6 research outputs found
Produção de aflatoxinas e ácido ciclopiazônico por cepas de Aspergillus flavus isoladas de amendoim
Effects of Temperature on the Simultaneous Production of Zearalenone and Deoxynivalenol by Fusarium Graminearum on Maize
Fusarium graminearum (Schwabe), a fungus commonly encountered on
maize ( Zea mays L) in Zambia, was analyzed for toxin production
under temperature conditions prevalent during periods of high
infestations. Ground maize samples were adjusted to a moisture content
of 40% and inoculated with an isolate of F. graminearum. The samples
were incubated at 26\ub0C or 16\ub0C for 10 weeks. Samples were
analyzed for the toxins, zearalenone, deoxynivalenol, and nivalenol
every two weeks. Nivalenol was not detected in any of the samples.
Approximately five times more zearalenone than deoxynivalenol was
produced at all temperatures tested. More zearalenone was produced at
16\ub0C (5-1300mg kg-1) than at 26\ub0C (5-750mg kg-1). When the
fungus was grown at 16\ub0C for five weeks and transferred to
26\ub0C, production of zearalenone was stimulated. Although more
deoxynivalenol was produced by the fungus at 26\ub0C (1-62mg kg-1)
than at 16\ub0C (1-50 mg kg-1), most deoxynivalenol was produced by
the fungus at 26\ub0C (1-62 mg kg-1) than at 16\ub0C (1-50mg kg-1),
most deoxynivalenol was produced by the fungus grown at 16\ub0C for
five weeks and then transferred to 26\ub0C for the next five weeks
(1-137 mg kg-1). Growth of the fungus at 26\ub0C for 5 weeks before
transfer to 16oC did not result in any significant rise in either
zearalenone or deoxynivalenol production
Effects of Temperature on the Simultaneous Production of Zearalenone and Deoxynivalenol by Fusarium Graminearum on Maize
Fusarium graminearum (Schwabe), a fungus commonly encountered on
maize ( Zea mays L) in Zambia, was analyzed for toxin production
under temperature conditions prevalent during periods of high
infestations. Ground maize samples were adjusted to a moisture content
of 40% and inoculated with an isolate of F. graminearum. The samples
were incubated at 26°C or 16°C for 10 weeks. Samples were
analyzed for the toxins, zearalenone, deoxynivalenol, and nivalenol
every two weeks. Nivalenol was not detected in any of the samples.
Approximately five times more zearalenone than deoxynivalenol was
produced at all temperatures tested. More zearalenone was produced at
16°C (5-1300mg kg-1) than at 26°C (5-750mg kg-1). When the
fungus was grown at 16°C for five weeks and transferred to
26°C, production of zearalenone was stimulated. Although more
deoxynivalenol was produced by the fungus at 26°C (1-62mg kg-1)
than at 16°C (1-50 mg kg-1), most deoxynivalenol was produced by
the fungus at 26°C (1-62 mg kg-1) than at 16°C (1-50mg kg-1),
most deoxynivalenol was produced by the fungus grown at 16°C for
five weeks and then transferred to 26°C for the next five weeks
(1-137 mg kg-1). Growth of the fungus at 26°C for 5 weeks before
transfer to 16oC did not result in any significant rise in either
zearalenone or deoxynivalenol production
Role of Pigments and Tannins in the Reaction of Tan and Red Near-Isogenic Sorghum Lines to Leaf Diseases
Sorghum ( Sorghum bicolor L. Moench) plant pigments have been
associated with resistance to leaf diseases and grain deterioration.
Four near-isogenic pairs of tan and non-tan (red) sorghum lines were
assayed for their phenolic content and evaluated for their reaction to
leaf diseases along with six other sorghum lines. Leaves, stems,
sheaths, glumes and seeds of mature plants were assayed for tannins,
pigments, and precursors of these pigments. No tannins were detected in
the various plant tissues although other genotypes can have high levels
of these compounds in seed coats. The red plants (especially the glumes
and sheath) were found to accumulate 3-deoxyanthocyanidins, the major
pigments in sorghum, but these were absent in the tan plants. The
glumes and sheath of tan plants accumulated apigenin. Near-isogenic
pairs were tested for differential reactions to anthracnose (
Colletotrichum graminicola Ces.) at Tifton, Georgia and to rust (
Puccinia purpurea Cooke) at Isabella, Puerto Rico during the 1991
growing season. Tan and red isogenic pairs, which differ significantly
in phenolic composition, did not show significant differences in their
disease reaction. The six other sorghum lines which showed marked
differences in their reaction to leaf diseases also showed differences
in their phenolic composition. However, for the phenols that were
analyzed, there was no correlation with resistance or susceptibility.
It is proposed that tannins, pigments, and pigment precursors are not
responsible for disease resistance in these genotypes
Control Of Tribolium Confusum J. Du Val By Diatomaceous Earth (Protect-Itâ„¢) On Stored Groundnut ( Arachis Hypogaea ) And Aspergillus Flavus Link Spore Dispersal
Environmental and human health problems associated with the use of
synthetic pesticides have prompted the demand for non-polluting,
biologically specific insecticides. The current study assessed the
losses caused by Tribolium confusum and its control by diatomaceous
earth and the effect on Aspergillus flavus spore dispersal during
storage of groundnuts. When losses due to Tribolium confusum were
assessed over a period of 60 days, it was found that an increase in
insect population in stored groundnuts resulted in increased weight
loss of stored groundnuts. The true weight loss due to insect feeding
was 0.60 g per 400 g of stored groundnuts. When diatomaceous earth (DE)
was applied to groundnuts followed by the introduction of insects in a
compartment (A), increased mortality of insects with increased
diatomaceous earth concentration was observed. For a concentration
range of 0-2.5 g DE/kg groundnut, 2.5 g/kg treatment was the most
effective (only 5 surviving T. confusum adults out of 50 were recovered
in samples treated with 2.5 g/kg compared to 38 adults in the control
samples). Larval emergence from groundnuts treated with DE also
declined with increased diatomaceous earth concentration. When
groundnuts were inoculated with A. flavus spores, followed by DE
application and T. confusum introduction into compartment A, the
transfer of spores between inoculated groundnut samples in compartment
A and uninoculated samples in compartment B was reduced. The mean A.
flavus spore concentration recovered from initially sterile compartment
B was1.08x103; while it was 45 in the control and in samples treated
with 2.5 g/kg dosage respectively. There was a significant difference
in the mean numbers of spores recovered from groundnuts in different
compartments (A, B) (H = 13.99, df = 4 and P = 0.007). Thus, from this
study, losses due to T. confusum on groundnuts and fungal spore
transfer in storage by this insect can be minimized by the application
of diatomaceous earth (Protect-ITâ„¢) to stored groundnuts