107 research outputs found

    Increasing genetic variability in black oats using gamma irradiation

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    The black oat (Avena strigosa Schreb) is commonly used for forage, soil cover, and green manure. Despite its importance, little improvement has been made to this species, leading to high levels of genotypic disuniformity within commercial cultivars. The objective of this study was to evaluate the efficiency of different doses of gamma rays [ ^60 Co] applied to black oat seeds on the increase of genetic variability of agronomic traits. We applied doses of 0, 10, 50, 100, and 200 Gy to the genotype ALPHA 94087 through exposure to [ ^60 Co]. Two experiments were conducted in the winter of 2008. The first aimed to test forage trait measurements such as plant height, dry matter yield, number of surviving tillers, and seedling stand. The second test assessed seed traits, such as yield and dormancy levels. Gamma irradiation seems not to increase seed yield in black oats, but it was effective in generating variability for the other traits. Tiller number and plant height are important selection traits to increase dry matter yield. Selection in advanced generations of mutant populations can increase the probability of identifying superior genotypes

    Pine seeds treatment with Trichoderma for Fusarium control.

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    This study analyzes the in vitro antagonistic activity of Trichoderma sp. isolates against Fusarium subglutinans and evaluates the effect of the pine seeds treatment with Trichoderma sp. on the incidence of root rot. Twelve Trichoderma sp. isolates and two F. subglutinans isolates were included in the study. Trichoderma sp. inhibited F. subglutinans mycelial growth through direct contact with hyphae and the production of volatile antifungal compounds. Pine seeds treatment with the antagonist Trichoderma sp. reduced the incidence of root rot, increased the emergence and initial growth in the height of seedlings, and improved seedling health

    Temporal dynamics and management of downy mildew on the table grape "BRS Vitória" in northern Paraná.

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    Downy mildew caused by Plasmopara viticola is a major disease of grapes in Paraná State, Brazil and other wine-producing regions. The seedless table grape "BRS Vitória" stands out for its tolerance to this disease and is a viable alternative to reduce fungicide applications. The objectives of this study were to analyze the influence of weather-related factors, such as temperature and rainfall on disease progress and to evaluate the efficacy of fungicide spray programs for controlling downy mildew of grapes during the summer-fall and winter-spring crop seasons in northern Paraná, Brazil. Field trials were conducted in Marialva, Paraná, during the winter-spring crop seasons (August to December) in 2013 and 2014 and the summer-fall crop seasons (January to May) in 2014 and 2015. The experimental design used was completely randomized with repeated measurements over the phenological periods, with five treatments and 10 replicates. The following treatments were compared: (1) conventional, in which fungicides were applied according to conventional standards; (2) preventive fungicide sprays every seven days; (3) preventive fungicide sprays every 14 days; (4) fungicide sprays after observing the first downy mildew symptoms; and (5) no fungicide sprays. In the conventional fungicide program, sprays were performed two or three times per week. Treatments 2 and 3 received sprayings between the start of branch budding and fruit ripening. In treatment 4, sprays started from the first occurrence of oil spot symptoms, and then, the applications were spaced every seven days until fruit ripening. The severity of disease was evaluated weekly. The disease was severe only in the 2014 and 2015 summer-fall crop seasons, reaching a maximum severity of 17.3% and 21.3% of the leaf area, respectively. The highest disease severity in the summer-fall crop seasons was associated with higher frequencies of rainy days and higher temperatures. Disease severity in conventional treatments did not differ from severity in treatments with sprayings made every seven and 14 days during the summer-fall crops in both years. Severity index on bunches were not observed for the evaluated trials. The seedless grape ?BRS Vitória? is less dependent on the use of fungicides to control downy mildew in northern Paraná. Key words: Control. Epidemiology. Plasmopara viticola. Vitis vinifera
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