comment: 5 pages, 3 figure

Compensation temperatures and exchange bias in La1.5Ca0.5CoIrO6

We report on the study of magnetic properties of the La1.5Ca0.5CoIrO6 double perovskite. Via ac magnetic susceptibility we have observed evidence of weak ferromagnetism and reentrant spin glass behavior on an antiferromagnetic matrix. Regarding the magnetic behavior as a function of temperature, we have found that the material displays up to three inversions of its magnetization, depending on the appropriate choice of the applied magnetic field. At low temperature the material exhibit exchange bias effect when it is cooled in the presence of a magnetic field. Also, our results indicate that this effect may be observed even when the system is cooled at zero field. Supported by other measurements and also by electronic structure calculations, we discuss the magnetic reversals and spontaneous exchange bias effect in terms of magnetic phase separation and magnetic frustration of Ir4+ ions located between the antiferromagnetically coupled Co ions.Comment: 10 pages, 8 figures and supplemental materia