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Can foliar pulverization with CaCl2 and Ca(NO3)2 trigger Ca enrichment in solanum tuberosum L. tubers?
Publication . Coelho, Ana Rita F.; Lidon, Fernando C.; Pessoa, Cláudia Campos; Marques, Ana Coelho; Luís, Inês Carmo; Caleiro, João; Simões, Manuela; Kullberg, José; Legoinha, Paulo; Brito, Maria; Guerra, Mauro; Leitão, Roberta G.; Galhano, Carlos; Scotti-Campos, Paula; Semedo, José N.; Silva, Maria Manuela; Pais, Isabel P.; Silva, Maria José; Rodrigues, Ana P.; Pessoa, Maria F.; Ramalho, José C.; Reboredo, Fernando H.; DCT - Departamento de Ciências da Terra; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; LIBPhys-UNL; DQ - Departamento de Química; DF – Departamento de Física; MDPI - Multidisciplinary Digital Publishing Institute
This study aimed to assess the efficiency of Ca enrichment in tubers of three genotypes of Solanum tuberosum L., through foliar spraying with CaCl2 and Ca(NO3)2 solutions. In this context, soil heterogeneity of three potato-growing fields, as well as the implications of Ca accumulation among tissues and some quality parameters were assessed. Three potato varieties (Agria, Picasso and Rossi) were grown in three production fields and during the life cycle, four pulverizations with calcium chloride (3 and 6 kg ha−1) or calcium nitrate (0.5, 2 and 4 kg ha−1) were applied. For screening the potential phytotoxicity, using Agria as a test system, the potential synthesis of photoassimilates was determined, and it was found that after the 3rd Ca application, leaf gas exchanges were moderately (net photosynthesis), to strongly (stomatal conductance) affected, although without impact on Ca accumulation in tubers. At harvest, the average Ca biofortification index varied between 5–40%, 40–35% and 4.3–13% in Agria, Picasso and Rossi, respectively. Moreover, the equatorial region of the tubers in general showed that Ca accumulation prevailed in the epidermis and, in some cases, in inner areas of the potato tubers. Biofortified tubers with Ca also showed some significant changes in total soluble solids and colorimetric parameters. It is concluded that Ca enrichment of potato tubers through foliar spraying complemented the xylem mass flow of Ca from roots, through phloem redistribution. Both fertilizers showed similar efficiency, but Rossi revealed a lower index of Ca accumulation, eventually due to different metabolic characteristics. Although affected by Ca enrichment, potato tubers maintained a high quality for industrial processing.
High-precision measurements of n=2→n=1 transition energies and level widths in He-and Be-like argon ions
Publication . Machado, J.; Szabo, C. I.; Santos, J. P.; Amaro, P.; Guerra, Mauro; Gumberidze, A.; Bian, Guojie; Isac, J. M.; Indelicato, P.; DF – Departamento de Física; LIBPhys-UNL; American Physical Society
We performed a reference-free measurement of the transition energies of the 1s2p1P1→1s21S0 line in He-like argon, and of the 1s2s22p1P1→1s22s21S0 line in Be-like argon ions. The highly charged ions were produced in the plasma of an electron-cyclotron resonance ion source. Both energy measurements were performed with an accuracy better than 3 parts in 106, using a double flat-crystal spectrometer, without reference to any theoretical or experimental energy. The 1s2s22p1P1→1s22s21S0 transition measurement is the first reference-free measurement for this core-excited transition. The 1s2p1P1→1s21S0 transition measurement confirms recent measurement performed at the Heidelberg electron-beam ion trap. The width measurement in the He-like transition provides test of a purely radiative decay calculation. In the case of the Be-like argon transition, the width results from the sum of a radiative channel and three main Auger channels. We also performed multiconfiguration Dirac-Fock calculations of transition energies and rates and have done an extensive comparison with theory and other experimental data. For both measurements reported here, we find agreement with the most recent theoretical calculations within the combined theoretical and experimental uncertainties.
Revisiting the Fe xvii Line Emission Problem: Laboratory Measurements of the 3s-2p and 3d-2p Line-formation Channels
Publication . Shah, Chintan; López-Urrutia, José R.Crespo; Gu, Ming Feng; Pfeifer, Thomas; Marques, José; Grilo, Filipe; Santos, José Paulo; Amaro, Pedro; LIBPhys-UNL; DF – Departamento de Física; AAS - American Astronomical Society
We determined relative X-ray photon emission cross sections in Fe xvii ions that were mono-energetically excited in an electron beam ion trap. Line formation for the 3s (3s-2p) and 3d (3d-2p) transitions of interest proceeds through dielectronic recombination (DR), direct electron-impact excitation (DE), resonant excitation (RE), and radiative cascades. By reducing the electron-energy spread to a sixth of that of previous works and increasing counting statistics by three orders of magnitude, we account for hitherto unresolved contributions from DR and the little-studied RE process to the 3d transitions, and also for cascade population of the 3s line manifold through forbidden states. We found good agreement with state-of-the-art many-body perturbation theory (MBPT) and the distorted-wave (DW) method for the 3s transition, while in the 3d transitions known discrepancies were confirmed. Our results show that DW calculations overestimate the 3d line emission due to DE by ∼20%. Inclusion of electron-electron correlation effects through the MBPT method in the DE cross-section calculations reduces this disagreement by ∼11%. The remaining ∼9% in 3d and ∼11% in 3s/3d discrepancies are consistent with those found in previous laboratory measurements, solar, and astrophysical observations. Meanwhile, spectral models of opacity, temperature, and turbulence velocity should be adjusted to these experimental cross sections to optimize the accuracy of plasma diagnostics based on these bright soft X-ray lines of Fe xvii.
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Fundação para a Ciência e a Tecnologia
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5876
Número da atribuição
147413