1,720,968 research outputs found
Non invasive vitality evaluation of tree seeds (Fagus sylvatica L.) by means of Magentic Resonance Image analysis
No full textGestione delle risorse genetiche nella filiera vivaistica del ciliegio selvatico (Prunus avium L.).
No full textAcorn storage in airtight polyethylene bag maintains high germination in recalcitrant holm oak (Quercus ilex L.)
No full textStorage of recalcitrant seeds of wild species is one of thorniest problems not yet resolved in forestry science. In particular, the acorns show a rapid deterioration and a sudden decrease in germination within the first year of storage. The aim of this work was to study phenomena related to the loss of germination of a Mediterranean recalcitrant forest species, the holm oak (Quercus ilex L.), possibly suggesting some treatments able to improve the storage of the oaks. Two different provenances were taken in order to check if the geographical area can affect the conservation of the seed lots. Three different treatments were applied to determine the best conservation method suited to increase seed storage: 1) standard conditions in plastic can with lid at +3°C with 60% RH, 2) stratification in sand and 3) airtight storage in thin polyethylene bags. During the crop year 2008-2009, every two months samples from each storage treatment were tested for moisture content and germination, two of the main characteristics of seed quality. Furthermore, leakage conductivity of acorns was measured as marker of seed membrane integrity. Preliminary data regarding some physiological markers involved in the decrease of the seed quality are presented, as possible explanation of the phenomenon; in particular the role played by oxidative stress during the storage process is discussed
Seed storage in polyethylene bags of a recalcitrant species (Quercus ilex): analysis of some bio-energetic and oxidative parameters
No full textSome technological and physiological aspects were analysed during seed storage of holm oak (Quercus ilex L.), a typical Mediterranean recalcitrant species. Considering the mild dormancy and desiccation sensitivity of these seeds, the influence of the storage environment on viability was examined. Acorns were maintained at low temperature and at high moisture content either inside thin polyethylene bags or mixed with peat in a bin. Storage in polyethylene bags, if compared with peat treatment, maintained optimal seed quality parameters. The effects of the two treatments on some physiological parameters were analysed during 1-year seed storage. Acorns stored in a bin with peat started to germinate early and exhibited a more rapid seed deterioration caused by metabolism-linked oxidative damage. The latter phenomenon was linked to a higher respiration and H 2O 2 level, induction of catalase activity, as well as lowered glutathione pool and ATP content. In addition, a more oxidized redox poise was observed. On the contrary, the plastic film of polyethylene, limiting gaseous exchanges, maintained acorn metabolic activity at low levels and allowed the accumulation of ethylene inside the storage atmosphere. These factors, inducing a dormant-like state, could have played a crucial role in prolonging seed storage. © 2012 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Stato energetico e capacità antiossidante in semi recalcitranti di leccio (Quercus ilex L.) conservati in sacchetti di polietilene.
No full textIl leccio (Quercus ilex L.) costituisce una tipica specie recalcitrante dell’area mediterranea che si caratterizza per una debole dormienza e per una spiccata sensibilità alla disidratazione nei semi. Per descrivere e comprendere meglio i meccanismi fisiologici e biochimici che sottostanno a queste peculiarità, sono stati misurati nel corso della conservazione alcuni parametri tecnologici e biologici. I semi, mantenuti in condizioni di elevata umidità e bassa temperatura, sono stati conservati secondo le usuali metodiche in bidoni riempiti con torba umida per un intero anno. Tale modalità è stata confrontata con una soluzione che prevedeva l’uso di sacchetti in polietilene. L’accorgimento adottato ha consentito di mantenere un livello accettabile di germinazione per un periodo superiore di circa 3 mesi rispetto al controllo e di rallentare il deterioramento del seme grazie a un miglior controllo dei danni provocati dal metabolismo ossidativo. La barriera costituita dal film plastico ha infatti limitato gli scambi gassosi, prevenendo le alterazioni dovute a una respirazione troppo elevata e alla liberazione di H2O2. L’ambiente ipossico ha mantenuto un miglior equilibrio ossidoriduttivo, preservando il contenuto di glutatione ridotto e di ATP. La conservazione nei sacchetti ha inoltre favorito l’accumulo di etilene nell’atmosfera di stoccaggio e ha abbassato le attività metaboliche dei semi, nonostante il loro intrinseco stato di debole dormienza. Un’appropriata modulazione di questi fattori biologici potrebbe consentire il prolungamento del periodo di conservazione in semi recalcitranti
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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