1,720,986 research outputs found
DON on wheat crop residues: effects on mycobiota as a source of potential antagonists of Fusarium culmorum
No full textFusarium culmorum, a pathogenic fungal species associated with Fusarium Head Blight (FHB) of wheat, can produce the mycotoxin deoxynivalenol (DON) that is frequently found as contaminant in cereals. Wheat haulms, as decomposing plant material, are an important inoculum source of F. culmorum for subsequent crops. In the present work we exploited the mycobiota of haulms buried in natural soil as a source of potential antagonists of F. culmorum and evaluated the role played by DON in determining the composition of such mycobiota. DON was added to wheat haulm pieces that were incubated in three natural soils, namely sandy, clayey and mixed, all with a previous history of wheat cultivation. Composition of mycobiota associated with DON-treated cultural debris was evaluated and compared with mycobiota from control haulms, in order to evaluate the effect of soil type and of the presence of the mycotoxin. Our results showed that DON affected neither the number nor species profile of fungal isolates. Among fungi associated with cultural debris, thirty-nine Pythium spp. isolates were collected and five of them, both from treated and not treated haulms, were tested for their antagonistic ability against F. culmorum. The two strains showing the highest antagonistic activity were further tested against F. oxysporum, a species considered a major competitor of F. culmorum for wheat residues, and frequently recovered from haulms in our experiments. The two Pythium spp. isolates showed a positive antagonistic and mycoparasitic activity against F. culmorum, without affecting the growth of F. oxysporum. Mycobiota of haulms buried in soil represents an interesting source of potential antagonists and competitors for future exploitation in a multitrophic approach for biocontrol of FHB
Fusariosi e grano tenero:quali sono le varietà più resistenti
No full textL’esperienza condotta ha fornito informazioni di interesse per le diverse figure professionali coinvolte nel gruppo di lavoro e più in generale per i diversi operatori della filiera cerealicola. Per quanto concerne in particolare i costitutori, si sono potute evidenziare valide fonti di resistenza da affiancarea quelle più note. Sarà quindi possibile inserire scientemente nei programmi di incrocio ulteriore germoplasma dotato di maggiori potenzialità agronomiche, rispetto a varietà esotiche (ad esempio Sumai 3) che associano ai pregi gati alla resistenza a FHB molteplici altre caratteristiche negative (ad esempio sensibilità ad altre fitopatie). La metodica messa a punto ha inoltre confermato la possibilitàdi effettuare uno screening per resistenza a FHB su di un elevato numero di genotipi, con adeguata riproducibilità dei risultati negli anni. Ne deriva l’opportunità di lavorare con continuità a un’attivitàdi selezione che trova nella discontinuità dell’infezione naturale un fattore limitante l’efficacia del breeding. Per la ricerca di base si rendono disponibili ulteriori genotipi, le cui caratteristiche di resistenza attiva potranno essere indagate in studi di metabolomica e genomica, allo scopo di cquisire conoscenze fruibili in programmi di selezione assistita (MAS), per l’ accumulo di fattori utili in germoplasma coltivabile.
La caratterizzazione effettuata su varietà di interesse commerciale offre agli operatori di filiera indicazioni per integrare le conoscenze disponibili, in particolare laddove la scelta varietale assume una valenza strategica nel piano colturale. In tal senso si pensi agli agricoltori che si trovano a produrre in condizioni di elevato rischio d’infezione (ad esempio dopo mais, semina su sodo e ambienti a elevata frequenza di FHB) o che devono comunque puntare all’ottenimento di livelli particolarmente contenuti della contaminazione da DON (ad esempio prodotti per l’infanzia). In conclusione, va rimarcato che le positive sinergie create all’interno del gruppo di lavoro consentiranno la prosecuzione dell’iniziativa, con l’intento di fornire utili contributi e aggiornamenti alla filiera cerealicola nazionale
Attività di fungicidi IBS verso gli agenti della fusariosi della spiga del frumento e loro influenza sul contenuto di deossinivalenolo nelle cariossidi
No full textNelle annate agrarie 2005-06 e 2006-07 è stata saggiata su frumento duro e tenero l’attività di alcuni fungicidi IBS (tebuconazole, epoxiconazole, prothioconazole, metconazole, prothioconazole+tebuconazole, epoxiconazole+prochloraz, cyproconazole+prochloraz e propi-
conazole+ prochloraz), applicati ad inizio fioritura (GS 60-61), verso Fusarium graminearum e F. culmorum due dei principali agenti causali della “fusariosi della spiga”.
Tutti i fungicidi hanno ridotto l’incidenza e la gravità della malattia con una efficacia media, variabile per la prima dal 51% al 69% e per la seconda dal 44 al 63%, e la percentuale di cariossidi infette con un’efficacia media compresa tra il 27% (epoxiconazole) ed il 58% (prothioconazole+tebuconazole). I medesimi fungicidi hanno, inoltre, garantito significativi incrementi medi di produzione (0,6-1,0 t/ha) e ridotto mediamente i livelli di deossinivalenolo (DON) nelle cariossidi da un minimo del 39% (epoxiconazole) ad un massimo dell’89% (propiconazole+prochloraz)
Effect of prothioconazole-based fungicides against Fusarium Head Blight and deoxynivalenol accumulation in wheat under field conditions
No full textFusarium head blight (FHB) of wheat is a disease caused mainly from fungi of the genus Fusarium and Microdochium nivale that, under favourable environmental conditions, can colonize plants during the production cycle and cause serious damages in terms of yields and quality of harvested grains. Deoxynivalenol (DON), a trichothecene mycotoxin produced by Fusarium culmorum and F. graminearum that can contaminate wheat causing haematic and anorexic syndromes and neurotoxic and immunotoxic effects in mammals, is often associated with FHB disesase.
Strategies for FHB control include the use of good agronomic practices (GAP), resistant varieties and effective fungicides. Prothioconazole is a triazolinthione fungicide with ideal systemic properties providing protective, curative and long lasting activity. In order to evaluate the effectiveness of prothioconazole-based treatments against FHB disease severity, grain yields and the consequent accumulation of DON in wheat kernels, several field experiments have been performed during four consecutive growing seasons (from 2004 to 2008) in the North of Italy. Fungicide treatments were carried out on different cultivars of soft wheat (Blasco and Serio) and durum wheat (Saragolla and San Carlo) after artificial inoculation with a mixture of toxigenic F. graminearum and F. culmorum strains. The application of fungicides containing prothioconazole at the beginning of anthesis (BBCH 61) resulted in a consistent reduction of FHB disease severity (by between 50 and 70%), a strong reduction of DON levels in wheat kernels (by between 40 and 90%), and an increasing of wheat yields ranging from 0.5 to 6.0 t ha-1 (average value 2.0 t ha-1), as compared to the untreated/inoculated control and to treatments with fungicides containing tebuconazole and cyproconazole plus prochloraz. These results show that the application of fungicides containing prothioconazole provide a strong reduction of the FHB disease, allowing both an increase in grain yields and a considerable reduction of DON content in the wheat kernels
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
Increase of Fumonisin B2 and Ochratoxin A Production by Black Aspergillus Species and Oxidative Stress in Grape Berries Damaged by Powdery Mildew
No full textPowdery mildew (PM), caused by the fungus Erysiphe necator, is one of the most widespread fungal disease of grape and may cause extensive openings on the berry surface during the infection.We evaluated the effect of damage caused by PMin grape berries on the growth of and mycotoxin production by Aspergillus and on the oxidative stress in infected berries. Berries of Vitis vinifera L. cv. Negroamaro with sound skin (SS) and those naturally infected by PM were surface sterilized and inoculated with either fumonisin B2 (FB2)-producing strains of Aspergillus niger or ochratoxin A (OTA)-producing strains of Aspergillus carbonarius and incubated at 20 and 30uC. The PM berries were significantly more susceptible to both Aspergillus colonization (5 to 15 times more susceptible) and OTA and FB2 contamination (2 to 9 times more susceptible) than were SS berries. The highest toxin concentration was detected in inoculated PM berries both for OTA (9 ng/g) at 20uC and for FB2 (687 ng/g) at 30uC. In inoculated SS and PM berries, although malondialdehyde and hydrogen peroxide concentrations did not increase, the two black Aspergillus species caused a significant decrease in ascorbate content, thus inducing a pro-oxidant effect. These results indicate that grape berries affected by PM are more susceptible to black Aspergillus growth and to production and/or accumulation of FB2 and OTA. Thus, preventive control of E. necator on grape berries could reduce the mycotoxicological risk from black Aspergillus infection
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
Bioremediation of aflatoxin B1-contaminated maize by king oyster mushroom (Pleurotus eryngii)
No full textAflatoxin B1 (AFB1) is the most harmful mycotoxin that occurs as natural contaminant of agricultural commodities, particularly maize. Practical solutions for detoxification of contaminated staples and reduction of agricultural wastes are scarce. We investigated the capability of the white-rot and edible fungus Plerotus eryngii (king oyster mushroom) to degrade AFB1 both in vitro and in a laboratory-scale mushroom cultivation, using a substrate similar to that routinely used in mushroom farms. In malt extract broth, degradation of AFB1 (500 ng/mL) by nine isolates of P. eryngii ranged from 81 to 99% after 10 days growth, and reached 100% for all isolates after 30 days. The growth of P. eryngii on solid medium (malt extract-agar, MEA) was significantly reduced at concentrations of AFB1 500 ng/mL or higher. However, the addition of 5% wheat straw to the culture medium increased the tolerance of P. eryngii to AFB1 and no inhibition was observed at a AFB1 content of 500 ng/mL; degradation of AFB1 in MEA supplemented with 5% wheat straw and 2.5% (w/v) maize flour was 71–94% after 30 days of growth. Further, AFB1 degradation by P. eryngii strain ITEM 13681 was tested in a laboratory-scale mushroom cultivation. The mushroom growth medium contained 25% (w/w) of maize spiked with AFB1 to the final content of 128 μg/kg. Pleurotus eryngii degraded up to 86% of the AFB1 in 28 days, with no significant reduction of either biological efficiency or mushroom yield. Neither the biomass produced on the mushroom substrate nor the mature basidiocarps contained detectable levels of AFB1 or its metabolite aflatoxicol, thus ruling out the translocation of these toxins through the fungal thallus. These findings make a contribution towards the development of a novel technology for remediation of AFB1- contaminated corn through the exploitation of the degradative capability of P. eryngii and its bioconversion into high nutritional value material intended for feed production
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
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