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Allelopatyczny wpływ gryki zwyczajnej (Fagopyrum esculentum Moench) na procesy fizjologiczne i metaboliczne niektórych chwastów
No full textWydział PrzyrodniczyGryka zwyczajna należy do roślin posiadających silne właściwości allelopatyczne, lecz mechanizmy jej fitotoksycznego oddziaływania nie zostały w pełni poznane. Celem niniejszych badań było określenie wpływu ekstraktów i rozkładających się w glebie części roślinnych gryki na niektóre procesy fizjologiczne i metaboliczne popularnie występujących chwastów. Kolejnym celem była identyfikacja obecnych w glebie związków fenolowych pochodzących z gryki wraz z oceną ich wpływu na chwasty. Badania obejmowały określenie allelopatycznego wpływu gryki na kiełkowanie, wzrost i biomasę siewek 8 gatunków chwastów (chwastnicy jednostronnej, owsa głuchego, włośnicy sinej, miotły zbożowej, maruny bezwonnej, przytulii czepnej, żółtlicy drobnokwiatowej, wyki drobnokwiatowej). Przeprowadzono dwa rodzaje eksperymentów: (1) in vitro- z użyciem 1% wodnych ekstraktów z nadziemnych części gryki; (2) w glebie- zawierającej rozkładające się części roślinne (całe rośliny lub korzenie) gryki. Kolejny etap doświadczeń dotyczył oceny zmian metabolicznych zachodzących w tkankach roślin akceptorowych. Dokonano pomiarów zawartości białka i barwników fotosyntetycznych, a także na podstawie stopnia peroksydacji lipidów, wycieku elektrolitów oraz zmian profilu kwasów tłuszczowych, oceniono stopień uszkodzeń błon komórkowych badanych roślin. W celu zbadania odpowiedzi antyoksydacyjnej analizowano całkowitą zawartość związków fenolowych, flawonoidów i antocyjanów oraz całkowitą zdolność antyoksydacyjną i aktywność peroksydazy. Określono także wpływ resztek korzeni gryki na profil kwasów fenolowych i flawonoidów w liściach gatunków wrażliwych (chwastnica jednostronna, przytulia czepna) i niewrażliwych (miotła zbożowa, wyka drobnokwiatowa) na działanie gryki. Dodatkowym elementem badań było zidentyfikowanie związków fenolowych obecnych w glebie zawierającej resztki gryki. Uzyskane rezultaty wykazały, że wodny ekstrakt z gryki hamował wzrost korzeni wszystkich testowanych roślin akceptorowych, natomiast długość części nadziemnych była ograniczona jedynie u owsa głuchego i maruny bezwonnej. Ponadto ekstrakt z gryki powodował uszkodzenia błon plazmatycznych, hamowanie akumulacji białek oraz stymulację aktywności peroksydazy w komórkach korzeni owsa głuchego po 2 dniach trwania doświadczenia. Po dłuższym traktowaniu (5 dni) nie obserwowano zaburzeń analizowanych procesów, co może być związane z przystosowaniem do warunków stresowych lub obniżeniem poziomu związków fenolowych w ekstraktach. Resztki gryki w glebie hamowały kiełkowanie i wzrost 6 z 8 badanych gatunków. Większy wpływ hamujący wykazano w glebie z resztkami samych korzeni gryki. Obserwowana inhibicja wzrostu i rozwoju chwastów może być związana z obecnością w glebie kwasów fenolowych (p-kumarowego, o-kumarowego, m-kumarowego, ferulowego, kawowego, protokatecho-wego) i flawonoidów (apigeniny, witeksyny i orientyny) uwalnianych na skutek rozkładu resztek gryki. Stres allelochemiczny, indukowany resztkami gryki w glebie, skutkował obniżeniem poziomu barwników fotosyntetycznych i zmianami zawartości białka w tkankach chwastnicy jednostronnej i przytulii czepnej. W warunkach tych nie stwierdzono natomiast uszkodzeń błon komórkowych testowanych gatunków chwastów. Z kolei modyfikacje stosunku kwasów nienasyconych do nasyconych wystąpiły jedynie u chwastnicy jednostronnej. W tkankach badanych chwastów dochodziło także do zwiększenia potencjału antyoksydacyjnego, zmian aktywności peroksydazy oraz podwyższonej akumulacji związków fenolowych, co może wskazywać na wystąpienie stresu oksydacyjnego. Pod wpływem resztek korzeni gryki nie stwierdzono jednak specyficznych modyfikacji składu kwasów fenolowych i flawonoidów w liściach roślin określonych jako wrażliwe i niewrażliwe, lecz wspólną ich reakcją w warunkach stresowych było podwyższenie zawartości glikozydów tych związków. Rezultaty prezentowanych badań powinny się przyczynić do lepszego poznania mechanizmów uwalniania związków allelopatycznych gryki, ich przemian w środowisku glebowym oraz fitotoksycznego oddziaływania na procesy metaboliczne chwastów, jak również wykorzystania praktycznego uzyskanej wiedzy w rolnictwie ekologicznym.The common buckwheat belongs to the plants that possess strong allelopathic potential, but the mechanisms of its phytotoxic action have not been fully understood. The purpose of the study was to determine the influence of extracts and decomposed buckwheat residues in soil on some physiological and metabolic processes of commonly occurring weeds. Another objective was to identify phenolic compounds coming from the buckwheat residues present in the soil, as well as to assess their impact on the weeds. The allelopathic influence of buckwheat was investigated on the germination, growth and seedlings biomass of 8 weeds species (barnyardgrass, wild oat, yellow foxtail, common windgrass, scentless mayweed, cleavers, gallant soldier, hairy vetch). Two types of experiments were conducted: (1) in vitro – using 1% water extracts prepared from aboveground parts of buckwheat; (2) in soil – where buckwheat residues (whole plants or roots) were incorporated. Second part of the experiments concerned to evaluate the changes in acceptor plants metabolism. For this purpose protein and photosynthetic pigments content were measured. Cell membrane damages of tested plants were evaluated as a degree of lipid peroxidation, electrolyte leakage and changes in fatty acids profile. In order to determine antioxidant response, the total phenols, flavonoids, anthocyanins and total antioxidant activity, as well as, peroxidase activity were analyzed. Likewise, the impact of decomposed buckwheat roots on the composition of phenolic acids and flavonoids in the leaves of sensitive (barnyardgrass, cleavers) and insensitive (common windgrass, hairy vetch) species were determined. An additional element of this research was to identify phenolic compounds present in the soil containing buckwheat residues. The results showed, that aqueous extracts from buckwheat inhibited the roots growth of all tested weeds, while the length of the aerial parts was inhibited only in wild oat and scentless mayweed. Moreover, buckwheat extracts caused plasma membranes damage, inhibited the accumulation of proteins and stimulated the peroxidase activity in wild oat roots after 2 days of the experiment. After prolonged treatment (5 days), there were no disturbances of the analyzed processes, which may be associated with adaptation to stressful conditions or reduction in the level of phenolics in the extracts. The residues of buckwheat in soil inhibited germination and growth in six of the eight species tested. Greater inhibitory effect was demonstrated when weeds were grown in soil with residues of buckwheat roots. The observed inhibition of growth and development of weeds can be associated with the presence of phenolic acids (p-coumaric, o-coumaric, m-coumaric, ferulic, caffeic, protocatechuic) and flavonoids (apigenin, vitexin and orientin) in the soil, released due to decomposition of buckwheat residues. The allelochemical stress, induced by buckwheat residues in soil, resulted in reduction of photosynthetic pigments levels and changes in protein content in the tissues of barnyardgrass and cleavers. In the same time there were no membranes damage in the tissues of the tested weed species. Moreover, changes in the unsaturated to saturated fatty acids ratio occurred only in barnyardgrass leaves. In the tissues of the examined weeds total antioxidant activity was enhanced. A higher accumulation of phenolic compounds and changes in peroxidase activity was noted, which may indicate the occurrence of oxidative stress. However, there were no specific modifications in the composition of phenolic acids and flavonoids in the leaves of the plants characterized as sensitive and insensitive to buckwheat residues, but their common reaction was an increased content of glycosides of these compounds. The results of this research should contribute to a better understanding of the mechanisms of releasing allelopathic compounds from buckwheat, their transformations in soil and its phytotoxic effects on the metabolic processes of weeds, as well as practical use of this knowledge in organic farming
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
Wpływ przechowywania na zawartość kwercetyny w suszonej i mrożonej szalotce [Effect of storage on quercetin content in frozen and dried shallot]
No full textThe studies on effects of freezing and drying on quercetin content in shallot, as well as storage time of obtained products, were carried out. Two landraces, marked PV-S and PV201, were taken for the studies. The process of drying was carried out using a semi-technological drier operated by forced airflow. Dried slices of shallot were stored in ambient temperature in closed glass containers, and quercetin was determined periodically. The process of drying and further 8 months of storage caused a small decrease (15 - 16%) of the quercetin level in shallot. During the process of freezing of sliced shallot and its subsequent storage over 8 months in temperature -21°C, the quercetin level declined slightly, too, although the decline was higher than in case of drying and storage of dried shallot
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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