Sensibilidade de Lecanicillium lecanii, agente de biocontrole de Hemileia vastatrix, à radiação ultravioleta-B
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Data
2012-08-10
Autores
Galvão, José Abrahão Haddad [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A ferrugem é a principal doença do cafeeiro e o seu agente causal, Hemileia vastatrix, é parasitado de forma natural por Lecanicillium lecanii, indicando potencial desse fungo para controle biológico. Um dos fatores que comprometem a eficiência de bioagentes é a radiação ultravioleta-B (UV-B). A incidência dessa radiação na superfície da Terra aumentou com a diminuição da camada de ozônio estratosférico, podendo afetar os processos naturais de controle de doenças de plantas e o uso de bioagentes. O objetivo desse estudo foi avaliar o efeito da radiação UV-B sobre L. lecanii. Dessa forma, foram realizados experimentos para selecionar os isolados mais tolerantes à radiação UV-B; avaliar a sensibilidade do bioagente à radiação UV-B em diversos estádios da germinação de conídios; estabelecer a curva de sobrevivência dos isolados expostos à radiação; avaliar a interação da radiação UV-B com temperaturas e concentrações de CO2 do ar; e avaliar o efeito da radiação UV-B no estabelecimento de Lecanicillium em pústulas de ferrugem. Os experimentos foram realizados em câmara de radiação, com irradiância média de 1.700 mW m-2 no interior, sendo os conídios expostos à radiação em placas de Petri contendo BDA e em discos de folhas de cafeeiro contidos em bandejas plásticas. Os estudos evidenciaram a efetividade biológica da radiação UV-B sobre os conídios de Lecanicillium, tendo como respostas a inativação dos propágulos, o atraso no processo de germinação de conídios e o incremento ou a diminuição do desenvolvimento do bioagente. Diferentes níveis de sensibilidade da germinação de conídios, entre os isolados de Lecanicillium testados, foram observados quando expostos a radiação UV-B. Os isolados mais tolerantes...
Coffee leaf rust is the most important disease of the coffee crop, and its causing agent, Hemileia vastatrix, has the Lecanicillium lecanii as its natural parasite, which indicates the potential of this fungus as a biocontrol agent. One of the factors that endanger the efficiency of the bioagents is the ultraviolet-B radiation (UV-B). The incidence of this radiation on the surface of Earth has increased with the reduction of the stratospheric ozone layer, which can affect the natural process of control of plant diseases and the use of bioagents. The aim of this study was to evaluate the effect of UV-B radiation on L. lecanii. Thus, bioassays were held in order to select the isolates which are more tolerant to UV-B radiation; evaluate the sensibility of the bioagent to the UV-B radiation in several stages of the conidia germination; establish the survival curve of the isolate which exposed to the radiation; evaluate the interaction of the UV-B radiation with different temperature and concentrations of CO2 in the air; and evaluate the effect of the UV-B radiation in the establishment of Lecanicillium in lesions of coffee leaf rust. The bioassays were held in a chamber with average irradiation of 1,700 mW m-2, and the conidia were exposed to the radiation in Petri dish with BDA and on coffee leaves discs kept in plastic trays. The UV-B radiation was effective on Lecanicillium conidia germination, and the response was the reduction and the delay in germination of conidia, resulting in increment or reduction of the development of the bioagent. Different levels of sensibility were found in the conidia germination, among the isolates of Lecanicillium studies, which... (Complete abstract click electronic access below)
Coffee leaf rust is the most important disease of the coffee crop, and its causing agent, Hemileia vastatrix, has the Lecanicillium lecanii as its natural parasite, which indicates the potential of this fungus as a biocontrol agent. One of the factors that endanger the efficiency of the bioagents is the ultraviolet-B radiation (UV-B). The incidence of this radiation on the surface of Earth has increased with the reduction of the stratospheric ozone layer, which can affect the natural process of control of plant diseases and the use of bioagents. The aim of this study was to evaluate the effect of UV-B radiation on L. lecanii. Thus, bioassays were held in order to select the isolates which are more tolerant to UV-B radiation; evaluate the sensibility of the bioagent to the UV-B radiation in several stages of the conidia germination; establish the survival curve of the isolate which exposed to the radiation; evaluate the interaction of the UV-B radiation with different temperature and concentrations of CO2 in the air; and evaluate the effect of the UV-B radiation in the establishment of Lecanicillium in lesions of coffee leaf rust. The bioassays were held in a chamber with average irradiation of 1,700 mW m-2, and the conidia were exposed to the radiation in Petri dish with BDA and on coffee leaves discs kept in plastic trays. The UV-B radiation was effective on Lecanicillium conidia germination, and the response was the reduction and the delay in germination of conidia, resulting in increment or reduction of the development of the bioagent. Different levels of sensibility were found in the conidia germination, among the isolates of Lecanicillium studies, which... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Café - Doenças e pragas, Radiação ultravioleta, Hemileia vastatrix - Controle, Mudanças climaticas, Coffee - Diseases and pests
Como citar
GALVÃO, José Abrahão Haddad. Sensibilidade de Lecanicillium lecanii, agente de biocontrole de Hemileia vastatrix, à radiação ultravioleta-B. 2012. ix, 58 f. Dissertação (mestrado) - Universidade Estadual Paulista Faculdade de Ciências Agronômicas de Botucatu, 2012.