Characterization of volatile production during seed storage

This paper contributes to the understanding of factors that regulate seed longevity and mechanisms that cause seed deterioration during storage. The over-all goal is to characterize the types of chemical reactions that occur in dry seeds and to relate these to the properties of the seed glassy matrix and the inevitable decline in seed quality and viability. Oxidation and peroxidation reactions occur in stored seeds and are implicated in chemical degradation. Oxidation of macromolecules gives rise to low molecular weight carbonyl compounds, many of which are volatile and so escape into the airspace of the storage container. The identity of volatile compounds indicates the nature of chemical reactions. Production of volatile compounds from seeds of different species was investigated. Volatile composition produced by seeds differs with the species: species such as Carum carvi were detected to produce large amounts of volatile compounds, while others, such as Eruca sativa, produced low quantities of only a few compounds. Qualitative and quantitative differences in volatile composition were noted as a function of storage RH: above about 30% RH glycolysis-like reactions increase with increasing RH, and below about 30% RH peroxidation-like reactions increase with decreasing RH. Assessment of volatile production from seeds during storage provides a probe to address questions about the nature and kinetics of chemical reactions that occur in the glassy matrix of stored seeds. This information reveals important information about the glass such as the proximity of reacting ligands and inter- or intra-molecular motions required to effect chemical reactions. Moreover, it could be developed as a non-invasive and early detection method of seed ageing rates

Morphological and germination response variability in seeds of wild yellow gentian (Gentiana lutea L.) accessions from northwest Spain

Gentiana lutea L. (yellow gentian, Gentianaceae) is an important medicinal plant under protection as endangered species in most European countries. The aim of this work was to evaluate variation in seed mass, seed water content, and seed germination among 56 wild accessions of G. lutea. The effect of gibberellic acid (GA3), putrescine, moist chilling, and level of ripeness of seeds on subsequent germination was also investigated. Seeds of G. lutea showed physiological dormancy (final germination percentages ranged from 0% to 11%, depending on the accession) and GA3 enhanced seed germination drastically in all the accessions. The highest germination (99%) of GA3-treated seeds was reached at 15 °C. Final germination percentage and germination rate (as expressed by mean germination time), as well as seed mass and seed water content, varied significantly among accessions. In general, 1 year moist chilling did not significantly enhance G. lutea seed germination. For most accessions, no significant differences were found between fully ripe seeds and less ripe seeds for seed water content, seed mass, and seed germination. Applications of GA3 were always most effective than those of putrescine for increasing seed germination

Integral field spectroscopy of HII regions in M33

Integral field spectroscopy (IFS) is presented for star forming regions in M33. A central area of 300 x 500 pc^2 and the external HII region IC 132, at a galactocentric distance {\sim} 19arcmin (4.69 kpc) were observed with the Potsdam Multi Aperture Spectrophotometer (PMAS) instrument at the 3.5 m telescope of the Calar Alto Hispano- Alem\'an observatory (CAHA). The spectral coverage goes from 3600 A to 1{\mu}m to include from [OII]{\lambda}3727 A to the near infrared lines required for deriving sulphur electron temperature and abundance diagnostics. Local conditions within individual HII regions are presented in the form of emission line fluxes and physical conditions for each spatial resolution element (spaxel) and for segments with similar H{\alpha} surface brightness. A clear dichotomy is observed when comparing the central to outer disc HII regions. While the external HII region has higher electron temperature plus larger H{\beta} equivalent width, size and excitation, the central region has higher extinction and metal content. The dichotomy extends to the BPT diagnostic diagrams that show two orthogonal broad distributions of points. By comparing with pseudo-3D photoionization models we conclude that the bulk observed differences are probably related to a different ionization parameter and metallicity. Wolf-Rayet features are detected in IC 132, and resolved into two concentrations whose integrated spectra were used to estimate the characteristic number of WR stars. No WR features were detected in the central HII regions despite their higher metallicity.Comment: 72 pages, 37 figure

Fast measurement of cooling and heating rates in standard cryopreservation protocols based on vitrification

Estudio de la cinética de la crioconservación de tejidos vegetale

Glassy State and Cryopreservation of Mint Shoot Tips

Vitrification refers to the physical process by which a liquid supercools to very low tem- peratures and finally solidifies into a metastable glass, without undergoing crystallization at a practical cooling rate. Thus, vitrification is an effective freeze-avoidance mechanism and living tissue cryopreservation is, in most cases, relying on it. As a glass is exceedingly vis- cous and stops all chemical reactions that require molecular diffusion, its formation leads to metabolic inactivity and stability over time. To investigate glassy state in cryopreserved plant material, mint shoot tips were submitted to the different stages of a frequently used cryopreservation protocol (droplet-vitrification) and evaluated for water content reduction and sucrose content, as determined by ion chromatography, frozen water fraction and glass transitions occurrence by differential scanning calorimetry, and investigated by low-tempera- ture scanning electron microscopy, as a way to ascertain if their cellular content was vitri- fied. Results show how tissues at intermediate treatment steps develop ice crystals during liquid nitrogen cooling, while specimens whose treatment was completed become vitrified, with no evidence of ice formation. The agreement between calorimetric and microscopic observations was perfect. Besides finding a higher sucrose concentration in tissues at the more advanced protocol steps, this level was also higher in plants precultured at 25/21?C than in plants cultivated at 25?C

Optimizing seed conservation protocols and cryopreservation at the CRF-INIA genebank to reduce genetic erosion

The CRF-INIA is the Spanish National Centre for Plant Genetic Resources where a duplicate of all seed active collections belonging to the Spanish Network of the National PGR Program should be deposited. First samples date from 1980?s. Nowadays, the long term collection (base collection) comprises approximately 39,000 samples. The CRF-INIA genebank also maintains the largest active collection in Spain, with up to 22.000 accessions, meanly of cereals and grain legumes. At the CRF-INIA genebank the seed conservation protocol follows the FAO/IPGRI recommendations: seed desiccation at 13-15% RH and 20 °C, and storage at -4 or -18 °C, for the active and base collections, respectively. Seed viability monitoring is performed systematically through germination tests. For most species, the current conservation protocol shows good performance (Martín et al. 2014). However, in some plant groups there is an accumulation of samples with low longevity, for which sample regeneration is costly. For example, after 20 or 30 years of storage, some accessions of Brassica ssp., Lactuca sativa or Secale cereale, have shown low seed viability after storage. In some cases, samples with low germination rates might be not only due to low longevity but also to other reasons, such as problems with dormancy interfiering with the germination test performance and low initial quality of the samples. The general aim of this project is to find alternative storage protocols to reduce genetic erosion, present and future, of the conserved material at the CRF-INIA seedbank. Cryoconservation of seeds at different water contents are being tested in species with low seed longevity and of problematic regeneration (rye, onion and cabbage). Results would be compared to the conventional storage at -18 °C after medium/long term storage

Conductivity test in seeds of different passion flower species

The objective of this work was to evaluate the use of the conductivity test as a means of predicting seed viability in seven Passiflora species: P. alata, P. cincinnata, P. edulis f. edulis, P. edulis f. flavicarpa, P. morifolia, P. mucronata, and P. nitida. Conductivity of non?desiccated (control), desiccated, and non?desiccated cryopreserved seeds was determined and related to their germination percentage. The obtained results suggest that the electrical conductivity test has potential as a germination predictor for P. edulis f. flavicarpa seed lots, but not for the other tested species. Index terms: Passiflora, seed cryopreservation, seed desiccation, seed viability

Mejoramiento barrial en Itaca

La propuesta se basa principalmente en dos ejes: la ordenación del territorio de una forma natural, eficiente y ordenada, con una ocupación del espacio y expectativas de mejora progresivas a partir de unos centros de servicios comunes entorno al agua; y el desarrollo y conexión de los centros de producción, tanto los ya existentes en Matola y los previstos en entorno inmediato, como los propuestos en la actuación

Manejo en bancos de germoplasma: estrategia para la ruptura de dormición de semillas de leguminosas

La gestión de los bancos de germoplasma mediante la conservación de semillas se encuentra en ocasiones con dificultades técnicas que pueden llegar a hacer su tarea poco eficiente. Una de esas dificultades puede ser el llevar a cabo los ensayos de viabilidad de las semillas de forma que los resultados se acerquen lo más posible a la verdadera situación de los lotes estudiados. Este aspecto tiene especial importancia en aquellos casos en los que las semillas presentan dormición. Una característica de las semillas de especies de la familia Fabaceae es presentar cubiertas duras. En estos casos la estrategia a aplicar se basa en utilizar tratamientos de escarificación. Sin embargo, en ocasiones, la variabilidad dentro de un lote de semillas y entre lotes (por ejemplo distintas poblaciones de una misma especie) puede ser muy elevada. El objetivo de este trabajo fue estudiar la variabilidad de la dureza de las cubiertas seminales entre cuatro poblaciones de cada una de estas especies: Medicago polymorpha, Trifolium glomeratum y T. subterraneum. Estas especies presentan además semillas de muy pequeño tamaño que dificultan los tratamientos de escarificación. Se utilizaron diversos tratamientos de escarificación que incluían el lijado de las semillas y tratamientos térmicos (frío, calor o cambios bruscos de temperatura). Los mejores tratamientos variaron con las especies y se pudo determinar aquellos que dieron los mejores resultados en las cuatro poblaciones estudiadas, de forma que la germinación aumentó desde un 0-10 % de las semillas control a 84-100 % en las escarificadas. Mediante el equipo Texture Analyzer TAXTPLUS se midió la dureza de las semillas, en relación a su resistencia a la rotura. Se observó una gran variabilidad dentro de cada población y entre poblaciones. La contribución en la reducción de la dureza de las cubiertas del mejor tratamiento de escarificación varió entre especies y entre poblaciones. Se discute la utilidad del estudio previo de la dureza de las semillas para determinar el mejor tratamiento a emplear. Agradecimientos: Proyecto RF2012-00014-C02-0