1,721,131 research outputs found
Soil-borne plant pathogenic fungi in relation to some collembolan species under laboratory conditions
No full textInteractions between springtails (Onychiurus armatus, O. tuberculatus, Folsomia candida) and plant pathogenic fungi (Gaeumannomyces graminis var. tritici, Fusarium culmorum, Bipolaris sorokiniana and Rhizoctonia cerealis) living in the same soil layer were investigated under laboratory conditions. The fungi are responsible for the foot and root disease complex of winter cereals and can cause serious reduction in yield. Since these species coexist in agricultural soils, feeding preference tests were performed in such a way that the springtails were allowed to interact simultaneously with all the tested fungi. O. armatus, O. tuberculatus and F. candida fed on the mycelia of G. graminis var. tritici, F. culmorum and R. cerealis: in the first hours of the trials individuals of all springtail species distributed themselves among the colonies, though moving from one to the other. Subsequently F. culmorum mycelium became the preferred food of all species tested; however, the other two fungi continued to be consumed. Mycelia of G. graminis var. tritici, F. culmorum and R. cerealis were shown to be an adequate food source for reproduction of Folsomia candida. Bipolaris sorokiniana mycelium had both repellent and lethal effects on F. candida and O, armatus is, whereas this fungus was lethal, although not repellent. for O. tuberculatus. Long-term experiments on T. candida indicate that conidia of B. sorokiniana were eaten and proved to be a sufficient diet for reproduction
Interactions between Collembola and soil-borne cereal pathogen fungi
No full textLaboratory studies on the interactions between some species of Collembola and the most important pathogenic fungi of the foot and root of cereals were performed. Onychiurus armatus and Onychiurus tuberculatus actively grazed on the hyphae of Gaeumannomyces graminis var. tritici, Fusarium culmorum and Rhizoctonia sp. They did not have a higly specific feeding preference; they fed on the mycelium of all the three fungi even when present contemporaneously.Experiments carried out utilising another cereal pathogenic fungus, Bipolaris sorokiniana, indicate that its hyphae were repellent and produced one or more non-volatile metabolites that were lethal at least for some species of Collembola. Our investigations suggest that B. sorokiniana did not produce the toxic metabolite or metabolites throughout its entire life cycle. The substance(s) is/are produced when only hyphae are present, whereas we observed that Onychiurus pseudogranulosus actively fed on conidia that the forms only later
Functional relationships between Collembola and plant pathogenic fungi of agricultural soils
No full textThe interactions between the collembolan Mesaphorura krausbaueri and four soilborne plant pathogenic fungi all living in the same layer of agricultural soil were studied under laboratory conditions. Mycelia of Gaeumannomyces graminis var. tritici, Fusarium culmorum and Rhizoctonia cerealis were palatable to Collembola and were a food source adequate for reproduction. Hyphae of Bipolaris sorokiniana were toxic and repellent for M. krausbaueri, but its conidia were eaten and proved to be a sufficient diet for reproduction. The four fungi fed had a different impact on the life processes of M. krausbaueri. Depending on the species of fungus, the animals produced significantly different numbers of eggs and had different life spans. In particular, animals fed with G. graminis var. tritici showed early maturation, early burst in egg production, early loss of fertility and early death. The different nutritional values of the four fungi pathogen for cereals might have a different influence on the life strategy of Collembola in the field. Thus, since these fungi usually coexist in agricultural soils, though in different percentages, this influence might also affect the capacity of different fungi to attack the plant and thus modulate the appearance of disease
Effects of Collembola on plant-pathogenic fungus interactions in simple experimental systems
No full textTake-all and brown foot rot, caused respectively by Gaeumannomyces graminis var. tritici and Fusarium culmorum, are two important components of the foot and root fungal disease complex of winter cereals world-wide. These fungi persist in soil and in crop debris in the same layer of agricultural soil as Collembola, a well represented taxon of soil animals. Previous in vitro tests showed that these fungi grown on agarised medium were readily consumed by springtails. In a simplified experimental system with wheat plants and the pathogenic fungi grown on millet and wheat kernels, the severity of disease was significantly reduced by collembolan feeding activity
Effects of Collembola on some soil-borne cereal pathogenic fungi.
No full textThe interactions between some species of Collembola and four of the most important soil-borne pathogenic fungi of the foot and root of cereals are studied in the laboratory
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
Do collembola affect the competitive relationships among soil-borne plant pathogenic fungi?
No full textThe feeding preference of the collembolan Protaphorura armata in the presence of Fusarium culmorum and Gaeumannomyces graminis var. tritici, two soil-borne fungi pathogenic for winter cereals, was studied in a simplified experimental system including wheat seedlings. Analysis of gut content of all animals from microcosms containing inoculum of both fungi showed that F. culmorum was clearly preferred but that G. graminis var. tritici was also fed. At microscopic examination the majority of F. culmorum conidia present in the gut lacked cytoplasmic content, and only few conidial cells were intact. The feeding preference of P. armata favoured G. graminis var. tritici over F. culmorum in the competition for infection sites on wheat plants; in fact, the former resulted the prevalent cause of plant disease. The viability of fungal propagules after passage through the gut of P. armata was also studied. No colonies of G. graminis var. tritici and only a few colonies of F. culmorum developed from faecal pellets set on agar medium. Fungal propagules dispersed by springtails were not sufficient to induce disease, as demonstrated by introducing animals, previously fed on fungal cultures separately, into microcosms containing a sterile substrate where wheat kernels were seeded. & 2004 Elsevier GmbH. All rights reserved
I Collemboli nell’interazione pianta-fungo patogeno.
No full textIn microcosmi allestiti in tubi di vetro contenenti un substrato sterile e posti in condizioni controllate di luce, temperatura e umidità, è stata studiata l’interazione fra Collemboli funghi patogeni (Gaeumannomyces graminis var. tritici, Fusarium culmorum)e piante di frumento duro. I dati ottenuti indicano che gli animali hanno svolto un attivo ruolo di bioprotezione determinando una significativa riduzione della malattia causata da entrambi i patogeni, principali responsabili del marciume del sistema radicale e della parte basale del culmo dei cereali vernini in Italia
Determinazione delle furocumarine contenute nelle foglie di ficus carica mediante l’impiego di HPLC
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